Elaboration and Characterization of an Organic/Inorganic Hybrid Material: Effect of the Interface on the Mechanical and Thermal Behavior of PP/CaCO3 Composite

Abstract

The present work deals with the study of the effect of the interfaces on the thermal and mechanical behavior of a composite based on polypropylene and calcium carbonate that was treated with bifunctional coupling agents. In order to enhance the coupling of the filler and the polymer, a compatibilizer, namely maleic anhydride grafted polypropylene, was used. The synthesis of the compatibilizer was carried out in a brabender mixer at 180°C. The grafting reaction was assessed by two techniques that were titration of the anhydride function and identification by means of Fourier transform infrared spectroscopy. It was found that the resulting structure depends much on the nature of the coupling agent. The use of the treated calcium carbonate had a great effect on the thermal and mechanical properties of the composites. It resulted in an important increase in both the modulus and tensile stress. The extent of reinforcement obtained with the zirconate coupling agent was higher than that of the composite containing the filler treated with the silane coupling agents. The decrease noted in the strain could reflect an important coupling between the filler and the polymer. This coupling was favored by a complex interfacial structure depending on the individual structure of each coupling agent. The thermal analysis showed that the fusion temperature and the crystallization temperature were not affected by the presence of the filler nor the coupling agents. However, the percentage crystallinity varied with both the amount of the filler and the type of the coupling agent.