Caracterização de nanocompósitos (PLA/HDPE-g-AM/HDPE-Verde/n-CaCO3)

Abstract

There is an imperative need for the development of polymers and their composites that use raw materials from renewable sources, due to ecological and environmental issues. Considering the context of the search for environmentally friendly materials, a possible alternative to solve the serious problems presented to the problem related to the disposal and disuse of polymers from fossil sources is the use of biodegradable polymers obtained by means of renewable resources (biopolymers) as raw material for consumer items. This work aimed at the microstructural characterization by polarized light, Vickers microhardness (HV) measurements and the attrition rate, through the abrasion test, of nanocomposites obtained through blends or polymeric blends and calcium carbonate nanoparticles (PLA / HDPE -g-AM / HDPE-Green / n-CaCO3) with properties for application in the packaging sector. The production of these nanocomposites occurred through a mixture of PLA (polylactic acid) and high density polyethylene from renewable source (HDPE-Green), made possible by the action of the compatibilizing agent maleic anhydride grafted polyethylene (HDPE-g-AM) and of the nanoparticulate calcium carbonate additive (n-CaCO3). A qualitative analysis of the results obtained by microscopy of polarized light transmitted in thin samples showed the presence of crystalline regions in the composites and some places with strong preferential orientation. The results of the hardness measurements suggest that although the values of this mechanical property in the composites are close to the matrix value (HDPE), there is an indication that the dispersed phase (PLA) had an influence on the values change. The composites with the highest hardness values were those with the highest PLA content. The results of the abrasion test when compared to the hardness test showed that the material with the highest hardness value was also the one with the highest wear rate, that is, the pure PLA. Scanning electron microscopy (SEM) analysis of only one of the tested conditions showed regions with agglomerates of calcium carbonate nanoparticles distributed by the composite that did not appear to contribute to the fragility of the material through a fracture process. The results obtained by reflected polarized light were inconclusive.