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SynopsisThe creep behavior of a series of poly(ethy1 acry1ate)-poly(methy1 methacrylate) interpenetrating polymer networks was investigated. For comparison purposes, soMe stress relaxation data were included. Master curves containing a single broad transitibn covering approximately 20 decades of time were found for midrange compositions. qthough the time-temperature superposition principle and the WLF equation should not strictly apply, reasonable agreement was found over a large portion of shift factor versus temperature plots. Application of a modified Tobolsky-Aklonis-Dupre glass-rubber theory suggested that the breadth of the transition could be attributed to a near continuum of phase compositions in the material, each phase composition making its specific contribution to the relaxation spectrum. Whether or not these phase regions @re so small as to arise from random concentration fluctuations in an otherwise compatible polymer pair remains unknown.

W A mathematical model is presented to predict the efficiency of capture of aerosol particles by spherical collectors. This model includes consideration for inertial, viscous, gravity, and electrostatic forces, and the interception phenomena. The model shows that the efficiency of collection can be improved by the presence of electrostatic charges on the particles. The model, based on potential flow around the collector, is written in dimensionless form. Model predictions are plotted in terms of the appropriate dimensionless groups and are compared with previous works that considered electrostatic and viscous forces separately.The collection of aerosol particles smaller than 10 p is an important and difficult area of air pollution control. These smaller particles are difficult to collect because they tend to follow the air streamlines through the collection equipment. Collection may be achieved by one or more of the following six mechanisms (Strauss, 1966): inertial impaction, interception, gravity, electrostatic attraction, diffusion, or temperature gradient motion.Inertial forces are normally most significant for aerosol collection in scrubbers and high-speed filters. Gravity forces and interception can be important for larger particles and slow-speed operations, while the relative magnitudes of the diffusion (Brownian Motion) and the temperature gradient mechanisms become greater for small particles. The temperature gradient mechanism is almost never significant for industrial collection processes. The diffusion mechanism can be important for low-speed filters but is not significant in scrubbers and high-speed fill To whom correspondence should be addressed.46 Environmental Science 8, Technology ters. Thus, for these devices, higher collection efficiencies are likely to be achieved only through the inertial and electrostatic mechanisms. The book by Strauss (1966) and the papers of Davies (1952) and Goldshmid and Calvert (1963) discuss the various collection mechanisms and list references to numerous related papers.When a small particle approaches a collector, the balance between particle inertia, electrostatic forces, and fluid friction, which tends to pull the particle past the collector, determines if collision (and thus collection) is to occur. Theoretical consideration of this problem involves the application of the equations of motion to determine the limiting collision trajectory for particle collection. The simultaneous effects of inertial, electrostatic, gravity, and viscous forces are considered in this work. The results are compared with those of previous publications in which the inertia-viscous and electrostatic-viscous interactions were considered separately. Our work serves to connect these earlier results. The relationships can be used to estimate the magnitude of electrostatic charge necessary to improve collection by spherical collectors, such as droplets in spray scrubbers. Theor?The trajectory of an aerosol-particle can be predicted from Newton's law of motion ( F = mu) if the initial pos...

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