objective qus wd answer

7/29/2019 Objective Qus Wd Answer

1/98

INDIAN RUBBER INSTITUTE

Karnataka Branch

PAPER- I POLYMER SCIENCE

OBJECTIVE QUESTIONS & ANSWERS

YEAR 1996

(a) Select appropriate answers:i) Fischer Tropsch process refers to

a) Stereo regular polymerization b) Conversion of methanol to formaldehydec) Reaction between carbon monoxide and hydrogen

d) Dehydrogenation of ehtylbenzene to styrene

ii) Heptane is assigned an Octane number of

1. 100 b) 0 c) 42 d) none of these

iii) If the repeat units are joined in a 3-dimensional array, the resulting polymer will bea) linear polymer

b) branched polymer

c) cross linked polymerd) none of the above

iv) The ratio of Mw and Mn for most of the synthetic polymer is

a) more than 1 b) less than 1

c) equal to 1d) none of the above

v) In polycondensation to prepare polyamides, the reaction takes place between

a) carboxyl and hydroxyl group

b) amino and hydroxyl group

c) amino and carboxyl group d) none of the above

vi) The relation between degree of polymerization, molecular weight of a polymer and molecularweight of monomer is given by Mn = DPn x m

vii) The chain carrier in case of anionic polymerization are

a) carbonium ionsb) hydroxyl ions

c) carbanions d) none of the above


2/98

viii) The Florys principal of equal reactivity states that---------------------

ix) In suspension polymerization technique the initiator used area) water soluble

b) monomer soluble

c) insoluble in either water or monomerd) soluble in both water and monomer

x) Critical micelle concentration refers toa) concentration of surfactant at which there exists complete molecular dispersion

b) a state of equilibrium between dissolved surfactant molecule and micelles

c) concentration beyond which only micelle formation is possible d) none of the above

10x1=10

1. (b) State whether the following statements are True or False:

i) In chain polymerization the normal mode of addition of the incoming monomer to the

growing chain is always head to tail (T)

ii) Atmospheric oxygen is a good inhibitor for polymerization (T)

iii) Polymers produced by cationic polymerization technique is called living polymer (F)

iv) Co-ordination polymerization is also known as insertion polymerization (T)

v) Emulsion polymerization technique can be used to prepare high molecular weight

polymers (T)

vi) Diene rubbers are susceptible to oxidation (T)

vii) The ration Mn /Mw = 1+P (F)

viii) Glass transition temperature (Tg) of a polymer does not depend on flexibility of the chain

segments (T)

ix) Copolymer of isobutylene and acrylonitrile is called nitrile rubber (F)

x) Ultracentrifuge method is used to determine weight average molecular weight (F)

10x1=10


3/98

PAPER - I POLYMER SCIENCE

YEAR 1997

1. a) Multiple choice questions. Select the right answer

i) Polyethylene, polypropylene and nylon are known as

a) Glassy polymers

b) Amorphous polymers

c) Crystalline polymers

d) None of these

ii) Fibers have molar cohesion per 5 A chain length in the range

a) less than 2 Kcal/gm. mole

b) 4-10 Kcal/gm mole

c) 2-5 Kcal/gm mole

d) none of these

iii) Azobisisobutyronitrile on thermal decomposition produces free radicals along with

a) CO2

b) NO

c) N2

d) None of these

iv) Polymer produced by anionic polymerization is called

a) Dead polymer

b) Living polymer

c) Ladder polymer

d) None of these


4/98

v) Mw/Mn value for synthetic polymers obtained by co-ordination polymerization technique is

a) between 2-3

b) greater than 10

c) between 8-10

d) none of these

vi) Glass transition temperature of polyvinyl chloride is

a) 1000C b) 800C c) +800C d) none of these

vii) Expandable polystyrene beads are produced by

a) bulk polymerization technique

b) solution polymerization technique

c) suspension polymerization technique

d) none of these

viii) Atactic polymers area) high melting and highly soluble

b) low melting and easily soluble c) high melting and less soluble

d) none of these

ix) Weight-average molecular weight of a polymer can be determined by

a) Osmometry

b) Viscometry

c) Light scattering d) None of these

x) Most important criteria of a polymer to form strong fiber is

a) partially crystalline

b) amorphousc) highly crystalline d) none of these

1x10=10


5/98

b) State whether the following statements are true or false

i) Ionic polymerizations are generally carried out in presence of water (F)

ii) Cationic polymerization is normally done at high temperature (T)

iii) Heat is essential to initiate free radical polymerization (T)

iv) Inhibitors are added for storage of monomers (T)

v) Copolymers are physical mixture of two polymers (F)

vi) Elastomer have Tg above room temperature (F)

vii) Nylons do not have many common organic solvents (T)

viii) Polyethylene can be dissolved only at higher temperature (T)

ix) All crystalline polymers are stereo regular (T)

x) Step growth polymers show very high molecular weight. (F)

1x10=10


6/98


YEAR 1998

1. a) Give one example each of the following and write down chemical structure of the repeat

unit in each case:

i) An amorphous polymer which is glassy at room temperature, but rubbery at

1450C - PC

ii) A crystalline polymer whose Tg is below room temperature PE (LDPE)

iii) An inorganic polymer which is useful as a rubber over a wide temperature

range - PDMS

iv) A rubber which is a terpolymer- EPDM

v) A rubber which is a block copolymer

b) State whether the following statements are true or false:

i) Ring-opening polymerization is a free radical reaction (F)

ii) The effect of high temperature is to increase the tensile property of rubber (F)

iii) Emulsion polymerization is nothing but a solution polymerization (F)

iv) Polymers are polydispersity materials (T)

v) Bezoyl peroxide is normally used in ionic reactions (F)

c) Select the correct answer

i) Block polymers are mostly produced through

a) ionic polymerization

b) condensation polymerization

c) free radical polymerization


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ii) A cross linked polymer is

a) always flexible

b) always rigid

c) may be made flexible or rigid

iii) A fiber forming polymer has

a) very regular repeating units

b) weak intermolecular forces

c) amorphous structure

iv) In step polymerization, each polymer formed can react further with

a) monomers only

b) polymers only

c) both monomers and polymers present

v) Tacticity in polymers is due to the presence of

a) double bond in polymer backbone

b) heterochain polymer backbone

c) asymmetric carbon atom


8/98

PAPER- I- POLYMER SCIENCE

YEAR 1999

1. A. State whether the following statements are correct or wrong:

i) High-pressure polymerization of ethylene gives high density polyethylene (X)

ii) Free radical polymerization of propylene gives good yield of structural polypropylene

(X)

iii) Natural rubber is 1,4 Cis Polybutadiene ()

iv) Polybutadiene rubber has high resilience ()

v) Polymerization is accompanied by a decrease in the total number of molecules (X)

vi) Polymers prepared from monomers with bifunctional groups always are branched in

structure (X)

vii) Monomers with polar groups always give rise to polar polymers ()

viii) Isotactic structures facilitate crystallinity in polymers ()

ix) A monomer can be converted to polymer through reactions that create new bonds ()

x) Trans configuration in polymers results in high elongation and low modulus (X)

xi) Atactic polymers usually have higher melting point than syndiotactic polymers (X)

xii) Branched polymers are held by primary bonds in one direction and through secondary

bonds in other two directions (X)

xiii) Bond energy of S-S bond is higher than that of C-C bond (X)

xiv) Butyl rubber is produced by ionic polymerization ()

xv) Block copolymers are type of branched polymers (X)

B. Select the correct term from the bracket

i) (Cellulose, cellulose acetate, Polybutadiene) is a natural polymer

ii) Rubbers are usually useful only after (cooling, heating, cross linking)

iii) Degradation of addition polymers commonly takes place by a (step, chain) mechanism

iv) Basic requirements of a fiber forming polymer is (low Tm, low Tg, high molecular

symmetry/molar cohesion)

v) Dissolution of polymer (precedes, follows) swelling

(15x1)+(5x1)=20


9/98

PAPER1 POLYMER SCIENCE

YEAR 20001. (a) Multiple choice questions. Select the right answer(s)

i) Living polymers formed by

A. Cationic polymerization

B. Anionic polymerization C. Polycondensation

D. None of these

ii) Number average molecular weight of a polymer can be determined byA. Viscometry

B. End group analysis C. Osmometry D. Light scattering

iii) For a Hookean material stress is directly proportional to

A. Shear rate

B. Strain C. ViscosityD. Strain rate

iv) The chain carrier in case of cationic polymerization are

A. Carbanions

B. Hydroxyl ions

C. Carbonium ions D. None of these

v) Copolymer of isobutylene and acrylonitrile is calledA. Nitrile rubber

B. Butyl rubber

C. Acrylic rubberD. None of these vi) Glass transition temperature of polystyrene is

A. 500C

B. -1000C

C. 1000C D. none of these

vii) Zeigler-Natta Catalysts are used to produceA. Condensation polymer

B. Block copolymers

C. Stereo regular polymers D. None of these


10/98

viii) For all the synthetic polymers MW/Mn value is

A. 1C. =1

D. =

ix) Glass transition temperature can be measured usingA. glass thermometerB. capillary rheometer

C. DSC D. Osmometer

x) Benzoyl peroxide is a well known

A. InitiatorB. chain transfer agent

C. inhibitorD. short stop

(10x1=10)

(b) Give one example with structure of each of the following

i) A monomer which can be polymerized by radical, coordination, cationic and/or anionic

method

ii) An inorganic polymer which is useful as a rubber over a wide range of temperature Silicone rubber

iii) A linear polymer which does not contain any hydrogen atom and useful for insulating

purpose CF2-CF2iv) A rubber which is resistance to both hydrocarbon oil and flame - PC

v) A polar rubber which is a copolymer and useful for light footwear

(5x1-5)

