The influences of calculated molecular weight,different diamines and different dianhydrides on properties of 2,3,3',4'-biphenyltetracarboxylic dianhydride( a-BPDA)-added polyimide foam were studied. The results show that a-BPDA/m-PDA/NA system can provide excellent high-temperature resistant rigid polyimide foam with a calculated molecular weight of 1500 g/mol. The foam has high glass transition temperature( > 350 ℃),high closed-cell content( >88%) and high compressive strength( 1. 34 MPa). Moreover,partly ...