Devolatilization Via Purging With Nitrogen To Synthesize Nylon 69 And The Experimental Study Of Its Thermal Analysis

Nylon is always in the top set of the five important engineering plastics and widely used in the areas of machine,electronics,cars, information, aerospace and so on for its properties of strong toughness,antiwear,shockproof,antifatigue,corrosion resistant,oil-proof and so forth.The monomers to produce nylon are mainly obtained from the byproduct of the petroleum,which is a non-reproducible resource.Therefore it is much significant to find reproducible resources for the nylon monomers.Azelaic acid,both an important raw material of organic synthesis and a kind of nylon monomers,is one of the outgrowth of the preparation of biodiesel using Chinese tallow trees,which is a kind of reproducible resource.If the above-mentioned azelaic acid,stems from Chinese tallow trees,can be used as one of the monomers to synthesize nylon,not only can the purpose for gradient application of the biodiesel be achieved,but also a kind of reproducible resource to get nylon monomers can be found. This paper can be dived into three parts:the synthesis of nylon69,the melt crystallization kinetics of nylon 69,and the thermal degradation kinetics of nylon 69.The main relevant content and the result are as follows:(1) Azelaic acid and 1,6-hexamethylenediamine are first reacted with each other to synthetize nylon 69 salt,then nylon 69,with devolatilization through purging with nitrogen gas,is synthetized from the salt through melting polycondensation.With the DSC method we get the melting point 213.17℃,and the relative viscosity 1.63 is gained with the Ubbelohde viscosity meter.(2)A systematic study of the isothermal and nonisothermal melt crystallization kinetics of nylon 69 was carried out with DSC.In the isothermal research,the temperature is set respectively at 200,202,204,206,208℃,it is discovered that the total time to finish crystallization is increased with the temperature goes up,namely the velocity of the isothermal crystallization is decreased;the Avrami exponent was determined for nylon 69 under isothermal conditions to be 2 or 3,which means that the crystallization of nylon 69 during isothermal conditions is of two-dimensional growth;the activation energy of the isothermal crystallization for nylon 69 is -146.95kJ/mol.(3)The TG/DTG results of nylon 69 indicate that the thermal degradation process of nylon 69 is one-step reaction in the N2 and its activation energy was determined using Kissinger and Flynn-Wall-Ozawa methods,with the results 210.33kJ/mol and 232.12 kJ/mol respectively.By comparing the activation energy,which is obtained from the Coats-Redfern methods,with the two results mentioned above,we may safely get the conclusion that the thermal degradation reaction of nylon 69 follows the R2 and R3 mechanism.