Interfacial properties and permeability of three patterned glass fiber/epoxy composites by VARTM

The interfacial properties for three different glass fiber (GF) mats were evaluated by examining permeability through combining the results of wettability and interlaminar shear strength (ILSS) testing. Three types of GF mats were studied: (1) unidirectional (UD), (2) bidirectional (BD, 0/90°), and (3) randomly-chopped (RC). Single fiber tensile tests were used to compare the fibers in the 3 mats, forty single fibers were extracted from each mat. FE-SEM was used to study damages on the GF in each of the mat types. Fibers from the UD mat exhibited the best mechanical properties and less damage was observed with the FE-SEM. Vacuum assisted resin transfer molding (VARTM) was used to manufacture glass fiber reinforced composite (GFRC) specimens, with the three different mat types. The permeability of the different GF mats was measured, during manufacture of the GFRC, and related to the spreading of the epoxy resins in the GF mats. Short beam tests were performed as a measure of interfacial properties and related to the observed permeability and spreading. GFRC manufactured with UD GF mat exhibited the best interfacial and mechanical properties and displayed the least physical damage while GFRC manufactured with BD GF mat had the poorest interfacial and mechanical properties while exhibiting the most visible damage. The UD GF mat also displayed the smallest change in contact angle and the best permeability. The longitudinal fiber pattern in the UD GF mat apparently promotes capillary effects leading to an increase in wetting rate. This study demonstrates that GF mat pattern affect the interfacial and mechanical properties as well as matt permeability and resin spreading.