Titration secondary technique

Wet chemical methods determining titratable amine ate reported for products entering urethane (amine number as meq/g) or epoxy (AHEW = amine hydrogen equivalent weight) trade appHcations. For secondary amines /V-nitrosamine contaminants are reportable down to ppb using Thermoelectron Corporation thermal energy analy2er techniques. 

As already mentioned in the beginning of this text (almost) every experimental technique described here has its technological counterpart. In the case of Coulometric Titration, this is the intercalation process in secondary electrodes treated in Section II.3.ii. The technological counterpart of what remains to be discussed in the next section, are the emf sensors. Since we dealt with general aspects on equilibrium cells quite extensively already in the application part (Section II.3.i), we will restrict ourselves to only very few remarks. 

In contrast to direct potentiometry, the potentiometric titration technique offers the advantage of high accuracy and precision, although at the cost of increased time and increased consumption of titrants. Another advantage is that the potential break at the titration endpoint must be well defined, but the slope of the sensing electrode response need be neither reproducible nor Nernstian, and the actual potential values at the endpoint are of secondary interest. In many cases, this allows for the use of simplified sensors. 

Owing to metal chlorides titration by the coulometric method, and carboxylic acid titration by the potentiometric method, it is possible to follow the metal soaps consumption during thermomechanical heat treatments. This new technique provides a better understanding of the stabilization mechanisms of PVC with the calciumr-zinc system, and offers a better explanation of synergistic effects between metal soaps and secondary stabilizers such as epoxidized soya-bean oil, a-phenylindole, and butanediol-p-aminocroto-nate. The influence of these last stabilizers on zinc chloride formation enables us to classify them into short- and longterm stabilizers. 

At Johnson Johnson, the structure of oxidized cellulose was investigated by several techniques. Chemically, a differential titration was developed to measure the carboxylic acid content and any saponifiable secondary functions. The titration measures carboxy lic protons by ion exchange. By treating the resulting ion exchanged solution with a measured excess of base, the saponifiable function is measured by acidimetric back-titration. Using the differential titration, a previously measured 20 wt% carboxylic acid content is revealed to be 18 wt% carboxylic acid and 2 w t% saponifiable moiety (unpublished). 

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