polymers based on cashew nut shell liquid and...
TRANSCRIPT
1.1 INTRODUCTION
The present century is known as the century of polymers.
Without Polymers we cannot go ahead a single step in future. Our
day-to-day life requirement is fulfilled by polymeric products. Polymers
that are used in medical applications include naturally occuring materials
like natural rubber and cellulose. Synthetic bio-materials include silicone
rubber, polyvinylchloride, nylon, polytetrafluroethylene, polyethylene
terephthalate and polyurethanes.
Polyurethanes have a broad range of applications, including
machinery, transport, furnishings, textiles, paper making, packaging,
adhesives and sealants and medicine. The outstanding mechanica
properties and bio-compatibility of the polyurethanes make them some
of the most promising synthetic bio-materials.
Recently the use of renewable resources have gained
considerable importance as potential sources of energy and an
alternative energy sources to the ever preceding fossil based
derivatives. The recent need of high speed aviation radio engineering,
rocket technology and extreme conditions in space, magnetic belt and
radiation fluxes demanded new and heat resistant materials. So
polymer technology is now in search of novel materials which can
withstand prolonged exposure to high temperature.
Anacardium occidentale Linn. (Fam. Anacardaceae) commonly
known as "Mundri" in Tamil and "Kajutaka" in Sanskrit is cultivated in
plenty in the neighbouring Kanyakumari District (Fig. 1.1). After
r
2
removing the cashew nut, the shells are being wasted as a firewood
material in cottage industries. These cashew nut shells can be used as a
raw material for obtaining the most valuable Cashew Nut Shell Liquid
(CNSL) and also the monomer, cardanol for the synthesis of novel
polyurethanes.
Fig. 1.1 Cashew tree with cashew apple
1.1.1 Origin of the cashew tree
Cashew tree, native to Brazil is extensively cultivated in
Anadaman Islands, East Africa, Tanzania, Mozambique, Philippines and
other tropical countries" 2 . In India it is grown in the states of Kerala,
TamilNadu, Karnataka, Andhra Pradesh, Maharashtra, Orissa, West
Bengal, Assam and Goa. In Tamil Nadu, it is grown in Kanyakumari,
Pudukkottai and Cuddalore districts. Ohler has given an extensive
review' , ' on cashew growing with climate.
Cashew nut attached to a cashew apple as a grey coloured
kidney-shaped structure and is 2.5-4 cm long (Fig. 1.2). Cashew nut
consists of an ivory coloured kernel covered by a thin brown membrane
(testa) and enclosed by an outer brown porous shell that is the
mesocarp, which is about 3 mm thick and contains CNSL (Fig. 1.3). The
nut thus consists of the kernel (20-25%), the shell liquid (CNSL)
(20-25%) and the testa (2%), the rest being the shell. The kernels
freed from testa contain 1.6% water, 10% protein 5 , 57.4% fat, 5.3%
carbohydrate, 2.4% ash and 0.9% fibre6.
Fig. 1.2 Cashew apple with nut
Fig. 1.3 Cashew nut (with shell opened)
CNSL occurs as a reddish-brown liquid in the soft honey comb
structure of the shell of cashew nut. It is obtained in India as a
byproduct during isolation of the kernel by roasting the raw nuts in an
open or perforated rotating drum 7 . CNSL either leaks away or is burnt
in the fire. During this treatment the CNSL is polymerised.
1.1.2 Extraction of CNSL
Hot oil process8 and roasting process9' 10 are the two processes
which are used mainly in the extraction of CNSL
1.1.2.1 Hot oil process
This is the most common method of commercial extraction
largely used in Quilon and other areas in kerala. The raw nuts are
passed through a bath of hot CNSL (180200 0 C) itself, when the outer
part of the shell bursts open and releases CNSL (50% recovery).
Another 20% could be extracted by passing the spent shells through an
expeller and the rest by solvent extraction techniques". The expeller oil
however does not satisfy IS specifications and needs upgrading. This
can be done by acid washing followed by centrifugation and heating12.
Most industries follow the hot oil process, because it directly gives
cardanol due to decarboxylation of anacardic acid. Because of the
growing demand for cardanol or cardanol enriched CNSL, the hot oil
process has acquired reasonable significance.
1.1.2.2 Roasting process
In an Italian paten t13, the shells are scraped in rotary apparatus
with sand, steel and wool, heated to 100-300 0C for an hour and then
roasted to 400-700 0C in an inert atmosphere, when the oil again oozes
out.
^H
159
(i)
OH
H
-I15 29
(3)
5
1.1.2.3 Refining
CNSL contains sulphides, nitrogenous materials and minerals as
impurities, hence it needs refining. A number of acid treatment
methods, have been suggested for getting improved quality of CNSL'4'6
In these methods the crude CNSL is treated with aqueous solution of
acids such as hydrochloric, sulphuric, phosphoric and sulphates such as
sodium hydrogen sulphate. The refined CNSL is distilled under reduced
pressure. When steam is allowed to pass through sulphuric acid treated
CNSL followed by distillation, a decolourised form of CNSL is obtained.
1.1.3 Chemistry of CNSL
The principal components of natural CNSL are 3-pentadecenyl
phenol called cardanol (1), 3-pentadecenyl resorcinol called cardol (2),
3-pentradecenyl salicylic acid called anacardic acid (3) and 2-methyl-5-
pentadecenyl resorcinol called 2-methyl cardol (4).
