Effect of temperature on the fiber-matrix adhesion in glass fiber reinforced thermoplastics

Abstract

The apparent interfacial shear strength (IFSS) between sized glass fiber and neat high-density polyethylene (HDPE), HDPE with a maleic anhydride coupling agent, polyamide 6 (PA6), and polybutylene terephthalate (PBT) has been measured from 20 °C to 80 °C. A modification of a custom set-up involving the single fiber pullout test has been used to perform the characterizations. The calculation of radial stresses on the fiber due to polymer shrinkage during sample cooling has been conducted using data from dynamic mechanical analysis and thermomechanical analysis. A strong inverse relationship was found between IFSS and temperature. The IFSS of neat HDPE, PA6, and PBT decreased by 44% from 20 °C to 80 °C. Over the same temperature range the IFSS of HDPE with the coupling agent decreased by 66% but remained greater than neat HDPE. The effects of glass transition (Tg), measured to be 50 °C for PA6 and 68 °C for PBT, on IFSS were noticeable through analysis of the single fiber pullout data.