All about Butyl Rubber

The presentation describes about the butyl rubber about its properties, compounding, categories, applications, new innovations, advantages and disadvantages. The references are added at the end

1. JAYA VERMA PA-04 TY.BTECH POLYMER ELECTIVE-I: ELASTOMER TECHNOLOGY TUTORIAL PRESENTATION BUTYL RUBBER

2. INTRODUCTION Structure of Isobutylene isoprene rubber (IIR) Butyl rubber (IIR), also called isobutylene-isoprene rubber. It is a synthetic rubber. It is a co polymer of isobutylene with isoprene. Isoprene unit: Double bond that provides a site for crosslinking during vulcanisation and located randomly in the polymer chain.

3. PREPERATION/SYNTHESIS Produced by cationic copolymerisation between 98% isobutylene and 2% isoprene. Initiator: Friedel Craft acids (e.g. AlCl3). Medium: Methyl chloride (reaction diluent) & boiling liquid ethylene. Temperature: Controlled at low temperature -90 ˚ C to -100 ˚ C. TYPICAL METHOD Butyl rubber T he alkyl chlorides can be ranked in the following order with respect to a decrease in the carbocation stability: benzyl chloride > tert-butyl chloride > chlorinated isobutylene dimers > chlorinated propylene trimers.

4. Mixture of a major amount of diethyl aluminium chloride & a minor amount of ethyl aluminium dichloride (activated by minute amounts of water/ methyl alumino {MAO}). Modified initiators: Higher molecular weights, higher degrees of conversion and higher isoprene contents in butyl rubber. Medium: Hexane Temperature: -60 ˚C Activation by MAO allow higher polymerisation temperature which does not require much heat removal from reaction mixture. ALTERNATIVE METHOD

5. Halogenated butyl rubber (halo-butyl) was developed, in its chlorinated (chloro-butyl) and brominated (bromo-butyl) variants, providing significantly higher curing rates and allowing co-vulcanization with other rubbers such as natural rubber and styrene-butadiene rubber . The introduction of bromine or chlorine improves the resistance to ozone, weathering, chemicals, and heat. This, however, comes at the expense of electrical insulation and moisture resistance. Halo-butyl is today the most important material for the inner linings of tubeless tires . TYPES OF BUTYL RUBBER Because of its excellent weather and ozone resistance, and improved chemical resistance, chloro-butyl is an excellent choice for rubber articles needing good resistance to chemicals, weathering and ozone such as tank linings, special purpose conveyor belts and protective clothing. It is also a good choice for tire inner liners , seals and membranes. Furthermore, chlorinated butyl is often the material of choice for pharmaceutical closures due to its cleanliness and good resealing properties. Bromo-butyl together with chloro-butyl rubber provide excellent inflation pressure retention. However , the brominated sites are more reactive, providing faster cure and better adhesion to unsaturated rubber types. They are the most widely used rubbers for inner tubes of bicycles, trucks as well as industrial and agricultural tires. Bromo-butyl rubbers are also used for hoses, seals, membranes, tank linings, special purpose conveyor belts, engine mounts, protective clothing and for consumer products such as ball bladders for sporting goods ..

6. CHLORO-BUTYL Chloro-butyl (CIIR) is a copolymer of chlorinated isobutylene and small amounts of isoprene which provides unsaturated sites for vulcanization. This elastomer has many of the attributes of butyl rubber, including low gas and moisture permeability, good vibration damping, low glass transition temperature, excellent resistance to ageing and weathering. Compared to butyl rubber, the chlorinated sites are more reactive, providing faster cure with lower amount of curatives and better adhesion to unsaturated rubbers and metals. BROMO-BUTYL Bromo-butyl (BIIR) is a copolymer of isobutylene and small amounts of brominated isoprene which provides unsaturated sites for vulcanization. This elastomer has many of the attributes of butyl rubber, including low gas and moisture permeability, good vibration damping, low glass transition temperature, excellent resistance to ageing and weathering, and wide vulcanization versatility. The introduction of bromine increases adhesion to other rubbers and metals and provides much higher curing rates (i.e. lower amount of curative are required). Furthermore, brominated butyl can be co-vulcanized with general purpose high-unsaturation elastomers, such as natural rubber, polybutadiene, and styrene-butadiene rubber, while maintaining the mostly saturated backbone structure. MANUFACTURERS & DISTRIBUTORS Exxon Mobile, Arlanxeo BRAND NAMES Exxon Chloro butyl Rubber, Chlorinated X_Butyl MANUFACTURERS & DISTRIBUTORS Exxon Mobile, Arlanxeo, Sinopec BRAND NAMES Exxon Bromo butyl Rubber, Brominated X_Butyl