OH
15 H 29
6
OH
H 3 C
CHHO 15 29
(3) (2) (4)
1.1.4 Composition of CNSL
The composition of CNSL has been studied by various
investigators 1721 . Cold extracted CNSL consists mainly 90% anacardic
acid and 10% cardo1 2223 . Tyman showed that cold extracted CNSL
contains 82±1.05% anacardic acid, 13.8±0.17% cardol, 2.6±0.16%
2-methyl cardol and 1.6±0.17% cardanol by the use of gas-liquid
chromatographic methods 24 . During commercial extraction under hot
conditions the anacardic acid fraction of CNSL gets decarboxylated to
cardanol 25 . Commercial CNSL contains cardanol (83±0.51%) and cardol
(2.7±0.34%) as the major constituents. Murthy et al. 26 have reported a
higher content of cardanol (94.6%) and the absence of anacardic acid in
distilled CNSL. The phenolic composition of natural and technical CNSL
and IS specification for CNSL are presented in Tables 1.1 and 1.2.
7
Table 1.1
Phenolic composition of natural and
technical CNSL (Mozambique Origin)
Values are in %Component
Natural CNSL Technical CNSL
Cardanol 1.20 62.86Cardol 11.31 11.252-methyl cardol 2.04 2.08Anacardic acid 64.93 -Unknown phenolic compound 20.30 23.80
Table 1.2
I S specification for Cashew Nut Shell Liquid (CNSL)
Characteristics
Specific gravity 30/30° C
Viscosity at 30° C, Cp (max.)
Moisture % by weight (max.)
Matter insoluble in toluene °h by weight (max.)
Loss in weight on heating % by weight (max.)
Ash % by weight (max.)Iodine value (a) Wij's method
(b) catalytic methodPolymeric (a) Time, mm.
(b) Viscosity at 30°C(c) Viscosity after acid washinq at 30° C
Requirement
0.950-0.970
550
1.0
1.0
2.0
1.0250375430200
M[S1
1.2 APPLICATIONS OF CNSL
Compared with the conventional phenolic resins, CNSL
polymers have improved flexibility (due to the internal plasticization
effect of the long side chain) and hence better processability 27 . CNSL
forms the basic raw material for vast number of industrially imported
chemicals and chemical ingredients. A few of these include the use as
bactericides, fungicides, insecticides, dyestuffs etc 2829 . CNSL and its
derivatives have been found to be useful as ion exchangers 30 ' 31 , surface
active agents32 . The literature on CNSL is replete with innumerable
paten ts3336 , reports37 and reviews3840.
1.2.1 Use as friction materials
The major user of CNSL is the brake lining industry, which uses
mostly CNSL-modified phenolic resins and CNSL-based friction dust.
Brake linings and clutch facings based on CNSL resins have the property
of absorbing the heat generated by friction in the braking action while
retaining their braking efficiency longer. Brake linings and clutch facing
based on CNSL show very low fade characteristics and very high
recovery. CNSL-furfural reaction products show unusual evenness of
frictional characteristics over wide temperature ranges 4 ' (a significant
behaviour for a Friction material). A number of friction material
formulations based on CNSL polymer with improved abrasion resistance
have been patented 42-44. CNSL-based resins and cashew dust have been
used for preparing corrosion and skid-resistant friction materials4546.
1.2.2 Use as surface coatings
CNSL or its derivatives are used as anticorrosion primers, black
enamels and marine paints. Baking enamels were prepared by
condensing CNSL with formaldehyde in the presence of linseed oil and
turpentine. CNSL-formaldehyde condensation product in alkaline
medium on styrenation gives a resin which can be applied as a varnish
or pigmented to yield an enamel or paint. Varnishes resistant to water
and gasoline were prepared by incorporating sulphur in CNSL. Surface
coatings based on CNSL were prepared from formaldehyde, styrene,
hexamine and epichiorohydrin for the protection of bamboo surfaces47.
Insulating varnishes made by condensing CNSL with an alkyl ortho ester
can be used as such or after modification by cooking in drying oils.
Lacquers made from CNSL could be used for insulation, protective or
decorative coatings for furniture, buildings, and automobiles4849.
1.2.3 Use as Speciality Coatings
Specialty coatings for wooden surfaces of fishing boats have
been reported 5051 . CNSL-formalin reaction products give coatings with
improved heat resistance, flexibility and adhesion. Oil-modified alkyd
resins find wide use in surface coatings industry and printing inks.
Molten mixture of CNSL, asphalt, rubber and petroleum resin could be
used as a "rust-proof" tacky composition. Shellac-CNSL reaction
product can be used as a coating composition. CNSL distillation residue
10
is used as a coating for increasing the durability of light-roofing
corrugated sheets.
1.2.4 Use as adhesives and binder resins
CNSL - based adhesives have admirable properties to meet the
growing demand for quality and durability in timber and timber-based
products. The characteristics of saw dust boards improved markedly on
treatment with CNSL-based resins. Another new use for cashew phenol-
formaldehyde resin is in bamboo-based building boards. CNSL, modified
with furfural, aniline, xylol etc. also gives good plywood adhesives52.
CNSL-xylene-formaldehyde based compositions have been prepared as
binder resin for particle boards5354.
1.3 APPLICATIONS OF CARDANOL
The major constituent of CNSL which is separated after the
vacuum distillation is a meta-substituted phenolic compound called
cardanol. It can be converted into different varieties of polymeric
products which have a lot of industrial applications, such as surface
coatings, friction resistant components, laminates, moulding materials,
rubber compounding ingredients, ion exchange membranes, adhesives,
paints, varnishes, lacquers and binder resins5556.
In general polymers from cardanol are prepared by either
condensation with highly active aldehyde such as formaldehyde, furfural
etc. or by chain polymerization reaction through the unsaturation in the
11
side chain using acid catalysts. The hydrocarbon side chain itself by its
very presence imparts new properties such as internal plasticization,
flexibility etc. A study by Pillai et al .51-59 has shown that high
performance and speciality polymers could be produced from cardanol
by a variety of methods.
