No abstract

In this study, poly(lactic acid) (PLA)/pistachio shell (PS) biocomposites were fabricated by melt functionalization through a one-step compatibilization process in varying PS filler rates (0–30%). To enhance interfacial adhesion, alkaline-silane pre-treatment was applied to PS, and PLA was grafted with maleic anhydride (MA). The effect of filler ratio, pre-treatment, and maleation steps on the mechanical, thermal, and morphological properties of biocomposites was investigated. The tensile and flexural analysis showed that composites with optimum mechanical properties were obtained by blending 20% of pre-treated PS with maleated PLA. Mechanic and thermal analyses were performed to examine fiber/matrix surface compatibility. The mechanical analysis of biocomposites, such as tensile/flexural strength and modulus were determined with a universal testing machine. Thermal analysis and thermal degradation of biocomposites were determined by using Differential Scanning Calorimetry and TG/DTG. Morphological analysis performed by SEM proved that the composites prepared by maleated PLA and pre-treated PS showed better adhesion between the fiber and the matrix.

The contact with ultraviolet rays coming from sunlight causes color changes and deterioration in the main chain structures of composites in outdoor applications and affects the physical and mechanical properties of composite materials negatively. Photodegradation can be slowed and the mechanical strength of composite structures can be improved with adding photostabilizers in polymer matrix production. In this study, we modified low-density polyethylene (LDPE) polymer with an amine light stabilizer (Chimassorb 944), a light absorbent (Tinuvin 326), and an antioxidant (Irganox 1010) and then reinforced with jute fabric (JF). We examined the effect of protective additives, which are used to reduce the harmful effects of sunlight, on JF-reinforced LDPE composites. The color change, physical, and mechanical properties of the composites were determined after 120- and 240-h accelerated aging processes. The results indicate that both the antioxidants and the amine light stabilizers were more effective photostabilizers for JF-reinforced LDPE composites than the absorbents.

In this study, pistachio shell-polypropylene copolymer (PPc) biocomposites were prepared by using the melt compounding technique. Treated pistachio shell (TPS) (30%wt) was employed to increase mechanical and thermal properties of biocomposites. Maleation and filler pre-treatment processes improved the mechanical strength of the PPc-TPS composites. The UV additives, Chimassorb 944 (CHI) stabilizer, and the UV absorber Irganox 1010 (IRGV) were used to enhance oxidative and color stability of biocomposites after they were subjected to accelerated UV irradiation for 600 h. The mechanical properties of the UV additive containing composites were less affected after UV exposure. The oxidative induction time and discoloration analysis revealed that CHI and IRGV additives can be utilized in applications that require higher color stability while the former showed better performance for oxidative stability.

This study is devoted to characterization of the Glycyrrhiza glabra (licorice root) fibers (GGFs) that have different uses in industrial areas, globally. For this purpose, several properties of GGFs were investigated to determine their suitability for natural fiber-reinforced composite production. Such properties include; physical, chemical, thermal, morphological, X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy, as well. As a result of these analyses, it was found that the GGFs are composed of cellulose (40.46%), hemicellulose (15.94%), lignin (12%), waxes (1.3%), moisture (9.93%), and others. The density of GGFs was measured as 1.43 g/cm3. Additionally, the existence of cellulose with a 35.86% crystal index, was also verified by the XRD characterization results of these fibers. The thermogravimetric analysis (TGA) results showed that GGFs are thermally stable within the polymerization process temperature of 354.09°C. As a result, it was determined that GGFs have characteristics with significant potential as cellulose-based reinforcement fiber for industrial applications.