Sulfur compounds material balances

Table III lists the material balances for the preparative separations. These are the percent weight recoveries for either asphaltene or maltene defined, using the sulfur balance for an example, as the sum of the amount of sulfur in each cut times the cut weight percent divided by the total sulfur. In general, the balances are in the 80-120% range, which is reasonable considering the amount of sample handling involved. The recoveries are out of line only in a few cases, most notably the Prudhoe Bay maltene nickel balance. In addition, a comparison of the calculated elemental values for the total residua differ somewhat from the raw total values for several residua. These discrepancies are probably attributable to the small samples, multiple sample manipulations, and compounding of individual errors when the asphaltene and maltene data are summed. The data-fitting routine described in the next section was used to obtain a set of best fit data, which were used in the subsequent size calculations.

Vulcanization is a chemical process where sulfur or other materials form crosslinks in the elastomer and thereby improve the polymer s mechanical properties. In many instances, not all of the desired properties reach an optimum level simultaneously. The task is to achieve a balance of the most important property requirements through design of the cure system and time-temperature cure cycle so as to attain the necessary compound mechanical properties. Frequently, the curing equipment available, such as presses or autoclaves, do not allow the curing conditions to be varied as desired, and so a cure system compatible with the existing equipment must be designed and also meet the compoimd performance requirements. 

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