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Improved cell morphology and thermal properties of expanded polypropylene beads by the addition of PP with a high melting point
Author(s) -
Zhang Rong,
Xiong Yezhi,
Liu Qingting,
Hu Shengfei
Publication year - 2017
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.45121
Subject(s) - polypropylene , materials science , melting point , nucleation , morphology (biology) , crystallization , composite material , rheology , molding (decorative) , melting temperature , thermal , polymer chemistry , chemical engineering , chemistry , physics , engineering , meteorology , organic chemistry , biology , genetics
Expanded polypropylene (EPP) beads have attracted attention in recent years due to their potential use in fabricating complex, three dimensional structures. In this study, a small amount of polypropylene (PP) with a higher melting temperature (HPP) was blended with low melting point PP (LPP) to regulate the cell morphology and thermal behavior peaks of the resulting blends. These materials were then foamed to produce EPP beads in an autoclave with CO 2 at different temperatures, producing EPP beads. The rheological, thermal, and foaming properties of the LPP/HPP blends were characterized. The melt strength and elasticity of LPP/HPP were improved because of rapid crystallization and increase in crystal number with increasing HPP content. These results were attributed to the physical crosslinks and nucleation sites provided by the HPP. These enhanced properties were leveraged to produce regular foams without through‐holes, decreased cell size, and increased cell density. Furthermore, the lower melting point decreased with increasing HPP content, producing a wider temperature range over which steam‐chest molding could occur. Thus, the addition of HPP is a facile method for regulating the cell morphology and thermal behavior of EPP. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45121.