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susan8007

新虫 (初入文坛)

[交流] 【求助】 How to answer these questions about polymer

1. The glass transition, Tg, for poly(ethylene) is well below 0, yet a dishpan made from poly(ethylene) retains its shape at temperatures well above 0.

2. Radical polymerization of methyl acrylate carried out in tetrahedronfuran solution generates polymer of relatively low molecular weight.


3.  Whether the polymerization of an unknown monomer proceeds by a step-growth or chain-growth process can be determined experimentally. How would this be done

[ Last edited by wizardfox on 2009-2-19 at 12:45 ]
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joli

铁杆木虫 (职业作家)

joli-beautiful

1.PE容易结晶
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2楼2009-02-19 12:26:30
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zczc6

银虫 (小有名气)

1.PE属结晶性聚合物,靠色散力形成晶格,高于玻璃温度但地域熔点下任然能保持形状。
2.溶剂在丙烯酸自由基溶液聚合中产生链转移使分子量降低。
3.可通过反应程度P的计算确定逐步聚合的聚合度。
3楼2009-02-19 23:38:09
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taianxt

金虫 (著名写手)

PE的玻璃温度没有那么低吧
4楼2009-02-20 11:44:39
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