Kinetic Rate Equation Combining Ultraviolet-Induced Curing and Thermal Curing. I. Bismaleimide System

摘要

A novel and general kinetic rate equationcombining ultraviolet-induced (UV-induced) curing andthermal curing was successfully derived from the conven-tional thermal-kinetic rate equation. This proposed novelkinetic rate equation can be applicable to the curing sys-tem either simultaneously or individually by UV-inducedand thermal cure methods. This general kinetic rate equa-tion is composed of the reaction order n, activation energyE_a, curing temperature T, energy barrier of photoinitiationEQ, intensity of UV radiation Q, concentration of photoini-tiator [I], and a few other parameters. The proposed equa-tion was supported by experimental data based onthe curing systems of 4,4'-bismaleimidodiphenylmethane(BMI) and 2,2-bis(4-(4 maleimido phenoxy) phenyl pro-pane (BMIP). The BMI and BMIP systems were isother-mally cured at various temperatures, or simultaneouslycured with varying intensity of UV radiation (wavelength365 nm). Conversion levels for the various cured samples were subsequently measured with a FTIR spectrometer.The reaction order n = 1.2, activation energy E_a=40,800J/mol, and E_Q=7.5 mW/cm~2were obtained for curingBMI system. The reaction order n = 1.3, activation energyEa = 53,000 J/mol, and E_Q=9.1 mW/cm~2were obtainedfor curing BMIP system. The values of n and E_ain thesame curing system (BMI or BMIP) are irrespective of thecuring method (either simultaneously or individually byUV-induced and thermal cure methods). The salientresults of this study show that UV radiation only enhan-ces the initiation rate and UV ration do not influence theactivation energy Ea. The experimental results are reason-ably well represented by these semi-empirical expressions.