Supercritical Fluid - Crystal Phase Fractionation of Polymers: Polyethylene-Propane

相平衡将被确定为聚乙烯丙烷系统，包括固-液和液-气相边界，使用视图细胞（等槽法）。该方法在100 ~ 130摄氏度、9000 ~ 11000 psi的未分馏聚乙烯的早期工作中取得了成功。数据将收集高密度聚乙烯的馏分。结晶过程中搅拌对聚合物形态的影响也将被研究。这些数据将用于设计和测试一种半连续工艺，用于从超临界流体中通过结晶分离高密度聚乙烯。虽然聚合物已被证明可以从超临界流体中按分子量分馏，但这种过程是基于液相和气相共存的。这里尝试的过程将基于固体/超临界气体共存。先进的聚合物技术在先进工程材料的开发中起着核心作用。先进聚合物制造的一个关键方面是生产具有窄分子量分布的聚合物。通过聚合后按分子量经济地分离聚合物分子，该技术成为生产先进材料的又一工具。

Phase equilibrince will be determined for the polyethylene - propane system, including both solid-liquid and liquid-gas phase boundaries, using a view cell (isopleth method). This method was successful in earlier work with unfractionated polyethylene at 100 to 130 degrees centigrade and 9,000 to 11,000 psi. Data will be collected on fractions of high density polyethylene. The effect of agitation during crystallization on polymer morphology will also be examined. The data will be used to design and test a semi-continuous process for the fractionation of high density polyethylene by crystallization from a supercritical fluid. Although polymers have been shown to be fractionable by molecular weight from supercritical fluids, such processes have been based on the coexistence of liquid and gas phases. The process attempted here will be based on solid/supercritical gas coexistence. Advanced polymer technology plays a central role in scenarios for development of advanced engineering materials. One critical aspect of advanced polymer manufacturing is production of polymers with a narrow molecular weight distribution. By economically separating polymer molecules by molecular weight after polymerization this technology becomes another tool for producing advanced materials.