高度可溶性聚酰胺酸齐聚物改性环氧树脂
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摘要
以二酐单体均苯四甲酸酐与二胺单体4,4′-二氨基-3,3′-二叔丁基-二苯甲烷为原料,在N,N′-二甲基乙酰胺溶剂中合成了以三聚体为主的高度可溶聚酰胺酸齐聚物(PAA-n),将其添加到双酚A型环氧树脂中,以4,4′-二氨基二苯砜作为固化剂,制备得到了复合材料EP/PAAn。采用多种表征方法表明PAA-n与环氧树脂有很好的相容性,所合成的复合材料具有较好的力学性能、热机械性能、热稳定性。当PAA-n质量分数为2%时,冲击强度提高了72.2%,玻璃化转变温度Tg提高了13℃,残炭量增加3%。
Epoxy resins with highly cross linked network and superior performance such as excellent mechanical,thermal and electrical properties, outstanding chemical and moisture resistance, are widely used in the automotive and aerospace industries. In this work, Diamino diphenyl sulfone(DDS) cured diglycidyl ether of bisphenol-A(E-51) was modified by a highly soluble polyamide acid oligomer(PAA-n). PAA-n was synthesized via the reaction of polyphthalic acid anhydride and aromatic diamine containing tert-butyl groups. Results obtained by FT-IR, 1 H-NMR,DSC and ESI confirm that PAA-n with molecular weight of 839 and high purity was obtained. UV/vis shows that the solution composed of PAA-n and E-51 follows Beer law, which indicates there is a good compatibility between PAA-n and E-51. Bulky tertiary butyl on benzene ring of PAA-n may prevent close packing of oligomer chains by increasing free volume of polymer, and the space location-obstruct effect hamper polymer chains close to each other so as to reduce effectively the interaction between polymer chains of PAA-n. Thus, without using any organic solvent, 0～2%(mass fraction) PAA-n are added into E-51. Using DDS as a curing agent, the curing kinetics of E-51/PAA-n composites is studied. By SEM, E-51/PAA-n composites are composed a continuous phase, and no phase separation can be observed, due to the high chemical reactivity between amino or carbonoxylic groups of PAA-n and epoxy resin.The impact strength of composites can be increased upon increasing the amount of PAA-n, and reaches 42 kJ/m2 for composites containing 2% PAA-n(EP-PAA-2), which increases 72.2% compared with pure E-51. At the same time, the tensile and flexural strengths can be almost maintained, while their moduli are increased. DSC and DMA results reveal that the glass transition temperature(T_g) is increased gradually from 196 ℃ for pure E-51 to 219 ℃ for EP-PAA-2 with3% decrease in storage modulus.
Epoxy resins with highly cross linked network and superior performance such as excellent mechanical,thermal and electrical properties, outstanding chemical and moisture resistance, are widely used in the automotive and aerospace industries. In this work, Diamino diphenyl sulfone(DDS) cured diglycidyl ether of bisphenol-A(E-51) was modified by a highly soluble polyamide acid oligomer(PAA-n). PAA-n was synthesized via the reaction of polyphthalic acid anhydride and aromatic diamine containing tert-butyl groups. Results obtained by FT-IR, 1 H-NMR,DSC and ESI confirm that PAA-n with molecular weight of 839 and high purity was obtained. UV/vis shows that the solution composed of PAA-n and E-51 follows Beer law, which indicates there is a good compatibility between PAA-n and E-51. Bulky tertiary butyl on benzene ring of PAA-n may prevent close packing of oligomer chains by increasing free volume of polymer, and the space location-obstruct effect hamper polymer chains close to each other so as to reduce effectively the interaction between polymer chains of PAA-n. Thus, without using any organic solvent, 0～2%(mass fraction) PAA-n are added into E-51. Using DDS as a curing agent, the curing kinetics of E-51/PAA-n composites is studied. By SEM, E-51/PAA-n composites are composed a continuous phase, and no phase separation can be observed, due to the high chemical reactivity between amino or carbonoxylic groups of PAA-n and epoxy resin.The impact strength of composites can be increased upon increasing the amount of PAA-n, and reaches 42 kJ/m2 for composites containing 2% PAA-n(EP-PAA-2), which increases 72.2% compared with pure E-51. At the same time, the tensile and flexural strengths can be almost maintained, while their moduli are increased. DSC and DMA results reveal that the glass transition temperature(T_g) is increased gradually from 196 ℃ for pure E-51 to 219 ℃ for EP-PAA-2 with3% decrease in storage modulus.
引文
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[2]WANG L J,ZHANG C,GONG W,et al.Preparation of microcellular epoxy foams through a limited-foaming process:A contradiction with the time-temperature-transformation cure diagram[J].Advanced Materials,2017,30(3):1703992.
[3]LIU T,ZHANG L D,CHEN R S,et al.Nitrogen-free tetrafunctional epoxy and its DDS-cured high performance matrix for aerospace applications[J].Industrial&Engineering Chemistry Research,2017,56(27):7708-7719.
[4]DING J H,RAHMAN O U,WANG Q L,et al.Sustainable graphene suspensions:A reactive diluent for epoxy composite valorization[J].ACS Sustainable Chemistry&Engineering,2017,5(9):7792-7799.
[5]VERTUCCIO L,GUADAGNO L,SPINELLI G,et al.Effect of carbon nanotube and functionalized liquid rubber on mechanical and electrical properties of epoxy adhesives for aircraft structures[J].Composites Part B,2017,129:1-10.
[6]XU W Q,CHEN J W,CHEN S N,et al.Study on the compatibilizing effect of janus particles on liquid isoprene rubber/epoxy resin composite materialsind[J].Industrial&Engineering Chemistry Research,2017,56(47):14060-14068.
