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由青島化工學院塑料工程技術研究院研究的PP-R冷熱水管材及生產設備技術日前通過山東省科委組織的技術鑒定。 PP-R管是當今世界最先進的供水、供暖管材。
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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.