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Biopolymers are biodegradable and renewable and can significantly reduce environmental impacts. For this reason, biocomposites based on a plasticized starch and cross-linker matrix and with a microfibrillated OCC cardboard cellulose reinforcement were developed. Biocomposites were prepared by suspension casting with varied amounts of microfibrillated cellulose: 0, 4, 8, and 12 wt%. Polyethylene glycol diglycidyl ether (PEGDE) was used as a cross-linking, water-soluble, and non-toxic agent. Microfibrillated cellulose (MFC) from OCC cardboard showed appropriate properties and potential for good performance as a reinforcement. In general, microfiber incorporation and matrix cross-linking increased crystallization, reduced water adsorption, and improved the physical and tensile properties of the plasticized starch. Biocomposites cross-linked with PEGDE and reinforced with 12 wt% MFC showed the best properties. The chemical and structural changes induced by the cross-linking of starch chains and MFC reinforcement were confirmed by FTIR, NMR, and XRD. Biodegradation higher than 80% was achieved for most biocomposites in 15 days of laboratory compost. [ABSTRACT FROM AUTHOR]

This work investigates the rheological behavior and characteristics of solutions and convened biopolymer films from Chitosan (Chi) modified by kombucha-derived bacterial cellulose (KBC). The Arrhenius equation and the Ostwald de Waele model (power-law) revealed that the Chi/KBC solutions exhibited non-Newtonian behavior. Both temperature and KBC concentration strongly affected their solution viscosity. With the selection of a proper solvent for chitosan solubilization, it may be possible to improve the performances of chitosan films for specific applications. The elasticity of the prepared films containing KBC 10% w/w was preferable when compared to the controls. FTIR analysis has confirmed the presence of bacterial cellulose, chitosan acetate, and chitosan lactate as the corresponding components in the produced biopolymer films. The thermal behaviors of the Chi (lactic acid)/KBC samples showed slightly higher stability than Chi (acetic acid)/KBC. Generally, these results will be helpful in the preparation processes of the solutions and biopolymer films of Chi dissolved in acetic or lactic acid modified by KBC powder to fabricate food packaging, scaffolds, and bioprinting inks, or products related to injection or direct extrusion through a needle. [ABSTRACT FROM AUTHOR]

Fiber–matrix interfacial adhesion is one of the key factors governing the final properties of natural fiber-based polymer composites. In this work, four extrusion reactive agents were tested as potential compatibilizers in polyhydroxylbutyrate (PHB)/cellulose composites: dicumyl peroxide (DCP), hexamethylene diisocyanate (HMDI), resorcinol diglycidyl ether (RDGE), and triglycidyl isocyanurate (TGIC). The influence of the fibers and the different reactive agents on the mechanical properties, physical aging, and crystallization behavior were assessed. To evaluate the compatibilization effectiveness of each reactive agent, highly purified commercial cellulose fibers (TC90) were used as reference filler. Then, the influence of fiber purity on the compatibilization effect of the reactive agent HMDI was evaluated using untreated (U_RH) and chemically purified (T_RH) rice husk fibers, comparing the results with the ones using TC90 fibers. The results show that reactive agents interact with the polymer matrix at different levels, but all compositions showed a drastic embrittlement due to the aging of PHB. No clear compatibilization effect was found using DCP, RDGE, or TGIC reactive agents. On the other hand, the fiber–polymer interfacial adhesion was enhanced with HMDI. The purity of the fiber played an important role in the effectiveness of HMDI as a compatibilizer, since composites with highly purified fibers showed the greatest improvements in tensile strength and the most favorable morphology. None of the reactive agents negatively affected the compostability of PHB. Finally, thermoformed trays with good mold reproducibility were successfully obtained for PHB/T_RH/HMDI composition. [ABSTRACT FROM AUTHOR]