Preparation And Studies Of Rare-Earth Luminous Nylon-6

First, rare-earth luminous polyamide 6 was synthesized through in-situ polymerization. Infrared spectrum analysis (FTIR), SEM, TGA microscope and end-group titration were employed to measure the structure and properties of the rare-earth luminous polyamide 6 products. It is indicated that there is chemical coalescence between luminous pigments and polyamide 6. Through the microscope and SEM, it is found that the luminous pigments dispersed quite well in PA6.Rare-earth luminous polyamide 6 prepolymer was prepared via in-situ melt polymerization. It is difficult to fit the demand of some field because of its very low molecular weight. In-situ polymerization of the prepolymer was needed to increase molecular by further solid-phase polymerization. By changing the polymerization conditions, the effect of different polymerization temperatures, different polymerization time, different particle size, the addition of luminous pigments on solid phase polymerization were studied. The effect of reaction temperature on solid-state polymerization was very important. The higher reaction temperature was, the higher the molecular weight of samples after solid-state polymerization was. But reaction temperature can't be too high, too high reaction temperature made rare-earth luminous polyamide 6 heat degrade, and the problem of grains agglomeration was very serious. So the appropriate reaction temperature should be chosen. The addition of luminous pigments also had the effect on solid-state polymerization. Luminous particle in the amorphous regions of PA6 impeded the mobility of the end group, on the other hand, as there is chemical coalescence between luminous pigments and PA6, it made reaction rate of rare-earth luminous polyamide 6 become slower than that of pure PA6. So in the same reaction condition, the molecule weight of polyamide 6 after solid-state polymerization is higher than that of rare-earth luminous polyamide 6 after solid-state polymerization. The smaller particles of the sample were, the quicker the diffusion rate of by-product in the reaction process was. In the same reation condition, molecule weight of two kind of samples was almost the same, the smaller particle of the smaple was, the higher molecule weight of samples was.The effect of the luminous pigments and molecular weight on the isothermal crystallization was investigated by differential scanning calorimetry(DSC). The Avrami equation was used to study the isothermal crystallization kinetic. The crystallization rates of PA6 in composition increased as the luminous pigment content increased. It shows the luminous pigments acts as effective nucleating agents. The crystallization activation energy which is calculated by Arrhenius equation increased as the luminous pigment content was increased. The result showed that the transport of PA6 segments is retarded by the luminous pigment. The increase of molecular weight of PA6 and the luminous polyamide 6 after further polymerization led to increase of intermolecular forces and lowered the activation energies of crystallization.The non-isothermal crystallization and melting behavior of PA6 and its composites were investigated by DSC. Jeziorny method, Ozawa method and Mo method were employed to describe the nonisothermal crystallization process of pure polyamide 6 and the rare-earth luminous polyamide 6 composites with different molecular weight. The results showed that the Ozawa analysis seemed not to suit, while Mo's analysis was successfully used. Although Jeziorny analysis has some problem for whole crystallization process, it could be applied to analyze the main crystallization process well. The addition of the luminous pigments into PA6 has an effect on the mechanism of nucleation and the growth of PA6 crystallites. The luminous pigments act as effective nucleating agents but hinder the motion of PA6 chains which resulted in the decrease of crystallization rate. The result is different with the isothermal process, indicating the complexity of non-isothermal crystallization. The polymorphism is found for the nonisothermal crystallized samples, which is dependent on the cooling rates. From the heating thermograms of the neat nylon6 and the rare-earth luminous polyamide 6 non-isothermally crystallized at different indicated cooling rates, it is seen that the thermograms for rare-earth luminous polyamide 6 possesses two melting endotherms in the same cooling rates, while there is only one single peak for polyamide 6. The lower temperature peak corresponds to the y crystalline form and the higher temperature peak is related to the a crystalline form. The addition of the luminous pigments favors the formation of y crystalline form. High cooling rates favors the formation of y crystalline form of rare-earth luminous polyamide 6 and polyamide 6. However, after high cooling, the crystallization of rare-earth luminous polyamide 6 is higher than that of polyamide 6, which further proves the luminous pigments act as a heterogeneous nucleation for the crystallization of polyamide 6.The effects of hot water temperature, bath ratio, stirring etc on the extraction efficiencies of PA6 granules were analyzed through the kinetic extraction experiments. The concentration of the extractable in water was tracked by refractive index measured by Abbe refractometer at different extraction time, and it was obtained that the hot water temperature was the main effect on the extraction efficiencies. Based on mass transfer theory between solid and liquid, a kinetic extraction model of PA6 granules was proposed. Two model parameters C₁ , C₂ and the slope of equilibrium line, m, as a function of extraction temperature, can be obtained by fitting the experimental data.C₁ and C₂ increased when temperature increased. The larger the value of C₁ and C₂ were, the higher the concentration of the extractable in water was. It indicated that the effect of hot water temperature on the extraction efficiencies of PA6 granules was very large.