Hydrolysis and blistering of cyanate ester networks

Abstract

ABSTRACT:The hydrolysis of a cyanate ester network made from the monomer 2,2 -bis(4-cyanatophenyl)isopropylidene (bisphenol A dicyanate homopolymer) was studied. Hydrolysis reactions were performed isothermally at temperatures from 150 to 180ЊC under conditions of excess water. The kinetics of the reaction were characterized by the decrease in T g as measured by differential scanning calorimetry. The rate of change of T g was found to be adequately described as first order in T g , which is an indirect measure of the concentration of crosslink junctions. The activation energy of the reaction was found to be 115 kJ/mol. In addition, moisture-conditioned, glassreinforced laminate samples were heated and the time to delamination or blistering was recorded as a function of temperature. The blister time at solder temperatures ( T Å 220-260ЊC) was modeled using the above kinetic results. Heat transfer to the laminate was considered and the criteria used for blister time was the time at T Å T g of the sample. At lower temperatures ( T õ 220ЊC), loss of water from the laminate is sufficiently fast to prevent blistering.

Evaluation of bisphenol E cyanate ester for the resin-injection repair of advanced composites

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