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【求助】请问低分子量的硅氧烷和高分子量的硅氧烷如何分离？
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我现在在做的东西里含有低分子量的D4和分子量为3000左右的产物，由于产物里含有双键，所以蒸馏的方法基本上是不予考虑了。请问各位有什么比较好的方法分离不同分子量的硅氧烷么？最好能有相关资料，谢谢了！！！ 我个人在想的是过柱子或者通过冷冻结晶的方法，但是具体的做法还没查到。。。。 |
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2楼2010-12-21 10:30:28
3楼2010-12-21 10:39:59
4楼2010-12-22 10:23:59
iamvictorfan(金币+5):谢谢！ 2010-12-22 11:19:07
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在文献中看到的，“Model Networks Of End-Linked Polydimethylsiloxane Chains .1. Comparisons Between Experimental And Theoretical Values Of Elastic-Modulus And Equilibrium Degree Of Swelling” 其实双键含量不是很高的话，减压蒸馏关系不是很大的 The polymers used in this investigation were two samples of hydroxyl-terminated PDMS, hereafter designated A and B, described as having molecular weights the order of 2 x 104 and 1 xl 03 g morl , respectively. 26 Standard fractional precipitation techniquesl carried out at 25°C were used to separate these two polymers into several fractions. Toluene was chosen as the solvent and acetonitrile as the nonsolvent. (Methanol, which is widely used as the nonsolvent in polymer fractionations, cannot be used with polymer chains of this type, which have potentially reactive end-groups). Initial polymer concentrations were 1wt% in the case of sample A and 5wt% in the case of sample B. Four fractions (A-1 through A-4) were obtained from sample A, and two (B-1 and B-2) from sample B; each represented roughly 20% of the polymer from which it was obtained. [ Last edited by pengcil on 2010-12-22 at 10:33 ] |
5楼2010-12-22 10:31:43
6楼2010-12-22 10:33:12
7楼2010-12-22 11:19:59
8楼2010-12-22 11:28:38