Effects of Nanoparticles on Tensile, Electrical, and Thermal Properties of Hemp/PBTG Composites

Recently, the bio-composites composed of natural fibers, such as jute, sisal, hemp, kenaf, etc., and degradable polymers have started to be considered as alternative materials to replace the conventional composites produced with synthetic fibers and petrochemical polymers. However, bio-composites are required to enhance the thermal resistance and mechanical properties for the expansion of possible applications. Thus, the functional additives of nano-particles have been applied to solve the end-uses' limitations. In the present work, the hemp fibers reinforced with poly(butylene terephthalate-co-glutarate) (hemp/PBTG) composites were fabricated with three types of functional additives, namely, carbon black, carbon nanotube, and sepiolite, and the tensile, thermal and electrical properties of hemp/PBTG composites were investigated in order to understand the influence of the types and contents of additives. The tensile strength of composites was increased from 37.2 MPa to 40.6 MPa by adding 5 wt% of sepiolite, and the tensile modulus was also increased with the addition of carbon nanotube. The improvement of thermal resistance in hemp/PBTG composites with adding sepiolite has significantly increased due to the thermal barrier effect. Furthermore, the electrical conductivity of the composite containing carbon nanotube has rapidly increased owing to the formation of the electrical conductive path. As the result of cone calorimeter, the flame retardancy of hemp/PBTG composites containing sepiolite increased with the effective heat combustion by 7 % as 2.08 MJ/m(2).g, while the residue time increased 1.4 times as compared with the hemp/PBTG composites without additives.