Study On Ionization And Grafting Modification Of PPTA

PPTA is a kind of liquid crystal polymer, the fiber is a kind of the excellent performance of high performance fiber, has important use in the aerospace, military and other fields, because PPTA molecules rigid and intermolecular hydrogen bonding interaction, it is difficult to dissolve in ordinary solvents, Which bring great difficulties to the analysis and processing the test, This article will use the PPTA ionization to solve the problem of its solubility, then on this basis, the ionization of PPTA in rapid detection of PPTA molecular weight, molecular weight distribution analysis of the applications, and has carried on the exploration to ionization self-assembly properties of PPTA.The viscosity of PPTA has a fast detection method. Commonly used method of measuring viscosity of PPTA is dissolved in concentrated sulfuric acid. The PPTA completely dissolved in concentrated sulfuric acid, it can measure viscosity. In this experiment adopts the method of alkali soluble. Firstly Sodium hydride reacts with DMSO to generate negative anionic solution. Then we can dissolve the PPTA in the anion solution. It can break out hydrogen bond between PPTA molecules, so the PPTA molecules can move freely and achieve the goal of measuring viscosity. The method of measuring spends time as only one over ten as the original method, and the accuracy is similar, the experimental method is simple, it completely meets the needs of the laboratory and industrial production.For polymer materials, usability and processing performance of material is affected by the molecular weight and molecular weight distribution. In this experiment, it measures the molecular weight and molecular weight distribution of PPTA, Graft modification method is applied in this experiment, it breaks Hydrogen bonding between PPTA molecules and forms PPTA anionic solution, the propyl is grafted into the amide bond, the alkylation of PPTA is complete. It dissolves in tetrahydrofuran and chloroform and other organic reagents. So we can measure molecular weight and molecular weight distribution of PPTA by GPC. Through this method, we can determine the different viscosity of PPTA and get their molecular weight and molecular weight distribution. PPTA molecular has the rigidity, with the various structural unit is easy to form the structure of p-phenylene which liquid crystal stat. Belong to solute liquid crystal polymer. But because of PPTA chains containing large amounts of hydrogen bond, Molecules connected by hydrogen bonds has the strong Van der Waals force. The PPTA intermolecular force is very strong, so it forms linear structure. In this experiment, a ball and elliptic spherical nanometer structure of PPTA is formed, Nanometer ball is 100-300 nm in diameter, in the experiment, we can make appropriate combination in solution concentration, temperature, water velocity. By IR, NMR, SEM and other methods, these proved that the product structure and specificmorphology and size.