Fracture and failure behavior of partially consolidated ciscontinuous glass fiber mat-reinforced polypropylene composites(Azdel SuperLite®)

Abstract

The fracture and failure behavior of partially consolidated discontinuous glass fiber (GF) mat reinforced thermoplastic polypropylene (Azdel SuperLite®) composite sheets of various densities (0.35, 0.5 and 0.7 g·cm−3) but with the same amount of GF (55 wt.%) were studied under static (in-plane) and dynamic (out-of-plane perforation impact) conditions. The fracture toughness (KQ) determined on single edge notched static tensile loaded (SEN-T) specimens, increased with increasing density (or surface weight as the sheet thickness was constant, viz. 2 mm). Location of the acoustic emission (AE) and mapping the temperature rise during loading of the SEN-T specimens via infrared thermography (IT) served to estimate the damage zone and trace the crack advance. Both techniques seem to be promising tools to determine the energy release rate directly. The unexpected high KQ value was attributed to a combined effect of fiber nesting (achieved by the papermaking production technology) and high stress transfer GF length (owing to partial consolidation). This resulted in an efficient stress transfer and stress redistribution during damage zone development and growth. The resistance to perforation impact of the SuperLite® sheets also increased with their density (surface weight).