New Semi-aromatic Polyamide Synthesis And Characterization

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 jointed 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 thermal tolerance , dimension precision and stability.One often introduces the aromatic rings into the organic macromolecular main chain to enhance polymer's thermal tolerance 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 semi-aromatic polyamides. Aromatic polyamides were mainly used in manufacturing fibre, and difficult to mold. Some semi-aromatic polyamides, has a relatively lower melting point(T_m). Though it is easy for molding, but its thermal tolerance was not good enough. PA9T exploited recently was synthesized using terephthalic acid and nonane diamine owned combined merits of the heat-durability and the processing ability.In this study, we synthesized seven kinds of new semi-aromatic polyamides by bulk polymerization, The effect of polymerization condition on reaction was investigated. The thermal decomposition the behaviors of melting and crystallinity of product were studied. The above research works still have not been seen in the literature up to date. The results of our works summarized as follows:l.poly(decamethyleneterephthalamide)(PA10T),poly(decamethyleneisophthalam ide)(PA10I),Poly(dodecamethylene-biphenyldicarboxylic-amides)(PA12B), poly(decamethylene-dicarboxydiphenylether-amides)(PA 10O), poly(decamethylene -dicarboxydiphenylsulfone-amides)(PA10S),poly(dodecamethylene-dicarboxydipheny lether-amides)(PA12O),poly(dodecamethylene-dicarboxydiphenylsulfone-amides)(PA 12S) were synthesized using terephthalic acid, isophthalic acid, biphenyldicarboxylic acid , dicarboxydiphenyl ether acid , dicarboxydiphenyl sulfone acid with decamethylene diamine and dodecamethylene diamines. We studied some characters of these polymer.2. In bulk polymerization, the reduced viscosity of product increases withreaction temperature, but it will decreases under too high reaction temperature. In the same reaction temperature, the reduced viscosity increases with prolongation of reaction time. Optimal reaction condition was 220°C, 1 ~2h in the first step; then at the 260~270°C, for 4~5h. For PA10I, the reaction temperature was 230"C, for 5h.3. The morphology of semi-aromatic crystallization from melt was observed by PLM from Tg~Tm. Different spherulite forms were observed as varying the crystallization temperature and crystallization condition.4. The structures of polymerization products are ascertained by their spectrum of FTIR and 'H-NMR. The result show these products are semi-aromatic polyamides.5. The glass transition temperature (Tg), equilibrium melting point temperature and equilibrium heat of fusion of semi-aromatic polyamides were determined by means of differential scanning calorimetry (DSC). The equilibrium melting point temperature of semi-aromatic polyamides are to be 259.6°C(PA12O) and 275.4°C(PA12S) from the Hoffman's method. In the DSC heating curves of isothermally melt crystallized from cold quenching, there are two crystals, Peak I is to be microcrystallite formation in the boundary layer between the larger crystallites, Peak II is the major crystal in the isothermal crystallization process.6. The TG results of semi-aromatic polyamides indicate that the thermal degradation process of semi-aromatic polyamides is one-step reaction. The activation energy of the solid-state process was determined using Kissinger and Flynn - Wall -Ozawa methods, the results are to be 247.5 ~249.3KJ/mol for PA12O and 213. 2 -214. 8KJ/mol for PA12S. Analysis of experimental results suggests the actual reaction mechanisms of semi-aromatic polyamides is Deceleration type.7. Nonisothermal crystallization kinetics of semi-aromatic polyamides were investigated by DSC. The nonisothermal crystallization process of semi-aromatic po;yamides PA12O and PA12S were analyzed by Jeziorny modified Avrami equation. The Avrami exponent n is greater, which indicate that the mode of nucleation and the growth of the nonisothermal crystallization are complicated and that the nucleation mode might include both homogeneous and heterogeneous. The activation energies (AE) of PA12O and PA12S were determined to be -173.7KJ/mol and -215.2KJ/mol, respectively, for the nonisothermal crystallization processes by the Kissinger's methods.