Synthesis of Maleic Anhydride Grafted Polyethylene and

Synthesis of Maleic Anhydride Grafted Polyethylene and Polypropylene,with Controlled Molecular Structures

BING LU,T.C.CHUNG

Department of Materials Science and Engineering,The Pennsylvania State University,

University Park,Pennsylvania16802

Received4October1999;accepted27January2000

ABSTRACT:This article discusses a new chemical route to prepare maleic anhydride

(MA)grafted polyethylene and polypropylene polymers with controlled molecular struc-

ture,that is,MA grafted content and polymer molecular weight and composition

distributions.The chemistry involves a free radical graft reaction of maleic anhydride

with poly(ethylene-co-p-methylstyrene)and poly(propylene-co-p-methylstyrene)copoly-

mers.Under a suspension reaction condition,the grafting reaction takes place selec-

tively on the p-methylstyrene units in the copolymer,due to high reactivity of p-methyl

group and favorable mixing between p-methylstyrene units and chemical reagents in

the swollen amorphous phases.The resulting polymer shows no detectable molecular

weight change during the reaction,and the MA grafted content increases with the

increase of initiator and p-methylstyrene concentrations.©2000John Wiley&Sons,Inc.

J Polym Sci A:Polym Chem38:1337–1343,2000

Keywords:maleated PE;maleated PP;functional polyolefin;polyethylene copoly-

mer;polypropylene copolymer

INTRODUCTION

Maleic anhydride(MA)modified polyolefins,in-cluding PE,PP,and EPDM,have been one of the most important class of functional polyolefins in industry,because of low cost of maleic anhydride and high activity of the anhydride group.1MA modified polyolefin considerably improve adhe-sion and hydrophilicity of the polymer,and com-patibility with polar polymers.As a results,MA modified polyolefins are used in many commercial applications,such as glassfiber reinforced poly-olefins,2anticorrosive coatings for metal pipes and containers,3multilayer sheets of paper for chemical and food packaging,4and polymer blends with polyamides and polyesters.5–7 MA modified polyolefin is normally prepared by free radical grafting reaction of maleic anhy-dride with the corresponding polyolefin in the presence of organic peroxide initiator either in solution,8–12or in melt.12–23Equation1illus-trates the reaction mechanism of MA grafting

Synthesis of Maleic Anhydride Grafted Polyethylene and

polypropylene.

It is generally believed that the grafting reaction starts with hydrogen abstraction by alkoxyl rad-ical,upon the thermal decomposition of peroxide

Correspondence to:T. C.Chung(E-mail:chung@ems.

psu.edu)

Journal of Polymer Science:Part A:Polymer Chemistry,Vol.38,1337–1343(2000)

©2000John Wiley&Sons,Inc.

1337

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