1.3.1 Use as adhesives and binder resins
Cardanol derivatives are extensively used in laminating industry
for reducing brittleness and improving the flexibility of laminates
produced by the co-condensation of phenol, CNSL and formaldehyde,
the resins improve resistance to heat, minimize age-hardening and
improve bonding of the reinforcement materials like paper, cloth and
glass fibre to the matrix. National Chemical Laboratory, Pune has
developed a process for the preparation of cardanol-based polyurethane
adhesives34 . No-bake core binders, used by metal casting industry, are
reported to have been prepared by reacting isocyanate with cardanol-
paraformaldehyde and cardanol alkyd resins60 . Aqueous emulsion of
cardanol is used for coating plywood for laminating purpose. Epoxy-
resins have been prepared by reacting cardanol -forma ldehyde resins
with epichiorohydrin. Major uses of the epoxides are: as protective
coating materials, auto primers, linings for cans, drums and pipes,
bonding and adhesive applications, potting and encapsulation of
electrical and electronic components and in electrical laminates6163.
12
Aggarwal and Satpute reported 64 the synthesis of cardanol- based epoxy
flexi bilizens for composite propellants.
1.3.2 Use in Moulding Compounds and Rubber
Cardanol-cresol formaldehyde resin is reported to give excellent
vulcanizate properties when suitably compounded with rubber. Modified
novolac resin from cardanol and paraformaldehyde on isocyanate
modification gave higher values of tensile strength, modulus and
hardness in natural rubber vulcanizates 65 . Cardanol when used as a
plasticizer in natural rubber improved its tear strength, solvent
resistance and ageing properties. Cardanol is used as a dispersant and
plasticizer66 . The esters and ethers from cardanol are used as
plasticizers (extenders) for the compounding of PVC 67. The monoester
of cardanol with fatty acids and phenyl ether have been synthesised and
have been investigated as extenders in PVC68. Cardanol or dimerised-
cardanol has been reacted with paraformaldehyde to give novolac
resins, which with epichlorohydrin produced epoxy novolac resins69.
These products are found useful as surface coating materials. The films
of the above product are very much flexible and water resistant.
Cardanol dialcohols prepared by Ghatge et al. have been used 70 to make
modified phenolic resins for utilization in synthetic and natural rubber.
Cardanol-based resoles and modified resoles have been synthesised and
utilized for the vulcanization of butyl rubber by Ghatge and Shindle71.
13
1.3.3 Use in textile industry
Cardanol is used for the synthesis of polyisocyanato phosphorus
compounds72 . These are used for making water repellant finishes to
c-01A4'Lcl
natural and synthetic textiles and paper. The phosptoius containing7kospho.-r1k- pfmc-o-peuf,ds iare used n polypropylenes for modification in heat and lightst o-6 L LL the poL- '' Ctcir pho$o--ustabiIfty 3 . Similarly pospheis polyisocyanates,, prepared from
cardanol are used in flame and glow resistance to cellulose textiles. Silk
and Art Silk Mills Research Association, India has recommended the+±L LLki-L, Lc1L
treated textile samples as useful in shower proof cloth72.A
1.3.4 Use as industrial chemicals
1.3.4.1 Bactericides, fungicides, insecticides, disinfectants
Chlorinated products of cardanol and hydrogenated cardanol
are found to possess pesticidal action34.
1.3.4.2 Emulsifiers and surface active agents
Cardanol, tetra -hydrocardanol and their ethers are suiphonated
under different conditions and neutralized with various bases to give
emulsifiers and surface active agents for a wide variety of application S34.
1.3.4.3 Anti oxidants
Cardanol and its derivatives are used as antioxidants. They are
also used as stabilizers against light, air and heat for several organic
materials, such as flavour-s 1 foods, lubricants, polymers and rubbers7475.
A new and efficient synthesis of ortho- and para-benzoquinones of
14
cardanol derivatives by the catalytic system MeRe0 3-H 202 has been
reported".
1.3.4.4 Stabilizers
Cardanol condensed with epichlorohydrin and polyepoxidised
resins are found to be good stabilizers for poly vinyl chloride7778.
1.3.4.5 Polymerisation
Oligomerisation of cardanol has been studied by Patni et al.79
Synthesis of a self-cross linkable polymer from cardanol and its curing
mechanism have been studied by Pillai et al80.
1.3.4.6 Curatives
Cardanol-based resols and isocyanate modified resols used for
the vulcanization of styrene-butadiene rubber were found to impart
superior physical properties to the vulcanizates. Poly aminophenol epoxy
resins impart good curing properties to rubber-8'.
1.3.4.7 Miscellaneous applications
Chen et al. 82 reported the synthesis of 6 titanate coupling
agents using cardanol which had high reactivity and good hydrolytic
stability. Ghatge et al. 83 reported the preparation of a self catalytic resin
from cardanol. Formaldehyde and diethanolamine which are blended
with polyethylene glycol and resultant blend on treatment with polymeric
diphenylmethane diisocyanate (MDI) yields urethane foams of different
densities.
15
1.4 CHEMISTRY OF POLYURETHANE
There are a number of methods leading to the
formulation of polyurethanes. But, the reaction of an isocyanate with an
alcohol, leading to polyurethane formation is the commercially important
method.
n OCNRNCO + n HOR'OH OCN(RNHCOOR')OH
Diisocyanate Polyol Polyurethane
Isocyanates which have highly unsaturated -N=C=O group can
react with themselves or with all compounds containing active hydrogen.
