Study Of Elastomer Nanocomposites Based On Polyamide-b-polyether Copolymer

Polyamide elastomer has developed as a new thermoplastic elastomer in recent years.Due to its high low-temperature impact strength,good flexibility,high elastic recovery and high water absorption,polyamide elastomer has attracted extensive attention worldwide.However,the mechanical properties and heat resistance of polyamide elastomers currently produced are generally poor,which greatly limits their application.Therefore,preparation of high-stregth and high-heat-resistance polyamide elastomers has become an inevitable trend.Large specific surface area,high mechanical strength and high thermal stability are the outstanding characteristic of nanoparticles,such as CNTs,OMMT,GNs.In recent years,the above nanoparticles have usually been used as modifers in polymers.However,there are few researches reports on nanocomposites based on polyamide-b-polyether copolymer.In this study,elastomer nanocomposites based on polyamide-b-polyether copolymer were prepared via the in-situ hydrolyze ring-opening polymerization of caprolactam and melt copolycondensation,and graphene(GNs),carbon nanotubes(CNTs)and organomonomer(OMMT)were used as modifers respectively.IR,TG,DSC,XRD,SEM and tensile tests were used to characterize the chemical structure,thermostability,thermal behavior,crystalline property,morphology characteristics,and mechanical properties.The relationship between structure and properties of nanocomposites were explored.The following results are shown in this study:(1)The PA6-b-PEG elastomer was synthesized successfully using a simple one-step process.Caprolactam,PEG,adipic acid,europium acetate and bisoxazoline were added into a reactor to prepare PA6-b-PEG elastomer by melt copolycondensation reaction.The results showed that the best process parameters such as the reaction time,reaction temperature,catalyst,chain extender and vacuum degree are that as below: caprolactam ring-opening was 200°C for about 4 h,copolymerization was 220°C for 1.5 h,the copolymerization pressure was less than 600 Pa.At this time,the relative viscosity of copolymer was 1.8 and extraction rate with boiling water was 5.1%.(2)The best PA6-b-PEG elastomer is confirmed.The properties of PA6-b-PEG elastomer with hardness ratio of 70/30,60/40,50/50,40/60 and 30/70 were studied.The results showed that microphase separation was ocurred with the change of soft/hard ratios.The phase interface became fuzzy gradually.As the ratio of hardness to stiffness increases,the elongation at break of elastomer increases and the tensile strength decreases.Finally,the overall performance of the 40/60 soft/hard ratios was better.At this time,the elongation at break of the PA6-b-PEG elastomer was 145.6% and the tensile strength was 16.9MPa.(3)PA6-b-PEG elastomer nanocomposites with 40/60 hardness ratio were studied.PA6-b-PEG elastomer nanocomposites containing 1%,3%,5% and 7% of GNs,CNTs,OMMT were in-situ prepared respectively.Studies showed that composites containing 5% GNs,5% CNTs and 3% OMMT were best.Compared to unmodified elastomer,Their initial decomposition temperature of elastomers increased 142.3?,140.1? and 134.1? and the tensile strength of the copolymer matrix increases by 55.2%,49.7% and 21.4%,respectively.(4)Based on the results of stydies(1),(2)and(3),the PA6-b-PTMG elastomer nanocomposites were successfully synthesized using a simple one-step process.It was found that nanoparticles had a good compatibility with the matrix.At 240 ?,the thermogravimetric weight loss of GNs,CNTs and OMMT-modified elastomers was lower than that of unmodified ones,which were 2.5%,3.3% and 4.1% respectively.Compared to the unmodified ones,the elongation at break,tensile strength and elastic modulus were increased by 197.2%,33.1% and 28.6% respectively.PA6-b-PTMG copolymer modified by GNs had the best comprehensive performance,followed by OMMT.