Comparison between polyethylene glycol and tributyl citrate to modify the properties of wood fiber/polylactic acid biocomposites

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