Size Determination of Ultra Fine Particles and Molecular Assembly in Supercritical Fluids

超临界流体中超细颗粒和分子组装的尺寸测定

• 批准号: 07650906
• 负责人: MORI Yasushige
• 金额: $ 1.41万
• 依托单位: Doshisha University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1995
• 资助国家: 日本
• 起止时间: 1995 至 1996
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07650906/
• 关键词: Supercritical Fluid; Fine Particles; Phpton Correlation Spectroscopy; Particle Size Measurement; 分子集合体

Photon correlation spectruscopy (PCS) is one of the poweful in situ techniques to determine size of fine particles of nanometer order within a few second analysis time. We tried the size measurement of particles dispersed in high pressure liquid and supercritical fluid by using PCS.1. PCS was made, which had the pressure-resistant cylindrical light scattering cell with a high precision sapphire tube. It was found that an injector with a 5muL sampleloop could be used to injectparticles suspended in methanol, as usual way of a conventional liquid chromatography.2. The effect of pressure on the size measurement was carried out, with the purpose of the leak test for the pressure-resistant. Colloidal silica particles with a narrow size distribution in methanlo were measured under up to 30 MPa at 298K.The observed particle diameter agreed with the size measured at an atmospheric pressure. This fact indicates PCS could be used as the size measurement of sub-micron particles dispersed in high … More pressure and high dense phase.3. When polystirene latex particles in methanol were used, the particle size increased to 1.2 times larger than the nominal diameters during the pressure increased only up to 1 MPa, and then was almost constant under the pressure ranges from 2 to 30 MPa. It might be concluded that polystirene polymer could swell with methanol at the relatively low pressure.4. The results of the size measurement of polystirene latex particles in supercritical carbon dioxide at 20 MPa and 313 K indicated that the observed particle diameters increase with time and the calculated polydispersed indexes also become large. We concluded the polystirene latex particles agglomerated quickly, but could not determined the effects of methanol in supercritical carbon dioxide on the particle agglomeration, which was used as the solution at the sample preparation.5. The viscosity of the binary mixure of methanol and carbon dioxide at 20 MPa and 313 K estimated by Lobe's method was fairly agree with the viscosity calculated from PCS measurements in the mixture solvent and from particle size assuming same value as in pure methanol, at the region of less carbon dioxide content than 60 volume %.6. From this study, the viscosity of the pure or mixture solvent can be measured by PCS with uniform particles known size. However, the crucial aspect of this measuring method is the selection of suitable particles for a probe which form a stable suspension in the solvent to know the viscosity. Less

光子相关光谱分析(PCS)是一种能在几秒钟的分析时间内测定纳米级细颗粒尺寸的强有力的原位技术之一。我们尝试用PCS.1测量分散在高压液体和超临界流体中的颗粒尺寸。制作了耐压圆柱形光散射池，并使用了高精度的蓝宝石管。结果表明，与传统的高效液相色谱分离方法一样，采用5×10-1进样量的进样器可用于进样悬浮在甲醇中的微粒。研究了压力对尺寸测量的影响，并对耐压材料进行了泄漏试验。在298K下，在30 Mpa的压力下测量了在甲醇中具有窄尺寸分布的胶体二氧化硅颗粒，观察到的颗粒直径与常压下测量的颗粒尺寸一致。这一事实表明，PCS可以用来测量高…中分散的亚微米粒子的尺寸压力越大，相密度越高。当使用聚苯乙烯乳胶粒子在甲醇中时，当压力增加到1 Mpa时，粒子的尺寸增大到名义直径的1.2倍，然后在2~30 Mpa的压力范围内几乎不变。可以得出结论，聚苯乙烯聚合物可以在相对较低的压力下与甲醇发生溶胀。在20 Mpa和313K的超临界二氧化碳中对聚苯乙烯乳胶粒子的粒径进行了测量，结果表明，测量到的粒子直径随着时间的延长而增大，计算所得的多分散指数也变大。结果表明，聚苯乙烯乳胶粒子团聚速度快，但不能确定超临界二氧化碳中甲醇对聚苯乙烯乳胶粒团聚的影响，并将其作为样品制备时的溶液。在二氧化碳体积分数小于60%的范围内，用LOPE方法估算的甲醇和二氧化碳二元混合物在20 mA和313K下的粘度与PCS测量的粘度以及在二氧化碳含量小于60体积%的纯甲醇中相同大小的颗粒大小计算的粘度基本一致。通过本研究，可以用颗粒大小均匀的PCS测量纯溶剂或混合溶剂的粘度。然而，这种测量方法的关键方面是为探针选择合适的颗粒，这些颗粒在溶剂中形成稳定的悬浮液，以了解粘度。较少