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Collection performance of an electret filter with rectangular fibers was studied experimentally for cases in which electrostatic effect and Brownian diffusion are predominant by using particles from 0.02 to 0.4 ym in diameter and at different charging states. A single fiber collection efficiency qEl, was found to be expressible as a function of dimensionlegs parameters of Peclet number Pe, and Coulombic and induced force parameters, K c and K I,, as, here, A, B, C, and 1) are the numerical constants depending upon the charging density of electret fiber. Indices of each dimensionless parameter determined through the experiment coincided with the previous theory. A maximum penetration of particles appeared in the transition region of predominant collection mechanisms, i.e., between Brownian diffusion and induced force effect, ranging smaller than 0.1 pm in diameter for uncharged particles, and between Coulombic and induced force effects, ranging larger than 0.1 pm in diameter, for charged particles. Semiempirical expressions for a single electret fiber collection efficiency and a most penetrating particle size, applicable to particles in any charging state, were obtained taking account of Brownian diffusion, and induced and Coulombic force effects simultaneously. Undulation of the penetration observed in the filtration of particles in charge equilibrium was explained by using the semiempirical expression for a single fiber efficiency and charge distribution on a particle.

A three‐dimensional stochastic model, which is effective for the convective diffusional deposition of aerosol particles, was developed starting from Langevin's equation. The model was utilized to simulate collection and agglomeration processes of particles on a cylindrical fiber. By obtaining the distribution of captured particles on a fiber and the evolution of the collection efficiency of a dust‐loaded fiber through the simulation, the effect of Peclet number, interception parameter, and the accumulated mass of particles on them were discussed. Further, the collection efficiency of a dust‐loaded fiber was correlated by using a linear function of the accumulated mass of particles in a unit filter volume. Dependence of coefficient in the linear function, collection efficiency raising factor on Peclet number, and interception parameter were also discussed.

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In order to develop an effective dry surface cleaning method, removal of fine particles by pulse air jets was experimentally investigated. A dimensionless resuspension parameter, F*, which is the ratio of drag force on particles to van der Waals adhesion force, was introduced to correlate the removal efficiency. Resuspension experiments were carried out with monodisperse PSL particles and wax particles with diameter between 0.25 and 1.1 p m on silicon wafer and glass plate. As a result, it was found that deposition process of particles on the surface (gravitational settling and impaction at a relatively low impaction velocity) has little effect on the removal efficiency and that consecutive pulse air jet is effective in the removal of fine particles. Further, F* is the key parameter in determining the removal efficiency. The prediction method for the removal efficiency by pulse air jets with F* is proposed.

The collection performance of granular bed filters connisms were obtained, elucidating the influence of the sisting of uniform spheres with diameters of 0.5-2.0 mm Reynolds number on the particle collection. Furtherwas experimentally studied by using monodisperse more, by assuming the additivity of the individual meaerosol particles ranging from 0.02 to 2 pm in diameter chanical collection efficiencies, a prediction equation apat superficial velocity from 0.4 to 120 cm/s. Based on plicable to the wide range of filtration conditions is the experimental data, prediction equations of collection proposed. efficiency due to individual mechanical collection mecha

ABSTRACT:The dynamic mechanical properties of hybrids of chlorinated polyethylene (CPE) and 3,9-bis[1,1-dimethyl-2{␤-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy}-ethyl]-2,4,8,10-tetraoxaspiro[5,5]-undecane (AO-80) were investigated. The CPE/AO-80 hybrids showed a novel relaxation in addition to the glass transition of CPE. The novel relaxation is attributed to the dissociation of intermolecular hydrogen bonds within the AO-80-rich domain. The Payne effect, that is, the decrease of the storage modulus EЈ with increasing strain amplitude and the appearance of a loss modulus EЉ maximum at a strain of 0.6%, was observed for the CPE/AO-80 hybrids. This result demonstrates that the AO-80-rich domains within matrix polymer CPE form a network. The Payne effect is considered to be attributed to the mechanical disruption of segment-segment contacts at a sufficiently great strain.

ABSTRACT:The dynamic mechanical properties and the morphologies for the binary blends of acrylate rubber (ACM) and chlorinated polypropylene (CPP) with 3,9-bis[l,1-dimethyl-2(,B-(3-tert-butyl-4-hydroxy-5-methylphenyl)-propionyloxy}ethyl]-2,4,8,10-tetraoxaspiro [5,5]-undecane (AO-80), and their ternary systems were investigated. The AO-80 distribution to each phase of an immiscible ACM/CPP blend was studied in term of a shift in glass-transition temperature. It was found that when the AO-80 content is lower than 30% the AO-80 molecules are preferentially dissolved to an ACM continuous phase, whereas as the AO-80 content increases, a part of AO-80 molecules are incorporated to the blend interfaces, and then to the domains ofCPP. In addition, the reduction in the domain size ofCPP due to adding AO-80 was also observed. A ternary blend of ACM/CPP (7: 3) with AO-80 (35%) showed a novel tan 8 peak between two peaks corresponding to ACM and CPP. This peak is attributed to an interfacial layer where a super-molecular network is formed. As a result, a ternary blend of ACM/CPP with AO-80 was found to be a very good damping material.KEY WORDS Polymer Blend / Acrylate Rubber/ Chlorinated Polypropylene / Hindered Phenol / Interface/ Dynamic Mechanical Property/ Damping Property/ The individual phases in immiscible polymer blends often retain their physical properties. Multiphase polymer blends therefore offer unique possibilities to improve some properties of pure components. 1 Unfortunately, the morphology of the multiphase blends for the improvement of mechanical properties is often difficult to control. Block and graft copolymers were widely used as compatibilizers for the improvement of morphology of immiscible polymer blends. Modification of the polymer blends by adding properly selected polymeric compatibilizers generally provides better dispersion and increased interfacial adhesion, leading to improvement of the mechanical properties. The success of this concept has been reviewed in a number of articles. 2 • 3 On the other hand, low-molecular-weight compound are widely used in rubber industries to improve or control the mechanical properties, viscoelastic behavior, and processability. Very few fundamental studies have been reported on the factors and mechanism of these improvements in polymer blends. According to our recent studies, 4 -10 the addition of hindered phenols can lead to the discovery of some unknown functions and the modification of mechanical properties of some partially polarized polymers such as chlorinated polyethylene (CPE) and acrylate rubber (ACM). Adding AO-80 into CPE causes a novel transition that appeared above the glass transition temperature ofCPE. 4 -8 In addition, we found that such as broad damping properties 7 • 8 and shapememory effects 4 were accompanied by this novel transition. In particular, AO-80 was found to improve compatibility of CPE/ACM blends, and to act as a new type of compatibilizer. 8 This is due to formation of a supermolecular network where CPE and ACM couples by AO-8...