Acetylene-Containing Precursor Polymers

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Abstract
A significant effort has been devoted during the last 10 years to develop a route to thermally stable polymers without the evolution of volatile by-products. Most high-temperature polymers are prepared by condensation polymerization which involves the elimination of volatiles. These volatiles are responsible for severe problems encountered in the fabrication of parts, particularly thick and large components. Some success has been attained by reducing the volatile level through B-staging, which is generally accompanied by reduced resin flow and also by using an intricate bleeder system and a long cure cycle. These modifications are generally unacceptable for production-line use due to cost and reliability. A few high-temperature polymers can be processed as thermoplastics. However, the resin form is unacceptable for complex components (e.g., prepreg too boardy) and high temperature and pressure are generally required. In an attempt to circumvent these problems, work has concentrated on the development of systems which can thermally chain extend through an addition-type polymerization. A promising route developed in the late 1960s involved end-capping imide oligomers with the norbornene group which could be thermally polymerized through the unsaturation [1]. This technology became known as P13N and has since been extended to two other similar systems, PMR-15 [2] and LARC-160 [3].