(c) State whether the following statements are correct or wrong

i) Most of the elastomers after curing become thermoplastics (X)

ii) Gutta percha is same as cis-polyisoprene (X)

iii) If there are 1000 repeat units in a polymer molecule, DP of the polymer is 1000 ()CH

iv) The structure of isoprene is CH2=CH-C=CH2 (X)

v) Solution polyemerization technique is recommended where the polymer is used in its

solution form ()(5x1=5)


11/98


YEAR 20011. (a) Give one example with structure of repeat unit for each of the following

i) A rubber which is excellent resistant to oxidation, ozone attack and also good heat ageing

resistance EPM/EPDM

ii) A rubber which is useful for light footwear

iii) A copolymer which is non oil resistant rubber - SBR

iv) A homopolymer which is non oil resistant rubber - PBD

v) A naturally occurring polymer which is not a rubber - Cellulose

vi) A condensation polymer which is useful in making tyres - PU

(6x2=12)

(b) State whether the following statements are correct or wrong

i) All crystalline polymers can be converted into a useful fibers ()

ii) Natural rubber is glassy at 00C (X)

iii) Poly vinyl chloride can be made flexible even at room temperature ()

iv) All commercially useful rubbers are organic in nature ()

v) A thermoplastic material can be made rubbery through chemical modification ()

vi) Stress induced crystallization is not found in natural rubber (X)vii) Ionic polymerization are generally carried out in presence of water (X)

viii) Diene rubbers are susceptible to oxidation ()

(1x8=8)


12/98

PAPER I POLYMER SCIENCE

YEAR 2002

1. (a) Give one example with structure of repeat unit for each of the following:

i) A linear polymer which does not contain any hydrogen atom and useful for insulating

purpose CF2-CF2

ii) A terpolymer, which is useful for making automotive window seal - EPDM

iii) A rubber having good oxidation resistance and highly impermeable to gases used mainly

in tyre inner tubes - Butyl

iv) A polar homopolymer, which is useful for making adhesives

PMMA/acrylic/PVAC/PAN/PVA

v) An inorganic polymer, which is useful as a rubber over a wide range of temperature -Silicone

vi) A polymer, which can be prepared by radical, coordination, cationic and/or anionic

method

vii) A rigid homopolymer, which can be made flexible even at room temperature and useful

in cable industry - PVC

viii) A highly crystalline polymer used very much in tyre industry - Nylon

ix) A homopolymer which is capable of crystallizing when stretched and does not exhibit as

high a gum tensile strength

x) A copolymer, which is used as a oil and solvent resistant rubber and does not crystallize

on stretching - NBR

(2x10=20)


13/98


YEAR 2003

1. a) Multiple choice questions, select the right answer(s)

i) Polypropylene is known asa) Glassy polymer

b) Amorphous polymer

c) Crystalline polymerd) Ionomer

ii) Glass transition temperature of polystyrene is

a) 1000Cb) 100C

c) 1000C d) 1200C

iii) Within polymeric materials, localized mobility of the segments is called

a) Segmental motionb) Molecular motion

c) Brownian movement d) Micro Brownian movement

iv) Weight average molecular weight of a polymer can be determined by

a) Viscometry

b) End group analysisc) Osmometry

d) Light scattering v) Glass transition temperature of a polymer is determined by

a) Infrared spectrophotometry

b) Differential scanning calorimetry c) Mass spectrometry

d) Scanning Electron Microscopyvi) Most important criteria of a polymer to form strong fiber is

a) Partially crystalline

b) Amorphous

c) Highly crystalline d) Should be branched

vii) Polymer produced by Anionic polymerization is called

a) Dead polymer

b) Living polymerc) Ladder polymerd) None of these

viii) A crystalline polymer whose Tg is below 1000Ca) Polypropylene

b) Polystyrene

c) Polyethylene d) Polychloroprene


14/98

ix) Atactic polymers are

a) High melting and highly soluble

b) Low melting and easily soluble c) High melting and less soluble

d) None of thesex) Copolymer of Styrene and Butadiene, which is used in tire is

a) SBS

b) SBRc) SEBSd) XSBR

1x10=10

b) State whether the following statement is TRUE or FALSEa) Plastics exhibit elongation at break ranging usually 200-500% (T)

b) All crystalline polymers are stereo regular (T)

c) Elastomers have Tg above room temperature (F)

d) Natural rubber is 1,4 cis polyisoprene (T)e) Vinyl polymerization are highly exothermic (T)

1x5=5)

c)i) An example for inorganic polymer is Silicone

ii) A rubber, which is, manufactured both by radical and anionic polymerization

is Styreneiii) Example for anionic polymerization initiator is Alkyl Li, Alkoxides

iv) Example for a polymer with a low Tg but not a rubber is PE

v) Molecular weight control is achieved using chain transfer agents

(1x5=5)


15/98


YEAR -2004

1. a) Choose the correct answer from the given alternatives.

i) The weight average molecular (MW) weight is determined by

a) End group analysisb) Osmometry

c) Viscometry

d) Light scattering ii) The glass transition tempreture (Tg) of low density polyethylene is

a) -1200 C b) +1200C c) 00C d) does not have any (Tg)iii) Name a polymer which can be prepared via anionic, free radical and co-ordination

polymerizationa) Poly bytadiene

b) Polypropylene

c) Polychloroprene

d) Polyethylene terephthalateiv) For a Hooken region stress is directly proportional to

a) Viscosity b) strain rate c) strain d) Modulusv) Name rubber(s) which is prepared by condensation polymerization

a) Butyl rubber

b) Silicon rubberc) Acrylic rubber (ACM)

d) Fluoroelastomervi) Indicate the firore that contains carbon Nitrogen linkage.

a) Jute b) Cotton c) Silk d) Polyestervii) cellulose is a polymer

a) Natural b) Semi-synthetic c) Synthetic d) Artificialviii) Aramids are high performance

a) Polyalkenes b) Polyehters c) Polyimides d) Polyamides ix) SBR is a _______ copolymer of styrene and lutadine

a) Random b) Alternate c) Block d) Star shapedx) Vulcanization is the processing step for rubbers

a) Initial b) Intermediate c) Final d) Penultimate(1x10=10)

b) State whether the following statement are correct or wrong, correct the statement)

i) Dicumyl peroxide is a catisnic initiator False : Diamyl peroxide is radical initiator()

ii) Among all the polymerization techniques emulsion polymerization is the most

useful method. ()iii) GPC can be used to analyze all the molecular weights of polymer. ()iv) Carthers Equation DP= 1/1 p CDP degree of polymerization, P = Extent of

reaction) is associated with anionic polymerization


16/98

V) The Mark Howwinx equation (n) = Km ~ (K and ~ are constant) is used to obtain

M2 (2 average molecular weight ) of a polymer.

vi) Cellulose nitrate is a good plastic. ()vii) Back bone c-o-c linkage between repeat units renders a polymer more stiff. (X)

viii) Incorporation of aromatic ring structure in repeat units renders a polymer more

rigid and stiff. ()ix) Aromatic ring read rigidness and stiffness Natural rubber ceases to behave asrubber below 800 c

x) Polystyrene assumes rubberly character at temprature > 1000 c ()

(1x10=10)


17/98


YEAR 20051. Choose the correct answer from the given alternatives:

i. Hardening of plastics often involves cross-linking. This process is called

a) Curing b) Extrusion c) Compounding d) Plasticizationii. Gutta percha is

a) Cis 1,4-polyisoprene b) Trans1,4-polyisoprene c) Vulcanised polyisoprene d) Ebonite

iii. The concentration of polymers in solution are often expressed as

a) g/dl b) Molarity c) Molality d) Volume %

iv. Which of the following is the initiator for suspension polymerization

a) Potassium persulphate b) Benzoyl peroxide c) AIBN d) Lewis acids

v. Which of the following is a branched chain polymera) HDPE b) Isotactic polypropylene c) LDPE d) Starch

vi. The value of in Mark-Houwink equation () = kM in theta solvent is

a) 1.0 b) 0 c) 0.5 d) 0.8

vii. Which of the following techniques yields a number average molecular weight

a) Viscometry b) Osmometry c) Light scattering d) Ultracentrifugation

viii. Shellac is a

a) Natural resin b) Synthetic resin

c) Regenerated resin

d) Rubber

ix. Celluloid is

a) Un-plasticised cellulose nitrate

b) Plasticised cellulose acetate

c) Plasticised ethyl cellulosed) Plasticised cellulose nitrate

x. When the glass transition temperature (Tg) of a polymer is below the ambient temperature,

it is a

a) Plastic b) Fiber c) Rubber d) Dendrimer


18/98

xi. In the typical stress-strain curve, the stiffness is measured by calculating the

a) Total area under the curve till the point of rupture

b) Area within the Hookean region

c) Slope of straight portion within the Hookean region

d) Energy at break

xii. Polyethylene terephthalate is a

a) Polyamide

b) Polyimide

c) Polyether

d) Polyester

xiii. Mastication is the processing step for

a) Synthetic rubber

b) Natural rubber

c) Thermoplastic elastomer

d) Commodity plastics

xiv. EVA is

a) Homopolymer

b) Copolymer

c) Terpolymer

d) Non polymeric material

xv. Melamine-formaldehyde resin while in usable condition is

a) a thermoplastic

b) a thermosetting plastic

c) an engineering plastic

d) a pseudoplastic

(1x15=15)


19/98

(b) Write true or false and in case of false statements, correct it:

i. When more than two monomers are polymerized together, the process is called

copolymerization (T)

ii. Cross-linked polymers do not form solutions and can undergo only limited swelling

