On the influence of moisture content on the fracture behaviour of notched short glass fibre reinforced polyamide 6

The aim of this work is to analyse the influence of moisture content on the fracture behaviour of notched short glass fibre reinforced polyamide 6 (SGFR-PA6). For this purpose, the study combines two fibre contents (10 wt% and 50 wt%) with three different moisture contents (dry, 2% and 4–5%). Fracture tests were conducted on Single Edge Notched Bending (SENB) specimens, considering five notch radii (from 0 to 2 mm) for each combination of fibre and moisture content. Although notch effect is clearly observed in dry conditions, when the moisture content increases this effect tends to decrease for the notch radii considered here. The Line Method of the Theory of Critical Distances has been calibrated and validated for the conditions studied, providing a reasonable prediction of the apparent fracture toughness of the material in notched conditions. Concerning the fractographic observations, a Scanning Electron Microscopy analysis was performed, revealing the evolution of fracture micromechanisms when the moisture content increases.