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High‐melt‐strength polypropylene with electron beam irradiation in the presence of polyfunctional monomers
Author(s) -
Yoshii Fumio,
Makuuchi Keizo,
Kikukawa Shingo,
Tanaka Tadashi,
Saitoh Jun,
Koyama Kiyohito
Publication year - 1996
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/(sici)1097-4628(19960425)60:4<617::aid-app16>3.0.co;2-w
Subject(s) - materials science , crystallinity , polypropylene , monomer , composite material , irradiation , polymer chemistry , melt flow index , ultimate tensile strength , polymer , chemical engineering , copolymer , physics , nuclear physics , engineering
High‐melt‐strength polypropylene (PP) was achieved with irradiation by an electron beam generated from an accelerator in the presence of polyfunctional monomers (PFM). Among 16 PFMs, the relatively shorter molecular chain bifunctional monomers such as 1,4‐butanediol diacrylate (BDDA) and 1,6‐hexanediol diacrylate (HDDA) were the most effective for enhancing the melt strength of PP. The concentration and dose of the HDDA to obtain the high melt strength PP in irradiation under nitrogen gas atmosphere were 1.5 mmol/100 g PP and 1 kGy, respectively. DSC measurement and dynamic mechanical analysis showed that the thermal behavior of the high‐melt‐strength PP was different from that of the original PP. Crystallinity and crystallization temperature during cooling after heating were lower and higher in high melt strength PP than original PP, respectively. Elongational viscosity at 180°C of the high‐melt‐strength PP showed a remarkable increase at a certain elongational time with constant strain rate, demonstrating the typical property of high‐melt‐strength samples. This implies that a few higher molecular chains of PP, formed by intermolecular combination of its chain by HDDA in irradiation, give higher melt strength to induce entanglement of molecular chains. © 1996 John Wiley & Sons, Inc.