[7]SINH L H,SON B T,TRUNG N N,et al.Improvements in thermal,mechanical,and dielectric properties of epoxy resin by chemical modification with a novel amino-terminated liquid-crystalline copoly(ester amide)[J].Reactive&Functional Polymers,2012,72(8):542-548.
[8]RíO T G,RODRíGUEZ J,PEARSON R A.Compressive properties of nanoparticle modified epoxy resin at different strain rates[J].Composites Part B,2014,57:173-179.
[9]KATTI P,KUNDAN K V,KUMAR S,et al.Improved mechanical properties through engineering the interface by poly(ether ether ketone)grafted graphene oxide in epoxy based nanocomposites[J].Polymer,2017,122:184-193.
[10]KATTI P,BOSE S,KUMAR S.Tailored interface resulting in improvement in mechanical properties of epoxy composites containing poly(ether ether ketone)grafted multiwall carbon nanotubes[J].Polymer,2016,102:43-53.
[11]LIN C H,CHOU Y C,SHIAO W F,et al.High temperature,flame-retardant,and transparent epoxy thermosets prepared from an acetovanillone-based hydroxyl poly(ether sulfone)and commercial epoxy resins[J].Polymer,2016,97:300-308.
[12]LEE C H,CHEN S H,WANG Y Z,et al.Preparation and characterization of proton exchange membranes based on semi-interpenetrating sulfonated poly(imide-siloxane)/epoxy polymer networks[J].Energy,2013,55:905-915.
[13]ALESSI S,CONDURUTA D,PITARRESI G,et al.Accelerated ageing due to moisture absorption of thermally cured epoxy resin/polyethersulphone blends,thermal,mechanical and morphological behavior[J].Polymer Degradation and Stability,2010,96(4):642-648.
[14]LI S,HSU B L,LI F,et al.A study of polyimide thermoplastics used as tougheners in epoxy resins-structure,property and solubility relationships[J].Thermochimica Acta,1999,340/341:221-229.
[15]FRANCIS B,THOMAS S,ASARI G V,et al.Synthesis of hydroxyl-terminated poly(ether ether ketone)with pendent tert-butyl groups and its use as a toughener for epoxy resins[J].Journal of Polymer Science:Part B.Polymer Physics,2006,44(3):541-556.
[16]LIN C H,CHEN J C,HUANG C M,et al.Side-chain phenol-functionalized poly(ether sulfone)and its contribution to high-perfor mance and flexible epoxy thermosets[J].Polymer,2013,54(26):6936-6941.
[17]BOTELLA P,CORMA A,MITCHELL C J.Towards an industrial synthesis of diamino diphenyl methane(DADPM)using novel delaminated materials:A breakthrough step in the production of isocyanates for polyurethanes[J].Applied Catalysis A:General,2011,398(1-2):143-149.
[18]LIU R,WANG J,LI J,JIAN X.An investigation of epoxy/thermoplasticblends based on addition of a novel copoly(arylether nitrile)containing phthalazinone andbiphenyl moieties[J].Polymer International,2015,64:1786-1793.
[19]LIU Y,WU W,CHEN Y,et al.The Effects of polyamic acid on curing behavior,thermal stability and mechanical properties of epoxy/DDS system[J].Journal of Applied Polymer Science,2013,127(4):3213-3220.
[20]LIU Z,XU Q L,PENG X T,et al.Confinement effect as a tool for selectivity orientation in heterogeneous synthesis of4,4′-3,3′-dibutyl-diphenyl methane over montmorillonite catalysts[J].Journal of Molecular Catalysis A:Chemical,2010,325(1-2):55-59.
[21]KISSINGER H E.Reaction kinetics in differential thermal analysis[J].Analytical Chemistry,1957,29(11):1702-1706.
[22]OZAWA T.A new method of analyzing thermogravimetric data[J].Bulletin of the Chemical Society of Japan,1965,38(11):1881-1886.
[23]SENEN P A,MERCEDES P P,MARTA P P.Influence of the reactivity of amine hydrogens and the evaporation of monomers on the cure kinetics of epoxy-amine:Kinetic questions[J].Polymer,1997,38(15):3795-3804.
[24]VARLEY R J,CRAZE D A,MOURITZ A P,et al.Thermoplastic healing in epoxy networks:Exploring performance and mechanism of alternative healing agents[J].Macromolecular Materials and Engineering,2013,298(11):1232-1242.
[25]ZHAO Q,WANG X Y,HU Y X.The application of highly soluble amine-terminated aromatic polyimides with pendent tert-butyl groups as a tougher for epoxy resin[J].Chinese Journal of Polymer Science,2015,33(10):1359-1372.
[26]GAW K O,KAKIMOTO M.Polyimide-epoxy composites[J].Advances in Polymer Science,1999,140:107-136.
[27]HOSSEIN Y,MORTEZA E,HAMED V T,et al.Toughening mechanisms of rubber modified thin film epoxy resins[J].Progress in Organic Coatings,2017,113:286-292.
[28]TANG L C,ZHANG H,STEPHAN S,et al.Fracture mechanisms of epoxy-based ternary composites filled with rigidsoft particles[J].Composites Science and Technology,2012,72(5):558-565.
[29]MOHAMED A,DERRIC D,DAVIDC A,et al.The effect of interfacial chemistry on molecular mobility and morphology of multiwalled carbon nanotubes epoxy nanocomposite[J].Polymer,2007,48(19):5662-5670.
[30]ZHAO B,CHEN L,LONG J W,et al.Aluminum hypophosphite versus alkyl-substituted phosphinate in polyamide 6:Flame retardance,thermal degradation,and pyrolysis behavior[J].Industrial&Engineering Chemistry Research,2013,52(8):2875-2886.