基于粉末微波发泡法制备超轻质聚酰亚胺泡沫的结构与性能
|
摘要
以3, 3′, 4, 4′-二苯甲酮四羧基二酐和4,4′-二氨基二苯醚为主要原料,采用简单高效的粉末微波发泡法制备了一系列超轻质开孔柔性聚酰亚胺泡沫,克服了液相发泡法易掉渣的不足。泡沫密度6～200 kg/m~3可调,厚度1～400 mm可调,最大宏观尺寸可达1000 mm×1000 mm。对泡孔结构和性能进行了测试,分析了发泡原理,探究了高温下材料的拉伸、隔热和真空出气性能。结果表明,泡沫玻璃化温度达265℃、5%失重温度达560℃;随着密度由6 kg/m~3增加至60 kg/m~3,泡沫开孔率由99.1%降低至95%,拉伸强度由0.08 MPa增加至0.92 MPa,150℃时泡沫拉伸强度几乎不变;室温热导率则表现为先降低后增加的趋势,热端温度250℃,泡沫热导率均小于0.1 W/(m·K);150℃的真空质量损失仅为0.947%,远低于液相发泡法的泡沫。
A series of polyimide foams using 3,3',4,4'-benzophenone tetracarboxylic dianhydride and 4,4'-oxydianiline as main materials were fabricated by a facile and effective powdered precursor process with aid of microwave which has the advantage over liquid foaming process of no-dregs. In this case, polyimide foams can be produced in apparent densities of 6～200 kg/m~3, thickness of 1～400 mm, and dimension of 1000 mm×1000 mm. Then, the foaming mechanism, cell morphologies and properties were investigated in detail. Importantly, their thermal insulation, tensile performance and vacuum outgassing at high temperature were also illustrated. It is found that polyimide foams have T_g of 265 ℃ and 5% mass loss temperature of 560 ℃. The open cell content decreases from 99.1% to 95%, and the tensile strength increases from 0.08 MPa to 0.92 MPa when the apparent density increases from 6 kg/m~3 to 60 kg/m~3. Notably, the tensile property hardly decreases at 150 ℃. While the thermal conductivities decrease and then increase with foam densities. Moreover, and the thermal conductivities at 250 ℃ are lower than 0.1 W/(m·K) for all polyimide foams. In addition, the vacuum mass loss is 0.947% at 150 ℃, which is far below the value of polyimide foams based on the liquid foaming process.
A series of polyimide foams using 3,3',4,4'-benzophenone tetracarboxylic dianhydride and 4,4'-oxydianiline as main materials were fabricated by a facile and effective powdered precursor process with aid of microwave which has the advantage over liquid foaming process of no-dregs. In this case, polyimide foams can be produced in apparent densities of 6～200 kg/m~3, thickness of 1～400 mm, and dimension of 1000 mm×1000 mm. Then, the foaming mechanism, cell morphologies and properties were investigated in detail. Importantly, their thermal insulation, tensile performance and vacuum outgassing at high temperature were also illustrated. It is found that polyimide foams have T_g of 265 ℃ and 5% mass loss temperature of 560 ℃. The open cell content decreases from 99.1% to 95%, and the tensile strength increases from 0.08 MPa to 0.92 MPa when the apparent density increases from 6 kg/m~3 to 60 kg/m~3. Notably, the tensile property hardly decreases at 150 ℃. While the thermal conductivities decrease and then increase with foam densities. Moreover, and the thermal conductivities at 250 ℃ are lower than 0.1 W/(m·K) for all polyimide foams. In addition, the vacuum mass loss is 0.947% at 150 ℃, which is far below the value of polyimide foams based on the liquid foaming process.
引文
[1] Wang L,Hu A,Lin F,et al.Structures and properties of closed-cell polyimide rigid foams[J].J.Appl.Polym.Sci.,2013,130:3282-3291.
[2] Xu L,Jiang S,Li B,et al.Graphene oxide:a versatile agent for polyimide foams with improved foaming capability and enhanced flexibility[J].Chem.Mater.,2015,27:4358-4367.
[3] Ma J J,Zhan M S,Wang K.Ultralightweight silver nanowires hybrid polyimide composite foams for high-performance electromagnetic interference shielding[J].ACS Appl.Mater.Interface,2015,7:563-576.
