Synthesis and characterization of phenylsiloxane-modified bismaleimide/barbituric acid-based polymers with 3-aminopropyltriethoxysilane as the coupling agent

摘要

The preparation and characterization of phenylsiioxane (PhSLX)-modified N,N'-bismaleimide-4,4'-diphenyImethane (BMI)/barbituric acid (BTA) (10/1 mol/mol) oligomers are described. 3-Aminopropyltriethoxysilane (APTES) was used as the coupling agent. The resultant hybrid BMI/BTA-APTES-PhSLX polymers were characterized primarily using thermogravimetric analysis in combination with differential scanning calorimetry and Fourier transform infrared measurements. The thermal stability of the BMI/BTA oligomer was improved significantly by incorporation of a small amount (20-30 wt%) of the copolymer of PhSLX and APTES (PASi). After adequate post-curing reactions, the PASi-modified BMI/BTA oligomers (HYBRID20 and HYBR1D30 containing 20 and 30 wt% PASi, respectively) exhibited greatly reduced thermal degradation rates in the temperature range 300-800 °C and an increased level of residues at 800 °C as compared to the native BMI/BTA oligomer. This was further confirmed by thermal degradation kinetic studies, in which the activation energies for the thermal degradation reactions of the cured PASi-modified BMI/BTA oligomers were shown to be higher than that of the pristine BMI/BTA oligomer.