(T)

iii. Emulsion polymerization produces polymers of the highest purity (F)

iv. Atactic Polypropylene has the highest crystallinity of all the commercially available

polypropylene (F)

Ans: Isotactic cyrstalline

v. SBS (Styrene butadiene- styrene) is an example of thermoplastic elastomer (T)

(1x5=5)


20/98

YEAR 1996 RUBBER PROCESSING AND ENGINEERING

PAPER -I I

1. A) Mention only the right answeri) The upside down mixing method is efficient and effective for those compounds

a) containing a large volume of liquid plasticizers and large particle size fillers b) containing low structure, small particle size carbon black

c) containing high loading of both soft mineral filler and oil together with an elastomerof high Mooney viscosity

d) none of the above

ii) While blending natural rubber with styrene butadiene rubber on a mixing milla) first natural rubber is to be masticated to a lower viscosity to form a band and then

SBR is added b) natural rubber and SBR to be mixed simultaneously on the mill

c) SBR to be banded on the mill then NR addedd) None of the above

iii) A major disadvantage of mill mixing is

a) it is time consuming and depends upon the skill of the operatorb) it is difficult to prevent rapid rise of stock temperaturec) it provides no shearing action


iv) A common cause of poor dispersion and scorchiness in a mixer isa) sp gr. of the stock is too low

b) batch size too high c) dump temperature too low

d) tensile strength of the stock too highv) For better dispersion of filler on a mixing mill

a) Bank size should be very largeb) Bank size should be low

c) Bank size should be such that the material rolls constantly at the nip d) None of the above

vi) Scorchiness of a rubber compound depends on

a) heat history of the compound on the process equipment b) higher mastication time

c) too much of plasticizer


vii) A roller die consists ofa) a two roll calendar in combination with extruder feeding b) a 3 roll vertical calendar in combination with a two roll calendar feeding

c) a 2 roll calendar in combination with open mill feedingd) a 2 roll calendar in combination with internal mixer feeding

viii) The roll deflection in a calendar is mainly caused by

a) too much tension on the fabric being processedb) the excessive amount of feed material on the calendar


21/98

c) the force required in the nip to flatten the feed material d) the high speed of taking away the calendared material

ix) Both side topping is usually done by a calendar withb) 3-rolls

c) 2-rolls

d) 4-rolls e) none of the abovex) Frictioning on a calendar involves

a) coating a fabric with rubber stock at least 1/8 inch thick

b) depositing and coat of liquid cement on a fabric for better adhesionc) forcing the rubber into the interstices between fibers of a fabric through wiping with

roll pressure between the middle and bottom rolls d) producing a surface design on sheet material


22/98

PAPER- II RUBBER PROCESSING AND ENGINEERING

YEAR 19971. A. Mention only the right answer/s:

i) Efficiency of Mastication is the lowest at around the temperature of

a) 500C b) 1100C c) 800C d) 2000C

ii) Dispersion of compounding ingredients can be improved by

a) Mixing at higher temperature

b) Mixing for longer period

c) Allow the compound to cool at least for a day and rework it again

d) None of the above

iii) Mixing in an internal mixer results in

a) Good quality of compound

b) Consistent quality of compound

c) Better dispersion than mixing in open mill


iv) To achieve uniformity in color, the color has to be

a) Added at the beginning of the mixing cycle

b) Added at the middle of the mixing cycle

c) Added at the end of the mixing cycle

d) Partly added at the beginning and partly added at the end of the mixing

v) To get uniform (proper) blending of two polymers in a compound

a) the major polymer should have higher viscosity

b) the major polymer should have higher viscosity

c) the minor polymer should have lower viscosity

d) both the polymers should have viscosity nearest to each othervi) To produce a thick rubber sheeting, it is preferable to use

a) a calender

b) an extruder

c) a combination of extruder and calender


23/98

d) an extruder with roller head

vii) Crows feet and Church mark are common processing problems associated with

a) the manufacture of tread compounds

b) the calendered sheets

c) the extruded profiles

d) mixing of compounds

viii) Continuous vulcanization of an extruded sponge profile can be done by

a) Rotocure

b) UHF cure

c) LCM cure

d) Fluidized bed cure

ix) Spreading operation is done

a) to achieve high thickness of coating

b) for long length coating on fabrics

c) for tyre cord coating

d) for short length fabric coatings

x) Injection moulding is preferable

a) to produce large volume of moulded articles

b) to vulcanize an extruded product

c) to produce small volume of big size rubber products


1X10=10


24/98

PAPER II- RUBBER PROCESSING AND ENGINEERING

YEAR 1998

1. Mention correct answers from the alternatives given against each question. More than one answer are

possible.

i) PVI (Cyclohexyl thiophthalimide) does not retard well when the acceleration system in the

compound is:

a) sulphenamide based

b) thiazoles based

c) thiuram based

d) both (b) & (c)ii) During winter seasons, compound surfaces on storage appear to be grey/white. This

phenomenon is called:

a) scorchb) high tack

c) crows feet

d) blooming iii) Post cure inflation of tyres is not required for the following reinforcing materials:

a) Nylon-6 b) Rayon

c) Polyester (high modulus low shrinkage)Glass fiber

iv) Prewarming of polymer before using in compounds warranted, especially in cooler season for

the following:

a) Polybutadiene rubberb) Butyl rubber

c) Natural rubberv) Screw Marks is a phenomenon associated with:

a) Calendaring operation

b) Vulcanization c) Extrusion

vi) An Under cure /Laminated compound would result if following polymers get mixed:

a) Natural rubber and chlorobutyl

b) Styrene butadiene rubber and IIR (Butyl) c) Polybutadiene and Nitrile

vii) The most important criteria in selection of plasticizers are:

a) Elastomer compatibility


25/98

b) Viscosity and specific gravity

c) Odor and taste

d) None of the aboveviii) From the point of view of ingredients, the following physical changes occur during a mixing

cycle:

a) Entering, contacting, flowing and dumpingb) Incorporation, dispersion, distribution and plasticization c) Contacting, squeezing and moving

d) None of the aboveix) Batch to batch variation in mixed compound is seldom caused by:

a) Variation in initial loading temperature b) Variation in flow and/or temperature of cooling water

c) Variation in Ram pressured) Variation in time and/or dump temperature

x) The length, to diameter ratio (L/D) of a cold feed extruder is:

a) 10:1 b) 15:1 c) 20:1 d) none of the above

xi) The amount of die swell in extrudate is dependent on:a) The Sp.Gr. of the compound

b) The T.S. and elongation of the compound

c) The shear rate of the extruder and the viscosity of the compound d) None of the above

xii) When a 3-Roll calender is used for fractioning, the surface speed of the bottom roll is

usually:

a) Equal to middle roll b) Slower than middle roll

c) Faster than middle roll


xiii) Shrinkage of cured products is not affected by:a) Curing temperature

b) Amount and type of filler

c) Nature of mould materials and polymer

d) None of the above xiv) With every 100C rise in vulcanization temperature, the vulcanization time will be reduced

by:Half

a) Doubledb) Unaffected

c) None of the above xv) Mastication is favored by the presence of:(give at least two alternatives)

a) Oxygen b) Peptizers c) Antioxidantsd) Sulphur

e) Electron withdrawing groups in the structure

f) Electron donating groups in the structure


26/98

xvi) Of the four widely used elastomers listed below, the only one with oil resistance property is:

a) SBR

b) NBRc) CR

d) EPDM

xvii) Vulcanizing agents are ingredients, which must be present in a compound to:

a) Reduce its viscosityb) Increase the speed of mixing

c) Cause chemical reaction resulting cross-linking elastomerd) None of the above

xviii) If the modulus of a compound is progressively increased, its elongation at break propertyhas a tendency to:

a) Increase

b) Decrease

c) Remain constantxix) The maximum rebound height of a vulcanized compound is achieved when the polymer

used is:

a) Polybutadiene b) Butylc) Natural rubber

d) Chloroprene

xx) In a pin extruder, the pins mounted in the barrel provide an effective way to:a) Heat the stock inside the barrel

b) Improve homogenization of the stock in the barrel c) Increase head pressure

d) None of the above20x1=20


27/98


YEAR 1999

1. Mention correct answer from the alternatives given against each question. More than one

answers are possible. (20x1=20)

i) Because of its relatively poor processability, poly butadiene rubber is used primarily in blends

with other elastomers to improve

a) resistance to abrasion, cut growth, and flex cracking b) resistance to oil and gasoline

c) resistance to sunlight and ozone

d) none of above

ii) The properties and processability of a carbon black reinforced compound is greatly affected

by

a) the specific gravity of the type of black it contains

b) the particle size and structure of the type of black it contains c) the cost of the carbon blacks used

d) none of above

iii) The maximum effect on masticating crude natural rubber for viscosity reduction is obtained

a) either at temperature, below 550C or at temperature above 1300C

b) at temperature between 90 and 1050C c) only at temperature above 1300C

d) none of above

iv) The major disadvantage of mill mixing is

a) it is not only time-consuming, but also too dependent upon the skill of the operatorb) it is difficult to prevent rapid rise of stock temperature

c) it provides no shearing actiond) none of above

v) The major advantage of a screw extruder over a ram extruder is that

a) it was invented earlier and its technology was perfect and well known

b) it is a continuous process instead of an intermittent process c) it develops no frictional heat through the shearing action of the rotary screw

d) none of above


28/98

vi) The out put rate of an extruder is not greatly affected by

a) the Mooney scorch and Mooney viscosity of the compound

b) the head pressure

c) the resilience and tensile strength of the compound d) the screw design

vii) In a two-roll mill operation the maximum pressure occurs at

a) point of bite

b) point of separation

c) nip point d) just before nip

viii) Reduction in the rate of flow of cooling water in an internal mixer will result ina) increase in the stock viscosity

