Analysis of the mechanical behavior and characterization of pultruded glass fiber–resin matrix composites

Pultrusion is the fastest growing manufacturing process of composite materials. Although based on simple physical principles, the fabrication of pultruded parts is not a simple task, because it involves the proper control of heat transfer and the cure kinetics of the resin matrix. In fact, a careful control of the entire fabrication procedure is needed to avoid defective pultruded parts. Even if the proper boundary conditions are established, pultruded parts can show an uneven fiber distribution and voids. In this work, a complete analysis of the microstructure of I-shaped pultruded profiles was performed by digital image analysis and their flexural mechanical behavior was determined. The micro-characterization comprised, besides the common measure of fiber and filler fraction, the size and spatial distribution of the fibers. The results obtained showed the importance of performing a complete micro-characterization, in order to fully understand the performance of the profiles under load. The profiles with higher filler content showed as fabricated better properties, but have a worst behavior after being pre-damaged. This behavior, as well as the water absorption behavior, was correlated with the micro-structural and/or materials parameters.