| Semi-aromatic nylon is a kind of polyamide material. The molecule chain of it contains both aromatic and aliphatic compounds. Which makes the semi-aromatic nylon not only has excellent heat resistance, rigidity, dimensional stability and good plasticity but also has low water absorption and great chemical resistance. The demands for these high performance materials in the field of a utomobile and electronic device increase with the development of national economy. Since the domestic semi-aromatic nylon industry starts quite late, the high performance semi-aromatic nylon resin dependents on imports.Considering the raw materials used to synthesize the semi-aromatic nylon, we can divide the semi-aromatic nylon into homopolymerized nylon or copolymerized nylon. Homopolymerized nylon is synthesized by only one type of aromatic diacid and aliphatic diamine. And the copolymerized semi-aromatic nylon is synthesized by several different diacids and diamines. Compared with the homopolymerized semi-aromatic nylon, the raw costs of copolymerized semi-aromatic nylon is lower, the raw materials are more convenient to get and the property is easier to adjust. However, the disadvantage of copolymerized semi-aromatic nylon is that the toughness of it is poor and product performance is not stable enough.To solve the toughness problem of semi-aromatic nylon, in this study, we try to add a kind of long carbon chain nylon monomers which named sebacic acid decamethylenediamine(1010) salt in the polymerization process to improve the toughness of the semi-aromatic nylon. Impact of the addition of 1010 salt to the mechanical, thermal properties and non- isothermal crystallization behavior has been studied. The process of preparation has been explored. Finally optimized process and formulation for preparation of a kind of semi-aromatic nylon with outstanding toughness has been obtained. It provides a reference for the production of semi-aromatic nylon.In this study, we used terephthalic acid/hexamethylene diamine(6T) salts, solution of hexamethylenediamine/isophthalic acid(6I) salts, nylon 66 salts and nylon 1010 salts to synthesize copolymerized semi-aromatic nylon PA6T/66 /1010 and PA6T/6I/1010 through solution- melt polymerization. The effect of solvent usage and temperature to the salification has been probed. The effect of temperature and pressure to the prepolymerization has been explored. The effect of temperature and time to the solid phase condensation has been studied. And the semi-aromatic nylon with intrinsic viscosity of 1.2d L/g has been obtained. The results show that higher temperature in the salification is good for increasing the speed of reaction and the dissolution of 6T salt. Higher temperature in the prepolymerization can make sure the success of the prepolymerization and lower pressure is benefited to improve the viscosity of the prepolymer. In the solid phase condensation, higher temperature and longer reaction time makes the viscosity of the polymer higher. Eventually, we determine that the weight of water in the salification is 2.11 times of the terephthalic acid and optimized temperature is 60 oC. In the prepolymerization optimized temperature and pressure is 310 oC and atmospheric pressure. 100 Pa, 210 oC and reaction time of 8-10.5 h is the best choices of the the solid phase condensation.The structure, heat resistance, mechanical properties and behavior of non- isothermal crystallization had been studied by FTIR, TGA, DSC, DMTA and mechanical tests. Result of FTIR implies the forming of the polyamide. TGA curve shows the Td of the polymer is about 400 oC. DSC curve shows that the melting point and melting peak area decreases with the increasing of the content of 1010. The results of mechanical properties tests discover that the increasing of the 1010 contents make the rigidity of the polymer falls and the toughness rises. And the heat resistance of the polymer decrease with the increasing of the 1010 contents from the results of HDT and DMTA. Non-isothermal crystallization behavior shows that crystallization enthalpy increase and crystallization temperature decrease with the increasing of cooling rate. The Avrami index n is between 2.1 and 2.5.In this paper we synthesized copolymerized semi-aromatic nylon through two step process. The heat resistance and mechanical properties of copolymerized semi-aromatic nylon we synthesized is good. The addition of 1010 salt in the polymerization decrease the rigidity and heat resistance of the semi-aromatic nylon while increase the toughness of the polymer substantially. The polymer which synthesized by 66/6I/1010 salt with the the molar ratio of 55/25/20 owns outstanding toughness. |
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