Impact of water plasticization on dialcohol cellulose fibres melt processing-structure-properties relationship

Cellulose and its derivatives are considered sustainable alternatives to non-biodegradable fossil-based plastics. Chemically modified cellulose fibres to dialcohol cellulose (DAC) fibres demonstrated a melt processing window between the glass transition and degradation temperatures which enabled their extrusion by using only water as a temporary plasticizer . With the aim of supporting an industrial upscale of DAC fibres, this study investigates the processing design and the feasibility of melt processing, minimizing the moisture. Melt processes-structure-properties relationships were studied by varying the sequence of primary and secondary melt processes, i.e., extrusion and injection moulding , and by changing the moisture content . The effect of moisture and processing design on the fibre structural properties , such as molecular weight , crystallinity , fibre morphology and fibre suspensions rheology , was assessed. Then, the thermomechanical behaviour of the 3D-shaped DAC injected materials was correlated with DAC fibres structural features obtained by the different processing design and moisture content. Our results identified the injection moulding as a milder process for achieving the preparation of 3D-shaped material with enhanced mechanical properties. Moreover, we disclosed the relevance of controlled moisture in the extrusion process for enabling a secondary shaping directly after compounding and the possibility of 3D-shaping DAC fibres after a rehydration step.