Two commercial ethylene-propylene random copolymers(A and B) for hot water piping of which A has better long term heat stability and slow crack growth resistance performance than B were fractionated with respect to the isotactity distribution by preparative temperature-rising elution fractionation(TREF).The molecular weight and distribution of fractions and the original resins were investigated by gel permeation chromatography.The results indicated that both A and B had broad isotacticity distribution and A had fewer portions of high isotacticity than B.At the same time A had broader and more typical double-peak molecular weight distribution.The fractions of A had higher molecular weight and broader molecular weight distribution than those of B's.All of these results implied the differences between the catalysts or the polymerization processes for the two copolymers.
由青岛化工学院塑料工程技术研究院研究的PP-R冷热水管材及生产设备技术日前通过山东省科委组织的技术鉴定。 PP-R管是当今世界最先进的供水、供暖管材。
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