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Unlike thermoplastic petroleum-based materials, starch-based materials rely on aqueous systems but are incapable of hot melting, resulting in low processing efficiency and limited large-scale industrial applications. In this study, the combination of α-amylase liquefaction and urea plasticization was used for the first time to obtain enzymatic thermoplastic starch (ETPS) for hot melting by changing the molecular chain of starch. ETPS showed an apparent hot melting phenomenon when heated below 200 °C. Differential scanning calorimetry revealed that heat absorption peaks were obviously reduced, and the hot melting phenomenon occurred easily depending on the combination of enzymatic hydrolysis and plasticization. Dynamic mechanical analysis indicated that the combined modification effectively increased the number of freely movable chains. The red shift of -OH stretching vibration peaks indicated the formation of strengthened hydrogen bonds in ETPS. X-ray diffraction showed that the crystallinity of ETPS was reduced to 5.68 %, effectively reducing the regenerative phenomenon. Gel permeation chromatography revealed that the molecular weight of ETPS decreased, and the entanglements between molecular chains were reduced. A tensile test showed that the elongation at break of ETPS was as high as 235.29 %, which was much higher than those of enzymatic hydrolysis starch and thermoplastic starch. [Display omitted] [ABSTRACT FROM AUTHOR]

Biomass-based adhesives are gaining attention as environmentally friendly alternatives to toxic petroleum-based adhesives. However, biomass-based adhesives exhibit poor adhesive properties and are highly susceptible to failure in humid environments. In this study, a zein-based adhesive with high adhesive strength and good water resistance was prepared by optimizing the solvent composition and adding tannic acid. Adding 10 wt% acetic acid to an aqueous ethanol solvent increased the shear strength by 45.4 % to 3.09 MPa. Moreover, the addition of 6 wt% tannic acid improved the shear strength of the zein-based adhesive in humid environments from 0.63 to 1.58 MPa. The tannic acid-reinforced zein-based adhesive exhibited good adhesive strength in both humid and dry environments, which was maintained for 30 days on glass, and could be applied to a wide range of substrates. Moreover, the adhesive showed an antioxidant activity >94 %, excellent thermal stability, biocompatibility, and antibacterial effect. Therefore, this adhesive has great application prospects in medical, packaging, and other fields., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)