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Chemical modification of polypropylene with peroxide/pentaerythritol triacrylate by reactive extrusion
Author(s) -
Wang Xiaochuan,
Tzoganakis Costas,
Rempel Garry L.
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(19960822)61:8<1395::aid-app21>3.0.co;2-x
Subject(s) - peroxide , reactive extrusion , pentaerythritol , polypropylene , materials science , polymer chemistry , organic peroxide , tacticity , monomer , fourier transform infrared spectroscopy , polymer , hydrogen peroxide , polymerization , chemical engineering , chemistry , organic chemistry , copolymer , composite material , fire retardant , engineering
To explore the possibility of producing branched polypropylene (PP) by a reactive extrusion (REX) process, isotactic PP was reacted with a polyfunctional monomer, pentaerythritol triacrylate (PETA), in the presence of 2,5‐dimethyl‐2,5( t ‐butylperoxy) hexane peroxide (Lupersol 101). Experiments were carried out in an intermeshing, corotating twin‐screw extruder at 200°C using three concentrations of peroxide (200, 600, and 1000 ppm) and four concentrations of PETA (0.64, 1.8, 2.8, and 5.0%, by weight). Shear viscosity and MFI of the whole polymers was found to increase with PETA concentration and decrease with increasing the peroxide concentration at a given PETA concentration. The macrogel amount in the materials produced was determined in refluxing xylene using Soxhlet extraction and at PETA concentrations higher than 1.8wt % the macrogel content increased with increasing peroxide concentration. No macrogel was detected at low PETA concentrations (<0.64%) at all three peroxide levels, suggesting that low concentrations of PETA and peroxide should be used in order to minimize the formation of macrogels. The xylene soluble portions (sols) of the modified materials were characterized by FTIR and DSC. Generally, the relative intensities A 1740 / A 841 in the FTIR spectra increased with increasing PETA incorporated into PP. Two melting peaks ( T m1 and T m2 ) were observed in the DSC traces of some of the sols, and the crystallization temperatures ( T c ) were higher than those of the virgin and degraded polypropylenes. The DSC behavior of the sols suggests that the modified PPs contain branched and/or lightly crosslinked chain structures. © 1996 John Wiley & Sons, Inc.