...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Journal of Materials Science >Differences in mechanical behavior between alternating and random styrene-methyl methacrylate copolymers
【24h】

Differences in mechanical behavior between alternating and random styrene-methyl methacrylate copolymers

机译：交替和无规苯乙烯-甲基丙烯酸甲酯共​​聚物的机械性能差异

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

The viscoelastic behavior of an alternating copolymer styrene-methyl methacrylate (S-alt-M) of composition 50:50 mol% has been investigated over a wide temperature range covering the glassy state, the glass transition region (governed by the mechanical relaxation a), and the rubbery plateau. Data were discussed by comparison with the styrene-methyl methacrylate random copolymer (S-r-M) of same composition. These studies based on tensile and shear DMTA measurements, were carried out at various temperatures and frequencies. In addition, stress-strain curves in compression mode were recorded at various temperatures and strain rates in the glassy state. The activation enthalpy and activation volume of the plastic deformation process with temperature was measured for both S-alt-M and S-r-M. Data analysis was performed on a molecular scale, by putting emphasis on the correlation existing between the amplitude of relaxation and the p-relaxation character associated to the sequence length distribution of the copolymers. From the orientation measurements of SM copolymers, carried out by infra-red dichroism, on films stretched at various gaps (T - T-alpha) from the main relaxation temperature and at various strain rates, it turned out that the M segments stayed even more oriented than the S segments. Two distinct orientation relaxation curves were obtained for each type of segments, irrespective of the type of copolymer. It was shown that they could be reduced to unique ones after normalization by the zero time or zero (T - T-alpha) orientation value. All these results were interpreted in relation to the role of polar-polar intermolecular interactions between M-M units, which are likely to occur in the S-r-M copolymer, but were quite lacking in the S-alt-M copolymer. However, the influence of the triad MSM on the mechanical properties was shown to progressively decrease as long as the testing temperature approaches or exceeds T-alpha. (C) 2005 Springer Science + Business Media, Inc.
机译：已经在覆盖玻璃态，玻璃化转变区域（通过机械弛豫a控制）的宽温度范围内研究了组成为50:50 mol％的交替共聚物苯乙烯-甲基丙烯酸甲酯（S-alt-M）的粘弹性行为。 ，以及橡胶高原。通过与相同组成的苯乙烯-甲基丙烯酸甲酯无规共聚物（S-r-M）进行比较来讨论数据。这些基于拉伸和剪切DMTA测量的研究是在各种温度和频率下进行的。另外，在玻璃态下在各种温度和应变速率下记录了压缩模式下的应力-应变曲线。测量了S-alt-M和S-r-M的塑性变形过程随温度的活化焓和活化体积。通过强调弛豫幅度和与共聚物的序列长度分布相关的p-松弛特征之间存在的相关性，以分子尺度进行数据分析。通过红外二色性对SM共聚物进行的取向测量，该薄膜在距主弛豫温度和各种应变速率不同的缝隙（T-T-alpha）拉伸的薄膜上，发现M片段的停留更多。比S段定向。不管共聚物的类型如何，对于每种类型的链段均获得两条不同的取向松弛曲线。结果表明，归一化后，零时间或零（T-T-alpha）定向值可以将它们还原为唯一的。所有这些结果都被解释为与M-M单元之间的极性-极性分子间相互作用的作用有关，这很可能在S-r-M共聚物中发生，但在S-alt-M共聚物中却很缺乏。但是，只要测试温度接近或超过T-alpha，三重态MSM对机械性能的影响就会逐渐降低。 （C）2005年Springer Science + Business Media，Inc.

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号