No abstract

Cellulose nanocrystal (CNC) reinforced methacrylate (MA) resin nanocomposite was prepared by 3D stereolithography printing. A postcure process, where the printed nanocomposite was heat-treated under different temperatures, was applied to improve the property of the printed nanocomposites. To investigate the effect of CNC and postcure temperature on the kinetic behavior of the postpolymerization of printed nanocomposites, Fourier-transform infrared spectroscopy and differential scanning calorimetry measurement of the printed nanocomposites before and after postcure were analyzed. The postpolymerization of MA nanocomposites was promoted at a postcure temperature of 140 8C for the printed 0.5% CNC/MA nanocomposites compared to the printed MA resin. The addition of CNC retarded the polymerization of MA resin during 3D printing, resulting in poorer mechanical properties of the printed nanocomposites compared to the printed MA resin. However, after postcure, the mechanical properties of the printed nanocomposites were improved by the postpolymerization of the MA nanocomposites. V C 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018, 56, 935-946

An environmentally friendly bleached extruder chemi-mechanical pulp fiber or wood flour was melt compounded with poly(lactic acid) (PLA) into a biocomposite and hot compression molded. The mechanical, thermal, and rheological properties were determined. The chemical composition, scanning electron microscopy, and Fourier transform infrared spectroscopy results showed that the hemicellulose in the pulp fiber raw material was almost completely removed after the pulp treatment. The mechanical tests indicated that the pulp fiber increased the tensile and flexural moduli and decreased the tensile, flexural, and impact strengths of the biocomposites. However, pulp fiber strongly reinforced the PLA matrix because the mechanical properties of pulp fiber-PLA composites (especially the tensile and flexural strengths) were better than those of wood flour-PLA composites. Differential scanning calorimetry analysis confirmed that both pulp fiber and wood flour accelerated the cold crystallization rate and increased the degree of crystallinity of PLA, and that this effect was greater with 40% pulp fiber. The addition of pulp fiber and wood flour modified the rheological behavior because the composite viscosity increased in the presence of fibers and decreased as the test frequency increased.

In this work, polyethylene glycol (PEG) and tributyl citrate (TBC) are proposed to modify the properties of wood fiber (WF, 20 wt%)‐reinforced polylactide (PLA, 80 wt%) biocomposites. The reinforcing and toughening effects of these additives were systematically investigated by comparing their mechanical, thermal and rheological properties. It was found that 5 wt% TBC improved the compatibility between WF and PLA and resulted in increased tensile strength (15%) and thermal stability (4%) of the biocomposites compared with those of unmodified biocomposites. The glass transition temperature, melting temperature, and crystallinity of TBC‐modified biocomposites were lower than those of PEG biocomposites. In addition, the storage modulus, loss modulus and complex viscosity of TBC‐modified biocomposites were effectively improved at low TBC content (5–10 wt%), whereas reduced properties were obtained when the same PEG content was added. As wettability is always a problem in biocomposites, the contact angle was not changed with TBC content (up to 20 wt%), and a linear decrease was observed with a PEG content up to 30 wt%. POLYM. COMPOS., 40:1384–1394, 2019. © 2018 Society of Plastics Engineers