[4] Liu X Y,Zhan M S,Wang K,et al.Preparation and performance of a novel polyimide foam[J].Polym.Adv.Technol.,2012,23:677-685.
[5] Sun G H,Wang W P,Wang L C,et al.Effects of aramid honeycomb core on the flame retardance and mechanical property for isocyanate-based polyimide foams[J].J.Appl.Polym.Sci.,2017,134:DOI:10.1002/app.45041.
[6] Yan L,Fu L W,Chen Y J,et al.Improved thermal stability and flame resistance of flexible polyimide foams by vermiculite reinforcement[J].J.Appl.Polym.Sci.,2017,134:DOI:10.1002/app.44828.
[7] Williams M K,Hollanda D B,Melendeza O,et al.Aromatic polyimide foams:factors that lead to high fire performance[J].Polym.Degrad.Stab.,2005,88:20-27.
[8] Shen Y X,Zhan M S,Wang K,et al.Effects of monomer structures on the foaming processing and thermal properties of polyimide foam[J].Polym.Adv.Technol.,2010,21:704-709.
[9] Li J W,Zhang G C,Li J T,et al.Preparation and properties of polyimide/chopped carbon fiber composite foams[J].Polym.Adv.Technol.,2017,28:28-34.
[10] Pan L Y,Shen Y X,Zhan M S,et al.Visualization study of foaming process for polyimide foams and its reinforced foams[J].Polym.Compos.,2010,31:43-50.
[11] Shen Y X,Zhan M S,Wang K,et al.The pyrolysis behaviors of polyimide foam derived from 3,3’,4,4’-benzophenone tetracarboxylic dianhydride/4,4’-oxydianiline[J].J.Appl.Polym.Sci.,2010,115:1680-1687.
[12] Ma J J,Zhan M S,Wang K.Facile fabrication of polyimide foam sheets with millimeter thickness:processing,morphology,and properties[J].J.Appl.Polym.Sci.,2014,131:1001-1007.
[2] Xu L,Jiang S,Li B,et al.Graphene oxide:a versatile agent for polyimide foams with improved foaming capability and enhanced flexibility[J].Chem.Mater.,2015,27:4358-4367.
[3] Ma J J,Zhan M S,Wang K.Ultralightweight silver nanowires hybrid polyimide composite foams for high-performance electromagnetic interference shielding[J].ACS Appl.Mater.Interface,2015,7:563-576.
[4] Liu X Y,Zhan M S,Wang K,et al.Preparation and performance of a novel polyimide foam[J].Polym.Adv.Technol.,2012,23:677-685.
[5] Sun G H,Wang W P,Wang L C,et al.Effects of aramid honeycomb core on the flame retardance and mechanical property for isocyanate-based polyimide foams[J].J.Appl.Polym.Sci.,2017,134:DOI:10.1002/app.45041.
[6] Yan L,Fu L W,Chen Y J,et al.Improved thermal stability and flame resistance of flexible polyimide foams by vermiculite reinforcement[J].J.Appl.Polym.Sci.,2017,134:DOI:10.1002/app.44828.
[7] Williams M K,Hollanda D B,Melendeza O,et al.Aromatic polyimide foams:factors that lead to high fire performance[J].Polym.Degrad.Stab.,2005,88:20-27.
[8] Shen Y X,Zhan M S,Wang K,et al.Effects of monomer structures on the foaming processing and thermal properties of polyimide foam[J].Polym.Adv.Technol.,2010,21:704-709.
[9] Li J W,Zhang G C,Li J T,et al.Preparation and properties of polyimide/chopped carbon fiber composite foams[J].Polym.Adv.Technol.,2017,28:28-34.
[10] Pan L Y,Shen Y X,Zhan M S,et al.Visualization study of foaming process for polyimide foams and its reinforced foams[J].Polym.Compos.,2010,31:43-50.
[11] Shen Y X,Zhan M S,Wang K,et al.The pyrolysis behaviors of polyimide foam derived from 3,3’,4,4’-benzophenone tetracarboxylic dianhydride/4,4’-oxydianiline[J].J.Appl.Polym.Sci.,2010,115:1680-1687.
[12] Ma J J,Zhan M S,Wang K.Facile fabrication of polyimide foam sheets with millimeter thickness:processing,morphology,and properties[J].J.Appl.Polym.Sci.,2014,131:1001-1007.