Packing data plastic

Figure 9-128. Companson of cooling efficiency of several packing materials in terms of the coefficient of heat transfer K a. Used by permission of Plastics Technical Service, The Dow Chemical Co., Midland Mich, with data added from Fuller, A. L., et al. Chemical Engineering Progress, V. 53, No. 10 (1957) p. 501 all rights reserved.

Several factors influence TGA data. Sample size and shape affect the rate and efficiency of decomposition. Powdered versus solid bulk samples will have different decomposition profiles due to the differing surface areas from which exiting decomposition products can leave the sample and be registered as mass losses. Similarly, the packing of the sample in the pan must be even and reproducible from run to run. Loosely distributed particles will heat more evenly and evolve volatilized products more evenly than mounded or densely packed samples. This can be especially important when looking at determinations of residual solvents, moisture or diffusion controlled losses such as plasticizer in the samples. 

Pads of fine wire mesh induce coalescence of impinging droplets into larger ones, which then separate freely from the gas phase. Tower packings function similarly but are less effective and more difficult to install. The pads are made of metal wires or plastic strands or fiber glass. These data apply to stainless steel construction ... 

Aging. Billet (3) showed that for some plastic packings in aqueous systems, the efficiency after one week s operation was almost double the efficiency of new packings. Little further change was observed after one week. Billet explains the phenomenon by improved wetting. He recommends that data for plastic packings should only... 

The first of the widely used random packings were Raschig rings which are hollow cylinders of ceramics, plastics, or metal. They were an economical replacement for the crushed rock often used then. Because of their simplicity and their early introduction, Raschig rings have been investigated thoroughly and many data of their performance have been obtained which are still useful, for... 

Appendices 8.11, 8.12 and 8.13 open up a relatively new topic where a possible technical gap between the information given in polymer supplier data sheets and the properties of the plastic used in the final pack can be identified. 

Out of the many chlorinated derivatives, vinyl chloride has been a focus of interest since its carcinogenic effects were discovered. Approximately 6% of its world production is assumed to escape into the atmosphere. Vinyl chloride is used for the production of different plastics and methylchloro-form, and it is added to mixtures for the production of special packing materials. Until recently it has been used as a medium in aerosol sprays. The imission concentrations in the vicinity of production sources (0 to 8 km) are generally below 2.6 ng m. In the literature, there are only few data about its atmospheric reactions. It is very probable that it participates in photooxidation reactions in the presence of nitrogen oxides. Carbon monoxide formaldehyde, formic acid and HCl are products of its photooxidation. 

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