Epoxy-liquid polysulfide blends

Epoxy-Liquid Polysulfide Blends Epoxy resins in combination with liquid PSs appear to possess many added advantages as the elastomeric PS segments in epoxy chains impart permanent flexibility [18]. Epoxy-liquid PS blends have been reported as binders for Army illuminating formulations [8]. Similarly, novolac epoxy-liquid PS blends have been reported for inhibition of composite propellants [19]. 

For adhesive systems, the liquid epoxy resins most widely used with LP-3 polymers are liquid unmodified and diluent-modified bisphenol A resins and liquid blends of bisphenol A and bisphenol F resins. Solid bisphenol A, multifunctional, and aliphatic diepoxy resins have also been used. Ratios of liquid polysulfide polymer to epoxy are in the range of 1 2 to 2 1. The effect of various degrees of polysulfide on cure properties of a DGEB A epoxy is shown in Table 7.7. An increase in elongation and impact strength is the result of increased amounts of the liquid polysulfide polymer. 

Epoxy-polysulfide adhesives are suitable for used down to -100°C and lower temperatures. Some blends have been used down to liquid nitrogen temperatures of -198.5°C. The maximum service temperature is about 50°C to 71-82°C. The resistance of bonds to moisture is quite high, but may deteriorate if the bonds are stressed. Some formulations will corrode copper adherends. 

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