Preparation Of Polyamide Elastomer From Itaconic Acid Chain-extended Polyetheramine And Its Properties

As an important branch of TPEs family,thermoplastic polyamide elastomers(TPAEs)whose structure contains polyamide hard segments,present superior mechanical properties,thermal resistance,as well as the solvent and friction resistance besides the common properties of TPEs,However,the harsh synthesis conditions,complicated reaction process and lack of suitable polyamide hard segment have long been hindering the synthesis and commercialization of TPAE with excellent performance.In this paper,itaconic acid chain-extended polyetheramine(IA-PPA)was prepared by bio-based itaconic acid(IA)and polyetheramine D400(PPA D400).Based on IA-PPA,two different polyamide thermoplastic elastomers were prepared by different methods and their properties were analyzed respectively.(1)IA-PPA was prepared by melt polymerization of IA and PPA D400.The Fourier transform infrared spectroscopy(FT-IR),nuclear magnetic resonance hydrogen spectroscopy(~1H NMR)and gel permeation chromatography(GPC)was used to analyze and characterize the structure and molecular weight of the product.At the same time,the effects of reaction temperature,reaction time and reactant feeding ratio on the synthesis of IA-PPA were explored.The results showed that the Michael addition reaction and amide polycondensation reaction between IA and PPA D400 produce IA-PPA with a five-membered ring structure of pyrrolidone.During the reaction,the molecular weight of the polymer first increases and then decreases as the reaction temperature increases,and the molecular weight reaches its maximum at 240°C,so the preferred polymerization temperature is found to be 240°C.Not only that,the higher the reaction temperature is,the faster the reaction speed is.Meanwhile,the molecular weight of IA-PPA gradually stabilizes as the polymerization time increases.The GPC curve shows that the molecular weight of the IA-PPA increases first and then decreases with the increase of the feed ratio.When the mass ratio is 3.2:1,the molecular weight of the polymer is the highest,so 3.2:1 is determined to be a better feed ratio.Based on the results above,IA-PPA with controllable molecular weight and terminal group content can be prepared by controlling the reaction temperature,reaction time and reactant feed ratio.(2)At 180?,IA-PPA(P2000)with molecular weight of 2000 was synthesized by reacting PPA D400 and IA at a feed ratio of 3.2:1 for 3 hours.Using water as a ring-opening agent,P2000 and caprolactam were melt polymerized at 240°C for 12 hours to synthesize a series of polyamide thermoplastic elastomers(PA6-b-P2000).The PA6-b-P2000 was characterized by FT-IR and ~1H NMR.The results showed that the elastomer was a copolymer of alternating P2000 soft segment and PA6 hard segment.TGA analysis shows that PA6-b-P2000 has good thermal stability,although it is slightly lower than PA6.DSC and DMA analysis shows that PA6-b-P2000 elastomer has a phase-separated structure,and its crystallinity gradually decreases with the increase of the P2000 content in the soft segment.XRD results indicate that the crystalline phase of the PA6-b-P2000 is composed of the?crystal form of PA6.PA6-b-P2000 also exhibits excellent mechanical properties.When the soft segment content is40 wt%,the elongation at break of the elastomer reaches 789%,but when the soft segment content is too high,it will reduce the crystallinity of the polymer and deteriorate the mechanical properties.(3)In addition,at 240?,polyetheramine D400 and itaconic acid mass ratio of 2.4:1 melt polymerization for 3h,prepared a molecular weight of 2000,carboxyl end group itaconic acid extended chain polyetheramine prepolymer(P2000(T)).At the same time,a polyamide prepolymer(Pre PA6)with a molecule of 2000 and a terminal carboxyl group was prepared by water ring-opening polymerization of caprolactam with adipic acid as the end-capping agent.Finally,by using ethylene glycol as the chain extender,,a block polyamide 6 thermoplastic elastomer(PA6-b-P2000(T))was prepared through the esterification reaction of ethylene glycol with P2000(T)and Pre PA6.FT-IR and ~1H NMR test results show that PA6-b-P2000(T)is a block copolymer of P2000(T)soft segment and PA6 hard segment bonded by chain extender ethylene glycol.The test results of TGA,DSC,XRD,mechanical properties and DMA of PA6-b-P2000(T)show that when the amount of soft segment is the same,the comprehensive performance of PA6-b-P2000(T)is similar to that of PA6-b-P2000.