About elastomers, uses, types of elastomers

polymer science

1. COURSE CODE : PKC4050 PETROCHEMICAL TECHNOLOGY – II TOPIC: ELASTOMERS HATIF ALAM BELAL KHAN NISAR AHMAD MAHFOOZ B

2. 2 ELASTOMERS USES TYPES OF ELASTOMERS MAJOR ELASTOMERS STYRENE BUTADIENE RUBBER TYPES OF STYRENE BUTADIENE RUBBER PRODUCTION OF STYRENE BUTADIENE RUBBER POLY BUTADIENE RUBBER TYPES OF POLY BUTADIENE RUBBER PRODUCTION OF POLY BUTADIENE RUBBER REFERENCES

3. Elastomers are a type of polymer known for their elastic properties, meaning they can undergo significant deformation and return to their original shape when the applied stress is removed. These materials have a high elongation at break and a low modulus of elasticity. Elastomers find widespread use in various applications, including seals, gaskets, tires, adhesives, and other products that require flexibility and resilience. Elastomers 3

4. 4 Chemical structure of some common organic elastomer

5. 5 TYPES OF ELASTOMERS Following are the two types of elastomers: Saturated elastomers Unsaturated elastomers Saturated Elastomers:  Sulphur vulcanization can not cure them. They showcase superior stability against oxygen, radiation, heat, and ozone. Comparably they are less reactive. Their reactivity is limited to certain circumstances and conditions. Polyacrylic rubber and silicone rubber are examples of saturated elastomers. Unsaturated Elastomers:  They can be cured with the Sulphur vulcanization process. Butyl rubber and natural polyisoprene are examples of unsaturated elastomers.

6. 6 Property Elastomers Polymer Definition It is a polymer with very weak intermolecular forces and Viscoelasticity. Thus, they are famously known as elastic polymers. Is a macromolecule or large molecule made up of clusters of subunits. Physical property They inherit the unique property of elasticity. They inherit diverse properties based on the category. Morphology They are amorphous structure They vary from crystalline form to amorphous form. Flexibility They are elastic in nature. They are capable of configuring the right distribution of applied pressure to retain their original size and shape They are mostly brittle/ hard/rigid in nature except for elastomers. Application of force can result in permanent deformation

7. ELASTOMERS Major Groups Installed Capacity Production CAGR Products 2018-19 2019-20 2020-21 2016-17 2017-18 2018-19 2019-20 2020-21 STYRENE BUTADIENE RUBBER 271.00 271.00 277.00 167.33 193.97 228.64 227.83 212.91 6.21 POLY BUTADIENE RUBBER 114.00 100.00 100.00 117.09 113.63 122.23 130.25 128.55 2.36 ETHYL VINYL ACETATE 15.00 15.00 15.00 0.00 0.00 0.00 0.00 0.00 #DIV/0! NITRILE BUTADIENE RUBBER 25.30 25.30 13.70 0.35 0.05 0.00 0.00 11.88 140.69 GROUP TOTAL 425.30 411.30 405.70 284.78 307.66 350.87 358.08 353.34 5.54 7

8. STYRENE BUTADIENE RUBBER Styrene-butadiene or styrene-butadiene rubber (SBR) is a synthetic rubber copolymer consisting of styrene and butadiene. It has good abrasion resistance and good aging stability when protected by additives, and is widely used in car tiers, where it may be blended with natural rubber. Its common physical characteristics are - black in color, other colors can be compounded upon volume special request, 70 +/- 5 Durometer (hardness rating), excellent tensile strength and abrasion resistance at higher temperatures. 8

9. SBR Consumption Areas 9 9

10. Emulsion SBR (e-SBR) It can be produced by free-radical emulsion polymerization of styrene and butadiene. This takes place either at 50 to 60°C (hot emulsion SBR) or at about 5°C (cold emulsion SBR). Emulsion SBR (e-SBR) Hot emulsion SBR process  - SBR grades have exception processing characteristics such as: low mill shrinkage, good dimensional stability, and good extrusion characteristics The hot emulsion process leads to a more branched polymer than the cold process Cold SBR process  - SBR grades have better abrasion resistance. they provide better tread wear and dynamic properties. the cold process exhibits superior tensile strength than the hot process. TYPES OF SBR 10

