Radiation-Induced Structural Evolution and Interfacial Reinforcement of Cellulose Nanocrystals in Starch–Poly(vinyl alcohol)–Alginate Biopolymer Films

This study investigates how ionising radiation alters the structure and interfacial role of cellulose nanocrystals (CNCs) in starch–poly(vinyl alcohol) (PVA)–alginate biopolymer films for biodegradable packaging. Films containing alginate (0–15 wt%), CNC (0–2 wt%), glycerol (20–30 wt%), and either corn or wheat starch were prepared by solution casting and exposed to gamma and electron beam irradiation (0–15 kGy). The focus was on how radiation affects CNC-mediated hydrogen bonding, network organisation, and structure–property relationships in the multicomponent polysaccharide matrix. Moderate alginate content (5–10 wt%) combined with 1 wt% CNC promoted a more cohesive network through enhanced intermolecular interactions, improving resistance to radiation-induced structural disruption. Higher CNC or glycerol contents, however, induced phase heterogeneity and weakened interfacial stability. Distinct responses were observed between wheat and corn starch matrices, attributed to differences in amylose content that govern film formation and the effectiveness of CNC reinforcement under irradiation. Dose-dependent effects revealed a balance between chain scission and network rearrangement. At 5–10 kGy, reduced swelling, improved thermal stability, and preserved mechanical performance indicated partial structural preservation facilitated by CNC interfacial reinforcement. At 15 kGy, dominant degradation led to reduced gel fraction and deterioration of film integrity. Optimal performance was achieved for films containing 20 wt% glycerol, 5–10 wt% alginate, and 1 wt% CNC irradiated at 5–10 kGy. These findings highlight the central role of CNC in modulating radiation-driven structural evolution and demonstrate how composition and dose can be tuned to control the stability and functionality of cellulose-reinforced polysaccharide films.