Verarbeitungstechnik und mechanische Verfahrenstechnik, DDR -42 Merseburg Die Stabilisierung des Spinnprozesses sowie die Optimierung des Produktionsprozesses erfordern spezifische Aussagen zum rheologischen Verhalten der Spinnlosung. MeDergebnisse uber den EinfluD von Polymergehalt und Durchschnittspolymerisationsgrad auf das viskoelastische Verhalten von Cellulosexanthogenat-Losungen (Viskoselosungen) bei betriebsnahen Beanspruchungen werden mitgeteilt und die Ergebnisse im Zusammenhang mit der Stabilitat des Spinnprozesses unter Beriicksichtigung des kohasiven Bruchs diskutiert. Peomzua euc1co3bc. 1 . Bnuanue codeparcanus n o n w p a u ezo cpednd cmenenu nonrucepuaayuu na peonozuwcxoe noeedenue ~U C I C O~U A~F I c~a6wmaaqww npoqecca @opmoBaHwx Bonoma w onTwmuaaqww npoqecca npowaBoRcma ~eo6xonwmbl cne-3y~IbTaTbI, nonyseHHare npw wayyeHun BJIHFIHUFI co~epmaHmi nonwmepa H ero cpenHeti cTeneHw nonwmepwaaqaw qM@wYeCKKe RaHHHe OTHOCHTeJIbHO peoJIorwYecKwx CBOPCTB nPHJ&UJIbHOrO PaCTBOpa. B CTaTbe C O O~I Q~B T C F I pi?-H a BFIaKOynpyrHe CBOtfCTBa PaCTBOpOB KCaHTOreHaTa ~eJIJIloJIOabl (BUCKOBbl) . 3 T H PeayJIbTaTbl 0 6 c y m~a m~c~1 B CBRaEI CO CTa6UJIbHOCTbH) IIpOqeCCa @OpMOBaHMFI BOJIOKHa H C YWTOM KOPeaHBHOI' O PaapblBa. Rlreology of viscose. 1. Znfluence of polymer conlent and average degree of polymerization on the flow behaviour of viscoseThe stahilization of the spinning process and the optimization of the production process require information on the rheological behaviour of the spinning solution. Measurement results of the influence of polymer content and average degree of polymerization on the viscoelastic behaviour of cellulose xanthate solutions (viscose solutions) on industrial conditions are presented. Besides, results in connection with the stability of the spinning process considering the cohesive fracture are discussed.
Die Stabilität des Spinnprozesses wird mit Hilfc rhcologischcr Untersuchungen charakterisiert. Ausgehend vom Bean‐spruchungs‐Dehnungs‐Diagramm zur Beschreibung der Dehndeformation des Fadenbiindels im Naßspinnprozeß wird der Einfluß einer Veranderung technologischer Parameter der Viskosefaserherstellung auf die Spinnstabilitat mit Hilfe des Stabilitatsdiagrammes beurteilt. Die Beeinflussung der Spinnsicherhcit durch eine Vcranderung des Cellulose‐gehaltes der Viskose, dcr Spinngeschwindigkeit sowie des Schwefelsaurcgehaltes des Spinnbades wird aufgezcigt und mit Hilfe des Stabilitatsdiagrammes bewertet. Dabei wird festgestellt, daB bci einer Vcrmindcrung der Spinngcschwin‐digkcit Veranderungen in den tcchnologischen Parametern der Viskoscfaserherstellung einen geringeren EinfluB auf die Spinnstabilitat haben.
