POLYSTYRENE-POLYETHYLENE INTERPENETRATING-LIKE NETWORKS - INFLUENCE OF THE VINYL NETWORK CROSS-LINKING AGENT ON IPN PROPERTIES

The influence of a cross-linking agent (divinyl benzene) on new polyst yrene-polyethylene, IPN-like networks was investigated by means of the rmal, mechanical tests and a few microscopy observations. It was found that with increased concentration of cross-linking agent, i.e., with PS cross-linking density, Young's and storage moduli, measured in the molten rubbery state, increased linearly. Also the elongation and the stress at break were very sensitive to the content of cross-linking ag ent, mainly in the low concentration region (0 to 2%). PE and PS domai ns of about 1 mu m circular cross sections were observed on a smoothed surface of a PE/PS blend. Smaller and uniformly dispersed domains wer e observed for all the IPN-like systems. The crystallinity, measured b y DSC and WAXS, and the IPN morphological features, appeared to be ind ependent of the styrene cross-linking content, viz., the content of DV B. The overall behavior seemed to resemble that of classical simultane ous IPNs. (C) 1994 John Wiley & Sons, Inc.