Estruturação da blenda de PP/PVMS na presença de nanopartículas
Dutra, Regiane Defacio
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Blends technology get by mechanical blend extends the range of polymer properties and makes it possible to fit them for specific applications. The performance and the mechanical properties of immiscible polymer blends are driven by the morphology and dependent on the type and process conditions, in addition to the Interfacial properties. Polymer blends containing nanoparticles have been studied in relation to two main roles that they can play in a blend; one related to improvement of properties (mechanical, thermal, electrical barrier, etc) and other related to the modification of miscibility/compatibility and blend morphology. In this work was evaluated the structuration of PP/PVMS blend with nanoparticles of Silica (SiO2) and Halloysite (HNT), the possibility of them acting as compatibilizer and best process conditions in twin screw extruder and injection molding to achieve a good dispersion and distribution and PVMS phase into PP matrix. Was made a previous study about nanoparticle content, time and mixture sequence, by torque reometer, to define the compositions which were studied in the next (extrusion and injection). Morphology and micro-rheology were studied and their correlation with the mechanical properties was made. By means of this analysis it was noticed that the PVMS domains were smaller in the nanoparticle presence, however were not small enough to toughen the blend. An increase in impact resistance was observed, proving that the nanoparticles showed an additive effect, but no synergistic. The best results were obtained for the blend with HNT that can be attributed to its greater aspect ratio and the content to be above the percolation threshold allowing the formation of a three-dimensional network that prevented PVMS coalescence by means of a physical barrier. Micro-rheology analysis indicated that the nanoparticles was located preferentially in the PP, while the wettability parameter indicated their were located on the interface. Both analyses can be explained by kinetic aspects, which demonstrated that the mixing time used blends preparation was not enough to all particles migrate to the interface.