GRAFT COPOLYMER FROM MODIFIED ETHYLENE-VINYL ACETATE (EVA) COPOLYMERS.3. POLY(EVA-G-METHYL METHACRYLATE) FROM MERCAPTO-MODIFIED EVA

This paper describes a new route for synthesis of poly(ethylene-co-vin yl acetate-g-methyl methacrylate) (EVA-g-PMMA) based on free radical p olymerization of methyl methacrylate initiated by azobis(isobutyronitr ile) (AIBN), in the presence of mercapto-modified EVA as chain transfe r agent. This functionalized EVA, namely, poly(ethylene-co-vinyl alcoh ol-co-vinyl mercaptoacetate) (EVASH) is prepared by simple esterificat ion of hydrolyzed EVA with mercaptoacetic acid. Higher conversions of grafted poly(methyl methacrylate) (PMMA) were obtained by increasing t he [SH]/[AIBN] ratio. In addition, a uniform molecular weight distribu tion of PMMA segments in the graft and a higher thermal stability of t he graft copolymer can be achieved by controlling the [AIBN]/[SH] rati o. The PMMA segments in the graft copolymer do not affect the crystall inity degree of the EVASH backbone, as indicated by differential scann ing calorimetry (DSC) analyses.