Self-enhancement of food packaging film based on regulable microstructure evolution via circumfluent synergistic blow molding

Abstract

Blow molding has been prevalently utilized in manufacturing food packaging films for decades, owing to its commendable efficiency and cost-effectiveness. However, the low crystallinity and small crystallite size of blown film, induced by supercooling process, commonly circumvent their performance in applications such as food preservation. Herein, a novel circumfluent synergistic blow molding (CSBM) has been employed, where the synergistic effect of circumfluent could generate intersecting oriented microstructure and promote crystalline growth based on flow-induced crystallization. It has been proved that the intersecting oriented microstructure can significantly self-enhancing barrier performance of blown films, of which oxygen transmission coefficient (2.0 ×10⁻¹³ cm³×cm/(cm²×s × Pa)) and water vapor transmission rate (3.42 ×10⁻¹³ mL/m²·24 h) are 31 % and 53 %, respectively, lower than that of commercial cling film. Additionally, CSBM has merits on enhancing the homogeneity of mechanical properties in vertical and horizontal direction of blown films, which is benefit for long-term applications of food packaging films. For food preservation applications, it validates that the intersecting oriented microstructure greatly extending food shelf life, delaying browning and dehydration of fruits, and hindering food rot. Hence, this work provides a new strategy for the development of blown film in applications of food packaging.