Morphology and thermal properties of copolymer based on p-aminobenzonitrile type benzoxazine and diglycidyl ether of bisphenol-A

• A copolymer of p-aminobenzonitrile based benzoxazine and epoxy resin was prepared.
• The fracture surface of the copolymer shows a homogeneous morphology, and the roughness increases with rising epoxy content.
• In the glassy state, the storage modulus of the copolymer initially tends to increase with rising epoxy content, but decreases when epoxy content reaches to 50 wt%.
• The glass transition temperature of the copolymer is lower than that of polybenzoxazine, but the onset weight loss temperature is higher.

A copolymer of p-aminobenzonitrile type benzoxazine (BA-pabn) and diglycidyl ether of bisphenol-A (DGEBA) was prepared. With rising DGEBA content, the peak temperature of the differential scanning calorimetry curve for polymerization of BA-pabn/DGEBA blend shifts to higher value, and the roughness of the fracture surface of the BA-pabn/DGEBA copolymer increases. In the glassy state, the storage modulus of the copolymer initially tends to increase with rising DGEBA content over pure polybenzoxazine (PBA-pabn), but decreases when DGEBA content reaches to 50 wt%. The copolymer exhibits a single glass transition temperature lower than that of PBA-pabn. The onset weight loss temperature of the copolymer is higher than that of PBA-pabn, but the char yield at 800 °C is lower.