REINFORCEMENT OF POLYPROPYLENE BY CONTROLLING THE HIERARCHICAL STRUCTURE OF INJECTION MOLDED BAR
Molding processing is a necessary stage links pristine polymer materials and specific practical application. Obviously, the hierarchical structure of polymer material parts can be controlled via adjusting thermal and/or shear conditions during molding processing, and the structural design plays an important role for optimizing the ultimate performances of polymer application. It is well known that there exists a skin-core structure in the injection molded bar of a polymer due to the thermal and shear gradient. In the skin zone, a highly oriented structure is obtained and a isotropic texture exists in the core zone. A macroscopic bamboo-like bionic-structure was fabricated in the injection-molded bar of isotactic polypropylene via the combined effect of melt manipulation and pnucleator. Such structure consists of strengthened shell zone with high orientation and low β-phase amount, and toughened core part with isotropic texture and dominant β-modification. In the injection molding of polypropylene random copolymer (PPR), different processing melt temperatures ranged from 180 to 250 ℃ were used to adjust the skin/core ratio. Alrough the core area keeps relatively constant for all the samples, a thicker skin and a sharp transition were observed for the samples obtained at lower processing melt temperature (below 230 ℃), resulting in a lower impact strength and break elongation. However, for the samples obtained at higher processing melt temperature (230250℃), a thinner skin and a broad transition were observed, resulting in a greatly improved impact strength and elongation at break. Our study suggests an alternative approach to receive excellent comprehensive mechanics in polypropylene through macroscopically structural design during practical molding processing.
Run Su Feng Luo Ke Wang Hua Deng Qiang Fu
Department of Polymer Science & Materials, Sichuan University, State Key Laboratory of Polymer Materials Engineering, Chengdu, 610065, P.R.China
国际会议
PP’2010，Jinan International Symposium on Polymer Physics(2010济南国际高分子物理学术研讨会)
济南
英文
39-40
2010-06-06（万方平台首次上网日期，不代表论文的发表时间）