PAN-based systems

Carbon-carbon made with a cellulose based carbon fiber has a coefficient of thermal expansion (CTE) about twice that of a PAN based carbon fiber system. Since the cellulose based carbon-carbon has a CTE fairly close to that of SiC (or SisN4), it is consequently less of a mismatch than a PAN based system. Unfortunately, to take advantage of the improved strength of a PAN based system, it will be necessary to accommodate this serious mismatch of CTEs and will require a sustained program of research to find a solution. 

PAN-based systems have been the focus of much recent interest. Although the polymer is assumed to be nonsolvating, NMR studies [107] suggest that there may be some competition (albeit small) for solvation between the polymer and plasticizing... 

As an example, a recent intercomparison (37) included three N02 measurement techniques aTDLAS-based system and two chemical-based systems— the photolysis-ozone chemiluminescence system diagramed in Figure 7 and an instrument based on N02 plus luminol chemiluminescence. Above 2 ppbv the three instruments gave similar results, but at sub-ppbv the results from the three techniques became dissimilar. Tests on the prepared mixtures showed that the luminol results were affected by expected interferences from 03 and PAN. No interferences were found in the TDLAS system, but near the detection limit the data analysis procedures calculated levels of N02 that were too high. The outcome of this intercomparison was close to the ideal the sensitivity, specificity, accuracy, and precision of each instrument were objectively analyzed previous data sets taken by different systems can now be reliably evaluated and each investigator was able to perceive areas in which the technique could be improved. 

Suzuki et al. studied the adsorption of dimethyl sulfide (DMS) from city gas in a dynamic adsorption system using Pitch-based and PAN-based activated carbon... 

Rejowski, R., Pinto, J.M., 2001, Paper PIO, Proceedings of 2 . Pan American Workshop on Process Systems Engineering, Guaruja-Sao Paulo, Brazil. Sasikumar, M., Prakash, P.Patil S.M., Ramani, S., 1997, Knowledge-Based Systems 10, 169. 

The possible influences of the cookware also demonstrate the necessity of designing the cooktop as a system for example, the alteration of the flatness of the pan base while water comes to the boil must be taken into calculation. The flatness of the pan base is altered during heating-up (see Fig. 3.7) and, in turn, this alteration influences the boiling time and so the performance of the whole cooking system. 

Nitrogen gas pyrolysis system was designed and set up to transform the PAN hollow fiber membrane into PAN-based carbon hollow fiber membrane. The instrument involved in this system is illustrated in Fig. 5.3. Caibolite (Model CTF 12/65/550) wire wound tube furnace with the Eurotherm 2416CC temperature control system is used for the pyrolysis of the PAN hollow fiber membrane. The furnace can be operated at a maximum temperature of 1200°C and has the abihty to control the heating rate and the thermal soak time during the pyrolysis process. 

These structural differences may be important selection criteria in view of battery applications. In general, PAN-based membranes, having characteristics somewhat approaching those of a "tme" polymer electrolyte entity, are be expected to be more stable than PMMA-based membranes or, generally, than membranes having characteristics of purely hybrid systems. 

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