Study on the fracture toughness of wood fiber reinforced high–density polyethylene composites

Abstract

The fracture toughness of WPE significantly influences its service life and safety, particularly under sudden impact. This study examines the dynamic fracture properties of WPE with varying wood fiber (WF) contents through low-speed impact tests and digital image correlation (DIC) analysis. The results show that wood fiber plays a dual role: it increases the likelihood of brittle fracture while simultaneously enhancing resistance to rapid crack advance. The addition of WF enables the WPE composite material to withstand higher impact forces and absorb more impact energy during the initial impact stage (0-1 ms). The initial peak force of WPE8 in 80 % wood fiber specimens was optimal, and the crack propagation length under 10 J impact was 9.20 mm. The analysis of mode I stress intensity factors (SIFs) confirms this duality. Under increasing impact energy, all WPE composites exhibit rising mode I SIF values, with WPE8 reaching 2.32 MPa m1/2 at 10 J – 4.7, exhibiting a relatively high flexural strength (52 MPa) and modulus (3.2 MPa).