小中大有个术语叫抗张强度,结合了硬度和片厚计算,(tensile strength)是表示单位面积破碎力(kPa或MPa),反映物料的结合力和压缩成形性的好坏。
简明计算公式 Ts =2F/(πDL)
F—将片剂径向破碎所需的力, D—片剂的直径, L—片剂的厚度
TENSILE STRENGTH USP定义
The measurement of tensile strengths provides a more fundamental measure of the mechanical strength of the compacted material and takes into account the geometry of the tablet. If tablets fail in tension, the breaking force can be used to calculate the tensile strength. Unfortunately, this is practical only for simple shapes. If flat-faced round tablets (right circular cylinders) fail in tension, as indicated by a clean split into halves under diametral compression, the breaking force may be used to compute the tensile strength from the following equation (4), which applies only to cylindrical tablets:
in which X is the tensile strength, F is the breaking force, D is the tablet diameter, and H is the tablet thickness. Because only tablets that fail in tension are counted, the data are based on tablets that fail in a consistent way. Thus, reproducibility of data should be enhanced when compared to conventional breaking-strength testing. Moreover, the data will be normalized with respect to tablet dimensions, because both diameter and thickness are included in the equation. The derivation of this equation may be found in standard texts (5, 6); it is based on elastic theory and the following assumptions:
1.The tablet is an isotropic body
2.Hooke's law is obeyed
3.The modulus of elasticity in compression and in tension is the same
4.Ideal point loading occurs