In the reaction with those compounds containing active hydrogen, the
hydrogen atom becomes attached to the nitrogen of the isocyanate and
the remainder of the active hydrogen compound becomes attached to
the carbonyl carbon. The most important groups that can react with the
isocyanates are the amino and hydroxyl groups (Eq. 1 - Eq. 5).
0
R-N=C=O + H-A R-NH-C-A
0
R-N=C=O + R'NH2 01 R-NH-C-NH-R'Urea
(Eq. 1)
(Eq. 2)
0
R-N=C=O + R'OH
R- NH-C-OR'
(Eq. 3)Urethane
16
0
R-N=C=O + HOH
R-NH-C-OH
RNH2 + CO2 (Eq. 4)
0
R-N=C=O + RNH2 R-NH-C-NH-R
(Eq. 5)
Urea
Secondary reactions that are important in the formation of
urethane polymers are those with urea (Eq. 6) and urethanes (Eq. 7):
0
R-N=C=O + R-NH-C-NH-R R-N-CONHR
CON HR
Biuret
(Eq. 6)
0
R-N=C=O + R-NH-C-OR'
R-N-COOR'
CON HR
Allophanate
(Eq. 7)
17
A further cross linking reaction which occurs under basic
conditions is the reaction of the isocyanate groups themselves to form
isocyanurate trimers.
0
RN R
3RNCOOC/ 0
Theories of network formation by additional cross linking of
polyurethanes due to biuret and allophanate formation have been
studied by Karel Dusek 84 . The reaction of isocyanates with polyols to
form polyurethanes85 proceeds readily under the influence of catalysts.
If the reactants are liquid then mixing at ambient temperature in the
correct ratio is all that is required. Sometimes post heating is carried
out to complete the reactions.
Development of polyurethanes is generally taken up by
appropriate selection of dihydroxy compound and polyol. Although
polyurethanes obviously contain urethane groups, they also contain
other groups such as ester/ether groups, aromatic ring/aliphatic long
chains etc that affects the properties of the polymers. Greater changes
in the properties of polyurethanes result from varying structure of the
major component of the polymer, the polyol and the dilsocyanate.
Variety of polyurethane 86-89 products can be developed by varying these
components.
18
1.4.1 Polyurethane foams
Urethane foams are formed from diisocyanateS and hydroxy-
terminated polyethers or polyesters. Linear or only slightly branched
polymers produce foams, whereas more highly branched polymers
produce rigid foams90 . Foams are produced by mixing all ingredients in
one step process. The reactions can be more readily illustrated if they
are in steps (the pre-polymer process). The first reaction is between
excess dilsocyanate and the hydroxyl containing polymer (Eq.8) to give
isocyanate terminated pre-polymer and excess diisocyanates. These
products are formed with water (Eq.9)
4(RNCO) 2+HO-w'-OH OCN-R-NHCOO--w'OOCNHRNO+ 2R(NCO)2
(Eq.8)
OCN-R-NHCOO OOCNH-R-NCO + 2R(NCO)2
H20
ifOOCNHR-NHCONH-R-NHCONHRNHCONHR w'-. + CO2t
(Eq.9)
Thus foams are the polymers containing the polyesters or
polyethers. Polyurethane foams are widely used and well known. They
are available in flexible, semi-rigid, and rigid foams in a number of
different densities. Various flexible foams are used as cushioning for
furniture, automobile seating, and mattresses. At higher densities, they
are cast or moulded into drawer fronts, doors, mouldings and complete
19
pieces of furniture. Flexible foams are open-celled structures that may
be used as artificial sponges. Semi rigid foams find use as energy-
absorbing materials in crash pads, arm rests and sun visors. Replicas of
wood carvings, decorative parts and mouldings are produced from high
density, self-skinning foams. The insulation value of these foams makes
them an ideal choice for insulating refrigerators and refrigerated trucks
and railroad cars.
Rigid polyurethane is a closed cellular material produced by the
reaction of toluene diisocyanate (TDI) with polyether and reactive
blowing agents such as monofluorotrichloromethane (fluorocarbon).
Diphenylmethane diisocyanate foams have better dimensional stability
than the other foams.
1.4.2 Polyurethane coatings
By proper formulation of various resins and isocyanates,
coatings could be produced that exhibit flexibility, improved resistance,
toughness, hardness, weatherability, chemical and abrasion resistance.
Poly functional polyester based on adipic acid, phthalic anhydride,
ethylene glycol, trimethylol propane etc. are generally used for the
preparation of two component polyurethanes91 . One component
polyurethane coatings have also been developed by reacting a stable
isocyanate terminated pre-polymers and a poly-functional polyether92.
Blocked isocyanate is used in the development of one component
urethane coatings. Urethane coatings prepared from toluene 2,4- and
20
2,6- dilsocyanates are found to exhibit excellent properties. However
they exhibit poor colour stability when exposed to ultra-violet
radiation 93 . Polyurethane coatings with outstanding light stability could
be produced by using aliphatic diisocyanates like hexamethylene
diisocyanate in the place of aromatic diisocyanates94.
1.4.3 Polyurethane elastomers
Solid polyurethane elastomers such as millable gums, cast
elastomers and thermoplastic polyurethanes have been prepared95.
Mutable gum is prepared usually with a hydroxyl component in slight
excess and cured by incorporating a polyisocyanate and heating under
pressure. Cast elastomers have been prepared by pre-polymer
technique 96 . The pre-polymer is formed by reacting a diisocyanate with
hydroxyl terminated polyester or polyether to form an isocyanate
terminated pre-polymer (Eq.10)
OCN-R-NCO + HO-R'-OH go OCN-R-NH-C-OR'-O-C--NH-R-NCO
11 il0 0 ........