b) decrease in the stock temperature

c) increase in the stock temperature

d) no change in the stock viscosity

ix) Increase in the rotor speed of an internal mixer will result in:

a) increase in the temperature of cooling waterb) decrease in stock temperaturec) increase in the stock viscosity

d) decrease in the shear rate

x) The deflection of calender rolls during processing is mainly caused by

a) too much tension on the fabric being processed

b) the excessive amount of feed material on the calenderc) the force required in the nip to flatten the feed materiald) the high speed of taking a way the calendered material

xi) Off-gauge material processed by calendaring is not likely caused bya) incorrect crowning of rolls

b) improper use of roll-bending or roll-crossing devices c) use of wrong rubber compound

d) excessive wear in roll journal bearings

xii) The cored roll cooling design for calender rolls is_____________ to the peripherally drilled

roll design

a) superior

b) inferiorc) equivalent

d) not at all related

xiii) Reversion behavior can be visualized from testing in:

a) a high pressure capillary viscometerb) universal tensile testing machine


29/98

c) Monsanto Rheometerd) None of the above

xiv) The Mooney viscometer is the most effective in predicting behavior of

a) RIM

b) Castingc) Injection moldingd) Compression molding

xv) Compared to transfer molding, compression molding has the advantage ofa) a wider tolerance for different rubber compositions

b) shorter molding cycles c) better insert-to-rubber bondingd) ability to easily hold an insert in required position in mold cavity

xvi) Optimum cure time as calculated from a rheometer represents the time required to attain

a) 50% of the maximum torqueb) 70% of the maximum torque

c) 90% of the maximum torque d) none of the above

xvii) Rapid plastimeter is used to have an idea about:

a) the flow behaviorb) tensile strengthc) green strength

d) tack of raw rubber

xviii) L/D ratio of hot feed rubber extruder is in the range of:a) 4 to 6 b) 10 to 14

c) 15 to 18

d) 19 to 22

xix) In a horizontally placed single screw extruder the pitch of the screw is the:

a) horizontal distance between two flightsb) horizontal distance between three flights

c) vertical distance between flight and barrel

d) angular distance between two flights

xx) For preheating the rubber compound to produce bulky articles the preferred method of

heating is:

a) steam heating b) electric heating

c) microwave heating d) none of the above


30/98


YEAR 2000

1. Mention the correct answer from the alternatives given against each questioni) Crows feet is a phenomenon associated with

a) calendaring operationb) spreading operationc) extrusion

d) continuous vulcanization

ii) The material of the calender roll isa) carbon steel

b) alloy steel

c) chilled cast irond) stainless steel

iii) The deflection of calender rolls during processing is mainly caused bya) too much tension on the fabric being processed

b) the excessive amount of feed materialc) the force required in the nip to flatten the feed materiald) the high speed of taking away the calendaring material

iv) Microwave heating is effective for the following

a) non-polar rubber and curing agent

b) polar rubber and curing agentc) rubber with metal inserts

d) non-polar rubber with mineral fillers

v) Long cycle time is normally associated with the following molding method

a) transferb) injection

c) compressiond) RIM

vi) The viscosity of a fluid is the ratio of shear stress to shear rate. For most rubber the value ofis

a) greater than 1

b) less than 1c) equal to 1d) none of these

vii) Calendar grain gives the rubber sheet which isa) stronger across its lengthb) stronger along its length

c) having same strength at both directionsd) stronger at the diagonal direction

viii) Generally in a hot feed extruder the L/D is

a) 10:1

b) 15:1


31/98

c) 5:1d) none of the above

ix) Crows feet marks appear due to

a) low processing temperature

b) high processing temperaturec) scorchyness of the compoundd) softness of the compound

x) Cast iron safety bushes are fixed at the roll journals of Two-roll mixing mills in order to

ensurea) safety of the operator

b) safety of the rollsc) safety of the motord) none of the above

xi) For a thick molded rubber product the curing should be done at

a) higher temperature with shorter time

b) higher temperature with longer timec) lower temperature with shorter time

d) lower temperature with longer timexii) The content in the Liquid Curing Medium (LCM) continuous vulcanization process is a

a) mixture of saltsb) mixture of salts with water

c) mixture of oils

d) mixture of salt and oilxiii)The main objective to have a pin-barrel extruder is to

a) remove the porosity in the extrudate

b) reduce the scorch problem of the rubber compound

c) improve homogenization of rubber compoundd) reduce the die swell of the extrudate

xiv) Calendar machine having roll diameter of 20 inch, normally should have the roll length of

a) 40 inch

b) 54 inchc) 64 inch

d) 74 inch

xv) PCI (Post Cure Inflation) in manufacturing of nylon reinforced tyres is generally done bycirculating

a) hot water

b) hot airc) steamd) cold water

xvi) Both side frictioning of a fabric in one-pass is possible by using

a) a 4-roll type calenderb) a inverted L-type calender

c) a Z-type calender

d) two sets of 3 roll L-type calender


32/98

xvii) Mooney viscosity of a rubber compound is generally tested ata) 800C

b) 1000C

c) 1500

Cd) 500C

xviii) In mixing of Nitrile rubber compound, sulphur is added at the initial stage for

a) increasing the scorch safetyb) improving the viscosity

c) better dispersiond) to improve oil resistance

xix) While moulding a rubber product in a hydraulic curing press bumping is required to

a) remove entrapped airb) facilitate flow of compound

c) fill the mould cavity uniformly

d) reduce the curing timexx) While mixing on a Two-roll mill, the problem of bagging is often experienced with

a) NR

b) SBR

c) BR d) A blend of NR and SBR

(1X20=20)


33/98


YEAR 2001

1. Give the correct answer from the alternatives given against each question

i) Torque is defined as a product of

a) Force and distanceb) Force and areac) Pressure and distance

d) Pressure and areaii) The blends of polypropylene and EPDM are

a) Compatible

b) Incompatiblec) Mutually solubled) None of these

iii) S-B-S copolymers are

a) TPE

b) TPc) Rubbers

d) Thermosetsiv) The term Incorporation refers to

a) Bound rubber

b) Wetting of the filler surface with rubberc) Breaking down of the filler aggregates

d) None of thesev) For a highly shear sensitive rubber the filler dispersion in an internal mixer is

a) Very good

b) Goodc) Poor

d) None of these

vi) The flash or the mould spew occurs in different types of moulds in the order ofa) Injection moulds>Compression moulds

b) Injection moulds>Transfer moulds

c) Compression moulds>Injection mouldsd) None of these

vii) In an on-line vulcanization system the Shear head is fitted to aa) Internal mixer

b) Calender

c) Extruderd) Transfer mouldviii) Salt bath vulcanizing method uses a mixture of molten potassium and sodium

a) Chlorideb) Sulfates

c) Bromides

d) Nitratesix) To measure the stock temperature inside a Banbury mixer, the device used is


34/98

a) A pyrometer

b) A mercury thermometer

c) A thermocoupled) A gas-thermometer

x) The rheo-curve of the SBR based rubber compound is ofa) Plateau type

b) Marching typec) Reversion type

d) None of thesexi) Microwave heating is most effective for curing of

a) White rubber compounds

b) Textile reinforced rubber componentsc) Black rubber compounds

d) Compounds made from non-polar rubbersxii) Mould shrinkage increases with increase in

a) Rubber content of the compoundb) Filler content of the compoundc) Moulding pressure


xiii) Calender grain effect is most pronounced when the compound isa) Highly loaded with carbon black

b) Highly loaded with mineral fillersc) Highly viscous in nature

d) Highly elastic in naturexiv) Frictioning of both sides of textiles can be easily done in

a) A 4-roll calender of I type

b) A 4-roll calender of Z typec) A 4-roll calender of L type

d) Two nos. of 3-roll calendars of any configuration

xv) Variation in thickness of a calendered sheet between the centre and sides can be minimized

bya) Increasing the compound viscosity

b) Decreasing the calendaring speed

c) Decreasing roll temperature

d) None of the abovexvi) Porosity cannot occur during vulcanization of an extrudate in curing chamber if cured in

a) Hot air without air pressure

b) Open steamc) Hot air without open steam


xvii) A common cause of poor dispersion isa) Specific gravity of the mix is too low

b) Dump temperature is too lowc) Batch size is too low


35/98

d) Ram pressure is too high

xviii) Die swell in extrusion is dependent upona) Specific gravity of compound

b) Specific heat of compound

c) Green strength of compoundd) Shear rate of the extrudate

xix) Generally in a mixing mill if the diameter is 22 inches then the roll length is

a) 44 inches b) 60 inches c) 66 inches d) 22 inchesxx) When the material stops flowing through the extruder die even if the screw keeps rotating itimplies that

a) Drag flow>Pressure flow

b) Drag flow


36/98

PAPER II RUBBER PROCESSING AND ENGINEERING

YEAR 2002

I. Give the correct answer from the alternatives given against each question

1. The modulus at 300% elongation as obtained from Universal Testing machine (UTM) refers toa) Ratio of stress to strain at 300% elongationb) Stress at 300% elongation

c) Strain at 300% elongation


2. The tensile strength of rubber vulcanizates as measured from an UTM refers to

a) Nominal stress at the point of failure

b) True stress at the point of failurec) Force required to break the sample


3. The unit of the viscosity obtained by Mooney Viscometer are equivalent to being

a) Dimensionlessb) Unit of torquec) Unit of shear viscosity

d) Unit of pressure

4. The dynamic characteristics of rubber matrix during vulcanization are measured by aa) Moving die rheometer

b) Oscillating Disc rheometer

c) Universal Testing Machined) High pressure capillary viscometer

5. Mixing mill operated at smaller nip gap will exert in comparison to larger nip gap aa) smaller shear force

b) higher shear forcec) identical shear force


6. In the rubber processing terminology the terms like z-type, Inverse L-type are associated with

a) Mixing mills

b) Extruders

c) Compression mouldd) Calendars

7. As compared to Natural rubber Polybutadiene rubber has relativelya) Better processability

b) Identical processability

c) Poor processabilityd) None of the above


37/98

8. The Rheometric curve of an SBR based rubber compound indicates predominantly

a) Fast Reversionb) Plateau Effect

c) Marching Modulus


9. Reversion characteristics of a rubber compound can be easily visualized by testing the

compound in

a) a Monsanto Rheometerb) an Instron Tensile Tester

c) a DIN Abrader

d) a Dispergrader

10. The output rate of a given compound in an extruder can be significantly improved by

a) increased cooling water pressure

b) increased barrel and head temperaturesc) increased screw R P Md) reduced screw R P M

