The effect of hard block content on the orientation and mechanical properties of olefin block copolymer films as obtained via melt stretching
The effect of hard block content on the orientation and mechanical properties of olefin block copolymer films as obtained via melt stretching
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硬嵌段含量对熔融拉伸烯烃嵌段共聚物薄膜的取向和机械性能的影响
DOI：
10.1039/c5ra13864g
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发表时间：
2015-09
期刊：
影响因子：
3.9
通讯作者：
Fu, Qiang
中科院分区：
文献类型：
--
作者：
Sui, Guopeng;Chen, Feng;Zhang, Qin;Fu, Qiang
在这项研究中，一系列的单轴取向膜的基础上烯烃嵌段共聚物（OBC）的取向，结构和力学性能的硬段含量和拉伸比（DR）的差异进行了研究。使用具有35重量%、25重量%和12重量%的不同硬嵌段含量的三种OBCs。对于未拉伸的膜，观察到从紧密堆积的球晶到微小的微晶的变化，随着硬块含量的降低，伴随着结晶度几乎线性下降。然而，力学性能的变化并不遵循相同的路径，具有明显较高的拉伸强度和模量的OBC-35，但较低的拉伸强度和模量的OBC-25和OBC-12，尽管它们之间的硬段含量和结晶度的大的差异，几乎相同。对于熔融拉伸膜，无定形相的取向程度几乎相同，并且随着三种OBCs的拉伸比的增加而略有增加，而不管它们的硬嵌段含量。对于OBC-35，结晶取向和shish含量高得多，并且随着拉伸比从4.95增加到8而明显增加，对应于杨氏模量和应力的急剧增加。对于OBC-25和OBC-12，观察到类似的结晶取向和shish含量，其随拉伸比线性增加，并且与模量和应力随拉伸比增加的线性增加一致。我们的研究表明，硬嵌段含量的OBC的重要性，以确定机械性能和外部拉伸的响应。存在临界硬嵌段含量（在这种情况下为35wt%），在该临界硬嵌段含量以上，硬嵌段结晶相构成强网络，导致更高的拉伸强度和模量。当拉伸比达到一定值（在此为4.95至8）时，这种强网络被破坏，导致结晶取向的明显增加，以及拉伸强度和模量的急剧增加。当硬嵌段低于临界含量（在此，25重量%和12重量%）时，由硬嵌段构成的网络较弱并且较少依赖于其含量。
In this study, the orientation, structure and mechanical performance of a series of uniaxially oriented films based on olefin block copolymers (OBC) have been investigated in terms of the differences in hard block content and draw ratio (DR). Three OBCs with different hard block contents of 35 wt%, 25 wt% and 12 wt% were used. For un-stretched films, a change from close-packed spherulites into tiny crystallites is observed with decreasing hard block content, accompanied by an almost linear decrease in crystallinity. However, the change in mechanical properties does not follow the same path, with obviously higher tensile strength and modulus for OBC-35, but a lower and almost the same tensile strength and modulus for OBC-25 and OBC-12, in spite of the big difference in hard block content and crystallinity between them. For melt-stretched films, the degree of orientation of the amorphous phase is almost the same and slightly increases with the increase in the draw ratio for the three OBCs, disregarding their hard block contents. Crystalline orientation and shish content are much higher for OBC-35, and an obvious increase is seen as the draw ratio increases from 4.95 to 8, corresponding to the sharp increase in Young's modulus and stress. For OBC-25 and OBC-12, similar crystalline orientation and shish content are seen, which increase linearly with draw ratio and are consistent with the linear increase in modulus and stress as the draw ratio increases. Our study demonstrates the importance of the hard block content of OBC to determine the mechanical properties and the response to external stretching. A critical hard block content exists (in this case 35 wt%), above which a strong network is constructed by the hard block crystalline phase, resulting in a higher tensile strength and modulus. This strong network is destroyed as the draw ratio reaches a certain value (herein, 4.95 to 8), leading to an obvious increase in crystalline orientation, as well as a sharp increase in tensile strength and modulus. When the hard block is below the critical content (herein, 25 wt% and 12 wt%), the network constructed by the hard block is weak and less dependent on its content.
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影响因子：
4.6
作者：
Meng Wu;Zhiqiang Wu;Ke Wang;Qin Zhang;Qiang Fu
通讯作者：
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影响因子：
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作者：
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影响因子：
4.6
作者：
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通讯作者：
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影响因子：
3.1
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通讯作者：
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影响因子：
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通讯作者：
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