Thermally stable polybenzoxazines

摘要

Polybenzoxazines are a novel type of phenolic resins, which show many interesting properties such as, easy processibility in combination with high thermal stability and good mechanical properties. To further enhance their thermal stability an additional polymerizable functional group - phthalonitrile is introduced into the molecular structure of the benzoxazine monomers. The curing profile of these modified benzoxazines is studied by high pressure differential scanning calorimetry (DSC). Thermal properties of the cured resins are determined by thermogravimetry (TGA) and dynamic mechanical analysis (DMA). The cured phthalonitrile functional polybenzoxazines exhibit high char yield up to 80percent by weight (char yield is a solid residue at 800 deg C) in nitrogen and up to 30 percent by weight in air (at 600 deg C). These materials also show low flammability. Additionally, the monomers can be cured at relatively moderate conditions when compared with other phthalonitrile functional resins.