Preparation And Properties Of Nylon-66/Sericite Nanocomposites By In-situ Intercalative

As standard layered silicate and mineral soil with abundant reserves,the usage of sericite is low,and the value of sericite is difficult to improve.Nylon-66 is an excellent engineering plastic with excellent performance,and it is easily decomposed by light,water and heat due to the amide group,which affects the size stability and leads to limited application.The in-situ intercalation polymerization method was adopted to prepare Nylon-66 matrix sericite nanocomposites,which could not only improve sericite utilization with increased addition value,but also improve the basic properties of nylon-66 of mechanical properties,flame retardancy and water resistance to obtain wide application.The inorganic sericite with the small layer distance was firstly modified by organic intercalation.CTAB was intercalated into sericite layers after thermal-activation,acidification and sodium-conversion treatments.The modified organic sericite was prepared by ion-exchange to make long molecular chain enter the layer of sericite.The surface morphology analysis of organic sericite by SEM shows that CTAB covers the sericite surface.The small angle diffraction of XRD illuminates that the layer-distance becomes larger.The infrared results show that the reason for the increased layer-distance is the long chain of CTAB among the layers,which proves the success of organic modification for sericite.The small angle diffraction of XRD was used to analyze the effects of CTAB content,reaction temperature,mechanical stirring time and ultrasonic time on sericite interlayer distance.The results show that the interlayer distance of sericite can reach the maximum value of 3.8nm to achieve the expected distance when the optimal conditions are determined with CTAB cation content of 20 times CEC,reaction temperature of 120?,mechanical stirring time of 30 min and ultrasonic time of 30 min.The layers of sericite are exfoliated when the ultrasonic time is more than 30 min.After modification,the sericite was dried into powders.With adipic acid and hexamethylene diamine mole ratio of 1:1,the polycondensation of nylon-66 salt was conducted to prepare PA-66/organic sericite nanovomposites using anhydrous ethanolas solvent in a high-pressure reactor.According to organic sericite contents,the samples were marked as 0%,2%,4%,6%,8% and 10%.The effects of organic sericite contents on the nanocomposite performance of mechanics,thermal behavior and barrier were analyzed,and the differences of intercalated and exfoliated nanocomposites were discussed.The dynamic mechanical analysis shows that with the increasing of organic sericite content,the mechanical performance is increased with latter decreasing for organic sericite content over 8%.The impact resistance of exfoliated nanocomposites is better than that of intercalated nanocomposites.When the organic sericite content is less than 2%,the hardness of exfoliated nanocomposites is more than that of intercalated nanocomposites,while the situation is the opposite when the sericite content is more than 2%.When the organic sericite content is less than 6%,the tensile strength of intercalated nanocomposite is lower than that of exfoliated nanocomposite,while the situation is the opposite when the content is more than 6%.The compressive strength of intercalated nanocomposites is superior to the exfoliated nanocomposites because of the compact lamellar structure.The inner sericite lamellar structures of the intercalation are not destroyed to prevent the flowing of liquids or gases,so the barrier property of intercalated nanocomposites is better than that of exfoliated nanocomposites all the time.For the flame retardancy,the thermal stabilities of the two nanocomposites are similar and increased substantially with the increasing of sericites content.