SYNTHESIS, ELECTRON-IRRADIATION MODIFICATION AND CHARACTERIZATION OF POLYETHYLENE POLY(BUTYL METHACRYLATE CO METHYL-METHACRYLATE) INTERPENETRATING POLYMER NETWORK/

The present work reports the preparation of a porous structure by elec tron beam irradiation of interpenetrating polymer network (IPN) based on polyethylene and poly(methyl methacrylate-co-butyl methacrylates). Thin IPN films were synthesized by in situ polymerization. Low-density polyethylene (PE) was used as the first IPN component, and the second IPN component was formed by copolymerization of methyl methacrylate a nd butyl methacrylate. After the syn thesis the methacrylic phase rs f inely dispersed in a Pi: matrix. Porous films Of these materials were obtained by decomposition of the polymethacrylate phase by means of el ectron radiation followed by extraction with xylene. The thermal stabi lity in N-2 atmosphere of the irradiated and extracted IPN was improve d compared with the unirradiated samples. Three temperature regions of weight loss were observed, two of them caused by the copolymer and on e by the PE. The lowering of the melting temperature of PE observed by differential scanning calorimetry analysis indicated an increase in c rosslinking caused by irradiation. Morphology changes were studied by scanning electron microscopy which revealed a porous surface structure of the irradiated and extracted samples. Flux measurements showed tha t some irradiated samples were permeable to ethanol, demonstrating art interconnected porous structure which may be relevant for membranes. (C) 1998 John Wiley & Sons, Ltd.