Preparation and mechanism of lightweight wood fiber/poly(lactic acid) composites

The high density and poor thermal insulation of traditional wood-plastic composites limited the application in the field of building materials. In this paper, wood fiber (WF) and PLA were used as raw materials and azodi-carbonamide was used as the foaming agent. Lightweight WF/PLA composites were prepared by the hot-pressing foaming method, aiming to obtain renewable, low-density material with high strength-to-weight ratio and thermal insulation performance. The results showed that after adding 20 % WF into PLA, the cell morphology was excellent and the cell size was uniform. The magnification reached the minimum value of 0.36 g/cm(3) and the foaming magnification was 3.42 times. The impact strength and compressive strength were 3.16 kJ/m(3) and 4.12 MPa, its comprehensive mechanical properties were outstanding. The thermal conductivity of foamed materials was 0.110-0.148 (W/m.K), which was significantly lower than that of unfoamed materials and com-mon wood. Its excellent mechanical properties and thermal insulation can be suitable for application in the construction field to replace traditional wood.