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LR鹏鹏

铜虫 (小有名气)

应助: 0 (幼儿园)
金币: 186.2
红花: 1
帖子: 63
在线: 12.1小时
虫号: 1346715
注册: 2011-07-15
性别: GG
专业: 有机合成

[求助] 一共就这些金币求好人帮忙。。

The TFE content dependence of Tm and Tg of ETFE shows unique
behavior with the maximal and minimal points. The Tm may be classified
into three regions of the different characters as shown in Fig. 1.
The existence of the maximal Tm at 50 mol% TFE can be interpreted
by presuming the perfectly alternating hypothetical copolymer.
The Tm of perfectly alternating copolymer is estimated to be
295 C by performing the extrapolation to the perfectly alternating
ratio. This value is supported reasonably by utilizing the modified
Flory’s equation as derived by Eby.
On the other hand, the existence of minimal Tm at around
70 mol% TFE content is considered to come from the difference in
chain conformation between the regions B and C. The copolymer
in the region B may be assumed to be a copolymer consisting of
hypothetical EeTFE units and TFE units. The copolymer in the
region C includes the long TFE segments of helical conformation,
as evidenced by the X-ray diffraction data. The Tm increases
gradually with an increment of TFE units. Similarly the maximal Tg
was reasonably interpreted on the basis of the modified
GibbseDimazio’s equation. The Tg extrapolated to the perfectly
alternating copolymer was estimated to be 145 C.

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