Tunable gas permeability and interfacial engineering of poly(propylene carbonate)/bamboo powder composite films for...

The development of biodegradable packaging films with simultaneously high gas permeability and robust mechanical properties remains a challenge. Biodegradable poly(propylene carbonate) (PPC)-based composite film was fabricated aiming to feature controllable gas transport pathways and enhance interfacial compatibility for potential fresh produce packaging. Bamboo powder (BP) was incorporated as a bio-based pore-forming agent. A dual-end interfacial modification strategy was employed, involving vinyltrimethoxysilane (VTMS) coupling on the BP surface and maleic anhydride (MAH) grafting onto the PPC matrix. The effects of BP, VTMS, and MAH contents on the oxygen transmission rate (O₂TR), water vapor transmission rate (WVTR), tensile strength (TS), and elongation at break (EB) were systematically investigated through single-factor and orthogonal experimental designs. The optimal formulation (1.5 wt% BP, 1.2 wt% VTMS, 3.5 wt% MAH) yielded a composite film with a balanced performance: an O₂TR of 29.65 cm³·m^-2·day^-1·atm^-1, a WVTR of 273.12 g·m^-2·day^-1, a TS of 22.37 MPa, and an EB of 279.57%. Microscopic and spectroscopic analyses confirmed a uniform microstructure with well-dispersed BP and dense interfaces, attributable to successful VTMS silanization and MAH grafting reactions. Compared with neat PPC and the unmodified PPC/BP films, the films also demonstrated excellent biodegradability, with a mass loss of up to 25.43% after 150 days of soil burial. The synergistic combination of BP as a pore-former and the dual-end interfacial modification effectively decouples the traditional trade-off between permeability and tensile strength in polymer membranes. This work provides a sustainable and feasible approach to designing high-performance biodegradable films for food packaging applications.