(Eq.10)
The pre-polymer is then further reacted with an active
hydrogen compound such as glycol, diamine or tn-functional polyol such
as trimethylol propane. Chain extension using the glycol takes place with
the formation of urethane groups as shown in Eq.11.
OCN-R-NCO + H0-R"-OH '. OCN-R-NH-C-O-R"-O-C-NH-R-NCO
0 0(Eq.11)
21
When diamines are used as the chain extender, substituted
urea linkages are formed. (Eq.12)
OCN-R-NCO + H 2 N-R"-NH 2 30. OCN-R-NH-C-NH-R"-H-C-NH-R-NCO
11 110 0
(Eq.12)
Polyurethane elastomers have remarkable resistance to
solvents including gasoline, aliphatic hydrocarbons and aromatic
hydrocarbons'. Polyurethane elastomers have a wide number of
applications that include flexible coupling connectors, earth removing
equipment and farm machinery. They are used for conveyor rollers,
drive sprockets, cable jacketing and bumpers; common uses of cross
linked thermosetting elastomers include shoe heels, 0-rings, pump
impellers and tread stock for tires98.
1.4.4 Polyurethanes in bio-medical applications
Polyurethanes have got an ample number of bio-medical
applications99 . Polyurethanes have been used in the artificial heart'°°,
hollow fibre dialysers as a potting medium for embedding the fibres in
the outer casing 101 , heat exchanger component of oxygenators'° 2 , breast
implant devices 103 and implants in dentistry, urology, cardiology and
wound dressings. Several groups of workers have investigated the
potential applications of polyurethanes as components in sensors
inc!uding glucose sensors 104 and as ion selective membranes in
potentiometric sensors. In addition, because of their diverse properties,
L-xylene diisocyanate (9).
?H3
NCO
FtJco
CH 3
OCN NCO
(5) (6)
22
they have also been investigated for in use as nerve guides, artificial
corneas, and intraocular lens '°5 , in vertebral discs106 , sutures, repair of
cartilage defects, foam casts, tympanic membranes and nipple
prosthesis'° 7 . Polyurethanes are also used to support or assist in medical
imaging and surgery. Polyurethane resins are used to make "belly
boards" to enhance CT scanning of pelvic malignancies108.
1.5 RAW MATERIALS FOR POLYURETHANE SYNTHESIS
Generally, polyurethanes are synthesised using appropriate
materials, diisocyanates and polyols.
1.5.1 Diisocyanates
The commercially available diisocyanates are 2,4- toluene
diisocyanate (5), 2,6- toluene diiscocyante (6), 4,4'-diphenylmethane
diisocyanate (7), hexamethylene diisocyanate (8) and tetramethyl
OCN-_K) —CH 2 NCO
(7)
—CCH3
CH
LLjC—NCO
C H3
H(CH2)6
(8)
NCOOCN
(9)
23
1.5.2
Polyols
The commonly used polyols are poly (oxytetramethylene) glycol
(10), 1,2,6- hexane triol (11), sorbftol (12), trimethylol propane (13),
propylene glycol (14), ethylene glycol (15) and 1,3 butylene glycol
(16).
H (O-CH 2 -CH 2 -CH 7 -CH 2 ), OH
(10)
OH
HO-CH2-CH-CH2-CH2-CH2-CH2--j
(11)
OH H OH OH CH2OH
HOCH c-c- C— C---CH2OH CH3CH2— —CH 2OH
H OH H H CH2OH
(12) (13)
24
HO-CH2-Ch-OH HO-CH2-CH2-OH
CH3 (15)
(14)
HO-CH2-CH2-CH-CH3
[111.(16)
1.5.3 Diols / Diamines
The commonly used dios are ethylene glycol (15), 1,4- butane
diol (17), 1,6- hexane dio! (18) and xylene a, a'- diol (19).
HO-CH2-CH2-CH2-CH2-OH HO-CH2-(CH2)4-CH2-OH
(17) (18)
CHOH
áCH2OH
(19)
25
The commonly used diamines are 4,4'-diamino diphenyl
methane (20), 3,3'-dichloro-4,4'- diamino diphenylmethane (21),
benzidine (22), 3,3' dimethyl benzidine (23) and p-phenylene diamine
(24).
H2 N—Q._ C NH2 2 HN— CH2 2
(20) (21)
CH
2 Nd2 H2N-NH
(22) (23)
NH7óNH2
/4/ VIP
(24)
26
1.6 SCOPE OF THE PRESENT WORK
In recent years, emphasis has been given on effective
utilization of naturally available and renewable resources for the
development of raw materials for various polymer based products.
Cashew Nut Shell Liquid (CNSL), and one of its ingredients, cardanol can
be successfully exploited for the development of phenolic resins for the
manufacture of different industrial products. The multi functional role of
cardanol and cardanol pre-polymers has been well documented in the
literature in the last few years and it has left many options open to
derive useful products out of this agricultural by-product. The phenolic
nature of cardanol has prompted different researchers to react it with
formaldehyde or with other aldehydes to produce numerous resinous
materials just like those produced from phenol. An umpteen number of
literature has been cited in the previous sections of this chapter
highlighting the utilization of o- and p- functionality of cardanol. Besides,
cardanol has an acidic-phenolic hydroxyl group and a long meta-
substituted unsaturated hydrocarbon side chain which can be exploited
fruitfully, for carrying out further chemical reactions, leading to new
polymers.
