Virgin and recycled polypropylene composites reinforced with sisal by-product

Foram estudadas as propriedades térmicas e mecânicas de compósitos de polipropileno, virgem e reciclado, reforçados com 30% em massa de fibras residuais de sisal, assim como o perfil de processamento e a morfologia da matriz polimérica. Para tanto, foram determinadas a resistência à tração, o módulo de Young, alongamento na ruptura, e energia de impacto. As amostras também foram caracterizadas por MEV, DMTA e TG. Para ambos os compósitos de polipropileno, virgem e reciclado, com a adição das fibras, o alongamento na ruptura mostrou uma queda significativa, enquanto que a resistência à tração não sofreu grandes variações. Houve um aumento significativo nos valores de tração na ruptura e de energia de impacto com a adição das fibras de sisal na matriz de polipropileno. As análises térmicas mostraram ligações secundárias, como as ligações polares, entre as fibras e a matriz, concordando com o comportamento mecânico dos compósitos. Constatou-se que a temperatura de transição vítrea não variou após a adição da fibra.The mechanical and thermal properties of virgin and recycled polypropylene composites reinforced with 30% by mass of residual sisal fibers were studied, in addition to an analysis of the extrusion process and morphology of the polymeric matrix. Tensile strength, Young's modulus, elongation at break, and impact energy were determined. The samples were also characterized by SEM, DMTA and TG analyses. Elongation at break of the composites presented a significant decrease, while the tensile strength was not affected significantly by addition of sisal fibers. A significant increase was observed in the tension of rupture and in the impact energy of the composite reinforced with sisal fiber. The thermal analyses indicated secondary interactions, such as polar interactions, between the fibers and the matrix, consistent with the mechanical behavior of the composites. The glass transition temperature has not changed after fiber addition.Universidade Federal de São Carlos - Departamento de Engenharia de MateriaisFinepCNP

Electrical and thermal properties of PLA/CNT composite films

Conducting polymers presents many potential applications such as biosensors and biofuelcells. However, tobe used in those devices, a thin film must be deposited onto a conducting and biocompatible substrate. In thiswork, carbon nanotubes (CNT) were mixed in a poly (lactic acid) -- PLA -- matrix with different compositions(from 0.25 to 5.0 %) in order to form conducting composites suitable to the deposition of a conductingpolymer. Thermal properties of PLA/CNT composites were evaluated by Thermogravimetry (TG) and DifferenctialScanning Calorimetry (DSC), and the electrical properties were evaluated by 2-probe method andby Electrochemical Impedance Spectroscopy (EIS). Thermal analysis showed and influence of CNT quantitieson PLA crystallization, which also showed an influence on conductivity of the tested materials. Besides,the conductivity of PLA/NTC 1% film showed similar values of the conducting polymer (Pani) itself