Effect of cenosphere surface treatment and blending method on the tensile properties of thermoplastic matrix syntactic foams

The influence of cenosphere surface treatment and blending method on the properties of injection molded high-density polyethylene (HDPE) matrix syntactic foams is investigated. Cenospheres are treated with silane and HDPE is functionalized with dibutyl maleate. Tensile test specimens are cast with 20, 40, and 60 wt % of cenospheres using injection molding. Modulus and strength are found to increase with increasing cenosphere content for composites with treated constituents. Highest modulus and strength were observed for 40 and 60 wt % untreated mechanically mixed and treated brabender mixed cenospheres/HDPE blends, respectively. These values are 37 and 17% higher than those for virgin and functionalized HDPE. Theoretical models are used to assess the effect of particle properties and interfacial bonding on modulus and strength of syntactic foams. Brabender mixing method provided highest ultimate tensile and fracture strengths, which is attributed to the effectiveness of Brabender in breaking particle clusters and generating the higher particle-matrix surface area compared to that by mechanical mixing method. Theoretical trends show clear benefits of improved particle-matrix interfacial bonding in the strength results. (C) 2016 Wiley Periodicals, Inc.