There is an ample scope for extending the hydroxyl
functionality by reacting with epichiorohydrin and hydrolyzing the epoxy
resin to a high molecular weight nucleophilic compound containing
flexible as well as rigid molecular structures. Such a nucleophilic high
27
molecular weight compound can react with an isocyanate group which is
an electrophile to give urethane. Therefore, by carefully synthesising the
high molecular weight nucleophilic compound with various molecular
size, functionality and stereo regularity, it is possible to develop
polyurethanes having wide range of physico-chemical and mechanical
properties as well as high performance characteristics.
The currently available polyurethanes do not meet all the
requirements of long term reliability under various ageing conditions.
Polyurethanes having a synergistic structural architecture which can
meet various requirements such as physico-chemical, mechanical and
thermal properties, stability against thermal, hydrolytic and oxidative
degradations, stability under ageing conditions such as low and high
temperature ageing, chemical environment etc., need to be developed.
Cardanol-based active hydrogen compound containing various chemical
groups is a choice of raw material for the development of such
polyurethanes, as the systematic attempts are rather scanty. Further,
the fact that CNSL is a renewable natural resource abundantly available
at a low cost, adds to the scope of such an endeavor. The synthesis and
characterisation of polyurethanes based on cardanol is an attempt in this
direction.
1.7 OBJECTIVES OF THE PRESENT WORK
(I) To synthesise and characterise cardanol-formaldehyde high
ortho novolac resins.
(ii) To synthesise and characterise high molecular weight
multinuclear compound with hydroxyalkyl nucleophilic end
group using cardanol -forma ldehyde high ortho novolac resins.
(iii) To synthesise polyurethanes using various dilsocyanates and
cardanol-formaldehyde resins / hydroxyalkylated cardanol-
formaldehyde resins and to evaluate the material properties.
(iv) To synthesise polyurethanes using various dilsocyanates and
cardanol-formaldehyde resins / hydroxyalkylated cardanol-
formaldehyde resins and commercially available polyol,
polypropylene glycol 2000 (PPG-2000) and to evaluate the
material properties.
(v) To evaluate the energy of activation of the newly developed
polyurethanes using Coats Redfern equation and also to
perform regression analysis of a few candidate polyurethanes.
(vi) To evaluate the performance of the newly developed
polyurethanes under various ageing conditions and also to test
the biodegradability of the synthesised polyurethanes.
29
1.8 REFERENCES:
1. I.H.P. Tyman, Chem.soc..Rev.,8, 499 (1979).
2
R.J. Wilson, 'The Market for cashew nut kernels and cashew
nut shell liquid'., Tropical products Institute, London (1975).
3
J.H. Ohier, Tropical Abstracts.., 22, 4 (1967).
4
S. Singh, S. Krishnamurthy and S.L. Katyal 'Fruit culture
India'., ICAR, New Delhi (1967).
5. G.Lossner, Beitr, 'Trop. Subtrop. Landwirt Tropen
Veterinaermed'., 9, 131 (1971).
6. J.H.P. Tyman and S.K. Lam, Lipids., 13, 525 (1978).
7. A.R.R. Menon, J.D. Sudha, C.K.S. Pillai and A.G. Mathew, J.Sci.
Ind. Res., 44, 324 (1985).
Ii'
S.A. Compagine coloniale due Angoche Swiss pat., 311, 789
(1956).orL pLcbrv o phri
9. W. Knop and A. Scheib, 'chemistry and Application of-Phenolic7L 0 \ j-rvl'i-- r -.o p H.s cu-cL opLCI crn2'
resins polymer properties and Applicat-lons'., Springer Ve rI u g,
Berlin (1979).
10. C.K.S. PiIlai, Pop.plast &packaging., March issue (1997).
11 D.C.Russel, 'FAQ Agricultural Service Bulletin'., (FAO, Rome),
73-75 (1969).
30
12. A.G.Mathew, C.Balachandran, C.Krishnaswamy, and
H.Sreemulanathan, Proceedings of the Third Annual
Symposium on plantation crops-placrosym 111., edited by
K.V. George (Central plantation crops Research Institute,
Kasaragode) (1980).
13. G.Natta and R.Ripa monti, Ital.pat., 476,540 (1952).
14. S. Caplan, U.S. Pat., 2559, 593 (1951).
15. British Resin products Ltd. Br. Pat., 664169 (1952).
16. S.H. Park and C.K. Lee, Kungnip Kongop Yonguso pago., 21,
81 (1971).
17. A.A. Durrani, J.Chem. Technol. Biotechnol., 32, 681 (1982).
18. A.K. Misra, Chem. Age. India., 27, 944 (1976).
19. P.H. Gedam, P.S. Sampathkumaran and M.A. Sivasamban, Ind.
J. Chem., 10, 388 (1972).
20. R. Paramashivappa, P.P. Kumar, P.J. Vithayathil, and A.S. Rao,
J. Agric Food Chem., May; 49(5): 2548-51, (2001).
21. P.Phani Kumar, R. Paramashivappa, P.J. Vithayathil, P.V. Subba
Rao and A.J.Srinivasa Rao, Agric Food Chem., July 31; 50(16):
4705-8 (2002).
22. G.D. Gokhale, M.M. Patel and R.C. Shah, Curr. Sci., 9, 362
(1940).
23 S.Ruhemann and S.Skinner, J.Chem.Soc., 51,663 (1887).
24 J.H.P. Tyman, Anal. Chem., 48(1), 30(1976).
31.
25. K. M. Nair, E.V.V. Bhaskar Rao, K.K.N. Nambiar, and
M.C.Nambiar, Eds., cashew (Anacardium occidentale-L)
Monograph on plantation., C. P.C. R.I. Kasargode, Kerala,(1979).
