Thermal and Thermomechanical Characterization of Polypropylene-Seed Shell Particles Composites

Abstract

The use of plant waste, such ashusks, fibers, and bagasse, as additives in polymeric matrices generated great interest recently, since they became an option to be used as additives, reinforcers, or only as fillers. The pistachio is a seed for human consumption, while the Jatropha curcas (JC) is a seed from which oils are extracted, and are used to obtain biofuels; however, their shells are not used when discardedbecause no useful application is known.An interesting application for this waste material is to use it as a bioadditive in polymeric matrix. The objective of the present work is to prepare polymer composites with polypropylene (PP) as a matrix and as a bio-additive particle inseed shells, in this case Jatropha curcas shell particles (JA) and pistachio shell particles (PI), in different content from 2 to 10 phr. The composites were characterized by techniques such as differential scanning calorimetry (DSC) and X-ray diffraction (XRD) to evaluate crystallinity; by using thermogravimetric analysis (TGA), the thermal stability was studied, and by using dynamic mechanical analysis (DMA) the viscoelastic behavior of composites was evaluated. According to DSC, results suggest that a nucleating effect occurs with the addition of the JA and PI, which was reflected in an increase in thepercent of crystallinity of the composites. The TGA results show that thermal stability of the composites was modified with the presence of JA and PI, compared with that PP pristine.In addition, dynamic mechanical analysis (DMA) reported that the viscoelastic behavior was modified, findinga higher capacity to dissipate energy for composites, PI being the one that presented a greater effect on them.