Hollenbeck R G, Peck G E, Kildsig D O
J Pharm Sci. 1978 Nov;67(11):1599-606. doi: 10.1002/jps.2600671125.
A comprehensive characterization of the specific solid-liquid interaction for microcrystalline cellulose and water is presented. The procedure consisted of a conjoint vapor adsorption and immersional wetting experiment. The following information was obtained with respect to the solid. Estimates of the total surface are (138 m2/g) and the external surface (9.2 m2/g) were calculated from the adsorption and immersion data, respectively. Existence of an energetically homogeneous surface was verified by a linear decrease in the heat of immersion of samples containing adsorbed moisture approximately up to monolayer capacity. Integral and differential free energy, enthalpy, and entropy changes accompanying the adsorption process were calculated, and a lack of swelling was substantiated by comparison with a similar study of cellulose fibers. Immersional hysteresis was observed, and its magnitude suggested that sorption hysteresis was of enthalpic as well as entropic origin. The experimental method is potentially valuable for routine characterization of hydrophilic powders.
本文对微晶纤维素与水之间的特定固液相互作用进行了全面表征。该过程包括联合蒸汽吸附和浸渍润湿实验。获得了关于固体的以下信息。分别根据吸附和浸渍数据计算出总表面积（138平方米/克）和外表面（9.2平方米/克）的估计值。通过含有吸附水分的样品的浸渍热大致线性下降直至单层容量，验证了能量均匀表面的存在。计算了吸附过程中伴随的积分和微分自由能、焓和熵的变化，并通过与纤维素纤维的类似研究比较证实了没有膨胀现象。观察到浸渍滞后现象，其大小表明吸附滞后既有焓的起源也有熵的起源。该实验方法对于亲水性粉末的常规表征可能具有重要价值。
