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cuihuapeng

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[交流] 【交流】聚合物中PDI是什么意思（完毕）已有8人参与

请问，聚合物粒径测试试验中所说的PDI是什么意思啊？？

[ Last edited by cuihuapeng on 2010-5-29 at 20:03 ]

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PDI:多分散性指数

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cuihuapeng(金币+2):谢谢！ 2010-05-29 20:01:36
薰衣草儿(金币+4):2楼解释最详细，应该多给一些~欢迎讨论~ 2010-05-29 22:06:37

多分散性指数
wikipedia: In organic chemistry, the polydispersity index (PDI), is a measure of the distribution of molecular mass in a given polymer sample. The PDI calculated is the weight average molecular weight divided by the number average molecular weight. It indicates the distribution of individual molecular masses in a batch of polymers. The PDI has a value equal to or greater than 1, but as the polymer chains approach uniform chain length, the PDI approaches unity (1). For some natural polymers PDI is almost taken as unity. The PDI from polymerization is often denoted as:
PDI=Mw/Mn

Mn is more sensitive to molecules of low molecular mass, while Mw is more sensitive to molecules of high molecular mass.

A polymer material is denoted by the term polydisperse if its chain lengths vary over a wide range of molecular masses. This is characteristic of man-made polymers.[1]. Natural organic matter produced by the decomposition of plants and wood debris in soils (humic substances) has also a pronounced polydispersed character. It is the case of humic acids and fulvic acids, natural polyelectrolyte substances having respectively higher and lower molecular weights.