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A Study In The Synthetic Technology And Properties Of Semi-aromatic Polyamide PA6T/66

Posted on:2015-02-12Degree:MasterType:Thesis
Country:ChinaCandidate:S WangFull Text:PDF
GTID:2181330431495529Subject:Polymer Chemistry and Physics
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Compared with aliphatic nylon, semi-aromatic nylon shows strong advantages inrigidity, heat resistance, dimensional stability, and so on. Therefore, semi-aromaticnylon has wide application prospect in the manufacture of heat-resistant parts, such as,engines and circuit boards circuit boards. PA6T and its copolymers are an importantkind of semi-aromatic nylon. The melting point of PA6T close to370oC, which ishigher than its decomposition temperature (350oC), results in a big problem in itsprocessing and molding process. Copolymerizing PA6T with other polyamidemonomers to lower its melting point down is an efficient way to solve this problem.The copolymer of PA6T and PA66is a good example. After introducing PA66segment into the macromolecular chain, the melting point can be adjusted to280~320oC which facilitates the polymer’s processing. So PA6T/66is a hot topic in theresearch area of semi-aromatic nylon at home and abroad recently. Compared with themature industry production of PA6T/66abroad, the domestic study still stays in thepreliminary stage. This dissertation focuses on the study of PA6T/66synthetic process.A detailed discussion on the influence of the synthetic condition on the copolymer’sproperties is conducted.In PA6T salt formation step, water is used as the solvent, and the reaction endingpoint is judged by pH value of the solution. The optimal synthesis condition: the ratioof PA6T/water is1mol/500mL, reaction temperature is50~55oC, and pH value at thereaction ending point is7.2.The influence of reaction temperatures, deflating time, vacuum time,antioxidants and charging mode in pre-polymerization on the relative molecularviscosity of pre-polymer is discussed. The optimal condition is: the reactiontemperature is220oC, deflating time is1.5-2h, vacuum time is1h, the ratio of PA6Tsalt/PA66salt is50/50, the antioxidant is B215. Under the optimized condition, therelative viscosity of the pre-polymer can reach up to1.42maximum.In the solid polymerization, a series of experiments were conducted to explorethe optimal reaction condition. Under the vacuum of10Pa, the polymerization temperature was270oC, the reaction time is6~8h, The relative viscosity of PA6T/66with the highest relative viscosity of2.5will be achieved. DSC test shows: meltingpoint of PA6T/66is300~310oC, and its crystallization temperature is235~240oC.Meanwhile, the decomposition of the polymer is one-step with a initial decompositiontemperature of400oC by TG measurement.Furthermore, the mechanical properties of PA6T/66with different componentswere investigated. PA6T/66(50/50) which B215as the antioxidant shows the bestmechanical is2.12GPa, notched impact strength is3.1kJ/m2, and no-break happensduring the no notched.
Keywords/Search Tags:semi-aromatic polyamide, PA6T/PA66, synthesis process, mechanicalproperties
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