Binary blends of poly(vinyl chloride) stabilized by lithium acetate-thermal studies

A series of blends of poly(vinyl chloride) (PVC) with (1) poly(methyl metha crylate) (PMMA) or (2) polyoxymethylene (POM), with lithium acetate as a st abilizing agent, was investigated by differential scanning calorimetry (DSC ), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA) , either alone or coupled with Fourier transform infrared (FTIR) spectrosco py. It was found that lithium acetate has a significant effect on the therm al properties of blends under investigation. It causes the initial decompos ition temperatures to increase by about 60-150 degrees C for PVC-POM blends , a substantial suppression of the volatile products evolution for PVC/PMMA blends, and an improvement in the surface morphology for both polymer syst ems by lowering the degree of roughness. The origin of these effects was di scussed by analysis of the intermolecular complexation between metal salt a nd PVC structural arrangements in the blends. Such interactions may lead to the formation of long-range, directional-specific structural regularities, which in turn thermally stabilize the whole system (strong interactions mo del). (C) 1999 John Wiley & Sons, Inc.