Synthesis And Characterization Of Polyamide With Aromactic Ring

As one kind of the high performance engineering plastics, polyamide has been caught the sight for its excellent mechanical property and good electric performance, as well as wear resistance, solvent resistance, chemical resistance high temperature tolerance. The research for polyamide in our country is relative late, and there are many problems in commercial process, which need plenty of fundamental researches. On the other hand, as the consident of main chain structure, polyamde can be classified as aliphatic polyamide and aromatic polyamide, and not only the synthesis methods are significant different for the different structure, but also the the characterization are more difficult for the stronger rigidity of main chain as well as hydrogen bond. So, the study of synthesis and characterization of polyamide with different main chain structure has significant actual meaning.The innovation of this thesis is that synthesis the aliphatic and aromatic polyamide using water, NMP and ionic liquids as solvent and also compares the difference between this two methods. Realize the characterization of the mole mass and structure of the hard-to-dissolve polyamide using three methods. This thesis achieve some results as follow:Using water as solvent to synthesize polyamide copolymer of PA6T-co-PA66, reaction time and reaction temperature has influence on polycondensation result, and obtain polymer with high molecular weight. Comparing with polycondensation in water, the reaction time and reaction temperature are significant decreased when using ionic liquid as solvent to synthesis PA6T, but the molecular weight was increased and the distribution was narrowed. Melting point and crystallization temperature of PA6T obtained in ionic liquid were lowed, and the thermal stability had little changed. The content of water in ionic liquid has obvious influence on polycondensation, so it need to remove water from the used ionic liquids when reusing ionic liquid. Ionic liquid can be reused, and reusing time has little influence on polycondensation.Using terephthalyl chloride and p-phenylene diamine as monomer, and NMP-CaCl₂ as solvent, PPTA with relative high mole mass was synthesized, and the ratio between terephthalyl chloride and p-phenylene diamine, initial monomer concentration, initial temperature, and reaction time all have influence on molecular weight of PPTA. Among them, monomer ratio has sensitive effect on molecular weight.and it was at low rotational speed when it effect molecular weight, and it has little influence on molecular weigh of PPTA when it outrange a certain value.Hard-to-dissolve polyamide can dissolve in THF by acetylation semi-aromatic polyamide and alkylation wholly aromatic polyamide, realize characterization of mole mass and distribution by GPC. Relate the inherent viscosity by viscosimetry with the test result by GPC, M-H equation for PPTA was obtained at the temperature of 30℃and in the solution of H₂SO₄. Combining data in this thesis with data in literature, new numerical value of K and a in M-H equation was obtained, which can be applied for a wide range of molecular weight. Develop a new method to characterization mass distribution of insoluble polymer of polyamide-6,T (PA6T) by matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The main chain structure of PA6T polymerized in ionic liquid was analyzed, which was linear without the present of cyclic polymer. The mean mole mass and mass distribution were obtained by MALDI-TOF MS and GPC. It shows that the mean mole mass by MALDI-TOF MS is lower than that by SEC and mass distribution was narrower than that by GPC method.Three structures of end groups were obtained by MALDI-TOF MS, carboxyl group or amino group at both ends or carboxyl group at one end and amino group at the other. The thermal performance of aliphatic and semi-aromatic polyamide with different end groups was investigated. The thermal performace of this two kind polyamide was increased with the increase of molecular weight. Polyamide with amino as end groups was easier decomposed, and the thermal tolerance of PA6T with carboxyl as end groups was higher than that with amino as end groups, for the diacide was terephthalic acide which has benzene ring while the diamide was aliphatic. For PA66, the influence of end groups on melting point and crystallizing point was little. When the main chain has benzene ring, melting point and crystallizing point increased greatly, so as to decomposition temperature.The nonthermal crystallization kinetics of semi-aromatic polyamide and its copolymer was investigated by differential scanning calorimetry at different cooling rate. Crystal behavior in nonthermal crystallization process was analysis by using the classical Avrami equation, Jeziorny, Ozawas equation and Mo method, and kinetics parameters were obtained. The activation energy were calculated according to Augis-Bennet, Kissinger and Takhor, which increase with the content of 6T in copolymer.