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 polystyrene–polyethylene, IPN‐like networks was investigated by means of thermal, 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 agent, mainly in the low concentration region (0 to 2%). PE and PS domains of about 1 μm circular cross sections were observed on a smoothed surface of a PE/PS blend. Smaller and uniformly dispersed domains were observed for all the IPN‐like systems. The crystallinity, measured by DSC and WAXS, and the IPN morphological features, appeared to be independent of the styrene cross‐linking content, viz., the content of DVB. The overall behavior seemed to resemble that of classical simultaneous IPNs.