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

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.