Transition from miscibility to immiscibility in blends of poly(methyl methacrylate) and styrene-acrylonitrile copolymers with varying copolymer composition:: a DSC study
Transition from miscibility to immiscibility in blends of poly(methyl methacrylate) and styrene-acrylonitrile copolymers with varying copolymer composition:: a DSC study
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DOI：
10.1016/s0014-3057(01)00193-8
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发表时间：
2002-03-01
影响因子：
6
通讯作者：
Estellés, JM
中科院分区：
文献类型：
--
作者：
Cameron, N;Cowie, JMG;Estellés, JM
研究了不同丙烯腈含量的聚甲基丙烯酸甲酯（PMMA）与苯乙烯-丙烯腈（SAN）共聚物共混物的玻璃化转变和结构弛豫过程。50/50重量%）PMMA与含有30重量%的SAN共聚物的共混物的AN是不混溶的，而与含有13至26重量%，，是一种混溶的。因此，溶解度的上限为26 - 30重量%。（，一。在共混物和纯组分中，通过对每个样品中不同热历史后获得的DSC热分析图进行建模，确定了聚合物链在玻璃化转变周围的构象重排的弛豫时间的温度依赖性。在玻璃化转变温度附近的Arrhenius图中log τ对1/T的斜率在更接近可混溶性上限的共混物中比在SAN共聚物含有较少AN的其它可混溶共混物中显著更小。斜率的变化可以归因于不同重排区域的玻璃化转变温度的分布，反映了混合物中的微观不均匀性的外观，其不能被检测为混合物中的双玻璃化转变。(C)2002年由Elsevier Science Ltd.出版
The glass transition and the structural relaxation processes have been studied in blends of poly(methyl methacrylate) (PMMA) and styrene-acrylonitrile (SAN) copolymers with different acrylonitrile (AN) contents. The 50/50 wt.%) blend of PMMA with the SAN copolymer containing 30 wt.% of AN is immiscible, while blends with copolymers containing between 13 and 26 wt.%, of AN are miscible. Thus the upper limit of miscibility is between 26 and 30 wt.%(, of AN. The temperature dependence of the relaxation times of the conformational rearrangements of polymer chains around the glass transition have been determined in the blends and pure components by modelling DSC thermograms obtained after different thermal histories in each sample. The slope in the Arrhenius diagram log tau vs 1/T around the glass transition temperature is significantly smaller in the blend which is closer to the upper limit of miscibility than in the other miscible blends in which SAN copolymer contains less AN. The change of slope can be ascribed to a distribution in the glass transition temperatures of the different rearranging regions, reflecting the appearance of a microheterogeneity in the blend that cannot be detected as a double glass transition in the blend. (C) 2002 Published by Elsevier Science Ltd.