Anisotropic thermal expansion in polypropylene/poly(ethylene-co-octene) binary blends: influence of arrays of elastomer domains
Anisotropic thermal expansion in polypropylene/poly(ethylene-co-octene) binary blends: influence of arrays of elastomer domains
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DOI：
10.1016/j.polymer.2005.03.098
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发表时间：
2005-06
期刊：
影响因子：
4.6
通讯作者：
M. Ono;J. Washiyama;K. Nakajima;T. Nishi
中科院分区：
文献类型：
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作者：
M. Ono;J. Washiyama;K. Nakajima;T. Nishi
采用热力学分析（TMA）研究了不同粘度η(EOR)/η(iPP)比的等规聚丙烯(iPP)/聚乙烯-共辛烯（EOR）共混物的线性热膨胀系数（CLTE）。黏度比越小的共混物，其各向异性随方向的变化越大。透射电镜观察发现，随着η(EOR)/η(iPP)的增大，橡胶畴的形状从板状、圆柱形到椭球状不等。WAXD晶体取向分析表明，与“平板”型EOR结构域混合后，iPP晶体的c轴取向偏向FD（流动方向）和TD（横向于FD）， b轴取向偏向ND（厚度方向）。通过引入弹性体畴阵列和PP晶体取向的影响，各FD和TD的CLTE均符合CLTE的混合规律。另一方面，ND的CLTE计算值与观测值存在较大差异。研究发现，纳入回缩效应可以在一定程度上解释这一差异。
In injection molded specimens consisting of isotactic polypropylene (iPP)/poly(ethylene-co-octene) (EOR) blends with different viscosity ratio of η(EOR)/η(iPP), the coefficient of linear thermal expansion (CLTE) was investigated by thermal mechanical analysis (TMA). It was found that the blend with a smaller viscosity ratio showed the larger anisotropy of CLTE depending upon the directions. TEM observations revealed that the shape of rubber domains varied from slabs, cylinders to ellipsoids in shape, by increasing η(EOR)/η(iPP). The crystal orientation analysis by WAXD have revealed that the blend with ‘slab’ EOR domains showed the orientation of the c-axis of iPP crystals was preferably oriented to FD (flow direction) and TD (transverse to FD), and that the b-axis was exclusively oriented to ND (thickness direction). The CLTE of each FD and TD was in good agreement with the rules-of-mixing for CLTE by introducing the effect of the arrays of the elastomer domains and the PP crystal orientation. On the other hand, the CLTE in ND showed massive discrepancy between the calculation and observation. It was found that the incorporation of the retraction effect could explain the discrepancy to some extent.