Transition from two-stage to direct melt-crystallization in isotactic random butene-1/propene copolymers
Transition from two-stage to direct melt-crystallization in isotactic random butene-1/propene copolymers
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DOI：
10.1016/j.polymer.2013.03.032
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发表时间：
2013-04-26
期刊：
影响因子：
4.6
通讯作者：
Cavallo, Dario
中科院分区：
文献类型：
--
作者：
Androsch, Rene;Hohlfeld, Rona;Cavallo, Dario
用温度/时间分辨广角X射线散射法研究了等规聚丁烯-1在熔体缓慢冷却过程中的结晶动力学，其结晶动力学随丙烯链缺陷浓度在0 ~ 20mol%之间变化。均聚物熔体的缓慢冷却导致II型中间相的形成，然后在环境温度下等温退火时在10-20天的时间内转化为I型晶体。在聚丁烯-1中丙烯共聚单元/链缺陷的存在导致在冷却时II型中间相形成的延迟和同时中间相晶体相变的加速。在含有约7mol%丙烯的无规丁烯-1/丙烯共聚物中，结晶在不到一天内完成。对于具有大于7mol%丙烯的共聚物，I型晶体通过II型中间相的重组和直接从熔体形成。通过评价共聚对结晶度和晶体完整性的影响来完成研究。(C)2013爱思唯尔有限公司保留所有权利。
The kinetics of crystallization of isotactic polybutene-1 has been investigated as a function of the concentration of propylene chain defects between 0 and 20 mol% by temperature/time-resolved wide-angle X-ray scattering during slow cooling of the melt followed by annealing at ambient temperature. Slow cooling of the melt of the homopolymer leads to formation of Form II mesophase which then transforms on isothermal annealing at ambient temperature to Form I crystals within a period of 10-20 days. Presence of propylene co-units/chain defects in polybutene-1 leads to a retardation of Form II mesophase formation on cooling and simultaneously an acceleration of the mesophase crystal phase transformation. In random butene-1/propylene copolymers containing about 7 mol% propylene crystallization is completed in less than a day. For copolymers with more than 7 mol% propylene, Form I crystals develop by both reorganization of Form II mesophase and directly from the melt. The study is completed by evaluation of the effect of copolymerization on the crystallinity and crystal perfection. (C) 2013 Elsevier Ltd. All rights reserved.