| In recent years, with the rapid development of science and technology, the surface mount technology(SMT) was made general and universal application for making the electronic products miniaturization, precision and lower cost in semiconductor CMOS chips and electronic components which were joined together on the integrated device electronics in the electron industry. Such a new technology bring a higher demand for the used organic materials, such as thermo toleranceN dimension precision and stability.One often introduces the aromatic rings into the organic macroraolecular main chain to enhance polymer' s thermotolerance and reduce their water absorption. For example, aromatic acid or aromatic amine was used in place of aliphatic acid or aliphatic amine to synthesize the aromatic or semiaromatic nylon. Several products of this kind polymers have been used practically in many fields, such as Poly(p-phenylene terephthalamide) (PPTA), Poly(M-phenyleneisophthalamide) (PMIA), poly(hexamethyleneisophthalamide) (MXD6), poly(hexamethyleneterephthalamide) (PA6T),poly(nonamethyleneterephthalamide)(PA9T), etc. Aromatic nylons ,PPTA and MPIA were mainly used in manufacturing fibre, and difficult to mold. The MXD6, one of semiaromatic nylons, has a relatively lower melting point (Tm). Though it is easy for molding , but its thermo tolerance was not good enough. The another semiaromatic nylon, PA6T, can not be processed by general processing methods unless it is modified by copolymerization with other component owing to its excessive high Tm. But this modification would bring the materials on the increasing of the water absorption and the instability of the dimension. PA9T exploited recently was synthesized using terephthalic acid and nonane diamine and owned combined merit of the heat-durability and the processingability.In this study, poly(dodecamethyleneterephthalamide) (PA12T), poly(dodecamethyleneisophthalamide) (PA12I) and PA(12T-co -121) were synthesized using terephthalic acid, isophthalic acid with dodecamethylene diamines. The effect of polymerization condition on reaction and reaction kinetics was investigated. The thermal decomposition, the behaviors of melting and crystallization of product were studied. And the changes of crystallinity induced by the contents of PA12I were also discussed. The above research works are still have not be seen in the literature up to date. The results of our works summarized as follows:1. dodecamethlyene diammonium terephthalate(PA12T salt) and dodecamethlyene diammonium isophthalate(PA12I salt) can be prepared by using terephthalic acid or isophthalic acid with dodecamethylene diamines in ethanol solution, respectively. Equivalent point can be determined by conductometrictitration.2. In solution polymerization, the reaction rate increases with the increasingof the reaction temperature; The numerical average molecular weight ( Mn)increases with the increasing of the reaction temperature, reaction time and pumpdown time. But when the reaction temperature being excessive high(>120#) , the Mn will decrease with the prolongation of reaction time. The optimal reaction condition is 120#, 5h in these experiments; The effect of solvent NMP or DMF on Mn is not obvious.3. In bulk polymerization, The reduced viscosity(n) of the product increases with prolongation of reaction time under the relative lower reaction temperature ( <260# ) , and decreases under the higher reaction temperature, optimal reaction condition was 250#, 6~7h. By comparison with solution polymerization, the higher r\ can be obtained using the bulk polymerization method. Through research on polymerization reaction of PA12T, PA12I and their copolymers, some important results were gained as follows: n, toughness and transparency of polymers gradually increase andmelting temperature gradually decrease with the increasing of PA12I content in PA(12T-co-12I).4. The structures of polymerization products are ascertained by their spectrum of FTIR and 1H-NMR. The results show these products ar...
|
PDF Full Text Request