Effect of Porosity on Strength Distribution of Microcrystalline Cellulose

Abstract

Fracture strength of pharmaceutical compacts varies even for nominally identical samples, which directly affects compaction, comminution, and tablet dosage forms. However, the relationships between porosity and mechanical behavior of compacts are not clear. Here, the effects of porosity on fracture strength and fracture statistics of microcrystalline cellulose compacts were investigated through diametral compression tests. Weibull modulus, a key parameter in Weibull statistics, was observed to decrease with increasing porosity from 17 to 56 vol.%, based on eight sets of compacts at different porosity levels, each set containing ∼ 50 samples, a total of 407 tests. Normal distribution fits better to fracture data for porosity less than 20 vol.%, whereas Weibull distribution is a better fit in the limit of highest porosity. Weibull moduli from 840 unique finite element simulations of isotropic porous materials were compared to experimental Weibull moduli from this research and results on various pharmaceutical materials. Deviations from Weibull statistics are observed. The effect of porosity on fracture strength can be described by a recently proposed micromechanics-based formula.

Carbon nanomaterials for the treatment of water pollutant in the purpose of environmental remediation

“…a statistically significant decrease in flexural strength value from 3.43 MPa for KS44-0 (11% Avicel) down to 0.73 for KS44-0 (33% Avicel) is observed. This observation indicates the mechanical property of the carbon composites increases with decreasing porosity (i.e., higher open porosity compacts have lower reliability)[11]. This decrease which is correlated with the measurements of porosity is mainly due to the difference in avicel contents between the graphite carbon materials.…”

Flow and Tableting Behaviors of Some Egyptian Kaolin Powders as Potential Pharmaceutical Excipients

“…Porosity, porosity gradient and pore size distribution represent some of the variables that most influence the tablet strength. The tensile strength decreases exponentially with increasing porosity for all size fractions [70,73,74]. Figure 6.…”

Dynamic compaction of cohesive granular materials: scaling behavior and bonding structures

“…3 The compaction of fine cohesive particles in response to mechanical stress or vibrations is also one of the most common operations in powder metallurgy, the ceramic industry, and the pharmaceutical industry for the production of stable agglomerates of desired composition, shape, strength, and porosity. Some examples are pharmaceutical pills, [4][5][6][7][8] nuclear fuel pellets, 9,10 detergent tablets, 11,12 titanium compact tools, [13][14][15] and Li-ion battery electrodes. [16][17][18][19][20] The physics of volume change in granular materials is complex due to the interplay of the concurrent effects of mutual particle exclusions, collisional energy dissipation, friction, bond forces, and collective dynamics involving arching and force correlations.…”

“…3 The compaction of fine cohesive particles in response to mechanical stress or vibrations is also one of the most common operations in powder metallurgy, the ceramic industry, and the pharmaceutical industry for the production of stable agglomerates of desired composition, shape, strength, and porosity. Some examples are pharmaceutical pills, 4–8 nuclear fuel pellets, 9,10 detergent tablets, 11,12 titanium compact tools, 13–15 and Li-ion battery electrodes. 16–20…”