Talc powder was ball-milled with 10wt% of phenylalanine (PhA). The surface area of the powder, obtained by eliminating PhA from the ball-milled mixture upon dissolution into distilled water, was much larger than the area of talc powder ball-milled separately without PhA (S_w) after ball-milling for more than 5h, when S_w decreased gradually due to particle growth caused by the high surface energy of fine talc particles. The talc surface was coated with thin films of PhA in a mixture ball-milled for a long time; this prevents talc particles from coming in direct contact with each other and their particle growth. IR spectra showed that mechanochemical interaction of the amino and carboxyl groups of PhA with talc surface was great after ball-milling for more than 5 hours; when racemization of PhA at talc surface was also great. These results suggest that PhA molecules interact mechanochemically with a highly activated surface of fine talc particles lowering the surface energy; this prevents atoms of the talc surface from diffusion to the contact parts between these particles, and it therefore prevents particle growth.

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The Characteristics of granulation of fine powders have been investigated by using a rotary-vessel-type mixer with rocking motion. The liquid as a binder is introduced into the mixer maintaining its inclination by means of ball bearings mounted on the inlet cover. A scraper and an impeller-type chopper are installed in the vessel to prevent the powder from sticking and to disintegrate the coarser agglomerates into the desired size range. The interior construction and operating conditions for granulation have been discussed based on the yield, size and size distributions of the granules. It is found that the granule formed by this mixer was relatively highly porous and soft.

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Ultrafine Fe particles with a chain-like structure and TiO₂ and MgO particles of four different sizes with a lumpy structure were packed by uniaxial compression. The effects of bed height and particle size on the compression characteristics of the packed bed, the stress transmission characteristics of the bed, the pore size distribution of the bed and radial distribution of stress at the bottom of the bed were investigated. The characteristic curve of the stress transmission can be explained from the change in pore-size distributions of the bed measured by a mercury porosimeter. The bed voidage can be correlated well with the applied stress by Modified Cooper's Equation with three terms. The three terms are found to be represented by three regions in a stress transition characteristic curve and change by the change of measured pore size distribution. It is found that the stress transmission through the bed increases with increase in particle size.

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The novel emulsion-solvent-diffusion technique developed by the authors was proved to be a versatile particle design method to improve the particulate properties of adhesive pharmaceutical powders for direct tabletting, irrespective of the crystallization solvent system employed, viz. miscible or immiscible good-poor solvent system. The spherically designed agglomerates of the crystals with the miscible solvent system were free flowing and easily packable into a die, which were directly compressed into a tablet without any capping even at higher compression pressure. This excellent compressibility was attributed to the preferable stress relaxation that occurred rapidly after the compression, indicating the plastic behavior of the agglomerated crystals under the compression.

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The specific surface area by air permeability, S_a, and that by BET, S_B, were observed simultaneously during the dry fine grinding process of limestone powder with ball media, S_a values were calculated by Carman's equation in which the effect of molecular flow was taken into account. The process was characterized on the S_a-S_B coordinate plane and was divided into three phases: phase I where both surfaces increased, the intermediate or transitional phase II, and phase III where both surfaces decreased. A typical grinding process started from I and arrived in III via II, but in some cases, II or III was not clearly identified.

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