MECHANICAL-PROPERTIES, THERMAL-STABILITY, AND FLAME RETARDATION OF PULTRUDED FIBER-REINFORCED POLY(ETHYLENE OXIDE)-TOUGHENED NOVOLAK-TYPE PHENOLIC RESIN

The mechanical properties (flexural modulus, static tensile strength, notched Izod impact strength), miscibility, thermal stability, and fla me retardance of a poly( ethylene oxide) (PEO)-toughened phenolic resi n glass pultruded composite were investigated. The mechanical properti es of a pultruded glass fiber-reinforced modified phenolic resin compo site increased while the soft segment of PEO absorbs the loads in the network of brittle phenolic resin. The phenolic/PEO blend is completel y miscible, from the results of differential scanning calorimetry. Its thermal degradation temperature is always higher than 370 degrees C a nd decreased with increasing PEO content. The morphology of the interf ace between the fiber and matrix is well wetted-out with increasing PE O content from the result with a scanning electron microscope (SEM). T he modified phenolic composite also shows excellent flame retardance t hat is UL-94, V-0, and the limited oxygen index is more than 55. (C) 1 998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 1129-1136, 1998.