Super polyolefin blends achieved via dynamic packing injection molding: the morphology and mechanical properties of HDPE/EVA blends
Super polyolefin blends achieved via dynamic packing injection molding: the morphology and mechanical properties of HDPE/EVA blends
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DOI：
10.1016/s0032-3861(02)00637-7
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发表时间：
2002-12-01
期刊：
影响因子：
4.6
通讯作者：
Shen, KZ
中科院分区：
文献类型：
--
作者：
Na, B;Zhang, Q;Shen, KZ
作为超级聚烯烃共混物长期项目的一部分，在这项工作中，我们报告了高密度聚乙烯（HDPE）和乙烯-醋酸乙烯酯（伊娃）共混物的动态填充注射成型实现的机械增强和相形态。剪切应力（通过动态保压注射成型获得）和界面相互作用（通过使用具有不同VA含量的伊娃获得）对相形态和力学性能有很大影响。通过控制HDPE/伊娃共混物的相分离、分子取向和结晶形态，制备了高模量（1.9- 2.2GPa）、高拉伸强度（100-120 MPa）和高冲击强度（6倍于纯HDPE）的超级HDPE/EVA共混物。还发现在剪切应力下相转化向较低的伊娃含量移动。拉伸强度和模量的提高源于取向层的形成，而高冲击强度则与剪切诱导相形态有关。DSC研究表明，取向层中形成的串晶结构也有助于拉伸强度的提高。冲击强度的显著改善可能是由于沿流动方向形成了微纤维和细长的伊娃颗粒沿着。发现Wu的增韧理论不适用于伸长和取向的橡胶粒子，并且观察到脆-韧-脆转变随伊娃含量的增加。(C)2002爱思唯尔科技有限公司版权所有。
As a part of long-term project aimed at super polyolefin blends, in this work, we report the mechanical reinforcement and phase morphology of the blends of high-density polyethylene (HDPE) and ethylene vinyl acetate (EVA) achieved by dynamic packing injection molding. The shear stress (achieved by dynamic packing injection molding) and interfacial interaction (obtained by using EVA with different VA content) have a great effect on phase morphology and thus mechanical properties. The super HDPE/EVA blends having high modulus (1.9-2.2 GPa), high tensile strength (100-120 MPa) and high impact strength (six times as that of pure HDPE) have been prepared by controlling the phase separation, molecular orientation and crystal morphology of the blends. The phase inversion was also found to shift towards lower EVA content under shear stress. The enhancement of tensile strength and modulus originates from the formation of oriented layer, while the high impact strength is related to shear induced phase morphology. DSC studies indicated that the shish kebab crystal structure that also contributes to the enhancement of tensile strength is formed in the oriented layer. The dramatic improvement of impact strength may result from the formation of microfibers and elongated EVA particles along the flow direction. Wu's toughening theory was found non-applicable for the elongated and oriented rubber particles, and a brittle-ductile-brittle transition was observed with increasing EVA content. (C) 2002 Elsevier Science Ltd. All rights reserved.