Cellulose blends from gel extrusion and compounding with polylactic acid

Abstract

Cellulose, dissolved in ionic liquids (IL), can be used successfully in the processing of thermoplastics. To recover the ionic liquid while maintaining the thermoplastic properties, other spacers than IL might be introduced into the cellulose network. Such blend materials have been prepared before by solution blending as reported in the literature. In this study, the preparation and investigation of cellulose and polylactic acid (PLA) blends using an extrusion process with an ionic liquid and co‐solvent for intermediate compatibilization is reported. The obtained transparent films show a homogeneous morphology without phase separation. Thermal analysis showed no separated glass transition for PLA, and FTIR showed hydrogen bonding between cellulose and PLA chains. Thermal stability of the blends with a degradation onset around 270°C lies between regenerated cellulose and pure PLA. The blend tensile strength and elongation of ~40 MPa and 1.3%, respectively, were comparable to a multiphase composite containing twice the molecular weight of PLA. Generally, mechanical performance of the blends was strongly influenced by degradation reactions mainly caused by the ionic liquid used, as well as blend morphology. The study shows that transfer from solution to extrusion processing is generally possible to obtain novel cellulose blends.