Hybrid composites of fillers and/or fibers reinforced polymer was generally produced by masterbatch dilution technique. In this work, the simplified preparation was introduced for the large volume production of 30 wt % short-fiber and talcum reinforced polymer hybrid composite by direct feeding into twin-screw extruder. Multifunctional epoxide-based terpolymer and/or maleic anhydride were selected as in situ reactive compatibilizers. The influence of fiber and talcum ratios and in situ reactive compatibilizers on mechanical, dynamic mechanical, morphological and thermal properties of hybrid composites were investigated. The morphological results showed the strong interfacial adhesion between fiber or talcum and Poly(lactic acid) (PLA) matrix due to a better compatibility by reaction of in situ compatibilizer. The reactive PLA hybrid composite showed the higher tensile strength and the elongation at break than non-compatibilized hybrid composite without sacrificing the tensile modulus. Upon increasing the talcum contents, the modulus and storage modulus of hybrid composites were also increased while the tensile strength and elongation at break were slightly decreased compared to PLA/fiber composite. Talcum was able to induce the crystallization of PLA hybrid composites.

The aim of this work was to investigate the effect of reactive agents on the rheological behaviors, morphology and mechanical properties of two biodegradable polyesters; poly(lactic acid) (PLA) and poly(butylene succinate) (PBS) reinforced with eucalyptus fiber. Two types of reactive agents, chain extender (Joncryl^®) and peroxide (Perkadox^® 14), were selected. Biocomposites consisting of a constant fiber loading of 10 wt% with and without reactive agents were prepared by one-step melt-mixing methods via an internal mixer with the rotational speed of 60 rpm and the temperature of 150 and 190 °C for PBS and PLA, respectively. The biocomposite samples were then compression-molded for tensile testing. Rheological and morphological properties of the biocomposites were also investigated by means of dynamical mechanical analysis (DMA) and scanning electron micrograph (SEM). The results revealed the presence of Joncryl^® in PLA biocomposites caused the increase of mixing torque, complex viscosity, storage modulus and mechanical properties when compared to the addition of peroxide. The increase of complex viscosity of PLA biocomposites added Joncryl^® was due to the increase in the population of the higher molecular weights as confirmed by GPC analysis. In the case of PBS biocomposites, it showed a dramatic increase in the complex viscosity and storage modulus with decreasing crossover frequencies when adding peroxide rather than adding Joncryl^®. The SEM micrographs demonstrated that the compatibility between the polymer matrix and fiber was improved when adding a small amount of Joncryl^® and peroxide for both polymers, except for 0.5 phr peroxide loading, leading to an improvement of their modulus and tensile strength.