Study On The Polymerization Of Bismaleimide And Allyl Ether Phenolic Resin

The phenolics was the earlist industrialization synthetic resin in the world which was the nearly hundred years history up to now. It has showed good heat-resisting and mechanics performance after solidification. Therefore, the phenolics has gradually substituted for the engineering plastics and some metals and the alloy material in the many domains, i.e.automobile, the electron, the electricity, the transportation, the military and so on . Owning to the phenol hydroxyl and methyl radical easy to oxidize, the thermal stability was subject to influence.To improve phenolics thermal property, the ideas about modified phenolics and bismaleimide resin are introduced based on many documents.In this work, a liquid crystal bismaleimide containing ester bonds has been synthesized and characterized by Fourier transform infra-red(FT-IR) spectroscopy, Differential scanning calorimetry(DSC)and hot stage polarized light microscopy(HSPM). The Schlieren texture of nematic phase and good nematic liquid crystalline behavior can be observed by HSPM.The copolymerization was carried between 4,4′-diaminodiphenyl ether (DDE) and bismaleimide to improve some properties, such as high melting point and curing temperature, bad resolvability, great brittleness. The structure and liquid crystalline behavior was characterized by Fourier transform infra-red(FT-IR) spectroscopy, Differential scanning calorimetry(DSC)and hot stage polarized light microscopy(HSPM). The melting point of copolrmers has been decreased effectively by introduced of DDE. The introduce of DDE has no effect on the liquid crystal behavior of MBMI.Allyl ether phenolic resin(AEN) was synthesized from novolak and allyl chloride. The resultants were characterized by FT-IR spectral studies, hydroxyl contents and solubility. The hydroxyl contents were determined by acetylization method, then ether ratio were obtained by comparing hydroxyl contents of pre-reaction and post-reaction. The ether ratio of AEN was 61.95%, 47.61%and 25.43% with the ratio of phenolics to allyl chloride was 3:2, 2:1and 3:1 respectively while the productivity was 75.86%, 85.43% and 92.66% respectively. AEN resin can be dissolved in the non-polar solvent such as toluene and xylene as well as alcohol. FT-IR spectral of the AEN resin can testify allyl group in the resultant.Then copolymers of AEN/BMD,AEN/BMD/DCP and AEN/MBMI/DCP were produced in solution. Their structures and properties were proved by FT-IR spectral, different thermal analysis and thermal gravimetric analysis. The results show that the modified resins by bismaleimide, especially by liquid crystal bismaleimide, have higher temperature resistance.The non-isothermal curing kinetics of copolymerization was studied with DSC. The reaction heats and degree of curing at different heating rates were evaluated. The reaction heats at different heating rates were close to a constant. The kinetic parameters, i.e. apparent activation energy E and reaction order n were presented based on Kinssinger and Crane equations. Apparent activation energy E(α) as a function of curing transition degreeαis more reasonable than the constant activation nenergy.The heat resistance and thermal degradation kinetics of the AEN/BMD/DCP copolymer was studied by thermogravimetry(TG) at different heating rate. Iso-conversional method was applied to estimate the apparent activation energy Ea.