High-performance Modification Of Nylon6

Nylon6(PA6) is an indispensable polymer material which is widely used as engineeringplastics. However, as semi-crystalline polymer, PA6’s propertiesare largely depended on itsmolecular weight and crystallinity. Besides that, PA6also has the flammable drawback asmany other polymers. Thus the improvement of its molecular weight, crystallinity andflame-retardancy is of significance.In this paper, ADR and EPM were adopted as chain-extenders of PA6. The effects ofnucleating agents, TMA-3and TMB-5, which had been proved effected in PP, on thecrystallization behavior and non-isothermal crystallization kinetic were investigated. Flameratardant composites PA6/AlPi/EPM were prepared to investigate their flame retardantproperties and mechanism.EPM had better chain extension effects than ADR. When EPM content was2wt%, theintrinsic viscosity of PA6increased by42%compared to pure PA6while the terminal aminoand carboxyl group content decreased by53%and23%relatively.Crystallization rate of PA6/TMB-5was highest among PA6, PA6/TMA-3andPA6/TMB-5. Modified Ozawa function was adopted to investigate PA6’s non-isothermalcrystallization process. When cooling rate was5-10℃/min, crystallinity growth ofPA6/TMB-5tended to be one-dimensional growth, while at higher cooling rates(like20-40℃/min), crystallinity growth started in two-dimension, three dimension or even more complexways. At late stage of crystallization, crystallization rate of PA6was the highest. Concludedfromresults obtained according to Mo method, nucleating agents accelerated thecrystallization rate. Chain-extenders had little effect on the regularity of molecular chains, andthe crystallinity degree reduced only by1.9%to4.4%, while the crystallization rate stay at thesame level. Besides, they also promoted the formation of γ form crystalline.EPM had obvious effects on PA6/AlPi/EPM composites. UL94V-0rate (1.6mm) couldbe achieved for PA6/AlPi/EPM(86/13/1, mass ratio, same below) while PA6/AlPi(85/15) justreached UL94V-0rate (3.2mm).The flame ratardancy mechanism of PA6/AlPi and PA6/AlPi/EPM was different. AlPi mainly influenced the gas phase when solely used. The PHRR and THR of PA6/AlPi reducedby27%and16%relatively compared to pure PA6. When EPM was added, effects of flameretardancy occurred in condensed phase and gas phase. And smoke during combustion wascompressed. When EPM content reached2wt%, the PHHR and THR reduced by31%and10%relatively compared to PA6/AlPi.Since the low compatibility between PA6and AlPi, the Izod impact strength of PA6/AlPidecreased by7%compared to PA6’s. The addition of EPM improved the compatibility of thecomposites. The toughness of flame-retardant composite had increased. TheIzod impactstrength of PA6/AlPi/EPM(85/13/2) increased by17%compared to PA6/AlPi(87/13), and11%when compared to PA6.