Influência de compatibilização interfacial no comportamento mecânico de compósitos de polipropileno com reforço híbrido de fibras e microesferas ocas de vidro

Abstract

The hybridization of hollow glass microspheres with short glass fibers in polypropylene can result in low-cost, low-density polymer composites suitable for engineering. Although the addition of fillers in thermoplastic composites generally reduces mechanical strength, recent research indicates that by properly matching high and low aspect ratio fibers, it is possible to achieve desirable mechanical properties, such as stiffness, strength and toughness. In order to broaden the understanding of this mechanical reinforcement mechanism in ternary PP composites with hybrid reinforcement of FV (pretreated with aminosilane) and MEVO, this work evaluated the influence of polymer-reinforcement interfacial interactions on short-term mechanical properties. Three different interfacial compatibilization conditions were analyzed: (i) MEVO pretreated with aminosilane and PP matrix modified with addition of interfacial compatibilizer of PP functionalized with maleic anhydride (PP-g-MAH), (ii) MEVO without treatment and matrix modified with PP-g-MAH and (iii) MEVO without treatment and matrix without compatibilizer. The composites were injection molded with direct mixing of pre-extruded PP/FV and PP/MEVO binary concentrates. Tensile and flexural tests showed a slight increase in the elastic modulus of the ternary composites with higher hybrid reinforcement, regardless of the MEVO content and the interfacial adhesion of the microspheres with the PP matrix. The strength, in turn, strongly depends on the polymer-MEVO interfacial adhesion, presenting a decrease in the mechanical properties without MEVO treatment, even with the presence of the PP-g-MAH compatibilizer. With the pretreatment of MEVO with aminosilane and the use of the compatibilizer, the mechanical properties remained high, comparable to the reference binary composites PP/FV with 25% and 30% FV. The dynamic mechanical analysis (DMA) confirmed the importance of interfacial compatibilization in the mechanical behavior.