11. In an internal mixer, higher rotor speed provides

a) shorter mixing cyclesb) higher cooling water temperature

c) lower stock temperature build upd) higher batch weights

12. Post cure inflation is essential for tires built with

a) Rayon cordsb) Nylon-6 cordsc) Steel cords

d) Cotton

13. Heat setting of nylon cords should be carried out at

a) Room temperatureb) Below room temperature

c) Temperature higher than the melting point of nylon

d) Temperature nearer to the melting point of nylon

14. L/D ratio of a pin barrel extruder is

a) 4:1 to 6:1

b) 10:1 to 15:1c) 12:1 to 20:1

d) 10:1 to 40:1

15. Crows feet is a phenomenon associated with


38/98

a) Calendering operationb) Spreading operation

c) Extrusiond) Continuous vulcanization

16. Microwave heating is effective for the followinga) Non polar rubber and ingredients

b) Polar rubber and ingredientsc) Rubber with metal inserts

d) Rubber with mineral filler

17. Long cycle time is normally associated with the following molding

a) Transferb) Injection

c) Compression

d) RIM

18. Improved resistance of reversion in case of NR is obtained by

a) Urethane cross-linking system

b) Semi efficient vulcanizationc) Soluble EV systemd) None of the above

19. In a calendaring operation maximum pressure occur on the roll at a height h equal toa) height of nip

b) half the height of nipc) 4/3 the height of nip

d) the height of nip

20. The following rubber is not subjected to cracking by ozone

a) SBR b) BR

c) NBR

d) EPDM(20X1=20)


39/98


YEAR 20031. Give the correct answers from the alternatives given against each question

i) The viscosity of raw synthetic polyisoprene rubber as compared to raw natural rubber is

a) lower b) 1.5 times, higher c) equal d) 2 times, higher

ii) Excessive remilling of SBR compound may lead to

a) softening b) gelling c) high tack d) none of the above

iii) The ASTM series number for cold SBR gum rubber is

a) 1000 b) 1700 c) 1500 d) 2000

iv) Polybutadiene rubber containing 32-35% cis forms a tight elastic band on a two roll mill at

roll temperature range of

a) 200C-300C b) 400C-450C c) 1200C-1300C d) 650C-700C

v) Butyl rubber is generally compounded at higher temperature than NR due to its relatively

a) low level of unsaturationb) high unsaturation

c) low Mooney viscosityd) none of the above

vi) Die swell is associated with

a) calendaring b) extrusion c) mixing d) spreading

vii) Optimum cure time is generally denoted asa) Tc25 b) Tc50 c) Tc90 d) Tc98

viii) SI unit of viscosity of polymer is

a) Nm b) N/m2 c) Pas d) MPa

ix) In a rubber extruder a screen pack is used to

a) Remove undesirable particles of higher size from rubber mixb) Remove excess of plasticizer

c) Remove excess curativesd) Protect the breaker plates

x) Mastication is a process of

a) Curing rubber in sunlightb) Lowering of Mooney viscosity by adding process oil

c) Lowering of Mooney viscosity by mechanical shearingd) Devulcanization of rubber compound


40/98

xi) The Rotor design of the Mooney Viscometer is of the type

a) A disk with smooth surface

b) A disk having serrated grid patternc) A disk having perforation

d) A bi-conical disk

xii) The rapid rise in the temperature of the stock when the rubber is fed to the internal mixer is

due toa) Circulation of water through the body of the mixer

b) Viscous dissipation of energy due to high stock viscosity

c) Breakdown of the molecular chainsd) Disentanglement of rubber molecules

xiii) In an internal mixer the purpose of the rotor shaft seal is

a) To prevent the escape of particulate material

b) To prevent the escape of cooling waterc) To maintain the temperature inside the mixer


xiv) Blooming is a phenomenon where

a) Processability of a rubber compound is affected

b) Proper distribution of compounding ingredients are hamperedc) Blisters appear on the surface of the compound

d) Compounding ingredients move from bulk to the surface of a rubber compound

xv) An increase in Extruder Screw RPM will lead to

a) Decrease in output rateb) Increase in output ratec) No change in output rate


xvi) On a calender sheet the blisters appear due to

a) The calender roll temperature being too lowb) Feed stock temperature being too low

c) Calender rolls and/or feed stock being too hotd) None of the above

xvii) During the moulding of a rubber component bumping and breathing operations are

performed to

a) Eliminate the trapped air and vapours from the mouldingb) Improve the surface finish

c) Reduce the thicknessd) None of the above


41/98

xviii) In an injection molding system the spru is the flow channel

a) Between runner and gateb) Between runner and die

c) Between gate and mould cavity

d) Before the die

xix) For a flashless moulding of rubber articles the most suited moulding operation is

a) Compression moulding

b) Injection mouldingc) Blow moulding


xx) Shear head is the device used for

a) Raising the temperature of the rubber compoundb) Mixing fillers with rubbers

c) Controlling the pressured) None of the above

(1x20)


42/98

PAPER II- RUBBER PROCESSING AND ENGINEERING

YEAR 2004

1. Give the most correct answer from the alternatives given against each question

i) The scorching tendency of a rubber compound is not

a) dependent upon its base elastomerb) dependent upon curative system

c) dependent upon processing temperature

d) dependent upon its color

ii) Nitrile rubber is modified by PVC resins to improve

a) oil resistance

b) tear strengthc) resistance to weather, ozone, and sunlight

d) adhesion to fabric and metals

iii) The maximum effect on masticating crude NR for viscosity reduction is obtained

a) either at temperature below 550C or at temperature above 1300Cb) at temperature between 900C and 1500C

c) only at temperature above 1300Cd) none of above

iv) A common and often overlooked cause of poor dispersion and scorchiness isa) Specific gravity of the stock too low

b) Batch size too largec) Dump temperature too low

d) Tensile strength of the stock too high

v) The amount of die swell in extrusion is dependent upon

a) the shear rate of the extruder and the viscosity of the compoundb) the specific gravity of the compound

c) the tensile strength and elongation of the compound


vi) Surface roughness of the extrudate is not likely to be caused by

a) air entrapment or insufficient mastication

b) improper temperature profile

c) insufficient cooling at take away equipmentd) high screw speed

vii) The major causes of porosity problems are


43/98

a) use of high viscosity material and application of mold release

b) moisture and trapped airc) low molding temperature and along curing cycled) none of the above

viii) Sulfur is the most widely used vulcanizing agent. The second most popular vulcanizingagent is

a) Organic amines

b) Organic peroxidesc) Phenolic resins

d) Metallic oxides

ix) The major disadvantage of heated nitrogen over heated air as a source of thermal energy forvulcanization is

a) it cannot be easily compressed

b) it has no oxidizing effect on sensitive polymer composite being vulcanized

c) it is much more efficient in heat transferd) none of above

x) Molded good with irregular shape and complex configuration are most likely made bya) compression molding

b) transfer molding or injection moldingc) bladder molding


xi) The Mooney viscometer gives the viscosity in equivalent units as

a) Forceb) Torquec) Momentum

d) Acceleration

xii) The rotors of Mooney viscometer are designated as L and S, which stand respectively for

a) low and slow

b) long and short

c) large and smalld) none of the above

xiii) For a particular rubber compound the optimum cure time obtained using a moving die

rheometer as compared to oscillating disc rheometer isa) same

b) lowerc) higher d) none of the above

xiv) Increase in friction ratio of the two roll mill operation will

a) increase the temperature of stock


44/98

b) decrease the temperature of stock

c) increase the stock viscosity


xv) The friction ratio of a Banbury internal mixer is the consequence of

a) Tip diameters of the rotor wingsb) Root diameters of the rotors

c) Root diameter of one rotor and wing tip diameter of the otherd) None of the above

xvi) Cold feed extruder L/D ratio is higher than the hot feed extruder because it contains

a) Additional feeding arrangement

b) High capacity drive motor

c) Additional preheating zoned) None of the above

xvii) An extruder die invariably containsa) Lead-in and land sectionsb) Melting section

c) Conveying sectiond) Metering section

xviii) In an injection molding system the gate diameter is

a) Smaller than the runner diameterb) Larger than the runner diameter

c) Equal to the runner diameter


xix) In a pin barrel extruder the pins are used to impart

a) A smooth flow

b) A cross flowc) High viscosity


xx) The crows feet defect is observed normally in a

a) A calendered sheetb) An extrudate

c) A molded product

d) None of the above(20x1=20)


