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The Morphology and Structure of Isotatic Polypropylene Parts Molded by Water-assisted Injection Molding

Author: JiaZhenHua
Tutor: ShenChangYu；ZhengGuoQiang
School: Zhengzhou University
Course: Materials Processing Engineering
Keywords: Water -assisted injection molding Conventional injection molding Polypropylene Nucleating agent Crystal morphology Shish Shear stress
CLC: TQ320.662
Type: Master's thesis
Year: 2011
Downloads: 37
Quote: 0
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Abstract


Water-assisted injection molding (Water-Assisted Injection Molding, WAIM) in gas-assisted injection molding (Gas-Assisted Injection Molding, GAIM) and conventional injection molding (Conventional Injection Molding, CIM) evolved on the basis of a new type of polymerization material molding processing technology. WAIM in the preparation of thick-walled, flat, tubular products and large workpieces with unique advantages, in recent years has attracted wide attention from many scholars. But so far, the study focused mainly concentrated in the water penetration process simulation, product quality and the molding process macro relationships, waterways and water injection structure design, etc., and such WAIM products crystalline morphology study also rarely reported. In view of this, this thesis polarizing microscope, small angle X-ray scattering and wide-angle X-ray diffraction characterization methods, focus on the WAIM process conditions, isotactic polypropylene (Isotatic Polypropylene, iPP) products morphological structure formation and evolution mechanism, as well as p nucleating agent on the product morphology formation. And through WAIM and CIM in the process similarities and differences between the mechanism of physical fields comparative analysis study to clarify the crystal morphology and orientation of iPP products forming principle and influence the behavior of mechanisms, so as to further improve the performance of products WAIM provide theoretical guidance and experimental basis . The main results are as follows: (a) studies WAIM process conditions, iPP products, crystal morphology and orientation behavior and found that products from the mold side wall edge into waterways, according to the distribution of its morphology is different macro can be broadly divided into three : surface, core and waterways layer; And due to water penetration of the surface layer and waterways have more shish-kebab structure formation. (2) Through the different molecular weight of iPP WAIM products crystalline morphology and orientation behavior research, found that low molecular weight products iPP waterways layer surface and a high molecular weight than the corresponding layer of iPP products retain more shish structure. (3) study the p nucleating agent on WAIM process conditions iPP products hierarchical structure. The results showed that, β nucleating agent can significantly affect WAIM product hierarchy. Low levels of β nucleating agents WAIM articles in alignment region can significantly expanded; high content of β nucleating agent, the products within the grains becomes very small, the alignment region and the boundary of the isotropic region disappears products throughout the thickness direction of the uniform hierarchical structure more. (4) through the various β nucleating agent content of the layers WAIM products shish-kebab structure studies, we found, p WAIM nucleating agent can promote products in the generation of shish-kebab structure. When the β nucleating agent content to 1%, shish-kebab structure extended to the existing area of ??the core WAIM products. And the crystallinity of each layer WAIM products, β crystal content and orientation behavior p with increasing content of the nucleating agent is significantly improved.

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CLC: > Industrial Technology > Chemical Industry > Synthetic resins and plastics industry > General issues > Production process and production technology > Forming > Injection molding
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