Average polymer particle volume

Figure 5. Average particle polymer volume (1) and average total particle volume (2) vs. time (A=S=H=33. 33 gr)...

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. 

A research group in Lehigh University has extensively studied the synthesis and characterization of uniform macroporous styrene-divinylbenzene copolymer particles [125,126]. In their studies, uniform porous polymer particles were prepared via seeded emulsion polymerization in which linear polymer (polystyrene seed) or a mixture of linear polymer and solvent were used as inert diluents [125]. The average pore diameter was on the order of 1000 A with pore volumes up to... 

The number of polymer particles was determined from the monomer conversion Xj and the volume average diameter of the polymer particles dp measured with an electron microscope. 

Assuming that radical termination takes place excinsively in the polymer particle, the average number of radicals in a particle of volume v,(r.T) can be obtained as (Ugelstad and Hansen. 1976)... 

Methods that calculate average polymer properties without the DRI are significant because they circumvent complications that arise from the measurement of the interdetector volume between the light-scattering and concentration detectors 10, 11). It is necessary, however, that each local signal,, be divided by the computed particle scattering function, P 6)i. 

FIGURE 17.20 The effect of filler particles on gel properties, (a) Relative modulus (Gm/G0) as a function of particle volume fraction (broken lines are calculated for various values of the ratio Gp/Go, indicated near the curves. The drawn lines are average experimental values for acid casein gels (C) and polymer gels (polyvinyl alcohol, P), with emulsion droplets that are either bonded (B) or nonbonded (N) to the gel matrix, (b) Highly schematic pictures of the gel structure. Shaded area denotes primary gel. Particles are nonbonded (1) bonded (2) bonded but with intermediate layer (3) bonded and aggregated (4). (Adapted from T. van Vliet. Colloid Polymer Sci. 266 (1988) 518.)... 

A recent development in the production of polymer particles has created a revolutionary new technology for the production of submicron polymer particles from solution, In this experiment, generation and characterization of droplet streams with small (< 15 pm) average diameters have been used to create nano-polymer particles. This technique makes the initial volume of a dilute solution of any polymer material sufficiently small so that the solvent evaporation occurs on a very short time scale leaving behind a polymer particle. For micro and nano-scale generated polymer particles, the refractive index obtained from the data analysis is consistent with bulk (nominal) values and the level of agreement with Mie theory indicates that the particles are nearly perfect spheres. 

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