超临界二氧化碳发泡聚乙烯醇/贝壳粉复合泡沫的泡孔结构调控
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摘要
以水为增塑剂兼物理发泡剂,结合超临界二氧化碳发泡技术制备了聚乙烯醇(PVA)/贝壳粉复合泡沫,研究了多种因素对泡孔结构的影响。结果表明,贝壳粉作为异相成核剂,能增加成核点数,提高熔体强度,更好地支撑泡孔形成与生长;提高饱和压力和适度交联能增大二氧化碳在PVA基体中的溶解度,增多泡孔数目,减小尺寸,分布更均匀;发泡温度升高,二氧化碳扩散速度增加,孔径分布变宽。当贝壳粉含量10%、饱和压力15 MPa、发泡温度80℃、交联剂含量0.5%时,获得的复合泡沫结构最优,对Cu(II)、Pb(II)及Cd(II)均有较好的吸附性。
Polyvinyl alcohol(PVA)/shell powder composite foams were prepared by using water as both plasticizer and physical blowing agent combining with supercritical carbon dioxide technology. The results show that shell powders, as heterogeneous nucleating agent, could increase the nucleation point and melt strength of the system, thus better supporting the formation and growth of cells; proper cross-linking increases the solubility of carbon dioxide in the PVA matrix, leading to the decrease of the cell size and increase of the cell number and distribution uniformity. Rising the foaming temperature, the diffusion of carbon dioxide is accelerated, resulting in a more uneven growth rate and distribution of cells. With 10% shell powders and 0.5% crosslinking agent, and at 15 MPa saturation pressure and 80 ℃ foaming temperature, the cell structure of the composite foam is the best, and the foam has good adsorption ability on Cu(II), Pb(II) and Cd(II).
Polyvinyl alcohol(PVA)/shell powder composite foams were prepared by using water as both plasticizer and physical blowing agent combining with supercritical carbon dioxide technology. The results show that shell powders, as heterogeneous nucleating agent, could increase the nucleation point and melt strength of the system, thus better supporting the formation and growth of cells; proper cross-linking increases the solubility of carbon dioxide in the PVA matrix, leading to the decrease of the cell size and increase of the cell number and distribution uniformity. Rising the foaming temperature, the diffusion of carbon dioxide is accelerated, resulting in a more uneven growth rate and distribution of cells. With 10% shell powders and 0.5% crosslinking agent, and at 15 MPa saturation pressure and 80 ℃ foaming temperature, the cell structure of the composite foam is the best, and the foam has good adsorption ability on Cu(II), Pb(II) and Cd(II).
引文
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[3] Chowdhury S, Saha P. Sea shell powder as a new adsorbent to remove Basic Green 4 (Malachite Green) from aqueous solutions: equilibrium, kinetic and thermodynamic studies[J]. Chem. Eng. J., 2010, 164: 168-177.
[4] 尤宏争, 郑艳坤. 双壳贝类养殖容量及估算方法的研究进展[J]. 经济动物学报, 2013, 17(3): 178-181.
[5] You H Z,Zheng Y K. Advances on aquaculture capacity and estimation method of bivalve[J].J ournal of Economic Animal, 2013, 17(3): 178-181.
[6] Njoyim-Tamungang E, Laminsi S, Ghogomu P, et al. Pollution control of surface waters by coupling gliding discharge treatment with incorporated oyster shell powder[J]. Chem. Eng. J., 2011, 173: 303-308.
[7] Xing R, Qin Y, Guan X, et al. Comparison of antifungal activities of scallop shell, oyster shell and their pyrolyzed products[J]. Egypt. J. Aquat. Res., 2013, 39: 83-90.
[8] Yen H Y. Taguchi optimization for Cd(II) removal from aqueous solutions using oyster shell powders[J]. Desalin. Water Treat., 2015, 57: 1-9.
[9] Jia Y, Bai S, Wang Q, et al. Effect of boric acid on the foaming properties and cell structure of poly(vinyl alcohol) foam prepared by supercritical-CO2 thermoplastic extrusion foaming[J]. Ind. Eng. Chem. Res., 2017, 56: 6655-6663.
[10] Lee M, Tzoganakis C, Park C B. Extrusion of PE/PS blends with supercritical carbon dioxide[J]. Polym. Eng. Sci., 1998, 38: 1112-1120.
[11] Goel S K, Beckman E J. Generation of microcellular polymeric foams using supercritical carbon dioxide. I: effect of pressure and temperature on nucleation[J]. Polym. Eng. Sci., 1994, 34: 1137-1147.
[12] Liu P, Chen W, Jia Y, et al. A novel method to prepare microcellular poly(vinyl alcohol) foam based on thermal processing and supercritical fluid[J]. Polym. Adv. Technol., 2017, 28: 285-292.
[13] Wang N, Zhao L, Zhang C, et al. Water states and thermal processability of boric acid modified poly (vinyl alcohol) [J]. J. Appl. Polym. Sci., 2016, 133: DOI:10.1002/app.43246.