Heat Sealability and Convertibility of Cellulose Film in Vertical Form, Fill and Seal Machine for Food Packaging Applications

ABSTRACT The environmental challenges posed by petroleum‐based flexible packaging have accelerated interest in sustainable alternatives such as regenerated cellulose films. Despite their biodegradability, transparency and mechanical properties, their applicability in vertical form, fill and seal (VFFS) machines remains uninvestigated, particularly regarding sealability, frictional behaviour and material convertibility. This study investigates the commercial cellulose film under standard and tropical climate conditions. A comprehensive analysis was conducted through laboratory and VFFS machine experiments, including seal strength and integrity, friction measurements, convertibility tests using different forming shoulders, and assessments of oil and grease resistance (OGR) and oxygen transmission rate (OTR). Scanning electron microscopy (SEM) and 3D profilometry were employed to analyse sealing morphology and surface characteristics, respectively. The results revealed that cellulose films provided satisfactory seal strength at lower temperatures with serrated tools, but performance decreased sharply beyond 110 °C due to thermal degradation of the heat‐seal coating layer and cellulose film. SEM analysis confirmed better sealing interfaces with serrated tools, whereas flat tools led to unsealed microchannels. Convertibility and runnability were successful under standard conditions with minimal wrinkling, although tropical conditions caused surface adhesion and film softening. Surface topography measurements showed that the commercial sheet metal shoulder reduced wrinkle visibility as compared to the machined shoulder, although the machined shoulder offered better control. OTR results showed that commercial sheet metal shoulder and machined shoulder preserved the OTR properties up to 98% and 93%, respectively. OGR results confirmed that the material retained its surface integrity regardless of the forming shoulder type. These findings support the cellulose film's potential as a sustainable packaging solution. However, expanding their sealing window, enhancing mechanical resistance against deformation and refining shoulder designs are essential future improvements to ensure consistent barrier performance and visual integrity in VFFS applications.