Studies On Tne Synthesis Of Liquid Crystalline Bismaleimides And Its Modification On Epoxys

As one of three common thermoset resins, epoxy resin(EP) takes an unsubstituted role in many industrial fields because of its excellent physical and chemical properties. While its curing product has a low impact strength with a structure of three-dimential network, the extension of epoxy resins application meet an obstacle. Till now, toughening is one of researching hot-points in the field.In this work, the curing systems of E-54/amine modified by industrial bismaleimides(BMD) and liquid crystalline bismaleimides with aroma ester(Ia), were studied .It was found that BMD can improve the material's toughness and other mechanical properties in some degree, at the same time. Compared with BMD, Ia showed some advantages in the aspect of toughing EP, which may be attributed to some special characters of liquid crystalline. The change of material's properties may due to the influence of BMD and Ia to the system's crosslink density and the chain rigidity between the crosslinked points.Moreover, bismaleimides oligomers, which were sythesized by BMD or Ia with 4,4' -diamino biphenylether, were added to the curing system of E-54/amine to toughening the materials. Compared with monomers(BMD or Ia), oligomers showed some advantanges to improve the material's impact strength, while the properties of materials were deeply influenced by the solubility of oligomers in epoxy resin.During the process of researching, an obvious catalysis was observed in the system of epoxy curing system with 2% la. To study this phenomenon, four different epoxy curing systems' reaction characteristics were analyzed by DSC, and the data were introduced to the Kissinger equation and Crane equation to attain the kinetic parameters, i.e. AE and n. Moreover, rgei and Tcure were also detruded by Tge\ and Tp at different heating rates. The result showed that liquid crystalline bismaleimides can catalyse the curing reaction, while there is not catalysis phenomenon in the system of epoxy with BMD ,which is non-liquid crystalline bismaleimdes. Through analyzing the truth of curing reaction, the structure of bismaleimides and the theory of liquid crystalline molecules, some explains were putted forward at the fist time in this paper.What's more, three kinds of bismaleimide oligomers with biphenyl moiety were synthesized and characterized by Fourier transform infra-red(FT-IR) spectroscopy and Differential scan calorimetry (DSC). It was found that not only the product s melting point was lower than poly (bismaleimide/4,4/-diamino biphenylether)'s, which is the representative of poly bismaleimide/amine), but also the method of modification reported here has better practicability.In the end, terephthalyl chloride(TPC) and liquide crystalline epoxy resin with biphenyl structure(DGEPB) were synthesized and characterized by Fourier transform infra-red(FT-IR) spectroscopy, Differential Scan Calorimetry (DSC) and Heat Stage Polarization micrograph (HSPM).