Rapid Precipitation of Homogeneous Polymer Blends

该项目概述了一项研究， 均相聚合物共混物从三元溶液具有 超临界流体（SCF）作为溶剂。 尽管聚合物可以 在SCF’s中具有相当大的溶解度，它们不溶于 同样的液体在气态下。 因此，密度降低， 这可以在音速下完成，导致 溶解在SCF中的聚合物的沉淀。 因为 降水的时间尺度可以大大短于 聚合物发生相分离的时间尺度 扩散，扩展单相三元SCF溶液将 导致固体聚合物的单相共混物。 因此 超临界流体沉淀技术表明， 生产以下物质的均匀、相容共混物的可能性： 已经发现不相容的聚合物， 熔融共混或常规溶液共混技术。 该项目的目标是：（1）开发 生产相容的聚合物共混物的能力， 超临界流体共混过程，以及（2）评估 这些制备的共混物的稳定性。 这些目标将 通过研究聚合物/聚合物/SCF相平衡， 通过实验和理论研究， SCF膨胀过程的动力学，并通过检查 沉淀共混物中相分离的动力学。 如果 新的，精细状态的聚合物混合物可以使用此开发 新技术，它们可能具有高强度或其他独特的 这将是有用的，在制造高， 性能组件。

The project outlines a study of the rapid precipitation of homogeneous polymer blends from ternary solutions having a supercritical fluid (SCF) as the solvent. Although polymers can have substantial solubility in SCF's, they are insoluble in the same fluids in the gaseous state. Hence, density reduction, which can be accomplished at the speed of sound, results in precipitation of the polymer dissolved in the SCF. Because the time scale for precipitation can be significantly shorter than the time scale for phase segregation to occur by polymer diffusion, expanding a single phase ternary SCF solution will result in a single-phase blend of solid polymers. Thus, the supercritical fluid precipitation technique suggests the possibility of producing a homogeneous, compatible blend of polymers that otherwise have been found to be incompatible by melt blending or conventional solution blending techniques. The objectives of this project are: (1) to develop the capability of producing compatible polymer blends via a supercritical fluid blending process, and (2) to assess the stability of these prepared blends. These objectives will be achieved through studies of polymer/polymer/SCF phase equilibria, through experimental and theoretical investigations of the dynamics of the SCF expansion process, and through examination of the kinetics of phase separation in the precipitated blends. If new, fine-state polymer mixtures can be developed using this novel technique, they may have high strength or other unique properties that will be useful in the manufacture of high- performance components.