Polyisobutylene butyl

Grades of polyisobutylene, butyl mbber, halogenated butyl mbber, and partially cross-linked isobutylene—isopiene—divinylbenzene terpolymer have been developed to meet specific processing and property needs. Recently, two new polyisobutylene-based elastomers have been developed. One is now available commercially as Exxon SB Butyl Polymers (32) and the other is under market development as Exxon bromo XP-50. 

Polyisobutylene is readily soluble in nonpolar Hquids. The polymer—solvent interaction parameter Xis a. good indication of solubiHty. Values of 0.5 or less for a polymer—solvent system indicate good solubiHty values above 0.5 indicate poor solubiHty. Values of X foi several solvents are shown in Table 2 (78). The solution properties of polyisobutylene, butyl mbber, and halogenated butyl mbber are very similar. Cyclohexane is an exceUent solvent, benzene a moderate solvent, and dioxane a nonsolvent for polyisobutylene polymers. 

Berlin and coworkers (5,56) desired to obtain a material with an increased mechanical strength. They carried out a plasticization of bulk ami emulsion polystyrene molecular weight 80000 and 200000 respectively at 150-160° C, with polyisobutylene, butyl rubber, polychloroprene, polybutadiene, styrene rubber (SKS-30) and nitrile rubber (SKN 18 and SKN 40). The best results were obtained with the blends polystyrene-styrene rubber and polystyrene-nitrile rubber. An increase of rubber content above 20-25% was not useful, as the strength properties were lowered. An increase in the content of the polar comonomer, acrylonitrile, prevents the reaction with polystyrene and decreases the probability of macroradical combination. This feature lowers the strength, see Fig. 14. It was also observed that certain dyes acts as macroradical acceptors, due to the mobile atoms of hydrogen of halogens in the dye, AX ... 

The abovementioned materials can be mixed with one another. A series of other polymers and resins can also be added if the substances listed in 1 to 4 form the bulk of the material. Additional materials are PE, PP, low molecular weight polyolefins, polyterpenes (mixtures of aliphatic and cycloaliphatic hydrocarbons produced by polymerisation of terpene hydrocarbons), polyisobutylene, butyl rubber, dammar gum, glycerine and pentaerythritol esters of rosin acid and their hydration products, polyolefin resins, hydrated polycyclopentadiene resin (substance mixtures manufactured by thermal polymerization of a mixture mainly composed of di-cyclopentadiene with methylcyclopentadiene, isoprene and piperylene which is then hydrogenated). 

Application The Snamprogetti Cracking Technology allows producing high-purity isobutylene, which can be used as monomer for elastomers (polyisobutylene, butyl rubber) and/or as an intermediate for the production of chemicals—MMA, tertiary-butyl phenols, tertiary-butyl amines, etc. 

Polyisobutylene (Butyl Rubber, Copolymer with 0.5-2% Isoprene) (HR) Chloro-Sulfonated Polyethylene (CSM) Ethylene-Propylene Random Copolymer, 50% Ethylene (EPM) Ethylene-Propylene Random Terpolymer 50% Ethylene (EPDM) Poly(Ethyl Acrylate), Usually a Copolymer (ACM) Vinylidene-Fluoride-Chlorotrifluoro Ethylene Random Copolymer (FKM) Vinylidene— Fluoride— Hexafluoropropylene Random Copolymer (FKM)... 

The reaction of the pyrolysis vapors with mercury(II) oxide will differentiate between these materials. To do this, heat a dry sample of the plastic in the pyrolysis tube closed with a piece of prepared filter paper. To prepare the paper, drench it with a solution of 0.5 g yellow mercury(ll) oxide in sulfuric acid (1.5 ml concentrated sulfuric acid added to 8 ml water, carefully). If the vapor gives a golden yellow spot, this indicates polyisobutylene, butyl rubber, and polypropylene (the latter only after a few minutes). Polyethylene does not react. Natural and nitrile rubber as well as polybutadiene yield a brown spot Waxlike greases are the products in the pyrolysis of polyethylene and polypropylene. Polyethylene smells like paraffin, and polypropylene is slightly aromatic. 

Heat removal and viscosity increases during polymerization are facilitated by using a diluent solvent. However recovery and repurification of the solvent, together with flammability hazards, have limited this technique. Heat removal can be conveniently carried out using the latent heat of vaporization, e.g. the cationic polymerization of isobutene to make polyisobutylene (butyl rubber) is maintained at — 100°C by the refluxing ethylene solvent. 

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