11. Solution SBR (s-SBR) Solution SBR is produced by termination-free, anionic solution polymerization of styrene and butadiene with alkyl lithium initiator (e.g., butyllithium). This takes place in a hydrocarbon solvent, usually hexane or cyclohexane. Solution SBR has a narrower molecular weight distribution, higher molecular weight, and higher cis-1,4-polybutadiene content than emulsion SBR. s-SBR rarely has more than 2% non-rubber materials in its finished form. While e-SBR may have an emulsifier (soap) content of up to 5% and nonrubber materials sometimes in excess of 10%. Emulsion SBR (e-SBR) Solution SBR (s-SBR) Key Features Improved  flexibility  and performance Good resilience, tensile strength, and low rolling resistance when used in tires Outstanding resistance to abrasion and fatigue Low resistance to oil, other hydrocarbon fluids, and ozone Key Features Green strength becomes low with increasing oil extension Low resilience and low tensile strength Outstanding resistance to abrasion Low resistance to oil, other hydrocarbon fluids, and ozone Hot polymers are difficult to process with low green strength Poor tear strength High styrene resins have good low-temperature properties but stiffen 11

12. Property S-SBR E-SBR Tensile strength  (MPa) 36 20 Elongation at tear (%) 565 635 Mooney viscosity , 100 °C 48.0 51.6 Glass transition temperature  (°C) −65 −50 Polydispersity 2.1 4.5 uses Solution SBR's are the first choice to produce high performance tire tread compounds, particularly for silica filled tire treads for low rolling resistance tires and for the high-performance sector E-SBR is predominantly used in the production of passenger car and light truck tires. E-SBR is also used in truck re-treading compounds. 12

13. 13 Technologies Comparision Characteristics S – SBR e – SBR Polymerisation method Solution polymerisation hydrocarbon solvents Emulsion polymerization in aqueous medium Type of polymerisation reaction Anionic Radical Catalyst Different anionic catalyst normally n- butylithium Redox system Conversion of monomer 95-99 60-75 Styrene content 15-40 23-40 Structure of polymer Block or statistical Statistical Content of fatty acid <= 0.5 0.5<= but <= 0.6 MWD Narrow Wide Length of branched chain short Long https://go.gale.com/ps/i.do?id=GALE%7CA431199873&sid=googleScholar&v=2.1&it=r&linkaccess=abs&issn=0307174X&p=AONE&sw=w&userGroupName=tacoma_comm&aty=ip

14. 14 Emulsion Polymerization The flow diagram traces the emulsion process for manufacturing styrene-butadiene rubber. Fresh butadiene and styrene are received, stored, and blended with recovered butadiene and styrene. The two chemicals, along with a catalyst and soap solution, are pumped to the reactors where polymerization takes place. After the short-stop stage, in which an agent is added to the mixture in order to stop the reaction, unreacted butadiene and styrene are recovered for recycling and pumped back to the storage tanks. In the next stage , stripped latex is accumulated for blending, if required. The latex is then coagulated and converted into crumb and screened, washed, and filtered. Excess water is removed, and the crumb is dried in a hot-air dryer. It is then weighed out in 77-pound (35-kilogram) bales and wrapped in polyethylene bags for shipment. https://kids.britannica.com/students/assembly/view/53930

15. How to optimize SBR properties? SBR is often blended or copolymerized with other polymers or chemically modified to enhance its properties. The addition of small amounts of suitable rubber may improve: Oil or ozone Resistance Improve processing behaviour However, other properties are adversely affected by non-compatible rubber blends. These include tensile strength , low-temperature behavior , and co- vulcanizability . SBR is compatible with: NR (Natural Rubber) BR (Butadiene Rubber - Polybutadiene) EPDM (Ethylene Propylene Diene Rubbers) NBR (Nitrile Butadiene Rubber) CR (Chlorinated Rubber) https://omnexus.specialchem.com/selection-guide/styrene-butadiene-rubber-sbr-guide 15

