Poly(Vinyl Alcohol)/Straw Composite Films With High Performance Prepared by Solid‐State Shear Milling and Thermal Blowing

ABSTRACT Straw, derived from agricultural residues, is a valuable biomass resource. As the typical cellulose‐based biomass material, the strong intermolecular hydrogen bonds render the straw infusible, encountering the problem in utilization on scale. In this study, polyvinyl alcohol (PVA), as an environment‐friendly polymer with good water solubility, was adopted to mix with straw, combining solid‐state shear milling (S ³ M) and thermal blowing technologies to achieve the high‐performance composite film. Based on the powerful shearing action, S ³ M could destroy the inherent hydrogen‐bonded network of the straw and enable the stronger interaction with PVA, thereby improving interfacial compatibility and promoting the homogeneous dispersion of straw within the PVA matrix. The blowing flow field affected the crystallization and molecular orientation of the blown film. The composite film with 10 wt% straw content and blow‐up ratio of three exhibited exceptional tensile strength (35.6 MPa), elongation at break (276.4%), oxygen permeability coefficient of 1.96 × 10 ⁻¹⁷ cm ³ ·cm/(cm ² ·s·Pa), better thermal stability, excellent ultraviolet barrier property, water solubility, and soil absorption capacity. It makes good use of waste straw and offers a promising route toward fabricating PVA‐based composites for eco‐friendly packaging applications.