Mechanical Properties of Agglomerates

It is a good advice to visually inspect the crop under a microscope and to supplement the wording measurements of the particle size by microscopic images. 

The spherical agglomerates are obtained by drowning-out the paracetamol from THF with a mixture of hexane and trichloromethane in the presence of water as binding liquid. The water is not miscible with any of the solvents, so it will wet the paracetamol by forming a film on the surface. The hardness of the agglomerates is supported by building solid bridges. 

The mechanical properties of agglomerates are an indication of the mechanism of their formation and can also give an indication of the behavior of the agglomerates in their further processing. 

Toward a molecular understanding of crystal agglomeration. Cryst. Growth Des., 

Nichols, G., Bryard, S., Bloxham, M.(., Botterill, J., Dawson, N.J., Dennis, A., Diart, V, North, N.C., and Sherwood, J.D. (2002) A review of the terms agglomerate and aggregate with a recommendation for nomenclature used in powder and particle characterization./. Pharm. Sci., 91, 2103-2109. 

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The morphology of the agglomerates has been problematic, although some forms of network-like structures have been assumed on the basis of percolation behavior of conductivity and some mechanical properties, e.g., the Payne effect. These network stmctures are assumed to be determining the electrical and mechanical properties of the carbon-black-filled vulcanizates. In tire industries also, it plays an important role for the macroscopic properties of soft nano-composites, e.g., tear. 

Kristensen, H. G., Holm, P., and Schaefer, T., Mechanical Properties of Moist Agglomerates in Relation to Granulation Mechanisms. Part I Deformability of Moist Densified Agglomerates, Powder Technology, 44 227-237 (1985)... 

There have been many attempts to directly measure the mechanical properties of powders which have been agglomerated by compaction [85-90]. 

Kristensen HG, Holm P, Schaefer T. Mechanical properties of moist agglomerates in relation to granulation mechanisms Part I. Deformability of moist, densifled agglomerates. Powder Technol 1985 44 227-237. 

The use of irradiated PTFE powder in EPDM gives enhanced mechanical properties as compared to composites containing nonirradiated PTFE. The existence of compatibility between modified PTFE powder and EPDM is indirectly revealed by , DSC, and SEM. shows that modified PTFE powder (500 kGy-irradiated) is obviously but partially enwrapped by EPDM as compared to nonirradiated PTFE powder. This leads to a characteristic compatible interphase around the modified PTFE. The resultant chemically coupled PTFE-filled EPDM demonstrates exceptionally enhanced mechanical properties. Crystallization studies by DSC also reveal the existence of a compatible interphase in the modified-PTFE-coupled EPDM. The synergistic effect of enhanced compatibility by chemical coupling and microdispersion of PTFE agglomerates results in improvement of mechanical properties of PTFE-coupled EPDM compounds. In summary, an effective procedure both for the modification of PTFE powder as well as for the crosslinking of PTFE-filled EPDM by electron treatment has been developed for the preparation of PTFE-coupled EPDM compounds with desired properties. 

The gap between the predictions and experimental results arises from imperfect dispersion of carbon nanotubes and poor load transfer from the matrix to the nanotubes. Even modest nanotube agglomeration impacts the diameter and length distributions of the nanofillers and overall is likely to decrease the aspect ratio. In addition, nanotube agglomeration reduces the modulus of the nanofillers relative to that of isolated nanotubes because there are only weak dispersive forces between the nanotubes. Schadler et al. (71) and Ajayan et al. (72) concluded from Raman spectra that slippage occurs between the shells of MWNTs and within SWNT ropes and may limit stress transfer in nanotube/polymer composites. Thus, good dispersion of CNTs and strong interfacial interactions between CNTs and PU chains contribute to the dramatic improvement of the mechanical properties of the... 

Higli-temperatuie calcination of a-Al203 affects some physical properties, in particular specific surface area, density and mechanical properties of the agglomerates which influence the grinding process (Hlavac and Bartuska, 1964). 

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