Desenvolvimento de compósitos de POLI (acrilonitrila-CO-butadieno-CO-estireno) / microesferas ocas de vidro para utilização na indústria automobilística

Abstract

The application of polymeric materials in automobiles have increased due to weight reduction and the large number of possible applications of these materials. The poly (acrylonitrile-cobutadiene-co-styrene) (ABS) is widely used in the automotive industry, normally inside vehicles because of its excellent impact resistance and optimal balance of other properties combined with the cost. In order to reduce the density and cost of polymeric parts, the hollow glass microspheres (HGM) have been used in the development of composites with polymeric matrix. HMG are spherical glass particles of average diameter from 15 to 65 μm thin-walled from 0.5 to 1.5 μm and especially low density from 0.12 to 0.60 g.cm¯³. In this study, the investigated variables were: the percentage by mass of HGM (2.5, 5.0 and 7.5%), type of microsphere with different compressive strength values and different densities (S038HS and S060HS), feeding zone of the HGMs in the twin screw extruder, being Z1 the conventional feeding zone and Z2 in the center of the extruder. The incorporation of ground ABS SV-165 has been evaluated in the microspheres Z2, incorporation of ABS SD-190H (high-impact) to the composite, and finally the surface treatment of the HGMs with Triethoxyvinylsilane. The extruded composites were analyzed with and without enhancing the physical, morphological, thermal, chemical and rheological, emphasizing the properties of interest in the automotive industry: impact resistance, heat deflection temperature (HDT), deformation, bending strength and density. The different compressive strengths of the microspheres did not confer significant changes in the composites. The Z2 kept strengthening integrity whereas Z1 obtained a homogeneous distribution. Z2 in strengthening the clusters have been validated in trials with oscillating rheometer and the micrographs under the SEM. Considering the properties of interest of the study, 5% by weight HGM afforded the best results for the properties of impact resistance, HDT, creep, flexural strength and density. The use of ABS SV-165 ground in the center of the extruder together with HGM assisted in enhancing the homogeneity of the input matrix. The incorporation of ABS SD-190H Z1 promoted increase of the deformation and impact strength of the composite, assigned to the composite addition of butadiene, but the reduced thermal stability of the composite, as visualized by thermogravimetry and thermal dynamic mechanical analysis technique. The surface treatment with Triethoxyvinylsilane proposed for the HGMs led to improvements in composite properties due to the possible interaction of Triethoxyvinylsilane with the acrylonitrile monomer, viewed in the Fourier transform infrared spectroscopy assay. It is concluded that the composite microsphere S038 having the lower compressive strength and low density, surface treated with Triethoxyvinylsilane, incorporated in the center of twin screw extruder (Z2) with 5% by weight of ABS SV-165 and the ground 45% by weight of input ABS SV-165 and 50% by weight of ABS SD-190H Z1, promoted a reduction in the density of 7% increase in impact resistance of 13%, HDT and tensile and bending deformation remained with values equal to the sample control ABS/B, enabling the application of this composite replacing ABS in the automotive industry.