RESUMO A utilização de polímeros termoplásticos reciclados a partir de embalagens para a preparação de compósitos com fibras vegetais é uma alternativa tecnológica de grande potencial que pode conciliar viabilidade econômica com benefícios ambientais. No Brasil, muitos estudos têm sido feitos para a utilização de fibras vegetais em compósitos com matriz polimérica devido à grande disponibilidade de resíduos desses materiais. O País também merece destaque pelo alto índice de reciclagem mecânica de polímeros termoplásticos, principalmente do polímero poli(tereftalato de etileno) (PET). O presente trabalho teve como objetivo a preparação de compósitos por processamento termomecânico a partir de fibra de cana-de-açúcar tratada por explosão a vapor com matriz polimérica de PET e a avaliação do comportamento das propriedades do material em comparação aos compósitos com fibras não tratadas. Apesar das mudanças significativas na morfologia das fibras de cana-de-açúcar com o tratamento por explosão a vapor, não houve diferenças significativas nas propriedades dos compósitos PET/fibra tratada com relação aos compósitos PET/fibra in natura devido à não penetração da matriz polimérica no interior da estrutura da fibra modificada com o tratamento. O uso de outros tipos de matrizes poliméricas recicladas e adaptações nas operações de processamento dos materiais são alternativas que podem ainda potencializar o uso de fibra de cana-de-açúcar tratada por explosão a vapor na preparação de compósitos poliméricos e contribuir para a produção de materiais ambientalmente sustentáveis.

ABSTRACT The use of recycled thermoplastic polymers from packaging and natural fibers for preparation of polymeric composites is a technological alternative of high potential to conciliate economic viability with environmental benefits. In Brazil, several studies have been performed aiming the use of natural fibers in polymeric composites due to the high availability of the agricultural waste. The high index of mechanical recycling of thermoplastic polymers, mainly of the polymer polyethylene terephthalate (PET), also worth mentioning in the Country. This study aimed the preparation of PET/sugarcane fiber composites by thermomechanical processing after treating of the fibers by steam explosion and the evaluation of the composites properties when compared with composites using fibers without treatment. Although of the significant changes in the fiber morphology with steam explosion treatment, there were not significant difference between properties of the composites with treated fibers and the composites with not treated fibers due to the insufficient penetration of the polymeric matrix into structure of the modified fiber after treatment. The use of others recycled polymeric matrix as well as adjustments in the operations for materials processing are alternatives that can improve the use of sugarcane fiber treated by steam explosion in the preparation of polymeric composites, contributing for production of environmentally sustainable materials.

The present work aimed to study sugarcane bagasse fibers pre-treated with fungi and using NaOH/ anthraquinone (AQ) in chemical pulping processes for applications in composite materials. Bagasse was decayed with 250 mg of Ceriporiopsis subvermispora inoculum in a 20 L bioreactor. After that, samples were submitted to similar conditions of decaying without inoculum charge. Decayed and undecayed fibers were treated with NaOH 12.5 wt%, 0.15 of AQ and a 12:1 (v/w) liquor:bagasse ratio at 160°C. Then, all obtained fibers were characterized according to their chemical composition. Dried biotreated (decayed) and control (undecayed) fibers were mixed through an extruder process with polypropylene. Later, composite granulates were injected directly in mold with cavities for tensile, flexural and shear tests. Composite materials with 10 and 20 wt% fibers were submitted to static mechanical standard tests and DMA (Dynamic Mechanical Analysis) to evaluate the effect of biotreatment. Biotreatment, cook time (pulping), and fiber content contributed to improvements in the mechanical properties of the composites. The interface between fiber and matrix was increased with the biotreatment and pulping of fibers. Furthermore, DMA results also showed that fiber incorporation into PP improved the modulus, mainly for biotreated fibers/PP composites. The Tg (tan δ data) from composites was dislocated at lower temperatures with respect to neat PP due to the influence of fibers on matrix.