Examining the thermal degradation behaviour of a series of cyanate ester homopolymers

A series of thermally stable dicyanate monomers, containing different thermally stable structural units, viz 2,2’-bis (4-cyanatophenyl)propane (DCDPP), bis-4-cyanato-biphenyl (DCBP), bis-4-cyanato naphthalene (DCN), 3,3’-bis(4-cyanatophenyl) sulphide (DCTDP) and 3,3’-bis (4-cyanatophenyl) sulphone (DCDPS), is prepared and the identity of the products confirmed by FT-IR and NMR spectral methods. The corresponding cyanate homopolymers (designated by the suffix HP) are prepared and their properties evaluated and compared. The composites were analysed for their thermal stability and thermal degradation kinetics. The series of homopolymers exhibit excellent thermal characteristics e.g. relatively high glass transition temperatures of at least 215 ºC, which were inversely proportional to the molecular weight between the crosslinks, high thermal decomposition temperature, high integral procedural decomposition temperature (IPDT), and high activation energies for the decomposition of the cured resins. Determination of their limiting oxygen indices indicates that all the homopolymers are characterized as ‘self-extinguishing’ materials.