Fracture Toughness of Phenol Formaldehyde Composites

ABSTRACT: A commercial phenol formaldehyde-based resole thermosetting resin supplied by Borden Chemical Australia Pty. was reinforced with ceramic-based fillers (SLG) to increase its fracture toughness. This is the second study of the same series. By testing fracture toughness and viscosity at a range of filler addition levels, the optimal addition of SLG was determined in terms of workability, cost, and performance. The composites obtained were post-cured in a conventional oven as in the previous study. The original contributions of this article include lowering the cost of the composite (35wt % of SLG) by 50 % but at the same time the fracture toughness was reduced only by 20 % (compared to the neat resin), and increasing the fire resistance of the resins tremendously. It was also found that the values of fracture toughness of the samples in this study were higher than those obtained in the previous study when the percentage by weight of SLG varies from 0 to 35%. The shapes of the plots of fracture toughness against percentage by weight of SLG were also different. The possible reasons for the differences were explained. KEY WORDS: phenol formaldehyde, phenolic resin, microwaves, envirospheres, SLG, short bar test, viscosity