Potencial de uso da perlita como carga e/ou aditivo no poliestireno em aplicação nos setores de embalagens termoformadas e construção civil

Abstract

Composites based on polystyrene and expanded perlite (PS/Perlite) were prepared in order to assess the processing effect parameters and the mineral filler content on physical, mechanical, thermal, morphological and rheological properties of the final composites. The data obtained from the design of experiments applied to the INITIAL STAGE of the study indicated an increase in the density of the composites after the extrusion and injection processes, suggesting the probable breakdown of the perlite particles. The morphology analysis indicated a good interaction between the perlite and the PS matrix, however confirmed the breakage of the filler spheres. The statistical analysis of the design of experiments also showed that the process factors (speed and conduction elements) did not significantly alter the response variables (MFI, Impact Resistance and Young’s Modulus). A COMPLEMENTARY STEP replaced the injection process step (supposedly responsible for breaking the particles) by a tapering step to obtain new specimens after the extrusion process. However, the response variables once again indicated the perlite breakdown by the density increase and the morphology of the composites. The statistical analysis of the design of experiments confirmed this event by signaling the significant effect of the conduction elements and the perlite content on the composite’s density increase under the processing conditions used. The rheological study showed a pronounced elastic behavior tendency for the compositions processed with lower shear conditions (2 conductions elements). In addition, the composites with higher perlite content with smaller particle size (perlite 50BC 20%) flow behavior showed adequate dimensional stability for thermoforming, even with fractured perlites and also identified the absence of agglomerates in PS/Perlite composites, facts that were confirmed by SEM and TGA analysis. The thermal conductivity (K) increase and the heat capacity (Cp) decrease were not expected, however it reinforced the conclusion that the perlite breakage made the use of the composites as a thermal insulator unfeasible. On the other hand, the results pointed towards a material suitable for thermoforming, since the increase in thermal conductivity would be suitable for the cooling phase of the process, accelerating the production of the artifacts.