Research On The Imide Oligmer Modified High Performance Matrix Resins

Bismaleimide and epoxy are the importance high performance matrixes for advanced composites. Major application of them is in aerospace and aviation industry. However, their brittleness limits their applications.The dissertation reviews the development of BMI resin and the new methods for modification thermosets. Basis of this, a new method is studied and called pre-insitu polymerization (PISP) to increase toughness of high performance resin. Imide olig-mer (PEI) with a similar molecular structure to BMI is selected for modification BMI resin. We study on the relation structure with properties of modification BMI resin. The main contents and conclusions are shows as follows:RS that can react with BMI is explored and used as solvent for PEI synthesis and did not need to separate the mixture. BMI is dissolved in the PEI/RS to obtain modified BMI homogenous prepolymer and cured the PEI/RS/BMI system to obtain cured modified BMI resin.Nine PEI are polymerized in RS. Among of them , DAEIt and DAEId are new. DAEIL: DAEId:We study the effect of molecular structure of PEI on toughness of modification BMI resin. Modified BMI resin by PEI is synthesized by ODPA and DBPP has outstanding toughness. Co-polymerization PEI and PEI with lateral groups can improve toughness of BMI remarkably.We study the effect of PEI molecular weight on properties for modification BMI resin, e. p. DAEIa/RS/BMI system. DAEIa/RS/BMI resin with 3000-5000 molecular weight of DAEIa has good heat resistance and high toughness. DAEIa/RS/BMI system with 3100 molecular weight of DAEIa has high thermal stability, Tg=292 ℃, thermogravimetric analysis (TGA)in nitrogen atmosphere revealed temperature that the cured resin is decomposed 5% is 506℃, its char yield at 700℃ under nitrogen condition exceeds 44%, and excellent toughness impact strength is 27KJ/m2.We study the effect of loading of PEI on properties for modification BMI resin, e. p. DAEIa/RS/BMI system. Modified BMI resin has good heat resistance and high toughness with 10-20% DAEIa loading. DAEIa/RS/BMI system with 15% DAEIa loading has high thermal stability, Tg=283℃, thermogravimetric analysis(TGA)in nitrogen atmosphere revealed temperature that the cured resin is decomposed 5% is 492℃, its char yield at 700℃ under nitrogen condition exceeds 45%, and excellent toughness, impact strength is 29KJ/m2.Modulus and heat resistance and toughness are barter than BMI resin without PEI. This conclusion is not get by other methods of modified BMI.The property of curing reaction of modified BMI is studied by means of manifold methods, such as DSC, IR and gel characteristics. Cure reaction contents BMI react with ally compound and -NH2 based of PEI. BMI react with ally compound is mains. Reasonable cure technology has been set up.The DMA of modification BMI cured resin suggests a largely homogenous material with a signal peak from 30℃-350℃. Evidence for phase separation was not found by picture of impact failure specimens of SEM.Base of the modification BMI research we employ PISP for modification epoxy resin in succeed .We select the co-reaction monomer with epoxy (CME) and used CME as solvent for PEI (DAEIa) synthesis and we did not need to separate the mixture CME/DAEIa and modified E-44/DDS system. We dissolved CME/DAEIa and DOS in epoxy E-44 to obtain homogenous CEM/DAEIa/E-44/DDS system. We cured the CME/DAEIa/E-44/DDS system to obtain cured modified epoxy resin with high toughness and good technology.