26. B.G.K. Murthy, M.A. Sivasam ban and J.S. Agarwal, Ind. J.chem.,
3, 33, (1965).
27. Cashew nut shell liquid patents - USA vol.1 (Cashew Export
promotion Council, Ernakularn) (1964).
28. M.T. Harvey, U.S. Pat .,2, 36712 (1944).
29. Harvel Corp, Br.pat .,627, 926(1949).
30. H.A. Shah and S.L. Batna, J.Appl Chem., 3, 335 (1953).
31. N. Krishnaswamy, K.P. Govindan, and R.N. Pandya, Chem.
md., (London), 1456 (1957).
32. K.G. Kurda and M.R. Kamath, Br. Pat., 591, 906 (1947).
33. Cashew nut shelf liquid patents - UK, Indian and Japan, vol.
II, cashew nut Export promotion council, Ernakularn (1964).
34. Cashew nut shell liquid - Extraction and uses- a survey of
world patents up to 1976, Cashew Nut Export Promotion
Council, Emakulam (1978).
35. Indian cashew nut shell liquid - A Versatile Industrial Raw
Material of Great promise -- Regional Research Laboratory,
Trivandrum and Cashew Nut Export promotion council, Ernakularn
(1978).
36. Production and utilization of cashew nut shell liquid in India
Cashew Nut Export promotion Council, Cochin (1977).
32
37. A. K. Mishra and G.N. Pandey, J.AppI.Polym.Sci., 26, 361
(1984).
38. C.K.S. Pillai, Pop. Plast & Packaging., November Issue (1993).
39. P.H.Gedam and P.S. Sampath Kumaran Prog.Org.Coatings., 14,
115 (1986).
40. B.G.K. Murthy and M.A. Sivasamban, Cashew causenic., 1, 8
(1979).
41. B.Golding, Furfural-phenol condensation in polymers and
Resins., (D. Van Nostrand co Inc, New Jersey) 255 (1959).
42. J.C. Adelmann, U.S. pat., 3959194 (to Johos-Manville Corp), 25,
May (1976), Chemical Abstracts, 8547987 x (1976).
43. Jap. Pat., 57123279 (to Hitachi Chemical Co. Ltd) 31, July 1982,
Chemical Abstracts, 98, 36677p (1983).
44. Jap. Pat., 57121080 (to Sumitomo Electric Industries Ltd), 28
July 1982, Chemical Abstracts 98, 36679r (1983).
45. Akebono Brake Kogyo, Jap Pat., 82108269 (1982), Chemical
Abstracts 97220904r (1982).
46. Hitachi Chemical Corporation Jap. Pat., 5881237 (1983),
Chemical Abstracts 100, 8075g (1984).
47. Indian Jr. Of. Chem. Technology.,, 4, p145-149 (1997).
48. Chemical Abstracts 95, 152239j (1981).
49. V. Madhu Sudhan, B.G.K. Murthy & M.A. Sivasamban, Cashew
Causerie., vi (2), 12-16 (1984).
33
50. M.R.Jayanth, S.P. Potnis and J.S.Aggarwal, J. colour sc., 16,
7-10 (1976).
51. R. Balasubramanian, and A.G. Gopala Krishna Pillal,on-tkQ-• - r4 SJdL aon-the—of-cashew - nu Shell quid-as
ou Q rtx-L c'w woorv c, .Q00±'a, surface coating material on- wooden- fishidg Boats, incw rut kll )U ,-c' vj&e cz- f-i-ote vv
Cashew nut Shell Liquid fr Maclie paints and protective
coatins (Central Institute of Fisheries Technology, Cochin)
p 15-19 (1979).
52. C.P. Dhamaney, Paint India., 28(9) (1978) 28(12) (1978)
32-33, 26(9) (1976) 19; 28 (10) (1978) 27-28; 29 (2) (1979)
27-28 & 29 (2) (1979) 5-8.
53. C.P. Dhamaney, J.colour,sci.., 16(3) 25-27 (1977) Paint India.,
30 (4) 7-8 (1980); 27(3) 19-21 (1977).
54. A.J. Hawkes, A.A. Durrani and J.P. Tyman, Eur..pat.Appin.,
15761; 17 Sep., 1980; Chemical Abstracts 93 240530m
(1980).
55. M.S. Ramaiah, V. Madhusudhanam, M.B. Naidu and M.A.
Sivasamban, Paint manuf., 43(11), 36 (1973).
56. British Resin products Ltd. Br. Pat., 742286 (1955).
57. C.K.S. Pillai et al, Rubber Plast.Annual II., (1987).
58. C.K.S. Piilai, RubbReptr.., 12, 145 (1988).
59. C.K.S. Pillai, V.S. Prasad, J.D. Sudha, S.C. Bera and A.R.R.
Menon, J.AppI.Polym.Sci.., 41, 247 (1990).
60. S.S. Mahajan and R.S. Khisti, Res & md., New Delhi, 29, 26-28
(1984).cLcrv 7J.w) rttt >k2iL Lq A v-rcôdci= I
61. Lndian Cashew nut-Shell-liquid - A-versatile industrial-raw-ti-L of Jj rr
rnaterial or gieat promise (Regional Research Laboratory,
Trivandrum, cashew Export promotion Council, Cochin (1983).
62. Chemical Abstracts 90, 123147u (1979); Chemical Abstracts
91, 124955p (1979).
63. Chemical Abstracts 97, 25197k (1982).
64. J.P. Aggarwal and R.S. Satpute, J.Macromol.Sci, pure and
AppI.Chem., 30, 19 (1993).
