Trace Element Status of Activated Charcoals and Carbon Black: Influence on Thermal Stability of Modified Lyocell Solutions

摘要

The influence of surface-active additives on the thermal stability of cellulose/N-methylmorpholine-N-oxide monohydrate solutions were investigated. The application of a dynamic mixing tool incorporating the additive directly before the forming module enhances the thermal stability. Thermal stabilization by means of a polymeric stabilizer system and adjusting the pH value by sodium hydroxide increased the storage life-time for the additive suspension as revealed by calorimetric isoperibolic step measurements. Further investigations concerned the analysis of the trace element status of the additives. Analytical results for 16 elements have been obtained by inductively coupled plasma optical emission spectrometry (ICP OES) after microwave-assisted acidic digestion, and seven elements, Cr, Cu, Fe, Mn, Mo, Ni, and V have been determined using direct solid sampling high-resolution continuum source graphite furnace AAS (SS-HR-CS CF AAS) as a reference method. Partial least squares regression between measured and calculated temperatures for beginning exothermicity (T-on) has been used to investigate the prediction capability of the investigated techniques. Whereas the ICP OES measurement gives only an acceptable correlation employing all 16 metals plus Fe(II), results obtained by SS-HR-CS CF AAS exhibit a correlation coefficient of 0.99.