RECYCLING OF POLYPROPYLENE BY THE DISSOLUTION REPRECIPITATION TECHNIQUE .1. A MODEL STUDY/

The dissolution/reprecipitation technique is proposed here for the rec ycling of polypropylene (PP). It comprises dissolution of the plastic in an appropriate solvent, reprecipitation by using a non-solvent, tho rough washing of the material obtained and drying. Furthermore, the so lvent mixtures involved are separated by fractional distillation for r euse. In this paper model experiments on virgin material, either in th e form of pellets or of commercial pipes for hot water piping applicat ions, are presented. Xylene/acetone proved to be a particularly effect ive solvent/non-solvent system. Further investigation was focused on t he effect of sample history through successive recycling cycles. The r ecycled grades were evaluated in terms of the following properties: me lt flow index (MFI), crystallinity, mechanical performance in tensile and impact mode and grain size analysis. The properties of the recycle d grades proved to have no substantial difference from the starting ma terial. (C) 1997 Elsevier Science B.V.