Comparative effects of composition and molding conditions on the properties of starch/chitosan thermoplastics

초록

Biodegradable plastics based on starch (ST) and chitosan (CS) were produced by compression molding to improve mechanical strength and water resistance for food-packaging applications. Formulations varied in ST/ CS ratio (0-100% CS), molding temperature (100-160 degrees C), molding time (1-10 min), and citric acid (CA) content (0-4%), with CA serving as a cross-linking agent. FT-IR data supported stronger ST-CS interactions near a 1:1 mass ratio, consistent with increased tensile strength (18.2 MPa) and surface hydrophobicity (104.23 degrees) and reduced solubility (16.33% after 360 min at 25 degrees C). Moderate processing (100-120 degrees C for 10 min) promoted densification and network organization, further enhancing performance. Incorporating 2-4% CA improved strength (34.92 MPa) and water resistance (Contact angle: 114.76 degrees; solubility after 360 min at 25 degrees C: 14.49%), with spectral changes (attenuation/shift of carbonyl and amide regions) consistent with CA-mediated crosslinking. Overall, composition exerted a greater influence on material performance than molding conditions, although both factors contributed to the final properties of the thermoplastics. The results provide fundamental insights into the optimization of starch/chitosan thermoplastics and may serve as useful design guidelines for future adaptation to more scalable processing routes.

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