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首页> 外文会议>International Conference on Deformation, Yield and Fracture of Polymers; 20000410-20040413; Cambridge; GB >Chain Architecture Effect on Fracture of Semicrystalline-Glassy Block Copolymers
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Chain Architecture Effect on Fracture of Semicrystalline-Glassy Block Copolymers

机译：链结构对半结晶玻璃态嵌段共聚物断裂的影响

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摘要

Many glassy polymers with otherwise desirable characteristics are very brittle even at rather large molecular weights. Often this brittleness can be traced to a low entangled strand density (high entanglement molecular weight M_e), which predisposes the glassy polymer to form weak crazes that break down readily to form cracks. One such polymer is poly(vinyl cyclohexane) (PCHE) which has excellent clarity, excellent UV stability, low birefringence and a high glass transition temperature T_g of about 145℃. Its large M_e of ～40,000 g/mol~3 means that PCHE is also extremely brittle. One method of relieving this brittleness while retaining a relatively high modulus is to use PCHE and poly(ethylene) (PE) as blocks in a block copolymer with a majority of the PCHE glassy domain. Surprisingly these materials are optically clear and can exhibit practical toughness at relatively low molecular weight, making them easy to process. In this paper we investigate the influence of chain architecture on the microscopic deformation and fracture mechanisms of thin films of these poly(vinyl cyclohexane)-poly(ethylene) (PCHE-PE) block copolymers. We compare the deformation of ordered triblock copolymers PCHE-PE-PCHE [CEC] and pentablock PCHE-PE-PCHE-PE-PCHE [CECEC] copolymers with that of the PCHE homopolymer.
机译：即使具有相当大的分子量，许多具有其他所需特性的玻璃状聚合物也非常脆。通常，这种脆性可归因于低的缠结线密度（高缠结分子量M_e），这使玻璃状聚合物易于形成易碎的裂纹，并容易破裂而形成裂纹。一种这样的聚合物是聚（乙烯基环己烷）（PCHE），其具有优异的透明度，优异的紫外线稳定性，低双折射和约145℃的高玻璃化转变温度T_g。它的大M_e约为40,000 g / mol〜3，这意味着PCHE也非常脆。在保留相对较高模量的同时减轻这种脆性的一种方法是在大部分PCHE玻璃态结构域的嵌段共聚物中使用PCHE和聚乙烯（PE）作为嵌段。令人惊讶地，这些材料是光学透明的，并且在相对低的分子量下可以显示出实用的韧性，从而使其易于加工。在本文中，我们研究了链结构对这些聚（乙烯基环己烷）-聚（乙烯）（PCHE-PE）嵌段共聚物薄膜的微观形变和断裂机理的影响。我们比较了有序三嵌段共聚物PCHE-PE-PCHE [CEC]和五嵌段PCHE-PE-PCHE-PE-PCHE [CECEC]共聚物的变形与PCHE均聚物的变形。

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