Two major obstacles to utilizing polyhydroxybutyrate (PHB)—a biodegradable and biocompatible polymer—in commercial applications are its low tensile yield strength (<10 MPa) and elongation at break (~5%). In this work, we investigated the modification of the mechanical properties of PHB through the use of a variety of bio-derived additives. Poly(lactic acid) (PLA) and sugarcane-sourced cellulose nanocrystals (CNCs) were proposed as mechanical reinforcing elements, and epoxidized canola oil (eCO) was utilized as a green plasticizer. Zinc acetate was added to PHB and PLA blends in order to improve blending. Composites were mixed in a micro-extruder, and the resulting filaments were molded into 2-mm sheets utilizing a hot-press prior to characterization. The inclusion of the various additives was found to influence the crystallization process of PHB without affecting thermal stability. In general, the addition of PLA and, to a lesser degree, CNCs, resulted in an increase in the Young’s modulus of the material, while the addition of eCO improved the strain at break. Overall, samples containing eCO and PLA (at concentrations of 10 wt %, and 25 wt %, respectively) demonstrated the best mechanical properties in terms of Young’s modulus, tensile strength and strain at break.

This work describes the surface treatment of coconut fiber and its application in composite materials for reinforcement of polypropylene. Before testing coconut fiber in composite materials, its susceptibility to chemical treatment was characterized by exposure to the following: (1) hot water; (2) aqueous NaOH 2% (w/v); and (3) a sequence of chemical treatments in hot water, extran 20% (v/v), acetone/water 1:1 (v/v), and aqueous NaOH 10% (w/v).The efficiency of each treatment was evaluated by Fourier transform infrared spectrometry analysis, indicating a reduction in the C=O peak. Besides that the scanning electron microscope revealed that treatment changed the morphology of the fibers. Thermogravimetric analysis showed that the insertion of fibers into PP caused a decrease in the thermal stability and differential scanning calorimetry exhibited that crystallization of PP was favored in the presence of fibers.

The interest in natural fibre composites as load-bearing elements has increased strongly in recent years. As natural fibres offer good biodegradability, strong reinforcement and low production costs, some industry sectors have started to substitute conventionally used materials. One excellent example for natural reinforcements is curaua fibres. Regardless, the use of natural fibres in prepregs is still in its infancy, the manufacturing parameters need to be analysed. For this reason, the amount of curing agent, fibre treatment and filler amount of curaua fibre/epoxy prepreg are tested in this research. Thermogravimetric analysis and differential scanning calorimetry techniques were used for analysis. The compared material properties were the degree of crosslinking and the degradation stability. The results were analysed with a statistical comparison method (a factorial experimental design), which revealed a complex relationship of the influencing parameters on the thermal properties of the prepregs.