末端交联准理想无规3,3-二叠氮甲基氧丁环-四氢呋喃共聚醚弹性体应力应变特性
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摘要
聚合物应力应变特性与其应变过程聚集态演化密切相关,而有关应变诱发聚合物结晶研究多集中在均聚物与聚酯方面.以3,3-二叠氮甲基氧丁环(BAMO)和四氢呋喃(THF)等摩尔比准理想无规共聚醚端羟基3,3-二叠氮甲基氧丁环-四氢呋喃预聚物(PBT)为研究对象,利用氨基甲酸酯反应制备了末端三维交联PBT弹性体.变温力学性能测试表明PBT弹性体拉伸强度和延伸率由60℃时0.72 MPa,72%升至-40℃时16.2 MPa,740%,拉伸强度和延伸率随温度下降而单调上升;低于-20℃时弹性体拉伸强度和延伸率随温度下降迅速增加.理论分析表明,-40℃时弹性体网链沿应变方向取向,网链中BAMO微嵌段在应变320%处诱发结晶,增强分子链间相互作用,提高了PBT弹性体力学性能.定应变循环拉伸测试表明,PBT弹性体拉伸强度随循环次数增加而逐渐下降,低温、高应变下的拉伸强度高度依赖于弹性体拉伸前的有效网链密度.
The stress stain behaviors of polymers are closely related to the aggregation evolution in the course of strain process,while the study on strain-induced crystallization is mainly focused on the field of homopolymers,polyesters and so on.In this paper,taking hydroxyl terminated 3,3-diazidomethyloxetane(BAMO),tetrahydrofuran(THF)equal molar ratio quasi-ideal random copolyether of poly(3,3-diazidomethyloxetane-co-tetrahydrofuran)(PBT)as a prepolymer,the end-crosslinked PBT elastomer was prepared by a carbmate reaction.The test results of mechanical properties show that,both the stress and strain of the elastomer can monotonously increase with the decreasing of temperature,which rise up to 16.2 MPa,740% at-40 ℃from0.72 MPa,72% at 60 ℃.Therein,the stresses and strains can sharply increase with the decreasing of temperature below-20 ℃.The analysis of the aggregation evolution of PBT elastomer demonstrated that,the crystallization of BAMO micro-blocks existing in PBT strands is inducted at strain of 320%at-40 ℃ because of the strand orientation in strain direction and decreasing configuration entropy,which can enforce the interaction among strands and improvethe mechanical properties of PBT elastomers.Cyclic tensile tests with a constant strain show that,the stresses gradually decrease with increasing round times,and it strongly depends on the effective strand density of PBT elastomer before test.
The stress stain behaviors of polymers are closely related to the aggregation evolution in the course of strain process,while the study on strain-induced crystallization is mainly focused on the field of homopolymers,polyesters and so on.In this paper,taking hydroxyl terminated 3,3-diazidomethyloxetane(BAMO),tetrahydrofuran(THF)equal molar ratio quasi-ideal random copolyether of poly(3,3-diazidomethyloxetane-co-tetrahydrofuran)(PBT)as a prepolymer,the end-crosslinked PBT elastomer was prepared by a carbmate reaction.The test results of mechanical properties show that,both the stress and strain of the elastomer can monotonously increase with the decreasing of temperature,which rise up to 16.2 MPa,740% at-40 ℃from0.72 MPa,72% at 60 ℃.Therein,the stresses and strains can sharply increase with the decreasing of temperature below-20 ℃.The analysis of the aggregation evolution of PBT elastomer demonstrated that,the crystallization of BAMO micro-blocks existing in PBT strands is inducted at strain of 320%at-40 ℃ because of the strand orientation in strain direction and decreasing configuration entropy,which can enforce the interaction among strands and improvethe mechanical properties of PBT elastomers.Cyclic tensile tests with a constant strain show that,the stresses gradually decrease with increasing round times,and it strongly depends on the effective strand density of PBT elastomer before test.
引文
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[2]Toki S,Sics I,Hsiao B S,et al.Probing the nature of strain-induced crystallization in polyisoprene rubber by combined thermomechanical and in situ x-ray diffraction techniques[J].Macromolecules,2005,38(16):7064-7073.
[3]Liu G,Zhang X,Wang D.Tailoring crystallization:towards high-performance poly(lactic acid)[J].Advanced Materials,2015,26(40):6905-6911.
[4]Stoclet G,Seguela R,Lefebvre J M,et al.New insights on the strain-induced mesophase of poly(d,l-lactide):in situ WAXS and DSC study of the thermo-mechanical stability[J].Macromolecules,2010,43(17):7228-7237.
[5]Rao I J,Rajagopal K R.A study of strain-induced crystallization of polymers[J].International Journal of Solids&Structures,2001,38(6-7):1149-1167.
[6]Dakshinamoorthy D,Peruch F.Block and random copolymerization ofε-caprolactone,L-,and rac-lactide using titanium complex derived from aminodiol ligand[J].Journal of Polymer Science Part A Polymer Chemistry,2012,50(11):2161-2171.
[7]Mark J E.Rubber elasticity[J].Journal of Chemical Education,1981,58(11):898-903.
[8]He W N,Xu J T.Crystallization assisted self-assembly of semicrystal line block copolymers[J].Progress in Polymer Science,2012,37(10):1350-1400.
[9]Yang Z,Long X P,Zeng Q X.Simulation study on the liquid-crystalline ordering and fluidity of energetic diblock copolymers based on poly[3,3-bis(azidomethyl)oxetane][J].Journal of Applied Polymer Science,2013,129:2772-2778.
[10]Mark J E.The effect of strain-induced crystallization on the ultimate properties of an elastomeric polymer network[J].Polymer Engineering&Science,1979,19(6):409-413.
[11]Qu Z,Zhai J,Yang R.Comparison between properties of polyether polytriazole elastomers and polyether polyurethane elastomers[J].Polymers for Advanced Technologies,2014,25(3):314-321.