Melt homogenization

small particles of waxes are commonly produced by wet milling [59, 60]. Stirred ball milling, however, is difficult for these cases as their stickiness limits the application. This limitation can be solved by melt emulsification in general. Melt homogenization, in turn, is usually limited as emulsifiers, required for droplet stabilization, and have to be thermally stable at elevated emulsification temperatures. Using the SEM technology as represented here, droplets can be stabilized by instant cooling only, and thus the emulsifier problem does not arise. 

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Additives. Compounds are often added to the polymer at the extmder or melt homogenizer. Common additives are antioxidants (qv), thermal stabilizers, sHp agents, antiblock agents, anduv stabilizers. Popular antioxidants are 2,6-di-/-butyl-/)-cresol (BHT), octadecyl... 

To produce mouldings from polystyrene with minimum strain it is desirable to inject a melt, homogeneous in its melt viscosity, at a high rate into a hot mould at an injection pressure such that the cavity pressure drops to zero as the melt solidifies. Limitations in the machines available or economic factors may, however, lead to less ideal conditions being employed. 

During repelletizing, the PET is melted, homogenized and solidified in a uniform shape. Repelletizing is carried out after a pre-drying step or directly with undried flakes, depending on the ability to remove moisture inside the extruder and the intended final IV. Although IV retention is usually a major concern,... 

Siekmann, B. and Westesen, K., Electron-microscopic characterization of melt-homogenized solid lipid nanoparticles. Eur. J. Pharm. Biopharm., 2, 190, 1994. 

Siekmann B. and Westesen K., Melt-homogenized sohd hpid nanoparticles stabilized by the nonionic surfactant tyloxapol. II. Physicochemical characterization and lyo-philization, Pharm. Pharmacol. Lett., 3, 225, 1994. 

Siekmann B. and Westesen K., Thermoanalysis of the recrystallization process of melt-homogenized glyceride nanoparticles, Colloids Surf. B, 3, 159, 1994. 

The advantage of induction melting is the ability to melt cleanly and quickly. It is applicable to virtually any metal or alloy, even if they are not inductively suscepting, since it is possible to use the crucible as a susceptor as well. Furthermore, once the metal is molten, the induction lines from the secondary currents stir the melted charge and improve melt homogeneity. 

With this new concept it is possible for the first time to set the optimum process parameters for each process stage melting, homogenization, and pressure build-up. 

The decomposition of molten potassium azide has been shown to involve heterogeneous catalysis and induction periods which can be attributed to the presence of residual water in the melts. Homogeneous catalysis is of slight importance. 

Melt homogeneity in injection molding was further enhanced with the introduction of motionless mixers in the early seventies (37). These devices are placed in the nozzle of the injection molding machine. The mixers enhance the radial uniformity of temperature and composition of the melt. The devices are good for getting better cavity filling and also for saving on color concentrate. 

The diameters in use fall in the range of 2.5-30 cm, but most fall in the range of 5-15 cm. The ratio of the length to the diameter UD is 24, but has been moving to larger values (longer screws) of 36-42 in order to improve melt homogeneity. 

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