Synthesis And Properties Studies On The Modified Bismaleimide-Fluorinated Diamine Resin And Novel Polyimides Derived From Triptycene

Polyimides and bismaleimides have been widely used in the field of high technology such as solar photovoltaic, aerospace, military technology because of their beneficial characteristics of thermal stability, hygrothermal resistance, irradiation resistance, and chemical resistance. Bismaleimides derivate from polyimides and are machined easily like epoxy resin contrast to polyimides but their low thermal stability.therefore, they are often served as the matrix of composites. Unmodified Bismaleimides suffer from the drawbacks of poor solubility, high processing temperature and brittleness after curing which make investigations on modification of BMI be active in research area of polymer. Aromatic polyimides showed poor solubility, low transmittance, high dielectric constant and poor processing due to the effect of rigid molecular structure, crystallization and electron polarization. To address above problems, researchers conducted a lot of research on the modification.Aimed at above problems, main content includes the modified bismaleimide and synthesis of novel polyimide material in this paper. In the aspect of modification of BMI, commercial BMI was improved from the reaction of miachael by diamine containing triptycene and fluorine, compared with bismaleimide modified by ordinary diamine in performance. On the other hand, the novel diamine was based on former diamine which was superinduced fatty chain with triptycene and fluorine.The new PI films were synthesized by the novel diamine with commercial aromatic dianhydrides,and the ordinary diamine without triptycene participated in the comparative experiment. Our work was mainly divided into four parts.Firstly, the maximum yield of 1,4-Dihydroxytriptycene was synthesized in two steps from the reaction D-A of industrialized and cheap anthracene with p-benzoquinone followed by proton rearrangement under acidic conditions.We obtained two types of binitro by nucleophile substitution reaction respectively with parachloronitrobenzene as well as 2-chloro-5-nitrobenzotrifluoride and 1,4-Dihydroytriptycene, further produced diamine monomer by reduction with Pd/C and hydrazine hydrate. At last, the structure was carried out by IR, 1HNMR,13 CNMR.Secondly, there were six oligomers resins after commercial bismaleimide modified by two new diamine and diphenylmethane diamine. We observed the change of material groups before and after modification and curing to prove the feasibility of curing process.Solubility tests proved that the solubility of prepreg was improved greatly by functional groups of triptycene and fluorine. FBMI and BBMI polymers both enjoy low hygroscopicity in which FBMI series was the best.The BMI thermal stability was holded by modified BMI with diamine containing triptycene because it had a high heat resistance than DBMI series by means of measurement of TGA. The behavior of three types of oligomers from melting to curing was characterized by the testing of DSC. Then,we designed the autoclave molding process according to it.Thirdly, we selected three kinds of modified BMI oligomers which experienced preparation of prepreg, hot press molding to get advanced composites.The results showed that the composite material on the basis of BMI modified by diamine with triptycene and fluorine gave the advantages of low moisture absorption, good rigid strength and tenacity after the measurement of hygroscopicity, SEM and DMA.Lastly, A series of polyimides containing three kinds of special functional groups was synthesized by polycondensation of the novel diamine which was based on1,4-Dihydroxytriptycene by introducing fatty chain followed by the reaction of substitution and reduction with three different dianhydrides(BPDA BTDA,6-FDA).At the same time, similar diamine excluding triptycene was created to make a comparison.All aspects of the performance test shows that the PI with triptycene,trifluoromethyl and fatty chain was provided with the comprehensive performance of better permeability, fluorescence,solubility,low hygroscopicity, mechanical properties and heat resistance.