Synthesis And Characterization Of Nylon 65

Polyamide,commonly known as nylon,is the polymer material with excellent comprehensive properties and forming performance,which is widely applied in different fields,such as defense military,aerospace,practical life production and so on.The common varieties of nylon mainly include PA6,PA66,PA610,PA1010,etc.The total output of PA6 and PA66 accounts for more than 90% of the nylon market.However,the production of nylon industry is paying more attention to the green development direction of high utilization rate,superior yield,less pollutants with the depletion of petroleum resources.In this paper,a novel of even and odd nylon product(PA65)was synthesized by glutaric acid(GA)separated and purified from mixed dibasic acid tablets.At present,there are few reports on systematic research work about the preparation and performance of PA65 products.The PA65 was successfully prepared in this work and the effects of polymeric conditions on its relative viscosity were also investigated.Furthermore,the structure and physicochemical properties were measured systematically,and the results were also compared with other nylon products.The main innovative work and results are as follows:(1)The PA65 salt was obtained through a neutralization reaction caused by GA and hexamethylene diamine(HMDA).The infrared spectroscopy,nuclear magnetic resonance,elemental analysis,DSC,and TG were applied to study the structure and thermal properties of PA65 salt,respectively,which provided a theoretical reference for the polymerization process in the future.(2)The PA65 product with white block was synthesized successfully by a method of prior solution polycondensation and subsequent melt polycondensation.The structure characterization and thermal property determination were also performed through the infrared spectroscopy,nuclear magnetic resonance,elemental analysis,ubbelohde viscometer,DSC and TG,etc.The results indicate that the synthesized product is consistent with the structure of target PA65 product,which behaves a melting point of 245oC,a crystallization peak temperature of 215oC,an initial decomposition temperature of 400oC,and a maximum weight loss rate temperature of 440oC,respectively.The orthogonal test design along with a single factor experimental method was further applied to investigate the polymeric conditions,and the superior conditions for preparing PA65 obtained as follow: The reaction of pre-polycondensation is carried out at 170oC for 3 hours,then the temperature is raised to 250oC for the reaction of melt polycondensation for 3 hours after releasing the pressure.The reaction is finally performed for 2 hours under vacuum conditions.(3)The method of solid-phase polycondensation was used to improve the relative molecular mass of PA65.Based on the analysis and study of solid-phase polycondensation method,it was found that the relative molecular mass of PA65 increases effectively.Moreover,the effects of solid-phase polycondensed temperature and time on the relative viscosity of the product were investigated.The optimal process conditions for PA65 solid-phase polycondensation were obtained that the reaction temperature was 190oC for 8 hours with a nitrogen sweeping.PA65 granules were extruded and cut into pellets,then they were injected into various standard test splines by using an injection molding machine,which were used for water absorption test,mechanical properties and flame retardancy.The results reflect that PA65 has the excellent physical and mechanical properties,as well as the outstanding flame retardancy.Not only the equivalent elongation at break and flexural strength to PA66,but also PA65 behaves a higher flexural modulus and less saturated water absorption than PA66.In addition,the vertical combustion performance of PA65 can reach V-0 level,and 34% of limiting oxygen index is achieved in it,which is corresponding to a excellent flame retardant material.