Morphology and degradation behavior of IPN based on polyethylene and polymethacrylate

Thin TPN films composed of polyethylene and polymethacrylates were synthesized by the in situ method in a plate reactor. Low density polyethylene (PE), and methyl (MMA), ethyl (EMA), butyl (BMA), and dodecyl (DMA) methacrylates were used for the preparation of the polymethacrylate phase. The crosslinking of PE both by electron beam and by peroxide was investigated in terms of gel content. The degradation behavior of individual polymethacrylates was studied in the immediate presence of polyethylene by a gravimetric method. All polymethacrylates degrade more than crosslink independent of the length of the aliphatic ester side groups. Surprisingly, a notable degradation of PE/poly(dodecyl methacrylate) by irradiation was also found, which is inconsistent;with results reported for pure poly(dodecyl methacrylate). Scanning electron microscope (SEM) was used to observe morphology changes in the irradiated samples. Pores of about 200 to 400 nm in diameter were observed on the surface and in the bulk phase of irradiated IPN. Flux measurements showed that some irradiated samples were permeable to ethanol, indicating an open porous structure which may be relevant for membranes.