Dry-processing techniques

The dry-processing techniques (VDP and E-CVD) have some merits over wet-processing techniques however, only a few polymers have now been formed by these methods, and further research is necessary. 

In addition to time-related effects, the soUd-state physical properties are also affected by adsorbed water, which functions as a plasticizer. Water pickup is affected by the nature of the cation, with sodium ionomers absorbing about 10 times the level of the zinc equivalent (6) under the same conditions. Drying must be carried out at temperatures below 100°C and is therefore a slow process. In commercial practice, ionomers are suppUed dry, and techniques have been developed to minimize moisture absorption during processing. 

Thermoplastics. The highest consumption of color concentrates is in thermoplastic resins, such as low and high density polyethylene, polypropylene, PVC, and polystyrene. Processing techniques for thermoplastics are usually based on dry color dispersion in a compatible resin (36). 

Dry processes which obviate solvent difficulties are now preferred and are similar to those employed with the major thermoplastics. They include the use of two-roll mills, internal mixers, extruders and extrusion compounders. The use of dry blend techniques similar to that used more recently with PVC have also been used. ... 

It was observed that this technique was able to produce microparticles with a mean diameter of approximately 10.17 + 3.02 pm in a reasonable to satisfactory yield depending on the formulation. This value was observed to be higher for the polymer weight ratio of 1 3 (87.00 + 4.25 %), which indicates that ESIOO improves the final result of the spray-drying process. According to the SEM analysis, the polymeric microparticles were shown to be quite similar in shape. Regardless of the formulation, they appeared to be mostly concave and asymmetric (Figure 12). 

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