Hybrid blends of similar ethylene 1-octene copolymers
Hybrid blends of similar ethylene 1-octene copolymers
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DOI：
10.1016/s0032-3861(00)00066-5
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发表时间：
2000-06-01
期刊：
影响因子：
4.6
通讯作者：
Choe, S
中科院分区：
文献类型：
--
作者：
Rana, D;Kim, HL;Choe, S
研究了由Ziegler-Natta催化剂和茂金属催化剂制备的乙烯-辛烯共聚物（EOC）组成的FA + FM和SF + FM两种二元共混物的热性能、粘弹性能、流变性能、力学性能和形态结构。Ziegler-Natta催化剂和茂金属催化剂的EOC之间的最大区别在于侧链支化的分布和长度。FA + FM中的每种组分具有相似的熔体指数（MI）、密度和共聚单体含量，而第二对（SF + FM）中的组分具有相似的MI和密度，但共聚单体含量不同。熔融和溶液共混的材料都表现出两个不同的熔融和结晶峰，这意味着在结晶过程中组分相互排斥。随着茂金属EOC的含量，单个β弛豫向较低温度偏移，表明在非晶区中的可结晶性，而在实验误差内在相同位置观察到γ转变。流变学观察表明FA + FM是可混溶的，但不是SF + FM，这意味着侧链支化的分布和长度的差异影响EOC共混物的熔体性质，而不管密度和MI的相似性如何。此外，没有观察到共聚单体含量和侧链支化差异对机械性能的依赖性。从缓慢冷却的标本观察到的形态学研究显示大的球晶直径和环形空间的齐格勒-纳塔EOC。特别地，通过添加茂金属EOC，在共混物中主导草状球晶束结构。因此，由相似的MI和密度组成的混杂共混物的性质不仅受共聚单体的分布的影响，而且受侧链支化的长度的影响。(C)2000由爱思唯尔科学有限公司出版。版权所有。
Two binary blends of FA + FM and SF + FM comprising ethylene 1-octene copolymers (EOC), one component prepared by Ziegler-Natta and another by metallocene catalysts were investigated in terms of the thermal, viscoelastic, rheological, mechanical, and morphological properties. The big difference between the Ziegler-Natta and metallocene catalyzed EOCs is the distribution and the length of the side chain branching. Each component in FA + FM has similar melt index (MI), density, and comonomer content, while that of the second pair (SF + FM) has similar MI and density, but differs in comonomer content. Both the melt and solution blended materials exhibit two distinct melting and crystallization peaks, implying that the constituents exclude one another during crystallization. A single beta relaxation shifted to lower temperature with the content of metallocene EOC, indicates miscibility in the amorphous region, while the gamma transition is observed in the same position within experimental error. Rheological observations suggest the FA + FM to be miscible, but not SF + FM, implying that the difference in the distribution and the length of the side chain branching influences the melt properties of the EOC blends regardless of the similarity in the density and MI. In addition, no dependency of comonomer contents and the difference in the side chain branching on the mechanical properties is observed. Morphological studies observed from the slow cooled specimens show large spherulitic diameter and ring space for the Ziegler-Natta EOC. In particular, grass like spherulitic sheaf structure is dominated in the blend by the addition of metallocene EOCs. Hence the properties of the hybrid blends consisting of similar MI and density are influenced by not only the distribution of the comonomer, but also the length of the side chain branching. (C) 2000 Published by Elsevier Science Ltd. All rights reserved.