ExxonMobil Chemical has introduced a family of Specialty Polyolefin Elastomers, a novel type of polyolefin with isotactic propylene crystallinity, under the trade name Vistamaxx~(TM). These polymers contain a predominant amount of propylene (>80%) with isotactic crystallinity, the balance being ethylene and other α-olefins. These elastomers are highly elastic, with excellent recovery from deformation even without vulcanization. These elastomers, unlike the related EPR polymers, share the processability of conventional plastics such as polyethylene and isotactic polypropylene and can, thus, be easily formed into articles such as films, fibers and nonwoven fabrics, which are highly elastic, using conventional plastic processing processes. In this paper, we discuss the details of the structure-property relationships in these polymers and emphasize the factors leading to the elastic character of these elastomers.
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