Separation And Refining Of Mixed Binary Acids And The Preparation Of Copolymerization Nylon

The mixed binary acid is a by-product obtained from producting monomer,adipic acid,for nylon-66.It contains succinic acid,glutaric acid and adipic acid failed to separate completely,as well as other impurities.As many as several thousand tons the mixed binary acid was brought every year in China.It was originally to burn as a fuel and recently was used to manufacture a product of plasticizer,a low-level aliphatic binary ester mixture.In order to utilize it best,studies on the mixed binary acid related to technic design,separation,purify and polymerization have been developed in this paper.Glutaric acid is the best content in the mixed binary acids and has relatively high economic value.Studies on the mixed binary acid were designed as follows.Firstly glutaric acid was separated from mixed binary acids and was refined.Secondly,remaining part of mixed binary acid containing succinate acid and adipic acid was refined.Thirdly,refine succinate acid and adipic acid weae reacted with hexamethylenediamine to synthesize mixed salts of nylon-66 and nylon-64.Mixed nylon salts were polymerized in the green medium of supercritical CO₂ to obtain a new type of copolymrization nylon.Through above researches we find conclusions as follows:1,Benzene as a extraction solvent was selected to separate and refine glutaric acid from the mixed binary acid.Some influence factors such as temperature,solvent volume,extraction frequency and heating time on separation of glutaric acid were examined to obtained the best operating conditions:90～100 ml of benzene valume,75～80℃of heating temperature,3 times of extraction operation,and 20～25 min of heating and slack time.Glutaric acid of 5.50 g,the highest mass,was obtained from mixed binary acid of 10 g.The melting point of the refining glutaric acid is 96.1℃and accords with the value in literature.2,Two methods of active carbon adsorption and ion exchange resins absorption were used to remove impurities from remaining mixed acid.The refined mixture of succinate acid and adipic acid was characterized by mass spectrometry,DSC.The molecular ion peak of succinate acid and adipic acid in the mixed acid are 116.8 and 144.8,respectively,and accords with theirs chemical structure.The melting point of adipic acid in the mixed acid is 151℃and agrees with the literature value.No melting peak of succimc acid occures in the DSC curve,but there is a big endothermic peak in near 240℃,which is corresponding to the boiling point of succinic acid. The mass ratio and molar ratio of succinic acid and adipic acid in the mixed acid by determining acid value is 0.56:0.44 and 0.6053:0.3947,respectively.The mixed acid reacted with hexamethylenediamine to synthesize mixed nylon salts.The melting points of the refining mixed nylon salts were 195.1℃and 210℃,respectively.3,The mixed nylon salts was polymerizedin the supercritical CO₂ to synthesize a new type of copolymer of nylon-66 and nylon-64 in chemical structure.The polymerization conditions were estimated.The largest viscosity average molecular mass and the melting point of the copolymer samples is 20100 and 226℃,respectively.4,In order to upset condensation polymerization balance and enhance the molecular mass of the copolymer nylon,a science idea on cooperation synthesis of copolymer nylon and nano-particle in supercritical CO₂ was firstly proposed.The mixed nylon salt and the precursor of nano-particles were reacted simultaneity and severally.The precursor reacted with the water as a by-product produced in condensation of the mixed nylon salts to synthesize nano-particles when the copolymer nylon was synthesized.The results of research showed a copolymerization nylon/nanoparticle composite was obtained successfully.The viscosity average molecular mass and the melting point of the composite samples is 23200 and 232℃,respectively.The nano-particle of SiO₂ was generated and congregated on the surface of the composite samples and its size was 300～500 nm.5,Crystal dynamics of the copolymerization nylon and copolymerization nylon/ nanoparticle composite samples was sdudied to show the crystalline particles are growing by way of heterogeneous nucleation in one-dimensional direction and in two-dimensional direction, and the crystallization rate at cooling rate of 5℃/min are 1.0429 and 1.1728,respectively.