Preparation of Recycled Polypropylene/ Organophilic Modified Layered Silicates Nanocomposites Part I: The Recycling Process of Polypropylene and the Mechanical Properties of Recycled Polypropylene/Organoclay Nanocomposites

Abstract

The recycling process of polypropylene (PP) and the elaboration of recycled polypropylene/modified clay nanocomposite by melt intercalation method have been investigated. The purpose of this work is to characterize the influence of the recycle processing of an homopolypropylene on the mechanical, thermal, and rheological properties of the polymer, and then to obtain a predictive mechanism of polypropylene degradation in a twin-screw extruder in order to be able to reinforce its behavior for a new application. We can see that the mechanical properties decrease according to the recycling times at two chosen different temperature profiles. At the high temperature profile (195—230°C), the rheological behavior of homopolypropylene is more influenced than at the low temperature profile (175—190°C), the viscoelastic properties are highly modified, the viscosity increases, and the mechanical properties decrease as much as the polypropylene matrix appears to be less accurate. The thermal properties of the recycled polypropylene are investigated by differential scanning calorimetry (DSC) analysis: the crystallization temperature and crystallization time decrease as a function of the number of extrusion cycles. The incorporation of the organophilic layered silicates and maleic anhydride grafted polypropylene (MAPP) compatibilizer improves significantly the mechanical properties of the recycled polypropylene.