泡孔结构形貌对环氧树脂发泡材料抗压性能的影响
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摘要
采用超临界CO_2发泡制备了不同泡孔结构和形貌的环氧树脂发泡材料,通过万能材料实验机研究了其抗压性能。采用差示扫描量热分析考察了环氧树脂的固化程度;利用扫描电镜结合排水法密度测试,表征了泡孔形貌、泡孔尺寸、发泡密度及泡孔分布;研究了上述因素对发泡材料抗压性能的影响。结果表明,环氧树脂发泡样品的抗压性能随固化度的增大而增强;当样品完全固化时,闭孔环氧树脂发泡材料的抗压性能较开孔结构和破裂结构强,这与作为支撑结构的泡孔壁的形貌相关。对于闭孔结构的发泡材料,其抗压性能受泡孔尺寸的影响显著,泡孔尺寸越小,材料密度越大,其抗压性能越好。具有双峰泡孔分布的发泡材料,其抗压性能得以改善,较小的泡孔为发泡材料提供了更为致密的支撑骨架结构,比具有同样密度的大尺寸泡孔发泡材料的压缩性能更高。
Epoxy resin foams with different cell structures and morphologies were prepared by supercritical CO2 foaming. The compressive property of the foams,curing degree of epoxy resin,cell morphology,cell size,foam density and cell distribution were studied by mechanical testing machine,DSC and SEM combined with the displacement method.Meanwhile,the effects of epoxy resin curing degree,cell morphology,cell size,foam density and cell distribution on the compressive properties of epoxy resin foams with different cell morphologies were investigated. The results show that the compressive strength increases with curing degree. At a certain curing degree of 100%,the compressive property of closed-cells structure is higher than that of open-cells ones,while that of the cracked foams is the worst. The compressive properties of closed-cells are affected by foam density and cell size,cell size influences the mechanical property significantly. Samples with higher densities,smaller and more cells possess higher compressive strength and modulus. The smaller cell provides better compressive properties in the bimodal structure,exhibiting better compressive properties than the unimodal foaming materials.
Epoxy resin foams with different cell structures and morphologies were prepared by supercritical CO2 foaming. The compressive property of the foams,curing degree of epoxy resin,cell morphology,cell size,foam density and cell distribution were studied by mechanical testing machine,DSC and SEM combined with the displacement method.Meanwhile,the effects of epoxy resin curing degree,cell morphology,cell size,foam density and cell distribution on the compressive properties of epoxy resin foams with different cell morphologies were investigated. The results show that the compressive strength increases with curing degree. At a certain curing degree of 100%,the compressive property of closed-cells structure is higher than that of open-cells ones,while that of the cracked foams is the worst. The compressive properties of closed-cells are affected by foam density and cell size,cell size influences the mechanical property significantly. Samples with higher densities,smaller and more cells possess higher compressive strength and modulus. The smaller cell provides better compressive properties in the bimodal structure,exhibiting better compressive properties than the unimodal foaming materials.
引文
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[2]刘彦方,杜中杰,张晨,等.双酚A甲醛酚醛环氧树脂与甲基六氢邻苯二甲酸酐的固化反应及热性能[J].高分子材料科学与工程,2007,23(2):73-76.Liu Y F,Du Z J,Zhang C,et al.Curing reaction and thermal properties of bisphenol-A-type novolac epoxy resins with methylhexahydrophthalic anhydride[J].Polymer Materials Science&Engineering,2007,23(2):73-76.
[3]Song B,Chen W,Lu W Y.Compressive mechanical response of a low-density epoxy foam at various strain rates[J].J.Mater.Sci.,2007,42:7502-7507.
[4]Ito A,Semba T,Taki K,et al.Effect of the molecular weight between crosslinks of thermally cured epoxy resins on the CO2-bubble nucleation in a batch physical foaming process[J].J.Appl.Polym.Sci.,2014,131:DOI:10.1002/app.40407.
[5]Chen K,Tian C,Lu A,et al.Effect of Si O2on rheology,morphology,thermal,and mechanical properties of high thermal stable epoxy foam[J].J.Appl.Polym.Sci.,2014,131:2113-2124.
[6]Bledzki A K,Kurek K,Gassan J.The influence of micropores on the dynamic-mechanical properties on reinforced epoxy foams[J].J.Mater.Sci.,1998,33:3207-3211.
[7]Serry Ahmed M Y,Park C B,Atalla N.Control of the structure and morphology for production of novel LDPE acoustical foams[J].Cell.Polym.,2006,25:277-292.
[8]Huang Q,Seibig B,Paul D.Melt extruded open-cell microcellular foams for membrane separation:processing and cell morphology relationship[J].J.Cell.Plast.,2000,36:112-125.
[9]Gupta N,Karthikeyan C S,Sankaran S,et al.Correlation of processing methodology to the physical and mechanical properties of syntactic foams with and without fibers[J].Mater.Char.,1999,43:271-277.
[10]Stefani P M,Barchi A T,Sabugal J.Characterization of epoxy foams[J].J.Appl.Polym.Sci.,2003,90:2992-2996.
[11]Lyu J,Liu T,Xi Z,et al.Effect of pre-curing process on epoxy resin foaming using carbon dioxide as blowing agent[J].J.Cell.Plast.,2017,53:181-197.
[12]Lyu J,Liu T,Xi Z,et al.Cell characteristics of epoxy resin foamed by step temperature-rising process using supercritical carbon dioxide as blowing agent[J].J.Cell.Plast.,2016,DOI:10.1177/0021955X16681455.