45/98


YEAR 2005

1. a) Choose the correct answer from the given alternatives given against each question

i) A high value of die swell indicates

a) low viscosity b) high viscosity c) low elasticity d) high elasticity

ii) The fill factor in an internal mixer during curative mixing is

a) 50-55 b) 60-65 c) 70-75 d) 80-85

iii) In autoclave curing of rubber compounds an uncured surface layer is observed in the case of

a) sulfur curing b) peroxide curing c) metal oxide curing d) resin curing

iv) The advantage of a ram extruder over a screw extruder is

a) low heat development b) low operating cost c) metal oxide d) all of a,b & c

v) The Mooney viscometer measures the viscosity at a shear rate of.. s-1

a) 0-1 b) 1-2 c) 2-3 d) 3-4

vi) In a four roll calender the second and third rolls which apply coating to the fabric must be

of. speed, while the first and fourth rolls can be ..

a) even, even or uneven b) uneven, even c) uneven, even or uneven d) 1.0 and 1.25

vii) For friction coating in a three-roll calender the friction ratio is between

a) 1 and 1.5 b) 1.5 and 2.0 c) 1.25 and 1.5 d) 1.0 and 1.25

viii) ML1+8 is related to

a) NR b) SBR c) IIR d) NBR

ix) Crows feet can be observed after

a) Extrusion b) Moulding c) calendaring d) Mixing on a two roll mill

x) Reversion is often shown by

a) NR b) SBR c) IIR d) NBR

xi) Typical mill friction ratio is

a) 1:1 b) 1.25:1 c) 2.5:1 d) 5:1


46/98

xii) In hot feed extruders, L/D ratio is

a) 2:1 b) 6:1 c) 15:1 d) 20:1

xiii) Eutectic mixture of inorganic salts is used as vulcanization medium for

a) Hot air cure b) LCM cure c) Radiation cure d) Fluidized bed cure

xiv) Bag-O-matic press is used for curing a

a) Seal b) Mount c) Cable d) Tyre

xv) Die swell is related to

a) Injection moulding b) Calendering c) Extrusion d) Mixing

xvi) Cure rate is generally obtained from a

a) Plastimeter b) Mooney viscometer c) Rheometerd) Processability tester

xvii) Typical operating roll temperature of highly loaded EPDM isa) 10-200C b) 20-300C c) 30-500C d) 60-800C

xviii) Peroxide curing of rubber at 1600C shows rheometric rheological properties of a rubber

compound after the scorch time because

a) Marching modulus b) High scorch safety c) Reversion tendency d) Flat curing

xix) Mooney viscometer cannot be used for measuring Rheological properties of a rubber

compound after the scorch time because

a) test temperature is low

b) test shear is low

c) the rotors tear the cured rubber

d) temperature uniformity cannot be maintained

xx) Porosity in fluidized bed curing is avoided by

a) use of dessicant b) application of pressure c) use of dried filler d) all of a, b& c

(1x20=20)


47/98

PAPER III RUBBER MATERIALS

YEAR- 1996

1.

A) Select suitable curing system for following rubbers. Only write the answer against the

question number.i) NBR-EPDM blend requiring good compression set and heat resistant properties - EV

ii) Natural rubber for better heat resistant application Sulphur donor

iii) Neoprene W for general purpose application Ethylene thioureaiv) NR-BIIR blend for tyre application S/Zno

v) Butyl rubber for maximum heat resistant application - Resin

5x1=5

B) What is the effect of:

i) Increasing acrylonitrile content on heat resistance of NBR - Increases

ii) Increasing styrene content in SBR on rubbery characteristic - Decreases

iii) Introducing halogen group in IIR on compatibility with diene rubbers - Improvesiv) Increasing vinyl content in BR on the skid resistance Improves

v) Increasing butadiene content on oil resistance of NBR - Decreases5x1=5

C) Select suitable rubber/rubber blends for following applications:

i) Outer cover and inner tube of oil field hose - ?

ii) Aero tyre and cycle tyre NR/BR/RR

iii) Tread and inner liner for tubeless truck tyre NR/BR HIIR/NRiv) Lining material for sulfuric acid tank -NR

v) Artificial heart valve SILICONE

5x1=5D) What are the effects of increasing HAF black loading (upto 80 phr) on the followingproperties of optimum cured NR based compound (Give only typical curve)?

i) Tensile strength

ii) Elongation at breakiii) Rebound resilience

iv) Hardness

Hardness

T.S

E.B

Resilience20 40 60 80

5x1=5


48/98

PAPER- III -RUBBER MATERIALS

YEAR 1997

1.A. Why is Polybutadiene blended with other polymers, while butyl rubber is nearly usedalone? ANS: Cure compatibility

i) What is understood by the term Plateau Effect in Cure Curves?

Tq plateau

Time

ii) Place the following rubbers in order of increasing resistance to ozone attack: Natural

rubber, butyl rubber, acrylonitrile butadiene rubber and EPDM rubber. ANS:NR


49/98

C.

i) Why is DCBS more delayed action accelerator than CBS? ans: DCHA less than CHA

ii) Name one difunctional compound for curin rubber Quinane dioxin

iii) Name two ultra accelerators ZDC, TMTD

iv) Which of the following are accelerator activators: Zinc oxide , red lead, acetic acid,stearic acid , phenol

v) Which of the following are chemical plasticizers: Oil soluble sulfonic acid, pine tar,

pitch, xylyl mercaptan

D. What is the effect of?

i) Increasing nitrile content on the rubbery characteristics of nitrite rubber - Decreases

ii) Increasing trans content of polyisoprene on the processibility at room temperature -

Lowers

iii) Replacing natural rubber by butyl rubber on rolling loss of tyre tread compound -

Increases

iv) Blending NBR with EPDM on heat resistance - Improves

v) Replacing sulfur donor compound by sulfur Heat resistance inferior


50/98

PAPER- III RUBBER MATERIALS

YEAR 1998

1. A. Write only the answer against the question number:

i) Zinc oxide is the cross linking agent for which rubber - CR

ii) Name at least three elastomers which can be cross linked by dicumyl peroxide EPDM,HNBR, Silicone

iii) Which type of resin is used for vulcanizing butyl rubber? Ans: Modified PF

iv) Why is stearic acid used in diene rubbers? Ans: Activatorv) What is the dosage of sulphur required for curing SBR to ebonite stage? Ans: 30

5X1=5

B. Which type of oils or plasticizers are used.

i. For manufacturing oil-extended styrene butadiene rubbers - Aromatic

ii. For manufacturing oil-extended EPDM rubbers - Paraffiniciii. As plasticizer for polychloroprene rubber Ester plasticizer

iv. As softener for isobutylene isoprene rubber - Napthanicv. For imparting fire retardant properties chlorinated paraffin

5X1=5

C. Name one important application for each of the following polymer blends

i) NBR/PVC LPG tubingii) NR/BR Tyre head

iii) IIR/EPDM Inner tube

iv) NR/BIIR (bromobutyl) Inner linerv) NR/HSR (high styrene resin rubber master batch) shoe soles

5X1=5

D. Select the most appropriate filler for each of the following applicationsi) White sport shoe sole precipitated silica

ii) Passenger car tyre tread - ISAF

iii) Battery boxes made of ebonite (hard rubber) Ebonite partiv) Green colored garden hose of EPDM china clay

v) Hot water bottle Precipitated CaCO35X1=5


51/98


YEAR 1999

1. A. Write only the symbol of the correct answer/answers

i) Which rubber has the widest temperature range of application

a) NR b) EPDM c) Butyl (IIR) d) Silicone e) Polybutadiene (BR)ii) Select the most suitable elastomer for aero-tyre

a) BR b) NR c) IIR d) EPDM e) SBRiii) Among the following rubbers the best heat resistant one is

a) SBR b) EVA c) EPDM d) NBR e) IIRiv) The best example of self-reinforcing elastomer is.

a) EPDM b) BR c) NBR d) SBR e) NR

v) The Paraffinic oil is suitable plasticizer fora) NBR b) SBR c) CR d) EPDM e) Siliconvi) Increasing acrylonitrile content the property which decreases is

a) heat resistance

b) oil resistance

c) resilience

d) air impermeability

e) modulus

vii) Peroxide curing is not suitable for

a) IIR b) NBR c) BR d) SBR e) NRviii) Among the following the most delayed action accelerator is

a) MBT b) CBS d) TMTD d) ZDC e) ZMBTix) Among the following fillers the average particle size is the least for

a) Activated CaCO3 b) SAF c) ZnO d) HAF e) Fumed silica x) Zinc salt of pentachlorothiophenol is used as

a) Curing agent b) Plasticizer c) Filler d) Peptizer e) Tackifier


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B. Write only the answer against the question number:

ii) Which is the main monomer for butyl rubber?- ans: Isobutylene

iii) Name the feedstock for furnace blacks CBFS/Naphtha

iv) Name the tree, which produces natural rubber Hevea brasiliensis

v) Which type of catalyst is used for manufacturing Polybutadiene rubber? Ans: No

vi) Name an oxygen containing elastomer - Silicone

C. Select a suitable polymer or polymer blend for

i) LPG tubing NBR/PVC

ii) Meteorological balloon - Butyl

iii) Solvent based contact adhesives - CR

iv) Inner layer of steam hose - NBR

v) Tyre curing bag - IIR

10+5+5=20


53/98


YEAR 20001. Choose the correct answer (write the letter code in your answer):

i) Which property of Nitrile rubber is improved when it is modified with PVC resin?

