聚α-甲基苯乙烯空心微球的开裂机理
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摘要
干燥过程是制备高表面质量聚α-甲基苯乙烯(PAMS)空心微球的关键过程之一。文中通过实验研究了不同热处理温度(55℃、75℃、95℃)和不同干燥温度(室温、45℃、65℃、85℃、100℃)对PAMS空心微球干燥过程的影响。实验结果表明,采用不同温度对PAMS空心微球进行热处理后,具有严重初始微缺陷的空心微球所占百分比没有显著差异。因为最高热处理温度(95℃)远远低于PAMS的玻璃化转变温度(≈180℃)而不能使PAMS分子链段运动以消除残余内应力。随着干燥温度的升高,干燥后的空心微球表面出现裂纹的比例相应增加。干燥温度的升高将会导致空心微球球壳所受应力不断增大。而球壳所受应力是其产生裂纹的主要原因之一。
Drying is one of the most important processes to prepare hollow poly-alpha-methylstyrene(PAMS) shells. Effects of the heating treatment temperature and the drying temperature on the PAMS drying process were investigated. Effect of the heating treatment temperature on the percentage of PAMS shells with initial defects can be neglected, because the highest heating treatment temperature(95 ℃) is far below the glass transition temperature of PAMS(180 ℃) so that the polymer chains cannot move for rearrangement to release a great deal of residual stress. With the increase of drying temperature, the percentage of PAMS shells with cracks onto the surface increases, because the stress inside PAMS shells increases correspondingly.
Drying is one of the most important processes to prepare hollow poly-alpha-methylstyrene(PAMS) shells. Effects of the heating treatment temperature and the drying temperature on the PAMS drying process were investigated. Effect of the heating treatment temperature on the percentage of PAMS shells with initial defects can be neglected, because the highest heating treatment temperature(95 ℃) is far below the glass transition temperature of PAMS(180 ℃) so that the polymer chains cannot move for rearrangement to release a great deal of residual stress. With the increase of drying temperature, the percentage of PAMS shells with cracks onto the surface increases, because the stress inside PAMS shells increases correspondingly.
引文
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[2] Keith M M,Sweeney M A,Adams R G,et al.Pulsed-power-driven high energy density physics and inertial confinement fusion research[J].Phys.Plasmas,2005,12:55503.
[3] Letts S A,Fearon E M,Buckley S R,et al.Fabrication of polymer shells using a depolymerizable mandrel[J].Fusion Sci.Technol.,1995,28:1797-1801.
[4] Mcquillan B W,Nikroo A,Steinman D A,et al.The PAMS/GDP process for production of ICF target mandrel[J].Fusion Sci.Technol.,1997,31:381-384.
[5] 陈素芬,李波,刘一杨.乳液微封装法制备PAMS胶囊缺陷研究[J].强激光与粒子束,2012,24(1):89-92.Chen S F,Li B,Liu Y Y.Investigation of PAMS capsule defects with microencapsulation method[J].High Power Laser and Particle Beams,2012,24(1):89-92.
[6] 张占文,漆小波,李波.惯性约束聚变点火靶候选靶丸特点及制备研究进展[J].物理学报,2012,61(14):1-8.Zhang Z W,Qi X B,Li B.Properties and fabrication status of capsules for ignition targets in inertial confinement fusion experiments[J].Acta Physica Sinica,2012,61(14):1-8.
[7] 叶丽娜,陈素芬,黄勇,等.聚-α-甲基苯乙烯热降解动力学研究[J].强激光与粒子束,2012,24(10):2400-2404.Ye L N,Chen S F,Huang Y,et al.Thermal degradation kinetics of poly-alpha-methylstyrene[J].High Power Laser and Particle Beams,2012,24(10):2400-2404.
[8] Cheng X,Li J,Li X,et al.A highly sensitive sensor based on hollow particles for the detection,adsorption and removal of Hg2+ ions[J].J.Mater.Chem.,2012,22:24102-24108.
[9] Shao T,Feng X,Jin Y,Cheng Y.Controlled production of double emulsions in dual-coaxial capillaries device for millimeter-scale hollow polymer spheres[J].Chem.Eng.Sci.,2012,104:55-63.
[10] Bei Z M,Jones T B,Tucker-Schwartz A.Forming concentric double-emulsion droplets using electric fields[J].J.Electrostat.,2009,67:173-177.
[11] Nagai K.Solvent removal during curing process of highly spheric and monodispersed-sized polystyrene capsules from density-matched emulsions composed of water and benzene/1,2-dichloroethane[J].J.Polym.Sci.Part A:Polym.Chem.,2000,38:3412-3418.
[12] 陈素芬,刘一杨,苏琳,等.双重乳液固化速率对PAMS微球球形度的影响[J].化工学报,2013,64(7):2446-2452.Chen S F,Liu Y Y,Su L,et al.Influence of double emulsions solidification rate on sphericity of poly-alpha-methylstyrene capsules in microencapsulation process[J].Chinese Journal of Chemical Engineering,2013,64(7):2446-2452.
[13] Liu M F,Chen S F,Qi X B,et al.Improvement of wall thickness uniformity of thick-walled polystyrene shells by density matching[J].Chem.Eng.J.,2014,241:466-476.
[14] Pan D W,Huang W X,Chen Q,et al.Investigation of craze and cracks of polystyrene shells during drying process[J].Fusion Sci.Technol.,2018,73(1):59-67.
[15] 郑津洋,董其伍,桑芝富.过程设备设计[M].北京:化学工业出版社,2005:31-32.