| Abstract: | Hybrid polymer networks of diglycidyl ether of bisphenol (DGEBA) resin and phenolic novolac resins were prepared and tested for mechanical properties, hardness, and water absorption. The novolacs employed were based on each of phenol and substituted phenols such as p-cresol, t-butyl phenol, and cardanol. Cardanol is the main constituent of cashew nut shell liquid (CNSL), a renewable resource. Blends containing 10–15 wt% of novolac resin show substantial improvement in properties. These properties show a declining trend with higher novolac loading. The stoichiometric ratio between phenol and formaldehyde in the novolacs was optimized (1:0.8) for maximum property enhancement. The property profiles of the epoxy/novolac networks show that novolacs are effective modifiers for commercial epoxy resin. Incorporation of novolacs of substituted phenols results in relatively greater improvement in energy absorption during failure. |
