Study On Synthesis And Property Of Novel Polyisomide Resin Endcapped By Acetylene

The rapid advancement of the area of high-tech areas, such as aerospace and microelectronics, has put higher overall requirements of the materials. Polyimide resin, which received widespread attention, has excellent comprehensive properties such as resist to high temperature. However, polyimide has severe requirements on processability (e.g. insoluble and difficult to finance, high curing temperature, etc.) and eventually was constrained from large-scale use.In this thesis, we mainly investigated the synthesis and property of novel alkyne terminated polyisoimide resin from the point of molecular design. The contents and results are listed as follows.1. Non-symmetrical 3,4'-BPDA are used as the dianhydride monomer.3, 4'-ODA with a flexible ether bond as diamine, and 3-amino-phenyl acetylene as a blocking agent. A series of isoimide and imide prepolymers with different molecular weights are prepared by adjusting the proportion of the three reagents. Infrared spectrometer was used for products'structural confirmation, gel permeation chromatography for determination of molecular weight distribution, and XRD for characterization of the crystalline phase behavior.2. Basic properties, such as solubility, rheological properties, thermal stability, and glass transition temperature, are studied. The impacts of different molecular weight to properties of polyisoimide resins are summarized by comparison of their performances. Polyisoimide and its isomers-imide oligomers-are compared on the structure and performance, respectively.3. One of the polyisoimide resin is exemplified to study its curing mechanism. Three model compounds with different structures were synthesized and studied by infrared spectroscopy and differential scanning calorimetry, providing a model reference for the molding process. After evaluation of polyisoimides with different molecular weight from aspects of processability, thermal stability, temperatures of long-term and short-term when used as composites, two resins were determined to prepare composites. The influences of molecular weight to molding process and mechanical properties were studied; morphology of impacted fractures was observed by scanning electronic microscope (SEM). At last, one of those polyisoimide resins with excellent processing performance, good thermal stability was selected to prepare standard part. According to ultrasonic nondestructive testing, the prepared standard part has no holes or defects, which is expected to be used as structural components of a vehicle for long time under high temperature.