Defence Science Journal, V 01 47, ~o 3, July I ~97, pp. 401-409 Q 1997, DESIDO~ , , ~ I Structure-Properties Correlation in Copolymers of Methyl \ Methacrylate & Alkyl Methacrylates , Seema Agarwal Defence Researc,h & DevelJpment Establishment. Gwalior-474 002. and Veena Choudhary & I.K. Varrna Indian Institute of Technology, New Delhi-110 016 ABSTRACT I The resul~ o~ a study on the copolymerisation of methyl methacrylate (MMA) with varying mol fractions of octyl m~thacrylate, decyl methacrylate (DMA), lauryl methacrylate (LMA) and stearyl methacrylate (SMA~ by free radical polymerisation using benzoyl peroxide as the initiator are presented. It was hnticipated that ~ncorporation of alkyl methacrylate (AMA) having a long alkyl side chain in poly(methyl methadrylate) (PMMA) backbone may lead to an improvement in the toughness I of the cast sh~ets. Such copolymers can be u~ed for low temperature applications in defence. I The glas.s transition temperature of the polymers determined using differential scanning calorimetry was found to decrease with increase in length 9f the alkyl side chain and the comonomer content. A significant increase in percent!lge elongation and decrease in tensile strength, modulus anQ . per cent transmittance was observed on incorporation of AMA in PMMA backbone. In the copolymers of SMA and MMA, significant opacity was observed. I I. INTRODUCTION i plasticisation due to the presence of long alkyl side Varma and coworkersl-8 reported copolymeri- chain would lead to an improvement in toughness sation and thermaf behaviour of methyl methacrylate of the fast sheets without significantly affecting the (MMA) with several vinyl monomers. The effect of useful optical and mechanical properties. Such cast alkyl groupt and structure of the side chain! on sheets may be used for low temperature physico-met:hanical properties of cast acrylic applications in defence. Several copolymer sheets sheets was als() studied6. I. were therefore prepared by copolymerising t The present st~dy was aimed At investigating 0.05-0.25 mol fractions of octyl methacrylate , systematically the effect of length qf the side chain (OMA), decyl methacrylate (DMA), lau~yl in alkyl mcthacr}\late (AMA) bnd copolymer meihacrylate (I.MA) and stearyl methacrylate I I composition on the properties of MMA (SM~) with MMA. The effect of I~ngth of the alkyl Rcccivcd25 July 1996, rc:!viscd~8January 1997 I 401 brought to you by CORE View metadata, citation and similar papers at core.ac.uk provided by Defence Science Journal