65. N.D Ghatge and N.N. Maldar, Rubb..Reptr., 6(1), 13-17 (1981).
66. K. Prabhakaran, Asha Narayanan, C. Pavithran J.Euro. Ceramic
Society., 21, 2873-2878 (2001).
67. P.T.I Science Service., 5, July 16-31 (1990).
68. N.D. Ghatge and S.V. Vailva, Die Aggewandte Macromoleculare
chemie., 43, 1 (1975).
69. N.D. Ghatge and D.R. Pati!, IndJ.Tech., 18,203 (1980).
70. N.D. Ghatge, B.M. Sinde and A.S. Mand patil, Rubber News.,
(India) 17 (1) 38 (1978).
71. N.D. Ghatge and B.M. Shinde4, J. Elastomerics., w (2), 48
(1979).
72. N.D. Ghatge and S.D. Yadav, colourage. Annual., 160 (1971).
73. U.S. Pat., 2, 898, 180 (1959).
35
74. A.R.R. Menon, C.K.S. Pillal and G.B. Nando, .7.AppI.Polym.Sci.,,
51, 2157 (1994).
75. E.L. Short, V. Tychopoulous and J.H.P. lyman .7.Chem.Tech.
Biotechnol., 53, 389 (1992).o, V Q ci ô y' Q M Cc, 1 eJt&. C - i-4 Q'} CA-CA* ). - LLpper76. , 7.Chem.ioc., Perkin Trans., I, 581-586 (2000).
77. E.Neuse and J.D. van Schalkwyk, SAfr.J.Sci., 72(8) 223 (1976).78. S.P.Vernekar, Indian.J.,Technol., 18,170-2(1980).
79. M.K. Trivedi, M.J. Patni and Lavleen Bindal, Ind,J.Technol,, 27,
281-284 (1989).
80. George John and C.K.S. Piliai, J. Polym. Sc., 31, 1069-1073(1993).
81. Chemical Abstracts s5, 178528w (1976).
82. Chen.Tianein, Linchan Huaxue Yu.Gongye., 6(3), 9 (1986).83. N.D. Ghatge, K.B. Gujar and S.S. Mahajan, Ind.J, Technol., 23
(5), 195 (1985).
84. Karel Dusek, Polymer Bulletin., 17, 481-488 (1987).
EMS J.Kenneth,V. Wynne, .J. Makal, and vUk, Polymer Reprints.,43(2)
791 (2002).
T.Lashanda ,James-Korley,S. Gregory, Pollock, Nikola Kojic, Man
sze Ko,H. Gareth. Mckinley and T. Paula, Hammond, Polymer
Reprints,, 43(2), 474 (2002).
87. T.Lashanda, James-Korley and T.Paula. Hammond, Polymer
Reprints., 43(1), 662 (2002).
36
88. Hongtu Li Jinghui Sun Hongwen Zhang Mingzhi Wu Jingyuan
Wang, Fangping Qiu Polymer Reprints., 43(2), 1065 (2002).
89. Alberto Mariani and Stefano Flori, Laura Ricco and Saverlo Russo,
Polymer Reprints., 43(2), 875 (2002).
90. G.F. Boumann in 'Polyurethane Technology', Interscience pub,
New York P 95 (1969) M. Kittel, Adhesion 21, 162 (1977).
91. H.L. Heiss, J.H. Saunders, M.E. Morris, B.R. Davis and E.E.
Hardy, Ind..Eng.Chem., 46, 1498 (1954).
92. R.L. Jacobs and J.W. Long, J. Elast.plast., 11, 15 (1979).
93. T.C. Patton in 'Polyurethane technology' C.P.F. Bruins Ed,
Interscience press New Delhi, p 215 (1969).
94. Farben fabriken,A.G. Bayer, Products for surface coatings,
Desmodur, Desmophan Ed. 1.6 p 14 (1966).
95. M.W. Riley, Mater.Design Eng., 50 (4)92 (1959).
96. E. Muller, Rubber plastics Age., 39(3) 195 (1958).
97. K.A. Pigot, R.J. Cote, K.Ellegast et al. Rubber Age., 91, 629
(1962).
98. L.Terry, Richardson and Erik Lokensgard in 'Industrial plastics,
Theory and Applications' Delmer publishers, Inc. (1983).
99. Nina M.K.Lamba, Kimberly A.Woodhouse and Stuart L.Cooper in
'Polyurethanes in Biomedical Applications', CRC Press, USA
(1998).
100. J.W.Boretos, W.S. Pierce, R.E.Baier, A.F. Leroy and H.J.Donachy,
J. Biomed..Mater.Res, 9, 327 (1975).
37
101. F.F. Lee, C.J. Durning and E. F. Leonard, Trans.Am..
Soc.Artif. Intern. Organs.,, 31, 526 (1985).
102. M.F. Roester,C.BulI and M.T. lonesus Cardiovasc.Surg., 21, 271
(1980).
103. F. R. Ashley, Plastic Reconstr.Surg., 45, 421 (1970).
104. T.Sternberg, M.B. Barrau, L. Gangiotti and D.R. Thevenot,
Bio sensors., 4, 27 (1988).
105. W.L. Jongebloed, G.Vander veen, D.Kalicharan and J.G.F. Worst,
Blo materials., 15, 766 (1994).
106. C.K. Lee, N.A. Langrana, J.R. Parsons and M.C.Zimmerman,
Spine., 16, 253 (1991).
107. G.G. Hallock, Ann.Plast.Surg., 24, 80 (1990).
108. T.G. Shanahan, M.P. Mehta, K.L. Berteirud and T.J.Kinsteila,
Int.J.Radiat.Oncol,Biol.Phys., 19, 469 (1990).