Crosslinking of atactic polypropylene by the system peroxide‐pentaerythritol tetraallyl ether

Borsig, Eberhard; Lazár, M.; Malcherová, Elena

doi:10.1002/pi.4990300315

Cited by 21 publications

(9 citation statements)

References 8 publications

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“…Chain scission (β‐scission) is the dominant reaction in PP when subjected to free radicals at elevated temperatures during processing. Crosslinking of PP by peroxide may only be performed with unusual high peroxide concentrations at low temperatures or in the presence of multifunctional crosslinking coagents 14–19…”

Section: Introductionmentioning

confidence: 99%

Influence of grafting formulations and extrusion conditions on properties of silane-grafted polypropylenes

Huang¹,

Lu²,

Liu³

2000

J. Appl. Polym. Sci.

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The melt grafting of unsaturated silanes onto powdered polypropylene (PP) in a Haake TW100 twin‐screw extruder and curing in hot water were studied. The influence of grafting formulations and extrusion conditions on the melt flow rates of grafted PP and the gel percentages of crosslinked PP was investigated. The gel percentages of methacryloylpropyltrimethoxysilane (VMMS)‐grafted PP were markedly higher than those of vinyltriethoxysilane (VTES)‐ and vinyltrimethoxysilane (VTMS)‐grafted PP, while significantly less degradation of PP during grafting was observed for VMMS‐grafted PP. When benzoyl peroxide (BPO) was used as an initiator, no degradation of PP during grafting was observed, and the melt flow rates of grafted PP decreased with increasing BPO concentration. In contrast, use of dicumyl peroxide (DCP) as an initiator resulted in severe degradation of PP, and the melt flow rates of grafted PP increased gradually with increasing DCP concentration. BPO resulted in higher gel percentages than those of DCP at a fixed initiator concentration. Introduction of styrene into the grafting system greatly improved the gel percentage of crosslinked PP and reduced the degradation of PP during grafting. The optimum molar ratio of styrene to monomer is at about 1.5:1. Relatively low processing temperatures and high screw speeds are favorable. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1233–1238, 2000

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Section: Introductionmentioning

confidence: 99%

Influence of grafting formulations and extrusion conditions on properties of silane-grafted polypropylenes

Huang¹,

Lu²,

Liu³

2000

J. Appl. Polym. Sci.

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“…No detectable gel was found for the DCP‐modified PP. It was reported that the crosslinking of PP by a peroxide can be obtained using unusually high peroxide concentrations or in the presence of crosslinking coagents 29, 30…”

Section: Resultsmentioning

confidence: 99%

Thermal and crystallization behavior of silane‐crosslinked polypropylene

Wang

Gui

et al. 2004

Polymer International

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Silane-crosslinked polypropylene (PP) has been prepared first by the grafting of silane onto the backbone of PP in a melt process and then by crosslinking in warm water. The effects of type and concentration of silane and peroxide on the silane grafting on PP were investigated. The thermal behavior of the silane-crosslinked PP was studied by thermogravimetric (TG) and differential scanning calorimetry (DSC) methods. TG results show that PP prepared via silane crosslinking increases its thermal stability greatly. It has been found from DSC measurements that the crystallization temperatures, ie the onset temperature and peak temperature of the exotherm of the silane-crosslinked PP, increase compared with those of the pure PP. The silane crosslinking hardly changes the crystallinity degree of PP. The crystallization behavior of the silane-crosslinked PP was also studied by wide-angle X-ray diffraction analysis.

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“…Up to a certain dosage, irradiation does not signifi cantly affect the crystallinity of crosslinked PP. The use of coagents such as tetramethylolmethane tetraacrylate and trimethylolpropane triacrylate has been successful in inhibiting the fragmenting of PP and increasing crosslinking effi ciency [30,31] . [32] and I.G.…”

Section: Polypropylenementioning

confidence: 99%