Copolymer containing elastomers

Closely related to these but thermoplastic rather than rubber-like in character are the K-resins developed hy Phillips. These resins comprise star-shaped butadiene-styrene block copolymers containing about 75% styrene and, like SBS thermoplastic elastomers, are produced by sequential anionic polymerisation (see Chapter 2). 

Block copolymers containing polysiloxane segments are of great interest as polymeric surfactants and elastomers. Polycondensation and polyaddition reactions of functionally ended prepolymers are usually employed to prepare well-defined block copolymers. The living polystyrene anion reacts with a,co-dichloropoly(dimethyl-siloxane) to form multiblock copolymers398. ... 

One of the most important discoveries relating to synthesis and physical behavior was made by Dr. Milkovich while at the Shell Development Co. He and his colleagues showed that triblock copolymers containing polystyrene-polydiene-polystyrene blocks in appropriate sizes could behave as a physically cross-linked but linear thermoplastic elastomer. Thus Dr. Milkovich was involved with two very crucial discoveries in this field. Interestingly, he received his M. S. degree at Syracuse with Professor Szwarc and his Ph.D. at Akron with Professor Morton. I was pleased that Dr. Milkovich accepted my invitation to be a plenary speaker at the symposium, along with Professors Szwarc and Morton. 

Since approximately 1986 PP has ranked third in the bulk plastic production after PE and PVC, with an estimated annual production of 21 x 106 tons. PP is differentiated into three classes homopolymer PP copolymers containing primarily PP and PP elastomer mixtures. 

A random siloxane copolymer containing 90 mol% dimethyl-, 10 mol% methylphenyl-, and 0.3 mol% methylvinyl-chain units is used for the sample preparation. The copolymer is filled with hydrophilic Aerosil (300 m g ) (A300) and hydrophobic Aerosil (60 m g ) (AM60). The weight ratio filler/elastomer is 30 100. 

Alcohol resins, polyvinyl Alkyd resins Allyl resins Butadiene copolymers, containing less than 50 percent butadione Carbohydrate plastics Casein plastics Cellulose nitrate resins Cellulose propionate (plastics) Coal tar resins Condensation plastics Coumarone-iodene resins Cresol resins Cresol-furfural resins Dicyandiamine resins Diisocyanate resins Elastomers, nonvulcanizable (plastics)... 

Establishments primarily engaged in manufacturing synthetic rubber by polymerization or copolymerization. An elastomer for the purpose of this classification is a rubber-like material capable of vulcanization, such as copolymers of butadiene and styrene, or butadiene and acrylonitrile, polybutadienes, chloroprene rubbers, and isobutylene-isoprene copolymers. Butadiene copolymers containing less than 50 percent butadiene are classified in Industry 2821. Natural chlorinated rubbers and cyclized rubbers are considered as semifinished products and are classified in Industry 3069. 

Various copolymers of the fluorinated monomers have been prepared [243]. Copolymers of tetrafluoroethylene and hexafluoropropene have under vacuo a stability close to that of teflon (Fig. 66). Copolymers with trifluoronitroso me thane have a lower stability than PTFE (Figs. 66 and 67). The copolymer of vinylidenefluoride and hexafluoropropene is one of the most stable elastomers available at the present time (Fig. 66 and Table 12). For a typical copolymer containing 70% vinylidene fluoride, the rate of weight loss is 0.04% per min at 350°C and the activation energy is 57 to 46 kcal mole"1, according to Wright [243]. 

The synthesis of isobutene copolymers containing conjugated double bonds was accomplished only a few years ago by copolymerizing the isoolefin with suitable trienes. The results, largely unpublished, permit to compare the behaviour of these two classes of copolymers which display several analogies. The presence of the conjugated double bond functionalities gives rise to several possibilities of post-modification reactions which extend widely the utilization of these classes of synthetic elastomers. 

Commercial copoly(ether-ester) elastomers (e.g., Hytrel , DuPont Lomod , GEC) are segmented block copolymers containing a polyether soft segment such as poly(tetramethylene oxide) and a hard segment that is chemically identical to polybutylene terephthalate. When the soft segment is > 50%, these block copolymers exhibit... 

The effective removal of crystallinity by the incorporation of p-MS provides the opportunity to obtain elastic properties in polyethylene copolymers. The copolymer containing 18.96 mol % of p-MS is actually an elastomer with a Tg of -5.7 °C. Further increase of p-MS concentration provides the copolymers with higher Tg and the copolymers become glassy at room temperature. Figure 7 shows DSC curves of poly(ethylene-co-p-methylstyrene) copolymers with (a) 18.98, (b) 32.8 and (c) 40 mole % p-MS, respectively. The Tg increases from -5.7 °C to 30.9 °C and to 38.8 C. The single Tg with sharp thermal transition in each case is indicative of homogeneous copolymer structure even at as high as 40 mol % of p-MS concentration. 

The photoinitiated crosslinking of three ethylene-propylene-diene copolymers (EPDM elastomers) has been investigated in a series of studies > > >9. Commercial EPDM samples were used containing the following dienes ethylidene-norbomene (ENB), dicydopentadiene (DCPB) and hexadiene (HD). The main photoinitiators used were benzoyl-1-cyclohexanol (PI) from Ciba-Geigy and 2,4,6-trimethyl-benzoyl diphenylphosphineoxide (APO) from BASF, which both are photofragmenting (formulas 3 and 4) ... 

Some properties of sodium and zinc vulcanizates are compared with those of the acid precursor in Table 5.16. High tensile strength is a characteristic of ionic vulcanizates. As a comparison, a standard polybutadiene elastomer vulcanized with sulfur gives a strength of 1.9-5.8 MPa (275-841 Ibf/in. ), whereas an equivalent copolymer containing 1.5 mole% methacrylic acid, and vulcanized with... 

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