Preparing microcrystalline cellulose‐reinforced polylactic acid composites by an energy saving method

Abstract Microcrystalline cellulose (MCC) fibers are co mmonly used to reinforce polymers; however, their freeze‐drying process consumes a lot of energy. In this study, MCC dried at different temperatures, oven‐dried at 25, 50, 75, and 103°C and freeze‐dried, was evaluated based on their effect on the reinforced composites. The dried MCC was compounded with polylactic acid (PLA) by melt extrusion and compressed into an MCC/PLA composite film. The morphology, structure, and crystallinity of the dried MCCs and MCC/PLA composites were analyzed using scanning electron microscopy, laser particle size analysis, x‐ray diffraction, mechanical testing, and Fourier transform infrared spectroscopy. It was proved that MCC dried at 103°C was more uniformly dispersed and tightly bound to the PLA matrix than freeze‐dried MCC. Tensile measurements showed that the MCC dried at 103°C had nearly the same tensile strength (58.35 MPa) as that of the freeze‐dried MCC (58.7 MPa) and was higher than that of the other oven‐dried MCC. Energy consumption evaluation revealed that oven‐drying consumed much less energy than freeze‐drying MCC for 24 h to obtain the same final moisture content. MCC dried at 103°C has significantly better properties than MCC dried at 25, 50, and 75°C, similar to freeze‐drying. Concerning performance and energy consumption, drying at 103°C is determined the optimal choice to support the preparation of MCC‐reinforced PLA composites. Highlights Drying temperature effects aggregation of MCC. MCC Dried at 103°C can present similar properties to freeze‐dried MCC but save more energy. Oven‐drying can be a good way to dry MCC for the preparation of MCC/PLA composite.