a) Oil resistanceb) Resistance to weather, ozone and sunlight c) Tear strength

d) Adhesion to fabric and metals

ii) Fluorocarbon elastomers have excellent resistance to oils, fuels, acids and chemicals but has

poor resistance toa) Hydraulic fluids

b) Oxygen, ozone, sunlight

c) Oxygenated solvents such as acetone, MEKd) None of the above

iii) Which copolymer of ethylene and vinyl acetate exhibits rubbery behavior

a) Copolymer with 12% vinyl acetate b) Copolymer with 28% vinyl acetatec) Copolymer with 45% vinyl acetate

d) Copolymer with 90% vinyl acetate

iv) What is the weight percent of chlorine in PVC?

a) 15% b) 30% c) 45% d) 56%

v) Arrange in order of decreasing abrasion resistance of the following rubbersNR


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a) EPDM b) NR

c) PUd) BR

xi) Calcium oxide is used in EPDM microwave curing fora) Fast extrusion

b) Better shine on finished product

c) Absorbing moisture d) Uniform dispersion of reinforcing materials

xii) Paraffin mineral oil is the most compatible with

a) Butyl rubber

b) Silicone rubberc) Natural rubber

d) Nitrile rubber

e) Polyacrylic rubber

xiii) Aniline point of a oil is 300C, if it is highly

a) Paraffinic

b) Aromatic c) Napthenic

d) Linear molecules

e) Dark in color

xiv) Resin curing is the most suitable for

a) NBR b) BR c) NR d) IIR

xv) Neither peroxide nor conventional sulfur curing system is recommended for

a) NR b) SBR c) CR d) BR

xvi) Increasing ethylene content in EPDM reducesa) Tensile strength

b) Compression set resistance c) Ozone resistanced) Filler loading capacity

xvii) During reclaiming of a rubber vulcanizate unsaturation and molecular weight variations are

as followsa) unsaturation of rubber increases, but molecular weight decreases

b) unsaturation of rubber reduces as well as molecular weight reduces c) unsaturation increases and molecular weight increases

d) both remain sane as that of original compound

xviii) Sulfur, chlorine, oxygen containing rubber is

a) CR b) CIIR c) CSP d) CM


55/98

xix) The most suitable polymer for tyre curing bag is

a) IIR b) NBR c) SBR d) NR

xx) The most delayed action accelerator is

a) MBT b) MBTS c) TMTD d) MOZ (1X20=20)


56/98

PAPER-III RUBBER MATERIALS

YEAR 2001

1. (a) Choose the correct answers from the following

i) What is the basis of grading of ISNR as ISNR 3, 5, 10, 20, 50 etc.?a) Viscosity

b) Dirt content c) Ash content

d) Nitrogen content

ii) At 23.5% bound system level, the Tg of SBR is

a) 400C b) 500C c) 600C d) 700C

iii) A 100% hydrogenated NBR can be vulcanized by

a) Sulfur and accelerator

b) Peroxides c) Metal oxidesd) None of these

iv) Polychloroprene rubber is vulcanized by

a) ZnO b) ZnO and MgO c) S and Accelerator d) None of these

v) The Cis-content in Polychloroprene rubber of adhesive grade is

a) 70% b) 80% c) 85% d) 90%

vi) The significant characteristic of a thermoplastic elastomer is to

a) Behave like a thermoplastic at room temperatureb) Process like a thermoplastic at elevated temperature c) Behaves like an elastomer at room temperature

d) Process like a rubber at room temperature

vii) Many specialty elastomers require Post curing for achieving best balance of properties.

Name from the listed below the one, which does not require post curing.

a) Acrylic b) Fluorocarbon c) Cross linked Polyethylene d) Vamac

viii) Name the rubber which has better air impermeability than butyl rubber

a) Acrylic b) Hypalon c) ENR d) Polyepichlorophydrin

ix) Fluorosilicone rubber has outstanding properties of

a) Good swelling resistance and low temperature flexibility b) Long temperature heat resistance at elevated temperatures

c) Resistance to acids and basesd) Good tear and wear properties


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x) In latex processing the chemical used as gelling agent is

a) Ammonia b) ZnO c) Sodium silicofluoride d) Resorcinol(1x10=10)

(b) Mention the function of the following compounding ingredients in rubber

1 Dioctyl phthalate - Plasticizer

2 Zinc salt of mercapto benzothiazole - Accelerator

3 Precipitated silica Reinforcing filler4 Dicumyl peroxide cross-linking agent

5 Triallyl isocyanurate peroxide activator

(5)(c) Select the most suitable filler for

1 Inner tube of tyres - FEF

2 EPDM steam hose - SRF

3 Insulation compound for power cables - Talc4 LPG tubing Precipitated CaCo35 Passenger tire tread OESBR/SBR

(5)


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YEAR 2002

1. (A) Choose the correct answer:

i) Polyurethane rubber has outstanding resistance to

a) acids and solvents b) hot water c) abrasion and tear d) none of the above

ii) Nitrile rubber modified with PVC resin improves its

a) oil resistance b) tear strength c) resistance to weather, ozone and sunlight d) adhesion to

fabric and metals

iii) Acrylic rubber has inferior resistance to

a) ozone and sunlight b) oxidation c) water and steam d) gasoline and similar hydrocarbon

solvents

iv) Fluorocarbon elastomer has very little resistance to

a) hydraulic fluids b) oxygen, ozone and sunlight c) oxygenated solvents such as MEK d) none

of the above

v) The mercaptan modified neoprene rubber (type W) has better

a) resistance to oil and gasoline b) more tackiness and faster cure c) superior resistance to heat

and compression d) none of the above

1x5=5

(B) What these notations stand for and accordingly name the following types of black fillersi) N 110 - SAF ii) N 242 - HSisAF iii) N 440 - iv) N 339 - HSHAF v) N 990 - SRF

1x5=5

(C) Select most suitable rubber for the following applicationsi) Truck tyre tread - NR

ii) Weather strip - EPDM

iii) LPG tubing NBR/PVCiv) Air bag for tyre curing - IIR

v) Seals operating at 600C in hydrocarbon oil - NBR

1x5=5

(D) Select the most suitable fillers (with grades) for the following applications:

i) Passenger radial tyre tread N326ii) Green tyre tread (low rolling resistance environmentally friendly tyre tread)

precipitated silicaiii) Acid resistance tank liner BaSo4iv) White sidewall for tyres CaCo3

Automotive tube - FEF


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YEAR 2003

I. i) Which of the following rubber has maximum gas impermeability

a) NR b) Butyl c) Polyethers d) EPDMii) The properties of Hypalon are similar to Neoprene. However, it is superior to Neoprene in:

a) Resilience

b) Resistance to acid, solvents, ozone and oxidationc) Resistance to compression set

d) None of the aboveiii) Phynol formaldehyde resin can be used to

a) Reduce hardness

b) Improve flex properties

c) Reduce heat built up ord) Increase hardness

iv) Which of the following rubber can be used to get lowest resilinece

a) IIR b) BR c) FKM d) Siliconev) MST of latex should preferably be

a) 5 secs. b) 600 secs c) 1000 secs d) 5000 secs(1X5=5)

II. Name the type of accelerators and vulcanizing agents used in curing the following rubber

products

i) Butyl curing bags PF resinii) Disposable hand gloves made from NR latex ultra fast ZDBC

iii) Aero tyre tread - Sulfenamuls

iv) Cable jacket based on Neoprene rubber - Pbov) Truck tyre carcass - NBRS

vi) RTV silicone for automobile gasket DCP+TIAC

vii) Printing rolls from epichlorohydrin rubber Ethylene thiourea / Pb3O4viii) Cable sheathing compounds from Hypalon Pb3 O4+Terone A

ix) Crank shaft seals from Acrylate rubber - Diamines

x) Aircraft and rocket seals from fluorocarbon rubber Bisphenol/Metal oxide

(1x10=10)

III. Give two examples of each of the following

i) Antioxidants 6PPD, TDCP

ii) Process aids Zinc salt of fatty acid

iii) Retarders CTP, NDPAiv) Extenders Whiting, Clay

v) Blowing agents ADC, TSH


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YEAR 2004

1. Choose the correct answer / write the letter code in your answer:

i) Select a cure system for the best flex life of the cured product

a) Conventional b) Semi-EV c) EV d) Peroxide

ii) Amongst the following rubbers, which rubber can take maximum filler and oil loading

a) EPDM b) NR c) PU d) SBR

iii) Resin curing is the most suitable for

a) NBR b) SBR c) NR d) IIR

iv) The most suitable polymer for tyre curing bag is

a) IIR b) NBR c) SBR d) NR

v) A 100% hydrogenated NBR can be vulcanized by

a) Sulfur and accelerator b) Peroxides c) Metal oxides d) None of these

vi) In latex processing the chemical used as gelling agent is

a) Ammonia b) ZnO c) Sodium silicofluoride d) Resorcinol

vii) Lowest heat build up is observed for vulcanizate of

a) CR b) NR c) SBR d) IIR

viii) The highest air impermeability is shown by

a) NR b) CR c) NBR (50 ACN) d) IIR

ix) The best flame resistant rubber is

a) CIIR b) BIIR c) NBR d) CR

x) Arrange in increasing order of gum vulcanizate strength

SBR


61/98

xiv) Which polymer has the structure with highest cis-1,4 content?

a) NR b) CR c) SBR d) BR

xv) Which elastomer has highest fluorine content?

a) Fluorocarbon rubbers (FKM) b) Fluorosilicone rubbers (FVMQ)

c) Polytetra fuluroethylene (PTFE)

xvi) The most compatible plasticizer for EPDM rubber is

a) Aromatic mineral oil b) Paraffinic mineral oil c) DOP d) Caster oil

xvii) High voltage power cables are insulated with

a) Butyl rubber b) Silicone rubber c) EPDM d) XLPE

xviii) Which of the following is a thermoplastic rubber?

a) SBR b) SBS c) ABS d) SAN

xix) Which of these polymers has the lowest Tg?