7. PROPERTIES Low permeability to air, gases and moisture Vibration damping C onverting the mechanical vibrational energy of solids into heat energy Low glass transition temperature Low modulus of elastomer Elastomer : able to stretch a long distance and regain the shape. Low compression set Compression set: percentage deflection from original shape of rubber a item having been subjected to a constant compressive load, then released. Resistance to aging and weathering from atmospheric exposure Wide vulcanization versatility Vulcanization : Chemical process for converting rubber into a compound material (polymer) with the addition of sulphur.

8. PROPERTIES Fast cure rates Cure rates : Toughening or hardening of a polymer material by cross linking of polymer chains . Processing safety: No nitrosamines or nitrosamines precursors Nitrosamines : Carcinogenic and can cause cancer . High extensibility Broad range of durometer and tensile strength properties Low filler content for specific gravity, cost effective compounding Best sealant of all the known rubbers Sealant rubber – Type of product seals and protects different materials using rubber – based substances. Caulk – To make watertight or airtight by filling or sealing Blood compatible Allows this substance to be used in biomedical applications. Contd.

9. CURING OF BUTYL RUBBERS What is curing of rubber? Ans : Curing, also known as vulcanization, causes the long polymer chains that rubber is composed of to become crosslinked. This prevents the chains from moving independently, allowing the material to stretch under stress and then return to its original shape when the stress is released. Why to cure the butyl rubber? Ans: Vulcanized or cured butyl rubber is a strong, non-plastic material ; it has an elastic limit, as well as the ability to return substantially to its original length after being stretched as much as several hundred per cent. How to cure the butyl rubber? Ans: Butyl rubber is typically cross-linked or vulcanized by one of three basic methods. accelerated sulphur vulcanization, cross-linking with dioxime and related dinitroso compounds, and a phenol-formaldehyde (resol ) resin cure.

10. Curing of butyl rubber with a phenolic resin: BY: William Sarnia Hopkins, and Carl Walter von Hellens, Butyl rubber is cross-linked or vulcanized by phenol-formaldehyde (resol) resin cure. The curing agents generally used include phenols and phenol-formaldehyde resins produced by condensation of a phenol with formaldehyde in the presence of base. Typical agents include 2,6-dihydroxymethyl-4-alkyl phenols and their polycyclic condensation polymers . Curing occurs through the reaction of the methylol groups of the phenols or resin with the uncured rubber to form cross-linked structures . The resin-cured butyl rubbers with improved properties are obtained by curing the butyl rubbers with low amounts of phenol-formaldehyde resins with low levels of ether bridging. Such improved properties may include improved high-temperature ageing characteristics, faster cure rates, and better stress/strain properties. Base-catalysed phenol-formaldehyde resins are made by condensing a phenol with formaldehyde in the presence of base.

11. Curing characteristics, mechanical properties and morphology of Butyl rubber filled with Ground tire rubber ( GTR) By : Krzysztof Formela • Jozef T. Haponiuk The GTR content variation, within the range of 10–90 phr(parts per hundred rubbers), was studied with respect to the vulcanization process , static mechanical properties (tensile strength, elongation-at-break , hardness and resilience), dynamic mechanical properties and the morphology of the obtained vulcanizates. Rubber compounds based on butyl rubber filled with were obtained using a laboratory mill . The obtained rubber compounds were vulcanized according to the estimated optimal time at 160 ˚ C under a pressure of 4.9 MPa . Results and discussion obtained from the experiment: Swelling Degree : Swelling degree increased with GTR content in butyl vulcanizates, which was due to low cross-linking of butyl rubber matrix and lowering of cross-linking density of GTR arising from partial de-vulcanization of GTR . Cure characteristics : It was observed that there is an increase in minimum torque and lowered optimal time of vulcanization with the increasing GTR content. GTR aggregates with a complex structure, give rise to the formation of free spaces in the rubber matrix which results in increased viscosity of the blends.

