超临界二氧化碳/聚合物体系扩散度的测量方法

Measurement of diffusivity of supercritical carbon dioxide/polymer systems

基于国外先进技术的发展,介绍了超临界二氧化碳/聚合物体系扩散度的各种测量方法。测量二元体系扩散度的方法包括测压法、测重法、光学观测法和光谱技术。测压法和测重法简单易用,是最重要的2种测量方法,但测压法难以测量高温高压体系,测重法需要防止因气体泄漏引起的误差,并需对结果进行浮力校正。光学观测法和光谱方法用于瞬态测量,不对溶解度量化测量。三元体系的测量方法只需对二元体系方法进行适当修正,目前使用的有经过修正的测重技术、利用紫外-可见吸收光谱法和傅里叶变换红外光谱技术等。另外,三元体系方法还包括测量超临界空气条件下的添加剂的传递性质的卷薄膜方法和强制 Rayleigh 散射法。

Barometric methods and gravimetric methods are main measurement ones for binary systems because of simplic- ity and easy operation.However,barometric methods are difficult to use at high pressures and temperatures.As gravimetric meth- ods,the escape of gas during measurement will cause errors,and the results should be corrected by gas buoyancy.Optical obser- vation and spectroscopic technique are suited to the transient measurement but not quantitative selubility measurement.The ternary system measurement follows the same procedures as the binary systems with slight modifications,such gravimetric mea- surement and spectroscopic technique as ultraviolet-visible(UV-vis)and Fourier transform infrared (FTIR) spectroscopy.Film roll method and forced Rayleigh scattering method are specifically used in determining transport properties of additives in a su- percritical atmosphere.