Particle size of polymers

The dissolution profiles for LBZ B110-l-2 and PPL B110-l-2 tablets were also compared using similarity factor f2. A value obtained for f2 that is below 50 (37.48) indicates the influence of drug solubility in the dissolution profile. Furthermore, other parameters, such as dextran-drug ratio, particle size of polymer and drug, and influence of pH, have to be studied to obtain an optimum and robust formulation. 

Direct compression Particle size of polymer/drug, flow aid... 

Slurry" from more than one reactor is "dropped" into a "stripper" to remove unreacted monomer and then transferred to a large "blend tank." The suspended polymer particle can easily be separated from the water phase by filtering or centrifuging. The "wet cake" is then sent to a rotary kiln type dryer and bagged. The particle size of polymers obtained in this manner are usually much larger than those obtained with emulsion polymerization. They can be defined by a conventional screen analysis with respect to particle size. 

Fig. 8.10 Comparison of polymer particle size of polymer/carrier composites with commercial resin beads...

Wickramaratne NP, Perera VS, Ralph JM, Huang SD, Jaroniec M (2013) Cysteine-assisted tailoring of adsorption properties and particle size of polymer and carbon spheres. Langmuir 29(12) 4032-4038... 

Some of the variables that affect the coefficient of friction are temperature, sliding speed, contact pressure, metal surface conditions, particle size of polymer, degree of compaction, time, relative humidity, polymer hardness, etc. 

Age of Solution time at 25 C Remaining as Monomer (%) Particle Size of Polymer (nm) (From Solubility) Relative Rate of Reaction with Molybdic Acid... 

PlaStiSOlS. Plastisol-forming pol5rmers are produced by microsuspension polymerization or dispersion polymerization (9). Microsuspension produces very fine particles of monomer to ensure that small particle sizes of polymer are produced. In emulsion or dispersion polymerization the vinyl chloride is dispersed in a water-soluble initiator the vinyl chloride particles are small and stabilized using surfactants. There are also several variations of these two basic techniques. 

Polymer Areas Excellent for acrylic polymerizations at low surfactant use levels. Particle size of polymer in latex is controlled during polymerization when used in conjunction with other AEROSOL surfactants. Yields high solids, low viscosity latexes. 

AUoys of ceUulose with up to 50% of synthetic polymers (polyethylene, poly(vinyl chloride), polystyrene, polytetrafluoroethylene) have also been made, but have never found commercial appUcations. In fact, any material that can survive the chemistry of the viscose process and can be obtained in particle sizes of less than 5 p.m can be aUoyed with viscose. 

Polymer Solvent. Sulfolane is a solvent for a variety of polymers, including polyacrylonitrile (PAN), poly(vinyhdene cyanide), poly(vinyl chloride) (PVC), poly(vinyl fluoride), and polysulfones (124—129). Sulfolane solutions of PAN, poly(vinyhdene cyanide), and PVC have been patented for fiber-spinning processes, in which the relatively low solution viscosity, good thermal stabiUty, and comparatively low solvent toxicity of sulfolane are advantageous. Powdered perfluorocarbon copolymers bearing sulfo or carboxy groups have been prepared by precipitation from sulfolane solution with toluene at temperatures below 300°C. Particle sizes of 0.5—100 p.m result. 

The weathering properties of polyethylene are improved by the incorporation of carbon blacks. Maximum protection is obtained using blacks with a particle size of 25 p,m and below. In practice finely divided channel or furnace blacks are used at 2-3% concentration and to be effective they must be very well dispersed into the polymer. The use of more than 3% black leads to little improvement in weathering resistance and may adversely affect other properties. 

If PVC polymer particles are mixed, at room temperature, with plasticisers the immediate product may take one of two forms. If there is insufficient plasticiser to fill all the gaps between the particle a mush will be produced. If all the voids are filled then the particles will become suspended in the plasticiser and a paste will be formed. In the case of conventional granular polymer, or with emulsion polymer cenospheres, the particles are too large to remain in suspension and will settle out. Therefore compounds used in paste-processes must use polymers with a small particle size. On the other hand there is a lower limit to this, since small particles will have a very high surface/volume ratio and measurable plasticiser absorption will occur at room temperature to give a paste whose viscosity will increase unduly with time. As a consequence paste polymers have an average particle size of about 0.2-1.5 ptm. 

TSK-GEL PW and TSK-GEL PWxl columns are shown in Pig. 4.11. Although many methods for polymer analysis have been developed satisfactorily on TSK-GEL PW columns, higher resolution can often be achieved with a TSK-GEL PWxL column. The smaller particle sizes of the resins packed in TSK-GEL PWxL columns provide almost 2.5 times the resolution of their TSK-GEL PW counterparts. In addition, with shorter TSK-GEL PWxl columns, higher resolution separations are possible in less than half the time, as shown in Pig. 4.12. 

SEC columns have become much more efficient since they were introduced in the late 1950s. The major factor for this has been the ability of synthetic polymer chemists to produce smaller particle sizes of column packing materials. The first sorbents were several 100 /mm wide in diameter (20), whereas modem columns are filled with particles in the range between 3 and 20 /mm, which caused an immense improvement in separation power. The major drawback... 

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