Chemical Modification of Metallocene-Based Polyethylene–Octene Elastomer Through Solution Grafting of Acrylic Acid and its Effect on the Physico-Mechanical Properties Anjan Biswas, 1 * Abhijit Bandyopadhyay, 2 Nikhil K. Singha, 1 Anil K. Bhowmick 1 1 Rubber Technology Centre, Indian Institute of Technology, Kharagpur, West Bengal 721302, India 2 Department of Polymer Science and Technology, University of Calcutta, Kolkata, West Bengal 700009, India Received 25 December 2006; accepted 26 February 2007 DOI 10.1002/app.26374 Published online 30 May 2007 in Wiley InterScience (www.interscience.wiley.com). ABSTRACT: In the present work, the metallocene- based polyethylene–octene elastomer (POE) was chemi- cally modified by solution grafting of acrylic acid in presence of benzoyl peroxide. The relative proportions of graft and gel formation were optimized through %weight gain, Fourier Transform infrared spectroscopy, elemental analysis and proton nuclear magnetic reso- nance spectroscopy. The gel formation in the POE ma- trix was found to be the prime competitor. The effect of grafting at its maximum level on various physicome- chanical properties was thoroughly investigated, using X-ray diffraction analysis, differential scanning calorim- etry, mechanical, dynamic mechanical, and thermogravi- metric analysis. Ó 2007 Wiley Periodicals, Inc. J Appl Polym Sci 105: 3409–3417, 2007 Key words: grafting; acrylic acid; polyethylene–octene elas- tomer; carboxylated polymer; chemical modification INTRODUCTION Free-radical grafting of unsaturated carboxylic acids or their derivatives onto polyolefins is an effective method to impart certain degree of functionality in polyolefins. 1 Chemical modifications of different diene elastomers are well reported. 2–11 Naqvi and Reddy 12 have investigated grafting of acrylic acid (AA) and ethyl methacrylate (EMA) on low-density polyethylene (LDPE) under melt processing condi- tions. They have showed that it could be a highly effective way of diversifying the properties of LDPE. Ghosh et al. 13 have modified LDPE by graft copoly- merization with AA, ethyl acrylate (EA), and butyl ac- rylate (BA), using dicumyl peroxide as the initiator and finally showed that the grafting efficiency has been highest with AA. For the development of biode- gradable plastic from the combination of linear LLDPE and starch, grafting of maleic anhydride (MAH) or AA on LLDPE effectively improves the compatibility between LLDPE and starch. 14 The effect of solvents on the benzoyl peroxide initiated graft copolymerization of poly(ethylene terephthalate) fibers with AA have been studied by Sacak and Oflaz. 15 In addition to the method of free-radical graft copolymerization, the reactive extrusion method and the vapor phase photografting method have also been investigated. Park et al. 16 have employed preirradia- tion method of grafting of AA on polypropylene fab- ric, using Cobalt ray and the resultant fabric displays stronger biocidal effect upon all bacteria. Wu et al. investigated graft reaction of AA onto polyethylene– octene elastomer (POE) in a mixer at (85 6 2)8C at 60 rpm rotor speed, 17 although several questions re- main unanswered and there is scope for further work. Recently, the metallocene-based POE, has received much attention because of its several advantages over other polyolefins because of its unique uniform distri- bution of comonomer content and narrow molecular weight distribution. 18 Due to its nonpolar nature, there is also an opportunity to increase the property spectrum of POE by modifying it with polar group, for better compatibility with polar materials (like po- lar fillers, etc.) and also for better adhesion property towards polar substrate. In this respect, the POE-g- MAH (MAH grafted POE) has been used as the com- patibiliser in the nylon 6/POE system and the impact strength of nylon 6 has been enhanced quite consider- ably. 19,20 Keeping this in view, we have studied the graft reaction of AA on POE in solution system and observed its impact on thermal and mechanical prop- erties (both in static and dynamic condition) of the *On leave from Government College of Engineering and Leather Technology, LB Block, Sector III, Saltlake City, Kolkata 700098, India. Correspondence to: A. K. Bhowmick (anilkb@rtc.iitkgp. ernet.in). Journal of Applied Polymer Science, Vol. 105, 3409–3417 (2007) V V C 2007 Wiley Periodicals, Inc.