Epoxy-based hybrid composites reinforced with Amazonian Tucumã endocarp and kaolin: A statistical approach to mechanical properties

Abstract

Tucumã powder and white kaolin from the Amazon (Brazil) are incorporated into the epoxy polymer matrix to obtain a hybrid composite consisting of reduced petroleum-derived polymer (RPP). The amounts of Tucumã and kaolin are defined to obtain composites with equivalent bulk density to the pristine epoxy polymer. A robust statistical design (DoE) is carried out to identify the effects of Tucumã and kaolin contents on the compressive and tensile properties of the hybrid composites. The FTIR results show a proper interaction between the phases. Particle size analysis shows peaks from 0.6 to 290 µm. Composites made up of 42% RPP, i.e., 40 wt.% Tucumã and 2 wt.% kaolin, achieve greater compressive performance, leading to an increase in the elastic modulus (about 34%) and strength similar to that of the pristine polymer. In terms of tensile behaviour, composites of the 42% and 48% RPP class behave similarly in the elastic regime, with an increase of approximately 28% in tensile modulus. Tensile strength and toughness, however, are drastically reduced for ETK composites due to interfacial discontinuities and embrittlement effects. Tucumã-kaolin composites are promising for sustainable advances in secondary structural applications.