Rubber Manufacture, Processing and Value AdditionXPM 2119

Bandara Gajanayake PhDSenior Lecturer

Department of Plantation ManagementFaculty of Agric. and Plantation Management

Wayamba University of Sri Lanka

Rubber Manufacture, Processing and Value Addition

Evaluation Criteria

Assignments policy• Hand written answers for the questions in

assignment should be submitted on due date.

• Students are expected to do and submit their own answers to the assignment questions.

• Cheating and/or copying is not tolerated, and will result in an automatic failure for the assignment and thus subject.

Rubber Manufacture, Processing and Value AdditionAssignment

Q1) State the major contributing factors to the current price drop of rubber at the Colombo auction

Q2) A)Give the composition of natural rubber latex and list the factors responsible for the composition B) Illustrate a rubber particle using a diagram

Q3) List the parameters used in specification test in grading technically specified rubber and state the meaning of each parameter

Rubber Manufacture, Processing and Value AdditionAssignment

Q4) (i) List the unit operations in the manufacturing process of centrifuge latex and (ii) briefly discuss the important activities that need to be undertaken under each of the unit operations

Rubber Manufacture, Processing and Value AdditionAssignment (Cont…….)

Q5) (i) Briefly explain the fractionation process in crepe rubber processing industry and

(ii) Discuss in detail the processing steps of technically specified rubber from field latex

Q5) (i) List the manufacturing steps of RSS rubber and

(ii) briefly discuss the important activities that need to be undertaken under each of the unit operations

Rubber Manufacture, Processing and Value AdditionAssignment (Cont…….)

Q6) Write short notes of the followings(i) History and development of NR based

product manufacture(ii) Vulcanization process (iii) Importance of treating waste water from

rubber factory

Postharvest Processing of RubberFather of Sri Lankan rubber industry:

Sir Henry WickhamRRI of Sri Lanka is the oldest rubber research institute in the world and located in .

Rubber Technology Department of Sri Lanka RRI is located in Rathmalana.

Postharvest Processing of RubberImportance of Rubber:

Rubber Prices at the Colombo Auction:

Crisis in the Rubber Industry:

Postharvest Processing of RubberWhat is Rubber: Rubber is an elastomer—that is, a polymer that has the ability to regain its original shape after being deformed. Rubber is also tough and resistant to weathering and chemical attack. Elastomers can be naturally occurring polymers, such as natural rubber, or they can be synthetically produced substances or Synthetic rubber, (such as butyl rubber, Thiokol, or neoprene). For a substance to be a useful elastomer it must possess a high molecular weight and a flexible polymer chain.

Postharvest Processing of RubberComposition and Structure of Latex

The compositions of NR varies with1. Clone A= Rubber hydrocarbon2. Season B = Phospholipid layer3. Soil condition C = Protein Later4. Tapping method and frequency5. The Age of the tree

Chemical component % by weight of latex

1. Dry Rubber 30 - 35

2. Proteinous substances 1.0 - 1.5

3. Carbohydrate (sugar) 1

4. Lipids 1-2.5

5. Ash 1

6.Water 60 - 65

BBC

A

Why the preservation of latex after harvesting is very important?

.

Preservation of latexAcid development in Latex

CarbohydratesProteinsLipids

Short term preservation agentsSodium SulphiteAmmoniaFormalin

Long term preservation agentsAmmonia Boric AcidZnO ZDC (Zinc diethyldithiocarbomate)Lauric Acid

RSS• Major form of raw rubber produced in Sri Lanka (40%<)• Unit Operation of RSS manufacturing process

1. Latex collection2. Standardization (Standard DRC = 12.5%)3. Re-straining4. Sheet washing5. Milling6. Coagulation7. Dripping8. Smoking9. Grading and storing

Importance of Standardization of Latex in RSS manufacturing process

• Helps in achieving quality consistency of final RSS• Gives a softer coagulum which can be easily be

sheeted• Assist in faster settling of dirt• Improve the clarity of the sheets• Bringing down the viscosity of the latex thus

distributing the chemicals added to the latex more uniformly

• Facilitate the escaping of air and fermentation gases from the latex

Importance of each step in RSS manufacturing process

1.Latex collection2.Standardization (Standard DRC = 12.5%)3.Re-straining4.Sheet washing5.Milling6.Coagulation7.Dripping8.Smoking9.Grading and storing

Latex Crepe Rubber/Pale Crepe• Purest form of NR in the marketSteps in manufacturing process of LCR

1. Collection and preservation of latex2. Preliminary straining3. Weighing of latex4. Fractionation5. Addition of Sodium bisulphite6. Bulking and Standardization7. Bleaching8. Coagulation9. Milling10. Drying of laces

Concentrated Latex• Problems with preserved field latex for direct

commercial uses1. Low rubber content2. Very high water content3. Presence of non-rubber substances4. High transport cost

Unit operations in the centrifuge latex manufacturing process

1. Preservation in the field2. Reception of latex at the factory3. Removal of Mg4. Centrifuge process5. Post treatment of centrifuged latex6. Storage of centrifuged latex

TSRMarketed as Standard Lanka Rubber (SLR)

Should be able to explain each steps in processing of field latex into TSR

1. Preservation of Latex2. Bulking3. Coagulation4. Initial Processing5. Final Size Reduction6. Blending7. Drying8. Pressing9. Sampling and Grading10. Packing

TSR

Parameters used in specification tests for grading TSR

1. % Dirt content (amount of dirt reflecting the purity)2. % Ash content (mineral matter)3. % Volatile matter content (how much water)4. % N content (protein content)5. Initial plasticity (hardness)6. Plasticity Retention Index (PRI) [measure of oxidizibility of rubber]7. Colour (colour and purity)

Water Use in Rubber FactoriesPlentiful of water is required for the manufacture of rubber

- 30-50 L per kg of pale crepe- 50-60 L per kg of block rubber

•Dilution of latex•Washing away the serum substances •Preparation of solutions of chemicals•Cooling the mills•Cleaning the factory

• The required quality of water varies with the stage of manufacture

Waste Water in Rubber Manufacturing• NR plays a key role for both economic development

and industrial pollution.• Pollution happened mainly due to discharge of

untreated effluents into the surrounding area• There are over 160 raw rubber processing factories

producing mainly– Crepe rubber– Sheet rubber (RSS)– TSR– Centrifuged latex*

The nature of the effluent depends very largely on the type of raw rubber manufactured

Amount of Pollutant• Amounts of pollutants and their concentration

depends on variety of factors– Clone– Process– End product– Amount of dilution– DRC adjustment

Waste Water in Rubber Manufacturing• Average Effluent Quality Parameters

Product Type pH Typical BOD Total Solids

Block 5.7 1600-1800 1900

Sheet 4.9 2600 3750

Crepe 5.0 200-400 3500

Latex Concentrate 3.7-4.5 3000-4000 7500-13000

Importance of Dissolved Oxygen• NR• Pollution

Pollutant Abatement• Amounts

Abatement Protocols• Mandatory task• Many methods are used and the treatment

systems can be divided into – Primary : Recover rubber and remove large particles

through Screening, Floating, and Sedimentation– Secondary : Involves reducing the BOD of dissolved

material. Basically a biological process in which microorganisms digest the pollutants

– Tertiary : Provides the water a final polish before releasing. Done in extensive open ponds where aquatic life can be established