12. Mechanical properties : Higher values in tensile strength and elongation-at-break have been caused by the carbon black migration from GTR into the butyl rubber matrix. Dynamic mechanical analysis : Storage modulus is decreased with increasing GTR content as a result of the de-vulcanization of GTR structure and slightly cross-linking of butyl rubber matrix, which results in vulcanizates with lower stiffness . Morphology: Effect of GTR content on hardness and resilience of the butyl rubber vulcanizate The influence of butyl rubber content on residue after determining the degree of swelling and the sol fraction content in ground tire rubber. Tested contents of butyl rubber: a. 10, b. 20, c. 30, d. 40 and e. 50 wt% Conclusion: This phenomenon visibly increased elongation-at-break values of the obtained vulcanizates. The microstructure analysis of samples performed after tensile tests showed that there was a strong interaction between the butyl rubber matrix and GTR. The obtained results demonstrated that GTR can be successfully used as non-expensive filler in butyl rubber-based compounds.

13. BUTYL RUBBER COMPOUNDING By: P. Haworth and F. P. Baldwin Processing : Butyl undergoes little breakdown during milling. Butyl is an ideal material for Banbury mixing since no premastication in necessary before the Banbury operation can b e carried out. The condition referred to above which makes for rather difficult handling during the early stages of open mill mixing is not a factor in this operation . Physical properties : An increase in the unsaturation from 0.8 to 2.0 percent of butyl rubber changed the time of cure at which optimum tensile properties were obtained from over 6 0 minutes to 15minutes or less. Pigment loading : Carbon blacks are by far the best pigments for use in butyl rubber and the properties imparted by any one black depend upon particle size and surface condition. Elasticators : The rebound characteristics of butyl can be improved considerably by the use of small amount of Elasticators. Aging : Butyl possesses excellent aging characteristics since all, or nearly all, of its small amount of unsaturation is taken up during vulcanization, leaving few points for oxygen to attack . Butyl is exceptionally resistant to the action of ozone.

14. APPLICATIONS Tires & Lubes Adhesive, Sealants, Stoppers Gloves Others COMPONENT DETAILS Tires Provide excellent inflation pressure retention for bicycle, truck, agricultural, industrial and speciality tires Automotive Butyl rubbers’ barrier properties, high damping, resistance to ozone and heat aging make them ideal for automotive vibration control, hoses and gaskets Industrial Use butyl rubbers to improve formulations for conveyor belts, tank linings and condenser packaging Construction Improve weather ability of asphalt, contact cement and sealant tapes Adhesives Tailor adhesive properties in valve cement, tapes and flooring adhesives. Consumer Products For ball bladders for sporting goods and electrical appliance condenser packaging Sealant properties Butyl rubber caulk is known as the strongest bond, and is usually used to fill in cracks in bricks, concrete and metal Blood compatible Artificial joint materials and blood collection tubes.

15. Rubber roof sealants and repair Shock mounts Diaphragms Tubeless tire liners Bottle stoppers Pharmaceutical packaging and bottles Sealants and adhesives Butyl O-rings Pond and tank liners and seals Industrial liners Construction and mechanical systems Speaker surrounds Industrial hoses and connections APPLICATIONS

16. POLYCOTE Poloflex - Butyl Rubber Waterproofing Roof APPLICATIONS

17. INDUSTRIAL APPLICATIONS Butyl Rubber Molding Processes Transfer Molding Injection Molding Compression Molding

18. Due to its low gas and vapor permeability , butyl rubber is an important material in the manufacturing of tubeless tires, inner tubes, sports-ball bladders , glove-box gloves, etc. Owing to its low permeability , it is used in making gas masks. Though not as soft and compliant as silicone rubber, butyl rubber is flexible enough that it can achieve a good face seal . As a waterproofing material , it is applied as a liner in tanks and ponds. It is used as a patching material for membrane roofs and as a sealant for insulated windows. Combined with other chemicals, polyisobutylene makes oil and fuel additives and demisting agents for machining lubricants. As a vibration dampener , butyl rubber is used for shock mounts, suspension bushings, and car- and truck-body mounts. Speaker cone edges are often made from butyl rubber today where once they were commonly made of foam. Stoppers for labware and medical equipment are manufactured from the material. Compared with natural rubber, butyl rubber is costlier due to more complex processing requirements. Some anecdotal discussion exists regarding natural vs. butyl rubber motorcycle tire tubes, as the natural rubber is said to have better puncture resistance and tear strength but butyl rubber tubes can go longer between airings. Butyl rubber, in its food-grade form , is used to make chewing gum. It has all but replaced the gum of the Chicle tree except in a few specialty, natural products. There have been some efforts to collect used chewing gum and recycle it into new products. Improper disposal of chewing gum is a chronic urban blight. APPLICATIONS BASED ON PROPERTIES

