Podczeck F, Newton J M
Department of Pharmaceutics, School of Pharmacy, University of London, UK.
J Pharm Sci. 1995 Sep;84(9):1067-71. doi: 10.1002/jps.2600840907.
The extension of a centrifuge technique to measure adhesion and friction forces to an ultracentrifuge has been described. The equipment and procedure provide many experimental possibilities of which the adhesion of single particles to flat compacted powder surfaces has been used to measure the adhesion and friction force of starch microspheres to microcrystalline cellulose. The equipment used allows the positioning of the adhesion samples in the rotor in such a way that any angle between the centrifugal force vector and the flat sample surface can be obtained, and hence both adhesion and friction forces can be measured. The adhesion strength between starch microspheres and microcrystalline cellulose could initially be increased by applying a higher press-on force. However, a maximum plastic deformation and hence maximum contact area between the spheres and the surfaces was eventually reached, and any further application of press-on force appeared to lead only to more elastic deformation and hence not to an increase in adhesion strength. The friction between the starch microspheres and the compacted microcrystalline cellulose surfaces at a maximum deformation of the spheres is still very low, so that starch microspheres could be used as excipient in mixtures including microcrystalline cellulose for example in tabletting.
已经描述了将用于测量粘附力和摩擦力的离心技术扩展到超速离心机的方法。该设备和程序提供了许多实验可能性，其中利用单个颗粒对扁平压实粉末表面的粘附力来测量淀粉微球与微晶纤维素之间的粘附力和摩擦力。所使用的设备能够将粘附样品放置在转子中，从而可以获得离心力矢量与扁平样品表面之间的任何角度，因此可以同时测量粘附力和摩擦力。通过施加更高的压接力，淀粉微球与微晶纤维素之间的粘附强度最初可以提高。然而，最终达到了最大塑性变形以及球体与表面之间的最大接触面积，进一步施加压接力似乎仅导致更多的弹性变形，因此不会导致粘附强度增加。在球体最大变形时，淀粉微球与压实的微晶纤维素表面之间的摩擦力仍然非常低，因此淀粉微球可以用作包含微晶纤维素的混合物中的赋形剂，例如在压片中。
