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Mechanism of a one‐step method for preparing silane grafting and cross‐linking polypropylene
Author(s) -
Yang Shujing,
Song Guojun,
Zhao Yunguo,
Yang Chao,
She Xilin
Publication year - 2007
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.20753
Subject(s) - polypropylene , reactive extrusion , grafting , materials science , silane , polymer chemistry , catalysis , monomer , styrene , melt flow index , reaction mechanism , benzoyl peroxide , tacticity , chemical engineering , polymerization , polymer , composite material , copolymer , organic chemistry , chemistry , engineering
A high‐melt‐strength polypropylene (HMSPP) with partially cross‐linking, modified from a normal isotactic polypropylene (IPP), is prepared by a one‐step silane grafting and cross‐linking method in a twin‐screw reactive extruder. The melt grafting and cross‐linking of IPP is achieved by using vinyl unsaturated silane with long chain as a grafting monomer, benzoyl peroxide (BPO) as an initiator, styrene as a coagent, and a little water as a catalyst for cross‐linking. By analyzing the difference of the Fourier transformed infrared spectra between raw and modified PP, comparing the variety of the melt flow rate (MFR) and gel percentage between cured and uncured PP samples, and investigating the effect of catalyst on the MFR and gel percentage of modified PP, the partially cross‐linked polypropylene in the way of one‐step reactive extrusion has been verified. We put forward the reactive mechanism of one‐step method based on our experimental results. In this mechanism, the hydrolysis and condensation of silane occur first through the catalysis of water and a compound with two or more double‐bond is formed, which then the compound reacts with PP macroradicals to form the partially cross‐linked PP. POLYM. ENG. SCI., 47:1004–1008, 2007. © 2007 Society of Plastics Engineers