19. NEW INNOVATIONS AFTERLIFE FOR CHEWING GUM Gum under your shoe is normally annoying - but these soles are made from recycled gum The bright bins are themselves made of used chewing gum The gum mixture is heated to a high temperature before being expelled in an injection machine

20. CHEWING GUM Most modern chewing gum uses food-grade butyl rubber as the central gum base, which contributes not only the gum's elasticity but also gives it a stubborn, sticky quality which has led some municipalities to propose taxation to cover costs of its removal . Recycled chewing gum has also been used as a source of recovered polyisobutylene. Amongst other products, this base rubber has been manufactured into coffee cups and 'Gumdrop' gum-collecting bins. When filled, the collecting bins and their contents are shredded together and recycled again. GUMDROP CHEWING GUM COLLECTING BIN

21. REASONS TO USE BUTYL CHEMICAL PROTECTION GLOVES Cost Savings Using Butyl Gloves Offer Superior Chemical Protection Reduce Waste Quality Chemical Protection Products Different Thicknesses and Styles Available

22. ADVANTAGES Butyl rubber is the only known elastomer that is impermeable to gases . The material is flexible, with good room temperature damping characteristics . The material is biocompatible, resists many acidic and alkaline chemicals, ozone, heat, and weathering, and has good aging properties . It has good electrical insulating properties. Butyl rubber is usable between -50 and 250°F but its damping characteristics diminish at higher temperatures. It remains flexible at lower temperatures. Compression set: fair Flex cracking resistance: good to excellent Abrasion resistance: good to excellent Tear resistance: good Impact resistance: good Weather resistance: excellent Sunlight resistance: excellent Ozone resistance: excellent Oxidation resistance: excellent Water resistance: very good Steam resistance: excellent

23. DISADVANTAGES Butyl rubber is difficult to handle during manufacturing because of its tendency to trap air, blister, and creep. Characteristics and flame resistance are poor. Butyl is not recommended for use with petroleum oils, fluids, or solvents. It resists attack by phosphate ester hydraulic fluids and ketones but does not do well in the presence of mineral or petroleum-based fluids, hydrocarbons, or flame. It has poor resistance to aromatic hydrocarbons , aliphatic hydrocarbons (e.g., kerosene, turpentine), coal, tar, and di ester-based lubricants. Cold weather properties for butyl rubber are fair . Rebound rating: poor Flame resistance: poor

24. National and I nternational Manufacturers & Trade names National Manufacturers: Prime white Butyl RubberAnanta Polyrubb Pvt. Ltd. Connaught Place, Delhi Butyl Rubber Sheet, Packaging Type: Roll M.V.Rubber Ballabhgarh, Faridabad Black Butyl Rubber SheetsVishal Rubber Technologies Pvt. Ltd. Pimpri - Chinchwad, Pune Butyl Crumb Rubber Vsj Granurubr Private Limited Kharghar, New Delhi International Manufacturers: ExxonMobil Shareholder Services at 5959 Las Colinas Boulevard, Irving, Texas LANXESS Büro Berlin HB fuller  Willow Lake Boulevard National an International Trade Names: KALAR ® Cross-Linked Butyl Rubber ISOLENE® Liquid Synthetic Rubber KALENE® Liquid Butyl Rubber

25. REFERENCES Curing characteristics, mechanical properties and morphology of Butyl rubber filled with Ground tire rubber ( GTR) By : Krzysztof Formela • Jozef T. Haponiuk MECHANICAL PROPERTIES OF RUBBER Ronald J. Schaefer T homasnet.com/articles/plastics-rubber/all-about-butyl-rubber Blog.oureducation.in/butyl-rubber-its-properties-and-uses Adroitmarketresearch.com/blogs/essential-methods-and-uses-of-butyl-rubber Blog.oureducation.in/preparation-of-butyl-rubber Bostik-industrial.com/butyl-rubber-benefits-and-use-in-adhesive-manufacturing/ World Hacks: A surprising new after life for chewing gum By Dougal Shaw World Hacks, BBC News BUTYL RUBBER COMPOUNDING By : P. Haworth and F. P. Baldwin Synthesis of Butyl Rubber by Cationic Polymerization in Methyl Chloride in the Presence of Alkyl Chlorides O . V. Sofronova, E. A. Markina, S. M. Chelnokova, and A. G. Sakhabutdinov MDsassociates.com/why-use-butyl-gloves Curing of butyl rubber with a phenolic resin William Sarnia Hopkins, and Carl Walter von Hellens,