Preparation And Research Of Anionic Polymerized Nylon 6and Its Composites

Continuous fiber reinforced thermoplastic composites(CFRT)are widely used in various fields such as aerospace,transportation,and energy infrastructure.However,due to difficulties in preparation,high production costs,and high prices,and limits its large-scale application in the low-end field.The use of anionic ring-opening polymerized nylon 6 to prepare CFRT by reactive impregnation technology is a new way,but the domestic research and application of this technology is relatively lagging behind foreign countries.The article is based on the current domestic technical deficiencies,using sodium ethoxide as the initiator,commercial liquefied MDI(diphenylmethane diisocyanate)is an activator.Using a two-component method to carry out the preparation and research of anionic polymide-6(APA6)and continuous glass fiber reinforced APA6 composite materials,the specific work is as follows.(1)In the second chapter of this article,the temperature and viscosity changes during the polymerization of APA6 were monitored by using a resin gel tester and a rotary viscometer.The mechanical properties,DSC,monomer conversion rate were prepared by preparing castings.And other tests have studied the polymerization results.The research on the polymerization process found that with the increase of the amount of initiator-activator,the increase of the polymerization temperature and the decrease of the water content of the system,the polymerization rate gradually accelerated.The system viscosity test found that the fastest system viscosity can reach 2500 m Pa?s in 143 s and the slowest time is 324 s,and the system viscosity during a long period of time during the polymerization process is at a low viscosity platform period of less than 100 m Pa?s In the next 30 s,the viscosity increased by 5 times,and then increased to 25 times after tens of seconds to reach 2500 m Pa?s.The research on the polymerization results found that the castings prepared under different influencing factors have tensile properties greater than 85 MP,bending strength greater than 95 MPa,bending modulus greater than 3.2 GPa,and small changes in mechanical properties;in addition,the polymer The lowest crystallinity is 42% and the highest is 52%.The monomer conversion rate is over 98%.Both the crystallinity and monomer conversion rate are at a high level.In addition,storage stability tests were also conducted on the active materials prepared with the initiator-activator.It was found that under the influence of different storage times,the active materials have the same reactivity,and the mechanical properties are in addition to elongation at break All have good stability.Therefore,through the research in this chapter,it is found that the initiator-activator has good stability in use,not only can maintain stable mechanical properties,but also has good resistance to moisture,with batch,continuous and large-scale The advantages of producing APA6 and related products.(2)The third chapter of the thesis mainly uses the T-RTM process to prepare the glass fiber reinforced APA6 composite material,and obtains the best process parameters for the composite material preparation in this experiment.Based on the indepth study of APA6 in Chapter 2,the appropriate polymerization temperature range and the amount of initiator-activator were selected to prepare different APA6 composite materials by changing the polymerization temperature of the composite material and the type of glass fiber cloth.The mechanical properties and water absorption of composite materials were tested and characterized.The study found that under the polymerization conditions of 160 ?,the multiaxial fiber cloth treated with silane coupling agent helps to obtain high-performance composite materials,whose fiber mass content and volume content reach 72.3% and 54.8%,respectively,moisture absorption only 3.6%,tensile strength and bending strength reached 400 MPa and 448 MPa respectively,and the remaining bending strength after moisture absorption reached 58%.