<p>Magmatic volatiles play a major role in controlling magma dynamics, such as ascent characteristics and eruption style. In order to fully understand their influence in magmatic systems, it is crucial to examine their behaviour within silicate melts. Although numerous studies have been conducted on volatile solubility, exsolution and degassing, some aspects of&#160; magma degassing such as bubble formation, bubble growth and the affect on the distribution of fluid-mobile elements are poorly understood. For instance, magma degassing is likely to affect the abundance and dispersion of fluid-mobile elements, such as Li and B, in the magma. Thus, this study focuses on the diffusivity of Li and B in hydrated silicate melt as a proxy for degassing processes.</p><p>Lithium and boron are particularly suitable as geochemical tracers of degassing processes because they are light elements, present in natural volcanic systems in low concentrations, and have similar characteristics: both elements are fluid-mobile and each has two stable isotopes with different transport behaviours due to their atomic weights, which can lead to isotope fractionation. In order to successfully model their behaviour during magmatic ascent, their diffusivities in silicate melts have to be well constrained.</p><p>Diffusion data in hydrous settings are missing or underrepresented: very little studies have been conducted on boron diffusivity, the literature gives contradictory diffusion coefficients for lithium. In this study, we focus on elemental diffusion and isotopic fractionation of lithium and boron in hydrated silica-rich melts, in order to better understand B diffusivity and solve the discrepancies about Li data.</p><p>Sets of diffusion-couple experiments on synthetic water-bearing rhyolitic glasses have been performed, using an internally heated pressure vessel, at a constant pressure of 300 MPa and temperatures of 700&#176;, 800&#176; and 1000&#176; C, with durations of 0 seconds, 30 minutes, 2 hours and 4 hours. Lithium and boron elemental concentrations have been measured by LA-ICP-MS, resulting in 600 &#956;m long profiles, while isotopic ratios are being evaluated by SIMS analysis.</p><p>The zero-hour experiment indicates that lithium diffuses very rapidly, potentially already at temperatures below 700&#176; C (during the heating process), while boron diffusion is generally slower, hence the necessity of higher temperatures and longer experimental run durations. Overall, our experimental results confirm previous literatue findings that Li diffuses faster in water-bearing melts, and give first constraints on boron diffusivity in hydrated silicate melts, whereas previous studies only considered anhydrous samples. The determination of diffusion coefficients of the two elements gives us a better understanding of the diffusion timescales. This information allows us to interpret additional decompression experiments, simulating a wide range of magma ascent rates, and to correlate the elemental and isotopic behaviour of lithium and boron with decompression-induced bubble formation processes.</p>
Carl Schorlcinmer" Lcuna-Merseburg, Sektion Verfahrenstechnik, II'l3 Verarbeitungsteclinik und Mechanische Verfahrcnstcchnik, DDR-4200 hlerseburg *) VEB Filmfabrik Wolfen, Fotochemisches Kombinat, DDR-4440 Wolfen Viskosen aus unbehmideltem urid strahlenvorbehandelteni Zellstoff wurden rhcologisch untersucht. Dic MeBergebnisse werden hinsichtlich des Losungszustandes dcr Viskose diskutiert. Es zeigt sich, dalj bei den Viskosen aus strahlenvorbehandeltem Zellstoff eine Verminderung des CS2-Einsatzes bei der Viskoseherstellung bis auf Werte unter 30% CS, (hezogen auf Cellulose) rnoglich ist, ohne den Losungszustand der Viskose zu verschlechtern. Peonoeua euch'oabk. 2 . BJcuanue pacxoaa cepoyzaepoda 8 npoyecce xcanmozenuposanua yea~roaoa, nodeepzrtymbsx paaauwbzw npedsapumenbrmw 06pa6omrcaw, na ceogcmsa B U C R O~~C I/Z3J"teHO peOJI0rHYeCKOe nOBeAeHHe B H C K 0 3 , nOJIyYeHHMX H 3 He06pa6OTaHHOi4 I4 IIOABepI'HyTOfi 06JIYYeHHIo UeJIJIIo-~1 0 3 . 170JIyYeHHbIe IIpH 3TOM pe3yJIbTaTbI 06CyXEAaIOTCff C TOYKIl 3peHHH COCTOHHHH KCaHTOreHaTa qeJIJIIoJI03bI B PaCTBOpe. YCTaHOLLlIeHa BOSMOXEHOCTb CHHXEeHHH B npOqeCCe KCaHTOreHHPOBaHMH qeJIJIIoX03, IIOABeprHyTbIX 06nyYeH€m, pacxofia CS, HHme 30% 6e3 I~~M~H~H H F I COCTOHHHH KcaHToreHaTa qenmonom B pacmope. Rheology of viscose. 2. Effect of CS, addition in preparing viscose from differently pretreated pulp on the state of solutionViscoscs prepared from untreated pulp and from pulp pretreated by high-energy radiation were rheologically examined. The results are discussed with regard to the state of solution of the viscoses. I t turned out to be possible, when preparing the viscose from prctreated pulp, to rcduce the addition of CS, to a level below 30% (in relation to cellulose) without deteriorating the state of solution of the viscose.
Die Reaktivität von Chemiefaserzellstoffen, die zur Erklärung der Unterschiede im chemischen Verhalten bei der Verarbeitung zu Viskose herangezogen wird, wurde durch die Molmassenverteilung der Cellulose, durch 13C‐NMR‐Untersuchungen des Zellstoffs, Bestimmung des Filterwertes der Viskose bei reduziertem CS2‐Einsatz und durch die Verteilung der Xanthatgruppen charakterisiert. Drei Möglichkeiten zur Erhöhung der Reaktivität des Zellstoffs werden aufgezeigt: Die Behandlung des Zellstoffs mit Elektronenstrahlen vor der Verarbeitung zu Viskose, die stärkere Delignifizierung des Zellstoffs bei der diskontinuierlichen Kochung und die energieintensivierte Hi‐Heat‐Wäsche.
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