Study On Synthesis And The Properties Of Modified Poly(M-Phenyleneisophthalamide)

Poly(m-phenyleneisophthalamide)(PMIA) is considered to be high-performance polymer materials due to their outstanding thermostable performance and spinnability, which are widely used as the fibers of heat resisting and inflaming retarding. However, its fatigue resistance and light resistance are not good enough. There is great theoretical and practical significance to design and synthesize PMIA with oxidation stability, maintaining their excellent heat-resistant property and further improving inflaming retarding.In this paper, phosphorus-containing monomer, bis(3-aminophenyl) pheny phosphine oxide (BAPPO) and fluorine-containing monomer,3,5-diaminobenzotrifluoride (DBTF) were synthesized and characterized by FT-IR and1H-NMR. The synthesis and purification route and the influences of reaction conditions such as reaction temperature, reaction time on yield and so on were studied. Under the optimal synthesis and purification condition, the maximum yields were90%for BAPPO and83.1%for DBTF respectively.Series of the novel polymers were prepared by low-temperature solution polycondensation with BAPPO or BDTF as the third monomer, m-phenylenediamine (MPD) and m-phthaloyl chloride (IPC) in dimethylacetylamide (DMAc). The main factors which effect on the polymerization reactions, such as molar ratio of monomers, the initial reaction temperature, and monomer concentration and so on were investigated and obtained the optimal conditions and high molecular weight polymers. Inherent viscosities of the polymers containing phosphorus ranged between1.44and2.33dL/g, between0.81and1.43dL/g for the polymers containing fluoride. The structure of the co-polymers was characterized by FT-IR, NMR, and the thermal properties by DSC, TGA. The polymers of water absorption, electrical and mechanical properties were studied. Especially, the dissolubility and flame retardance of the polymers containing phosphorus, coagulability and stability performance of the solution of polymers containing phosphorus were studied. Tgs of PMIA-P and PMIA-F increased lightly with the amount of third monomer increased. Thermogravimetric analysis showed that the thermal property improved by adding phosphorus-containing monomer and reduced by adding fluorine-containing monomer. A large increase in LOI value was observed by adding phosphorus-containing monomer to PMIA, which could obtain better fire resistance. For all different kinds of coagulants, the coagulation value of polymers reduced with increasing of phosphorus-containing monomer, and the value reduced with increasing phosphorus-containing monomer. The stability test indicated that stability of polymers in sulfuric acid was not influenced by the incoporation of phosphorus-containing monomer. Compared with PMIA, the specific volume resistivity of films of the polymers containing fluoride increased more than100times, which improved insulativity of the polymers.