16. POLY BUTADIENE RUBBER Formed by polymerization of 1,3-butadiene monomer. Cured polybutadiene rubber imparts excellent abrasion resistance and low rolling resistance. It is the second largest volume synthetic rubber produced, next to  styrene-butadiene rubber (SBR). It is used in the production of tyres , golf balls, inner tube of hoses, railway pads, bridge blocks, footwear, wire and cable insulation, and conveyor belts. It is also used to improve the mechanical properties of plastics. 16

17. Tensile Strength 10 - 30 MPa Elongation at Break 300 - 800% Modulus of Elasticity 1 - 10 MPa Hardness (Shore A) 30 - 90 Abrasion Resistance Good Tear Resistance Moderate to Good Compression Set Moderate Flexibility Excellent Impact Resistance Good G lass transition temperature -90°C to 80°C PROPERTY 17

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19. Types of Polybutadiene 19 High Cis Polybutadiene The transition metal, or so called Ziegler catalysts are use to produce cis polybutadiene. High cis   polybutadiene will usually have cis   content >95% which gives rise to better “green strength” and increased cut growth resistance in the cured product . Green strength, is the strength of the uncured rubber compound, is important for the tyre building process and cut growth resistance is necessary for tyre performance. lower T g  less than –90 °C compared to alkyllithium -based BR because it has almost no vinyl structure

20. 20 High Cis Polybutadiene Neodymium catalyst Cobalt catalyst Nickel catalyst produces the highest cis content of about 99% and also makes the most linear chain structure (no branching) producing a polymer with the best tensile and hysteresis (low heat build-up) properties of all the high cis types produces a highly branched BR with a low solution viscosity that makes a good polystyrene and acrylonitrile-butadiene-styrene modifier makes polybutadiene with an intermediate level of branching

21. 21 Lithium-based Polybutadiene The alkyllithium or “anionic” catalyst system produces a polymer with about 40% cis, 50% trans and 10% vinyl when no special polar modifiers are used in the process. The alkyllithium process is probably the most versatile, because the growing chain end contains a “living” anion (negative charge) which can be further reacted with coupling agents or functional groups to make a variety of modified polybutadienes. Vinyl increases the T g  of the polybutadiene by creating a stiffer chain structure. Vinyl also tends to crosslink or “cure” under high heat conditions so the high vinyl polymers are less thermally stable than low vinyl. Growing “living” anion (negative charge) on end of live polybutadiene chain with Lithium counterion (positive charge)

22. 22 High Trans Polybutadiene Polybutadiene can be produced with more than 90%  trans  using catalysts similar to those of high  cis : neodymium,  lanthanum, nickel. This material is a plastic crystal (i.e. not an elastomer) which melts at about 80 °C. It was formerly used for the outer layer of golf balls. Today it is only used industrially, but companies like Ube are investigating other possible applications

23. properties BR-1203 Ti BR-1243 Nd grade В (LP) type 1,4-cis – at least 90% 1,4-cis – at least 97% Mooney viscosity 1+4 ( 100 °C), UM 45 ± 4 44 ± 5 Volatile matter % wt ≤0,8 ≤0,8 Tensile stress at 300 % elongation MPa ≥8,5 ≥11,0 Tensile strength Mpa ≥11,0 ≥16,8 Ultimate elongation % ≥360 ≥360 Uses Foot wear production Asbestos-rubber goods Tire production: tread Tire production: sidewall Colored rubber technical goods Hoses (hose products) Cable insulation Conveyor belts Tire production: tread Tire production: sidewall Conveyor belts Driving belts Hoses (hose goods) Asbestos-rubber goods 23

24. REFERENCE Class notes George Stephanopoulos - Chemical Process Control_ An Introduction to Theory and Practice (1984) 25

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