a) BR b) CR c) SBR d) NBR

xx) Field latex has the (rubber hydrocarbon content) of about

a) 25% b) 35% c) 50% d) 60%

(20x1=20)


62/98


YEAR 20051. Select most suitable answer/answers from the given choices against each question

i) Only solution grade of-------------is exclusively used for tyre tread

a) IIR b) CR c) NBR d) BR e) SBR

ii) Peroxide curing is not technically recommended for---------

a) BIIR b) IIR c) CR d) NBR e) HNBR

iii) The best combination of heat and mineral oil resistance can be obtained from

a) CR b) NBR c) BIIR d) HNBR e) MQ

iv) The most suitable rubber for Aero tyre is-----------

a) HNBR b) BR c) SBR d) NR e) ENR

v) The rubber which has the highest abrasion resistance--------

a) SBR b) XNBR c) CR d) NBR e) BR

vi) For tyre curing bag the most suitable rubber is------------

a) CR b) NBR c) BIIR d) CIIR e) IIR

vii) The best combination of mechanical properties, oil resistance and flame resistance can be

obtained from -----------------

a) CR b) BIIR c) CIIR d) NBR e) VMQ

viii) The highest resilience is shown by the rubber----------

a) SBR b) IIR c) BR d) HNBR

ix) The rubber which requires production at lowest polymerization temperature

a) IR b) NBR c) CR d) SBR e) IIR

x) The most important property of oil seals and gasket

a) Tensile strength

b) Compression setc) Heat build up

d) Resilience

e) Modulus at 300% elongation


63/98

xi) Carbon black with higher surface area is

a) N550 b) N330 c) N110 d) N234

xii) Accelerator having highest scorch safety in conventional rubber compound

a) NOBS b) MBT c) DCBS d) CBS

xiii) Additive used for enhancing static ozone resistance properties of general purpose rubber

compound is

a) TMQ b) 6PPD c) Wax d) Aromatic oil

xiv) The most unsuitable filler for improving acid resistance properties of rubber compound is

a) Whiting b) Barytes c) Carbon black d) Clay

xv) The maximum limit of dirt content of TSR 10 is

a) 0.1% b) 0.2% c) 0.5% d) 0.01%

xvi) The material derived from petroleum source is

a) NR b) Silica c) Vegetables oil d) BR

xvii) The Recycle material used in rubber industry

a) WTR (Whole Tyre Reclaim) b) Sheet Rubber c) N330 d) ZnO

xviii) High pH of carbon black results in rheometric curve of rubber compound

a) increase in cure rate b) decrease in cure rate c) cure rate remain unchanged d) maximum

torque increasesxix) DRC of commercial NR latex is

a) 40% b) 60% c) 30% d) 80%

xx) Preservative used for NR latex is

a) HCOOH b) Water c) Ammonia d) 6PPD

(20x1=20)


64/98

PAPER 4 RUBBER PRODUCT MANUFACTURING

AND THEIR EVALUATION

YEAR 1996

1. a) Select suitable answer from the given set:

(Only write the answer for each question in the answer script not in the question paper)i) Cycle tyre cord is mainly derived from..

a) Cotton b) nylon

c) rayond) polyester

ii) Tyre sidewalls are made thin because.

a) For better heat dissipation b) No abrasion is needed in side wallc) For better economy

d) None of these

iii) The most important property requirement for rubber compound in metal to rubber bonding is

a) tear resistance

b) elongation at breakc) tensile strength

d) heat build up

e) modulus

iv) Incorporation of . improves metal-rubber bond strength

a) clayb) plasticizer

c) carbon blackd) dicumyl peroxide

v) Heat treatment is necessary for cord prior to be used in rubber product

a) rayon

b) carbon fiber

c) steel

d) nylon

vi) For acid resistant tank lining the most suitable rubber is .

a) Natural rubberb) SBR

c) Nitrile

d) Hypalon


65/98

vii) For stabilization of latex the usual material is

a) NaCl, b) H2SO4, c) NH3, d) CaCO3

viii) Dry bonding agent used for fabric-rubber adhesion is based on.

a) Chemlok

b) Hexa+resorcinol+silica

c) Desmodur

d) None of these

ix) Air craft tyre is based on ..

a) NR SBR blend

b) NR BR blend

c) Pure NR

d) SBR BR blend

x) The most widely used black for oil seal application is

a) HAF

b) SRF

c) ISAF

d) FEF

1x10=10


66/98

B)i) Bursting strength of braided hose is given by the following formula

a) 3N8RSin/DL

b) 0.2NSRSin/DL

c) 0.2N3RSin/D

d) 0.2N3RCos/DL, where each term has its usual meaning

Ans: 2NRSin/DL

ii) The breaking load of conveyor belt is equal to

a) Sum of tensile strength of top and bottom cover compound + sum of strengths of top

and bottom plies

b) Strength of individual ply x number of plies

c) Sum of strength of top and bottom rubber cover

d) None of these

iii) The usual formula for calculation of tensile strength of rubber compound is.

a) Breaking load/cross sectional area at the time of breaking

b) Breaking load/thickness of the sample

c) Breaking load/original cross sectional area of the sample

d) Load at 300% elongation/original cross sectional area

iv) Neutral angle in braided hose is

a) 450 b) 390 c) 600 d) 540

v) The width/height ratio in classical and wedge type V-belt are respectively

a) 1.6, 1.0; b) 2.6,1.6; c) 1.6,1.2; d) 1.2, 2.1

vi) Bias angle in bias ply and radial tyres are

a) 540, 900 b) 650, 450 c) 900, 450 d) 300, 900


67/98

vii) If the volume of the mould is V, then the volume of initial compound used for preparation of

micro cellular rubber should be roughly

a) 1.7V b) V c) 0.7V d) none of these

viii) For preparation of flexible high voltage cable for 15KV power line the suitable polymer willbe

a) Nitrile rubber b) Butyl rubber c) XLPE d) EPR/EPDM e) PVC

ix) The included angle in classical V-belt is

a) 600 b) 450 c) 400d) 540

x) Drum friction test is relevant to..

a) Tyre b) V-belt c) Hose d) Conveyor belt e) Shoe

1x10=10


68/98

PAPER- IV RUBBER PRODUCTS MANUFACTURING AND THEIR

EVALUATION

YEAR 1997

1. From these multiple choice of answers select the most appropriate answer of the followings:

i) Best curing system for metal-rubber bonding should be based on:

2 Semi EV

3 EV

4 Conventional

5 Peroxide

ii) The most suitable cord material for V-belt reinforcement is:

2 Nylon

3 Polyester

4 Rayon

5 Cotton

iii) The tear strength is usually calculated for Crescent tear test using the formula:

1 Tearing load/thickness of the sample

2 Tearing load/original cross-sectional area of the sample

3 Tearing load/width of the sample

4 Tearing load/final cross-sectional area of the sample

iv) Hollography is the test to evaluate

1. Shoe

2 V-belt

3 Tyre

4 Hose


69/98

v) Peroxide vulcanization is not recommended for:

2 EPDM

3 Silicone

4 Butyl

5 Hypalon

vi) For coagulation of NR-latex the following material is used commercially

2 Sulfuric acid

3 Calcium nitrite

4 Acetic acid

5 Calcium carbonate

vii) Pressure sensitive adhesive can be derived from:

2 SBR

3 NBR

4 CR

5 Silicone rubber

viii) Thick rubber article should be cured for:

2 Longer time at elevated temperature

3 Shorter time at elevated temperature

4 Shorter time at lower temperature

5 Longer time at lower temperature

ix) LPG (domestic gas) tubing should be made from:

2 SBR

3 EPDM

4 Butyl


70/98

5 Polychloroprene rubber

x) The reason of porosity in tyre tread is mainly due to:

2 Improper polymer blends

3 Non-use of desiccant

4 Low boiling plasticizer

5 High dose of sulphur

xi)_ Ebonite bonding with metal is not suitable for high temperature application because:

2 It corrodes metal at high temperature

3 It gets aged for faster oxidation

4 Ebonite layer softens

5 Ebonite gets brittle

xii) For non-intercommunicating cell structure of a sponge the right-choice of blowing agent

should be

2 (NH4)3CO3

3 NaHCO3

4 Dinitroso pentamethylene tetramine (DNPT)

5 Hot air

xiii) In a braided hose, if the braid angle is less than the natural angle, the hose will

2 Increase in diameter

3 Increase in length

4 Elongate in the direction 450 to the hoop force

5 No change during service

xiv) If a latex foam collapse after vulcanization, necessary steps should be:

1 to reduce the gelling time

2 to increase gelling time


71/98

3 to increase foaming time

4 to increase vulcanization time

xv) Belt angle of a vulcanized radial tyre is:

1) 120-180 2) 850-900 3) 260-280 4)300-350

xvi) Hardness of ebonite is measured in the durometer scale of

2 Shore A

3 Shore B

4 Shore C

5 Shore D

xvii) For testing flex resistance of sole of footwear the suitable apparatus is:

2 De-mattia flexometer

3 Ross flexometer

4 Scott flexometer

5 Du-pont flexometer

xviii) Abrasion resistance is essential for

2 Pencil eraser

3 Radiator hose

4 Roller for paper mill

5 Rice dehusking roller

xix) Trough ability test is required in

2 Trolley wheel

3 Coated fabric

4 Rail pad

5 Conveyor belt


72/98

xx) PCI is a term related to manufacturing of

1 Hose

2 Conveyor belt

3 V-belt

4 Tyre


73/98

PAPER- IV RUBBER PRODUCTS MANUFACTURING AND THEIR

EVALUATION

objective qus wd answer

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