Tensile Strength Of Powder Bed Research Articles

Effect of Surface Treatment by Using TEOS on Adhesive Force of Spherical Fused Silica

Spherical fused silica produced by flame fusion process has been used as a filler for epoxy molding compound to encapsulate electronic devices such as IC and semiconductors. By FE-SEM and TEM observation, a lot of silica nanoparticles adhere to the surface of spherical fused silica of several μm in diameter. The effect of surface treatment by using TEOS (tetra-ethyl-ortho- silicate) on the particle adhesive force was investigated by AFM and conventional tensile strength of powder bed. It was confirmed that particle adhesive force decreased after TEOS treatment by using both testing methods, and the specific surface area increased by the surface treatment. The relationship between the change of adhesion force after surface treatment with different condition and surface nanometer and molecular scaled structure of spherical fused silica was discussed. The decrease of adhesion force and increase of specific surface area of spherical fused silica after surface treatment were developed on the amount of residual functional etoxy group.

Effect of Particle Shape of Active Pharmaceutical Ingredients Prepared by Fluidized-Bed Jet-Milling on Cohesiveness

Milling is a common procedure to improve bioavailability of many active pharmaceutical ingredients (APIs), which typically have low solubility in water. But such micronization can yield an increase in the cohesiveness of particles. Although particle cohesiveness is desirable for tablet strength in the subsequent formulation process, increased particle cohesiveness can lead to operational difficulties in a milling equipment due to compaction of particles inside. In this article, the impact of milling via a fluidized-bed jet-mill on the cohesive strength and interparticle force was studied using Ethenzamide as a pharmaceutical model compound. As a result, the particle shape was found to affect both the tensile strength of powder bed and the interparticle cohesive force. A powder bed, having relatively high void fraction by direct tensile test, shows a positive correlation between the cohesive force and the particle sphericity, while powders with low void fraction by diametral compression test show a positive correlation between the cohesive force and the angularity of the particle. © 2005 Wiley-Liss, Inc. and the American Pharmacists Association

コヒテスタによる粉体層の付着力測定について

The measurement of the tensile strength of powder bed has been carried out by means of the swing method measuring instrument, which has been developed by the authors.It was evident that a displacement in a breakable section of powder bed appears as the tensile stress increases, then the stress displacement curves are obtaind respectively for each powder. These curves provide the energy required to the tensile breakage which may be correlated with practical particulate phenomena.The most interesting problem is the application of the measurement of tensile strength for the design of powder equipment and material handling.The floodability of fine material, which will indicate the tendency to liquidlike flow due to natural fluidization of a mass of particles by air, has been discussed empirically but theoretical bases are not sufficient on the evaluation of the potential floodability of fine material.The dimensionless number deduced from our theoretical consideration is given by the following equationFc/mp·g=3·σ/(1-e)dp·ρp·gThe ratio of the cohesive force affecting a single particle to a particle weight indicates a good correlation with empirical floodability evaluated by R. L. Carr's method.

On the Tensile Strength of the Fine Powder Bed and Moisture Content

The measurement of tensile strength of the powder bed having various water contents has been carried out, using fine powder with its specific surface diameter below 10μ, and the effect of the water content on the adhesion force among the particles discussed.The adhesion force caused by the pendular rings of the water at the points of contact increases as the water content increases. It is considered that the pendular ring of the water formed at every contact point of the particles is of uniform size at relatively high void fraction. In this case, the relationship between the non-dimentional adhesion force of one contact point and the water content is to be expressed by the equation fc/πdpT=Kwc1.4. On the other hand, it is considered that at low void Fraction the pendular rings of the water blend into one another, or form a sort of bridges between the nearby particles. The adhesion force is considerably influenced by the true void of the powder bed.The present experimental result does not agree with the theoretical analyses of the two spheres of equal size hitherto reported by many investigators.