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Effects of mold temperature and vacuum in resin transfer molding

Akgül, Eralp
The purpose of this study was to investigate the effects of mold temperature, initial resin temperature, and the vacuum, applied at resin exit ports, on the mechanical properties of epoxy matrix woven glasss fiber reinforced composite specimens produced by Resin Transfer Molding (RTM). For this purpose, six different mold temperatures (25º, 40º, 60º, 80º, 100º, and 120ºC), two initial resin temperatures (15º and 28ºC), and vacuum (0.03 bar) and without vacuum (~1 bar) conditions were used. Specimens were characterized by using ultrasonic (C-Scan) inspection, mechanical tests (Tensile, Flexural, Impact), thermal analyses (Ignition Loss, TGA) and scanning electron microscopy (SEM). It was generally observed that mechanical properties of the specimens produced with a mold temperature of 60ºC were the best (e.g. 16%, 43%, and 26% higher tensile strength, Charpy impact toughness and flexural strength values, respectively). When vacuum was not applied, the percentage of “voids” increased leading to a decrease in mechanical properties such as 26% in Charpy impact toughness and 5% in tensile and flexural strength. Lower initial resin temperature also decreased mechanical properties (e.g. 14% in tensile strenght and 18% in Charpy impact toughness).