The Study Of BMI Resins Modified By Poly (Phthalazinone Ether)s

Bismaleimide (BMI) resins, as high performance composite matrices, high temperature insulating and adhesives, have been widely used in aviation, aerospace, automobile, petrochemical, machinery, electronicsand other industries because of their excellent weather resistance, heat resistance, fire retardancy, electrical insulation, radiation resistance, dimensional stability and good mechanical properties, molding process similar to the epoxy resin, etc. However, unmodified bismaleimide resins have the low toughness, low stress cracking resistance, poor impact resistance and other shortcomings, which limit their application to some extent. Therefore, the present study focuses on the modified BMI with thermoplastic poly(phthalazinone ether nitrile ketone) and copoly(phthalazinone ether ketone), which are candidates for the high-performance composite materials.Two seires of PPAEs/BMI blends were prepared by mechanical mixing with solvent. In order to produe the mixtures with toughness and thermal resistance, we focused on the effects of the PPENK curing conditions and amido-terminated PPBEKrespectively. The main studies and results are in the following:PPENK, with the polar cyano pendant group, was used to modify BMI resin. First, the curing kinetics of PPENK/BMI blends was measured by dynamic differential scanning calorimetry (DSC). Curing reaction activation energy, calculated by Kissinger method, implying that the additions of PPENK didn't change the curing mechanism and activation energy of BMI resins, and the curing condition was determined. The mechanical property of the blends was was measured by impact test, improved to some extent, and appeared maximum 2.95 kJ/m2, was increased by 61% compared to neat BMI when 10% PPENK was added. The scanning electron microscope (SEM) of fracture surface demonstated that the cracks deviated their original ways to initiate deflection and disproportionation, absorbed energy. So the toughness of PPENK/BMI blends was improved. The heat-resistance of blends was well maintained. The curing product had the best mechanical property ant the curing condition of 160℃/2h+190℃/2h+230℃/4h.PPBEK, containing the flexible BPA group in the chain and PPBEK-DA, its amido-terminated product, was used to modify BMI resin. The curing kinetics of PPBEK/BMI blends was measured by dynamic differential scanning calorimetry (DSC). Curing reaction activation energy, calculated by Kissinger method, implying that the additions of PPBEK didn't change the curing mechanism and activation energy of BMI resins. The mechanical property of the blends was was measured by impact and flexural tests, the result showed that, BMI modified by PPBEK-DA had better effect, and the impact and flexural strength appeared maximum when the contents of PPBEK-DA were 10% and 5% respectively, the value was 3.29 kJ/m2 and 190.8 MPa. The blends had good thermal resistance. The cracks deviated from their original ways to initiate deflection that increased the surface area of the cracks, absorbed energy, thereby increasing the toughness of blends.