Feasibility of Wet Compression Moulding of Native Bacterial Cellulose/Epoxy Laminates

Bacterial cellulose (BC) combines high stiffness, low density and a unique three-dimensional fibrillar network, making it a promising bio-based reinforcement for polymer composites. In this study, BC pellicles were cultivated under static, room-temperature conditions in Hestrin–Schramm medium, and purified, freeze-dried and processed into BC/epoxy laminates using wet compression moulding. The processing route was designed to minimise destruction of the native BC architecture, enabling a feasibility assessment of integrating a native BC network into an industrially relevant wet compression moulding process. Specimens were produced according to DIN EN ISO 527-4 at a fixed fibre mass fraction of approximately 8.8 wt%. Scanning electron microscopy (SEM) imaging revealed a predominantly in-plane oriented, channel-like BC network; however, the composites also exhibited inhomogeneities, including dry areas, voids, and resin-rich regions. Mechanical testing demonstrated an increase in Young’s modulus from 2.95 GPa for neat epoxy to approximately 4 GPa for BC-reinforced laminates, whereas the tensile strength of BC-reinforced laminates (approximately 25 MPa) remained below that of the neat epoxy reference. Hence, stiffness was improved while strength remained limited due to process-induced material defects and the low fibre content. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) measurements indicated no substantial differences in thermal degradation behaviour across the investigated processing temperatures. Taken together, these results demonstrate the feasibility of processing BC networks into epoxy laminates and identify impregnation inhomogeneity as a key limitation at this early stage. The work further stresses the need for improved control of BC morphology, drying, and impregnation, as well as improved fibre–matrix adhesion in future studies in order to better harness the structural potential of bacterial cellulose in fibre-reinforced polymer composites.