Emission During Processing

Other than inhalation of degradation products, fume fever may also be caused by fluoropolymer-contaminated smoking material. It is prudent to ban tobacco products from fluoropol5mier work areas. Local exhaust ventilation should be installed to remove the process effluents from the work areas. It has been suggested that no health hazards exist unless the fluoropol5mier is heated above 300°C.Fi 

Johnston and his coworkers l have proposed that heating PTFE gives rise to fiimes which contain very fine particulates. The exposure of lung tissues to these particulates can result in a toxic reaction causing pulmonary edema or excessive fluid build 

The products of fluoropolymer decomposition produce certain health effects upon exposure, summarized in Table 13.2. The risks associated with exposure to these effluents have prompted the establishment of a number of exposure limits by various regulatory agencies (Table 13.3). Resin manufacturers can supply available exposure information. 

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Emissions During Processing. During the production of flexible PVC products plasticizers are exposed for up to several minutes to temperatures of - ISO C. The exact conditions depend on the processing technique employed, but it is evident that the loss of plasticizer by evaporation and degradation can be significant. 

The measured value of 2040 g/h and the caleulated value of 1999 g/h are in good agreement, meaning that the equations ean be sueeessfully applied to predict the organic solvents emission during process of automatic degreasing. 

Emissions During Exterior End Use. When flexible PVC is used in exterior appHcations plasticizer loss may occur due to a number of processes which include evaporation, microbial attack, hydrolysis, degradation, exudation, and extraction. It is not possible, due to this wide variety of contribution processes, to assess theoretically the rate of plasticizer loss by exposure outdoors. It is necessary, therefore, to carry out actual measurements over extended periods in real life situations. Litde suitable data have been pubHshed with the exception of some studies on roofing sheet (47). The data from roofing sheet has been used to estimate the plasticizer losses from all outdoor appHcations. This estimate may weU be too high because of the extrapolation involved. Much of this extracted plasticizer does not end up in the environment because considerable degradation takes place during the extraction process. 

Fig. 16. Processes involved in Auger electron emission during X-ray photoelectron spectroscopy.

In a more general application, thermoluminescence is used to study mechanisms of defect annealing in crystals. Electron holes and traps, crystal defects, and color-centers are generated in crystals by isotope or X-ray irradiation at low temperatures. Thermoluminescent emission during the warmup can be interpreted in terms of the microenvironments around the various radiation induced defects and the dynamics of the annealing process (117-118). ... 

Kiibler, K. S., C. A. Caico, Lin-Vien, D. and French, R. N Byproduct Emissions from Poly(trimethylene terephthalate) Studies on the Release of Acrolein and Allyl Alcohol During Processing, Storage, and Shipping of PTT, Technical Information Report, WTC-3659, Shell Chemical Company, Houston, TX, 2000. 

The EE and phE mechanisms for neat polymers proposed by ourselves and others all involve the consequences of breaking bonds during fracture. Zakresvskii et al. (24) have attributed EE from the deformation of polymers to free radical formation, arising from bond scission. We (1) as well as Bondareva et al. (251 hypothesized that the EE produced by the electron bombardment of polymers is due to the formation of reactive species (e.g., free radicals) which recombine and eject a nearby trapped electron, via a non-radiative process. In addition, during the most intense part of the emissions (during fracture), there are likely shorter-lived excitations (e.g., excitons) which decay in a first order fashion with submicrosecond lifetimes. The detailed mechanisms of how bond scissions create these various states during fracture and the physics of subsequent reaction-induced electron ejection need additional insight. 

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