EFFECT OF SMALL ADDITIVES OF OLIGOMER ON THE VISCOELASTIC PROPERTIES OF CARBON-FIBER PLASTICS

The viscoelastic properties of carbon fiber composites whose phenol-fo rmaldehyde matrix is modified by thermodynamically incompatible isocya nate derivatives have been investigated. Data are given on fiber wetti ng (Table 1), internal stress (Table 2), viscoelastic properties (Fig. 1), and tensile strength (Fig. 2). The modified composites are streng thened by the addition of 0.5-4% oligomer additive. This process invol ves the formation of a two-phase structure, in which the additive phas e microparticles act as a polymer filler. Due to selective interaction s, the intermediate layer formed at the fiber-binder interface leads t o changes in the viscoelastic properties and tensile strength of the m atrix and improved maintenance characteristics for the material as a w hole.