Nowadays, hollow glass micropheres composites are also an object of study in additive manufacturing, such as 3D printing, to improve flow melting and thermal insulation. Özbay and Serhatlı studied processing and properties of different combinations of hollow glass microphere filled with polyamide 12 (PA12) matrix, by Selective Laser Sintering (SLS) manufacturing method. As a result, they obtained a 20% of density reduction and a significant rise in the E-modulus with the composition PA12/hollow glass microphere (80/20).
In the automotive industry, the polyamide (PA6) and polyamide 6.6 (PA66) are often used because of their typical hydrogen bonds, due to their polar chemical structure, with a short GF reinforcement, commonly 30 wt%. Composites of PA6 or PA66 reinforced with glass fibers ensure great mechanical and thermal properties and can be found in air intake manifolds, rocker covers, radiator end tanks, fuel rails, electrical connectors, engine encapsulation and others. In this sense, GF and hollow glass microphere combination may constitute an excellent solution to combine lower density, dimensional stability, and good mechanical properties. Berman et al. have studied the effects of replacing calcium carbonate (high density filler) with hollow glass microphere (low density filler) in an unsaturated polyester resin matrix sheet molding compound (SMC) reinforced with short GF (10~15 wt%). The composite was fabricated in SMC manufacturing, lay-up and hot pressing. As a result, they obtained a 12% of density reduction but compromised the mechanical properties. Nevertheless, all values of tensile, flexural and impact properties were higher than the corresponding properties of low and ultra-low-density composites reported in the literature.
Thus, the goal of this study was to fabricate a composite based in PA6 reinforced with GF and hollow glass microphere and to investigate the effects of hollow glass microphere content on the density, mechanical properties of the composites comparing its properties with the traditional PA6/GF (70/30) wt% composite, widely used today in automotive industries. It’s expected to find a formulation with at least 10% density reduction and maintenance of mechanical properties. In this paper, fundamental results for understanding the relationship between structure and property of both the matrix and the fillers will be discussed in terms of microscopic observations, mechanical properties, and thermal stability.
