Dialcohol cellulose based formulations to enhance thermoplastic behaviour and reduce water sensitivity

The growing demand for sustainable alternatives to traditional plastics has driven research towards bio-derived and biodegradable materials. The present study is a part of a Swedish National Project called “ProDAC”, which aims to facilitate a sustainable transition from fossil-based plastics to cellulose-based thermoplastics, with the aim to enhance the large-scale production by improving both melt processability and final properties. From cellulose, through an oxidation reaction, dialdehyde cellulose (diald) is obtained, while a subsequent reduction yields the dialcohol cellulose (DAC). Formulations based on melt processable DAC, used as matrix, with a gradual increase in diald content (0-25 wt.%) have been developed. The goal of this work is to explore the hypothesis that a reactive extrusion of DAC with diald could enhance the dimensional stability of DAC when exposed to environmental condition i.e. reduce the DAC water sensitivity. The formulations were developed using micro-compounding and micro-injection moulding techniques, selecting processing parameters to avoid degradation. Thermal and mechanical characterizations (TGA, DSC, DMTA and tensile test) have been performed. To study the chemical structure, FTIR analysis was accomplished. Water interaction was evaluated through absorption test and water contact angle measurement. The main results demonstrate improved melt processability of the materials and reduced water sensitivity (in particular, 75DAC-25diald absorbed just 1.61g of water with respect to 5.97g of DAC) maintaining a dimensional stability in water along 7 days.