Bimodal distribution particles

The most important material component of the environment with respect to degradation of electronic devices is particles (Sinclair, 1988 Frankenthal et al., 1993). Most of the mass of particulate matter in the atmosphere exists in the size range 0.1 to 15 pm. Within this range, the mass exhibits a bimodal distribution. Particles 2.5 -15 pm are largely derived from natural materials and are usually called coarse particles, while particles 0.1 -2.5 pm, usually called fine particles, are primarily derived from anthro-... 

All pore sizes are according to a slit-shaped pore model Bimodal distribution of Ce02 particles... 

In a similar study, Allen and co-workers (1996) determined the particle size distribution for 15 PAHs with molecular weights ranging from 178 (e.g., phenan-threne) to 300 (coronene) and associated with urban aerosols in Boston, Massachusetts. As for BaP in the winter (Venkataraman and Friedlander, 1994b), PAHs with MW >228 were primarily present in the fine aerosol fraction (Dp < 2 /Am). A study of 6-ring, MW 302 PAH at the same site showed bimodal distributions, with most of the mass in the 0.3- to 1.0-/zm particle size size range a smaller fraction was in the ultrafine mode particles (0.09-0.14 /xm) (Allen et al., 1998). For PAHs with MW 178—202, the compounds were approximately evenly distributed between the fine and coarse (D > 2 /am) fractions. Polycyclic aromatic hydrocarbons in size-segregated aerosols col-... 

For example, as seen in Fig. 14.41, aerosol particle number size distributions in the clean marine boundary layer outside of clouds are often observed to have a bimodal distribution. The larger mode above 0.1 /xm... 

The particle size distribution suggests that nonirradiated PTFE powder has a broad particle size distribution compared to 500 kGy-irradiated PTFE powder. The nonirradiated PTFE powder shows a characteristic bimodal distribution compared to the unimodal distribution of 500 kGy-irradiated PTFE powder (Fig. 14). This specific bimodal distribution clearly signifies that nonirradiated PTFE powder is mainly composed of bigger agglomerates that tend to reagglomerate. By contrast,... 

HIPS resin with both a high gloss and a high impact strength have been produced using a special in situ polymerization process. A bimodal distribution of the elastomer particles and particular size range and morphology type is maintained (8). 

The optimum particle size lies in the range 0.1-10 /um and depends on the interparticle distance that must be lower than a critical value. The claim about the better effect achieved by the generation of a bimodal distributions of particle sizes has yet to be proved. 

Most of the studies on size-resolved aerosol mass concentrations in areas with different levels of pollution show that particulate matter typically exhibit a bimodal distribution, with most of their mass being found in the submicron size range (dae < 1pm) and an additional minor mode in the coarse fraction (1 < dae < 10 pm) (Maenhaut et al., 2002 Smolfk et al., 2003 Wang et al., 2003 Gajananda et al., 2005 Samara and Voutsa, 2005). However, with instrumentation allowing more precise measurements, the aerosol mass size distribution was found to be multimodal with the preponderance of a fine mode (dae < 0.2 pm) and an accumulation mode (dae 0.5pm), with a minor coarse mode at d 3-4pm (Raes et al., 2000 Pillai and Moorthy, 2001 Berner et al., 2004). Traditionally, atmospheric researchers classify airborne particles into three size classes coarse (2.5 < c/ ie < 10pm), fine... 

Particle size distribution of a seeded PVC latex (bimodal distribution)... 

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