24小时热门版块排行榜

返回列表

当前主题已经存档。

zzj.2001

铁虫 (正式写手)

骑天大猪

应助: 0 (幼儿园)
贵宾: 0.36
金币: 12.5
散金: 3
帖子: 439
在线: 90.1小时
虫号: 418776
注册: 2007-07-03
性别: GG
专业: 有机高分子功能材料

[交流] 【求助】多分散性指数(polydispersity index)的意义，以及计算方法？谢谢

多分散性指数(polydispersity index)的意义，以及计算方法？谢谢

[ Last edited by yogidan on 2009-3-10 at 10:33 ]

回复此楼

» 猜你喜欢

1楼 2009-03-10 10:00:01

已阅回复此楼关注TA 给TA发消息送TA红花 TA的回帖

qhk

木虫 (正式写手)

应助: 13 (小学生)
金币: 1618.8
红花: 3
帖子: 321
在线: 258.7小时
虫号: 304266
注册: 2006-12-09
性别: GG
专业: 高分子合成化学

★ ★ ★ ★ ★
zzj.2001(金币+5,VIP+0):感谢 3-24 22:37

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 always 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

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.. 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.

赞一下(4人)