Structure et propriétés d’un PP copolymère métallocène, Effet d’agent de nucléation et de charge

Abstract

In this study we are interested to the preparation, characterization and a preliminary evaluation of properties of composites between a PPR as polymer matrix and different amounts of FND as plant fiber filler. Moreover, the effect of the addition of a sorbitol derivative, as nucleant and clarifying agent, is also investigated. First, we examined the effect of two thermal treatments applied from the melt: slow cooling, S, and rapid cooling Q; on the morphological, thermal and mechanical properties of the various composites. Additionally, the influence of individual and compound filler on the crystallization kinetics under non isothermal conditions (at cooling rate 20°C/min) and morphology feature, as well as on viscoelastic properties of PPR was also studied. The results obtained demonstrate that the important nucleation ability has been found for FND, and, evidently, for the sorbitol derivative. Thus, the peak crystallization temperature on cooling is increased considerably by both the nucleant and FND, furthermore resulting on a much higher proportion of orthorhombic crystals in relation to the monoclinic ones. Moreover, microhardness experiments were carried out to estimate the mechanical response. A significant increase of this magnitude was found with increasing FND contents. The t1/2 and kc results demonstrated that FND accelerates the crystallization rate of PPR. Although the heterogeneous nucleation effect of FND is good, and the ability of Millad3988 to induce polymorph γ and improve crystallization temperature is better than that of FND, as suggested by the results of XRD and DSC.