Porous biodegradable biomass composites based on cationic starch and plant fibers.

The development of eco-friendly, lightweight, and biodegradable composite materials using starch and plant fibers as raw materials to replace petroleum-based plastics has been a major research focus in the field of green materials. However, the foaming process of biomass materials is significantly affected by starch viscosity, as the inherently low viscosity of native corn starch (NS) restricts bubble growth. In this study, cationic starch (CS) was synthesized using 3-chloro-2-hydroxypropyltrimethylammonium chloride (CHPTAC). The introduction of trim-ethyl-ammonium ions into the starch molecular chains enhanced electrostatic interactions in solution, leading to molecular chain aggregation and an increase in starch viscosity. Additionally, the positively charged starch chains established electrostatic bonds with negatively charged plant fibers, thereby improving starch-fiber adhesion, optimizing the foaming effect, and enhancing the mechanical performance of the biomass composite material. Viscosity analysis revealed that CS exhibited a sixfold increase in viscosity compared to NS, while the viscosity of the biomass composite slurry increased by 1.4 times. The tensile strength of CS improved by 30 %, and its compressive strength increased by 89 %. Furthermore, the apparent density of the composite material suggested a notable improvement in foaming efficiency, while both sound insulation and thermal insulation properties demonstrated significant enhancements.