Measurement friability

More specifically a certain weight of tablets, W0, is subjected to a well-defined level of agitation in a fixed-geometry, closed container for a specific time. They are then reweighed, W. The measure of abrasion resistance or friability, B, is usually expressed as a percentage loss in weight ... 

Data from attrition tests are usually presented as simple numbers called friability or attrition indices. Most of these indices are used as measures in quality control by subjecting the materials to a standard procedure. By comparing the test results with those of known materials, it is possible to give a relative characterization of the tested materials. Examples are given in Sec. 4.3. 

When evaluating the effect of binder concentration on a number of tablet properties, surface area measurements were used to investigate the bond strength of the binder with the other particles [18]. A steady reduction in the surface area of the granules with increasing binder concentration indicated that the binder had covered or penetrated the particles, with the formation of particle-binder bonds. This was related to friability, and the increased bond strength was related to the decreased surface areas. 

Friability measurements were done for cores compressed at hardness ranging from 154 to 216 N, as shown in Figure 10. Data show that cores... 

Tablet hardness, friability, disintegration time and dissolution at 30minutes were the response variables that were measured. Tablets manufactured at 10 and 12kN were compared, as well as their compaction profiles. Table 4 shows the results from the fractional factorial DOE and Figure 19 shows the compaction profiles from the 20 batches.

Tablet SF, TS (in MPa), CS or pressure (in MPa), and friability were calculated from the tablet measurements, the compression forces, and the tooling dimensions. Plots of SF versus TS and TS versus CS were generated curves were fitted to the data and the properties at 0.85 SF and at the apex of the TS versus CS profile were determined.

The general instructions for the determination of the corresponding properties of tablets (hardness, disintegration, friability, dissolution) are contained the Pharmacopoeiae Ph.Eur. or USP. If it is not stated to the contrary, the disintegration time is measured in artificial gastric juice. The release is determined by the conditions laid down in the corresponding monographs for the tablets (usually USP) and in the prescribed medium. 

Toughness. An abrasive s toughness is often measured and expressed as the degree of friability, the ability of an abrasive grit to withstand impact without cracking, spalling, or shattering. 

While friability is a property that may be attributed to crystals and many chemical compounds, tests devised thus far pertain only to coals however, the same tests may be used on other materials having the same relative degree of friability. Several methods have been used to determine friability, and are based on two procedures (a) Measurement of work done in reducing coal of a given size to a smaller size, or (b) subjecting the coal to a definite amount of work and measuring the reduction in coal size due to such work. 

The first procedure, developed in England by Stopes and Wheeler (1923), consists in grinding a certain weight of coal in a ball mill, run under fixed conditions and for a stated length of time. The coal is then removed from the mill and the weight of the coal passing a 200-mesh used as a measure of friability. In this country the second procedure has been more widely used, resulting in two more or less widely accepted tests. 

Long term burial of artifacts recovered in archaeological excavations often leads to friability, salt encrustation, physical damage, and severe corrosion. Field conservation is limited to such measures as are required to preserve the artifact until it may receive the attention of specialists in the museum laboratory. Typical conservation treatments for textiles, waterlogged wood, bone and ivory, cuneiform tablets, and cast and wrought marine iron are reviewed with particular emphasis on the effects such treatments may have on the subsequent technical examination of the artifact. 

Breakdown of particles on impact can be tested either on single particles or on a quantity of the bulk solid, and the result is a measure of particle friability. The available tests have been well reviewed in the recent attrition report by the Board54 and only a mention of the main methods is given here. 

This result suggests that, for this family of structures at least, the value of 1.6 mL g 1 provides sufficient weakness to allow total breakdown and full access to all of the catalyst surface. This inference is also supported by a comparison of results obtained with the best commercial silica gels and with a pyrogenic or "fumed silica (Cabosil) formed by flame hydrolysis of SiCl4. The latter has no pore structure, and no such structural limitations. That the two exhibit similar activities indicates that the silica gel had disintegrated to the level at which nearly all of the surface contributed to the polymerization. Furthermore, once friability of the solid is obtained because the pore volume is sufficiently high, activity can still be influenced by the surface area. However, these are only general trends, and some small exceptions are evident in the data in the table as well. It is the structure itself, rather than any porosity measurement, that determines friability. 

Verain and coworkers (3) described the formulation of an effervescent paracetamol tablet dosed at 500 mg, containing saccharose and sorbitol as diluents. Other components were anhydrous citric acid, sodium or potassium bicarbonate, PVP, and sodium benzoate. The tablets were characterised by measurement of a number of responses, in particular the friability, the volume of carbon dioxide produced per tablet when it is put in water, and the time over which the tablet effervesced. The objective was to study the effects of 4 factors, the quantities of sorbitol and of citric acid per tablet, the nature of the bicarbonate (whether sodium or potassium bicarbonate), and the effect of different tableting forces on these responses. The... 

The mixtures were granulated and tableted, and the usual properties of granulates and tablets were measured - flow, friability, hardness, disintegration. They are listed in table 9.11. 

Enriched phillipsite and chabazite samples, practically free from other cation exchanger phases, were obtained from the parent rocks by enrichment processes (grinding and sieving, separation by heavy liquids or magnetic table, etc.), based on the greater friability and lower density of zeolite relative to other rock constituents [12]. Chemical analysis of the two zeolites in the enriched products was performed by electron microprobe analysis (CAMECA SX50). Water content was measured by thermogravimetry (Netzsch STA 409 thermoanalyzer). 

The friability of a rigid foam is not an easy property to determine, and it is seldom used as a quality control measurement. However, for certain materials such as phenol-formaldehyde foam it can be a useful tool in formulation work to ensure that the product is suitable for the application area. In certain instances the test method is best adapted to the foam being tested, for example the time duration of the test may be shortened if the material is being abraded too harshly. 

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