Effects of lithium chloride and chain extender on the properties of wood fiber reinforced polyamide 6 composites

Lithium chloride (LiCl) and 2,2‘-(1,4-phenylene)bis(2-oxazoline) (PBO) were first used as the modifier and chain extender to decrease the melting temperature and increase the molecular weight (Mη) of polyamide 6 (PA6), respectively. Then, poplar wood fiber reinforced composites based on PA6 were prepared via hot pressing. The results showed a decrease in the melting point of PA6 (from 220 °C to 190 °C) and the processing temperature (from 240 °C to 210 °C). Thereby, the thermal degradation and discoloration of the composites were significantly restricted. The molecular weight of PA6 could be increased from 33000 to 72800 by PBO. LiCl and PBO increased the impact strength by 50% and 43%, respectively, as well as enhanced the interfacial compatibility between PA6 and poplar wood fiber. Poplar wood fiber improved the flexural strength and modulus by 17% and 122%, respectively.