High molecular weight poly fraction

In general, a high-molecular-weight phenolic resin is less alkaline-soluble than a low-molecular-weight one. Therefore, these high molecular weight poly(p-vinyl phenol) components may contribute to the decrease in solubility. Furthermore, we assume that the etching type dissolution of these resists is non-fractional, as was previously shown in the case of poly (methyl methacrylate-co-acrylonitrile) (15). 

The high-molecular-weight poly (propylene oxide) produced with hexacyanometalate salt complexes shows no crystallinity. Moreover, it was shown by Price et al. (18) and confirmed in our laboratory that these polymers have more than 953 head-to-tail enchainment. The amorphous fractions of partially crystalline polymers made with metal-alkyl and ferrio-chloride-based catalysts were shown by those authors to have considerable head-to-head enchainment. They postulated that this was the cause of the amorphous nature of these fractions. It seems clear, however, that the amorphous nature of the polymers prepared with hexacyanometalate salt complexes must be the result of their low degrees of tacticity. 

The results obtained by Feigin et al. (1981) for aqueous systems complement the data of Croucher and Hair (1981) on nonaqueous systems. These are presented in Fig. 5.8. The UCFT of pols vinyl acetate) latices stabilized by relatively high molecular weight poly(oxyethylene) (20 000 in one case and 360 000 in the other) in 0-39 M MgS04 was measured over a range of latex volume fractions (10 -10 ). Once again, within the limit of experimental... 

Polymers account for about 3—4% of the total butylene consumption and about 30% of nonfuels use. Homopolymerization of butylene isomers is relatively unimportant commercially. Only stereoregular poly(l-butene) [9003-29-6] and a small volume of polyisobutylene [25038-49-7] are produced in this manner. High molecular weight polyisobutylenes have found limited use because they cannot be vulcanized. To overcome this deficiency a butyl mbber copolymer of isobutylene with isoprene has been developed. Low molecular weight viscous Hquid polymers of isobutylene are not manufactured because of the high price of purified isobutylene. Copolymerization from relatively inexpensive refinery butane—butylene fractions containing all the butylene isomers yields a range of viscous polymers that satisfy most commercial needs (see Olefin polymers Elastomers, synthetic-butylrubber). 

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