Abstract：
The magnitude of the frictional forces during the ejection of porous pharmaceutical tablets plays an important role in determining the occurrence of tabletting defects. Here, we perform a systematic comparison between the maximum ejection force, static friction coefficient, and kinetic friction coefficient. All of these metrics have different physical meanings, corresponding to different stages of ejection. However, experimental limitations have previously complicated comparisons, as static and kinetic friction could not be measured simultaneously. This study presents a method for simultaneously measuring the maximum ejection force, static friction coefficient, and kinetic friction coefficient in situ during tablet ejection in routine compaction simulator experiments. Using this method, we performed a systematic comparison, including variations of (1) ejection speed, (2) compaction pressure, (3) material, and (4) lubrication method. The relative importance of each variable is discussed in detail, including how ejection speed alone can be a decisive factor in tablet chipping. The reliability of the newly developed method is supported by excellent agreement with previous studies and finite element method (FEM) simulations. Finally, we discuss the suitability of friction coefficients derived from Janssen-Walker theory and explanations for the phenomenon of die-wall static friction coefficients with apparent values far above unity.
摘要：
多孔药物片剂排出过程中摩擦力的大小在确定压片缺陷的发生中起着重要作用。这里,我们对最大弹射力进行了系统的比较，静摩擦系数,和动摩擦系数。所有这些指标都有不同的物理意义，对应于喷射的不同阶段。然而,实验局限性使以前的比较变得复杂，因为静态和动态摩擦不能同时测量。这项研究提出了一种同时测量最大弹射力的方法，静摩擦系数,在常规压实模拟器实验中，片剂弹出过程中原位的动摩擦系数。使用此方法，我们进行了系统的比较，包括(1)弹射速度的变化，（2）压实压力，（3）材料，和（4）润滑方法。详细讨论了每个变量的相对重要性，包括喷射速度如何单独可以是一个决定性的因素，在片剂芯片。与先前的研究和有限元方法（FEM）模拟非常吻合，支持了新开发方法的可靠性。最后,我们讨论了从Janssen-Walker理论得出的摩擦系数的适用性，以及对表观值远高于1的模壁静摩擦系数现象的解释。
