SEC-MALS analysis of cellouronic acid prepared from regenerated cellulose by TEMPO-mediated oxidation

Cellulose ◽  
2006 ◽  
Vol 13 (1) ◽  
pp. 73-80 ◽  
Author(s):  
Izumi Shibata ◽  
Masahiro Yanagisawa ◽  
Tsuguyuki Saito ◽  
Akira Isogai
Author(s):  
Michael E. Rock ◽  
Vern Kennedy ◽  
Bhaskar Deodhar ◽  
Thomas G. Stoebe

Cellophane is a composite polymer material, made up of regenerated cellulose (usually derived from wood pulp) which has been chemically transformed into "viscose", then formed into a (1 mil thickness) transparent sheet through an extrusion process. Although primarily produced for the food industry, cellophane's use as a separator material in the silver-zinc secondary battery system has proved to be another important market. We examined 14 samples from five producers of cellophane, which are being evaluated as the separator material for a silver/zinc alkaline battery system in an autonomous underwater target vehicle. Our intent was to identify structural and/or chemical differences between samples which could be related to the functional differences seen in the lifetimes of these various battery separators. The unused cellophane samples were examined by transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS). Cellophane samples were cross sectioned (125-150 nm) using a diamond knife on a RMC MT-6000 ultramicrotome. Sections were examined in a Philips 430-T TEM at 200 kV. Analysis included morphological characterization, and EDS (for chemical composition). EDS was performed using an EDAX windowless detector.


2019 ◽  
Vol 821 ◽  
pp. 89-95
Author(s):  
Wanasorn Somphol ◽  
Thipjak Na Lampang ◽  
Paweena Prapainainar ◽  
Pongdhorn Sae-Oui ◽  
Surapich Loykulnant ◽  
...  

Poly (lactic acid) or PLA was reinforced by nanocellulose and polyethylene glycol (PEG), which were introduced into PLA matrix from 0 to 3 wt.% to enhance compatibility and strength of the PLA. The nanocellulose was prepared by TEMPO-mediated oxidation from microcrystalline cellulose (MCC) powder and characterized by TEM, AFM, and XRD to reveal rod-like shaped nanocellulose with nanosized dimensions, high aspect ratio and high crystallinity. Films of nanocellulose/PEG/PLA nanocomposites were prepared by solvent casting method to evaluate the mechanical performance. It was found that the addition of PEG in nanocellulose-containing PLA films resulted in an increase in tensile modulus with only 1 wt% of PEG, where higher PEG concentrations negatively impacted the tensile strength. Furthermore, the tensile strength and modulus of nanocellulose/PEG/PLA nanocomposites were higher than the PLA/PEG composites due to the existence of nanocellulose chains. Visual traces of crazing were detailed to describe the deformation mechanism.


2019 ◽  
Vol 33 (9) ◽  
pp. 1285-1297 ◽  
Author(s):  
Cornelia Wiegand ◽  
Martin Abel ◽  
Uta-Christina Hipler ◽  
Peter Elsner ◽  
Michael Zieger ◽  
...  

Background Application of controlled in vitro techniques can be used as a screening tool for the development of new hemostatic agents allowing quantitative assessment of overall hemostatic potential. Materials and methods Several tests were selected to evaluate the efficacy of cotton gauze, collagen, and oxidized regenerated cellulose for enhancing blood clotting, coagulation, and platelet activation. Results Visual inspection of dressings after blood contact proved the formation of blood clots. Scanning electron microscopy demonstrated the adsorption of blood cells and plasma proteins. Significantly enhanced blood clot formation was observed for collagen together with β-thromboglobulin increase and platelet count reduction. Oxidized regenerated cellulose demonstrated slower clotting rates not yielding any thrombin generation; yet, led to significantly increased thrombin-anti-thrombin-III complex levels compared to the other dressings. As hemostyptica ought to function without triggering any adverse events, induction of hemolysis, instigation of inflammatory reactions, and initiation of the innate complement system were also tested. Here, cotton gauze provoked high PMN elastase and elevated SC5b-9 concentrations. Conclusions A range of tests for desired and undesired effects of materials need to be combined to gain some degree of predictability of the in vivo situation. Collagen-based dressings demonstrated the highest hemostyptic properties with lowest adverse reactions whereas gauze did not induce high coagulation activation but rather activated leukocytes and complement.


2021 ◽  
Vol 13 (3) ◽  
pp. 1268
Author(s):  
Miriam Ribul ◽  
Kate Goldsworthy ◽  
Carole Collet

In the context of the circular economy, materials in scientific development present opportunities for material design processes that begin at a raw state, before being introduced into established processes and applications. The common separation of the scientific development of materials from design intervention results in a lack of methodological approaches enabling designers to inform new processes that respond to new material properties. This paper presents the results of a PhD investigation that led to the development and application of a Material-Driven Textile Design (MDTD) methodology for design research based in the materials science laboratory. It also presents the development of the fabrication of a textile composite with regenerated cellulose obtained from waste textiles, resulting from the MDTD methodology informing novel textile processes. The methods and practice which make up this methodology include distinct phases of exploration, translation and activation, and were developed via three design-led research residencies in materials science laboratories in Europe. The MDTD methodology proposes an approach to design research in a scientific setting that is decoupled from a specific product or application in order to lift disciplinary boundaries for the development of circular material-driven fabrication and finishing processes at the intersection of materials science and design.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Bernhard Ungerer ◽  
Ulrich Müller ◽  
Antje Potthast ◽  
Enrique Herrero Acero ◽  
Stefan Veigel

AbstractIn the development of structural composites based on regenerated cellulose filaments, the physical and chemical interactions at the fibre-matrix interphase need to be fully understood. In the present study, continuous yarns and filaments of viscose (rayon) were treated with either polymeric diphenylmethane diisocyanate (pMDI) or a pMDI-based hardener for polyurethane resins. The effect of isocyanate treatment on mechanical yarn properties was evaluated in tensile tests. A significant decrease in tensile modulus, tensile force and elongation at break was found for treated samples. As revealed by size exclusion chromatography, isocyanate treatment resulted in a significantly reduced molecular weight of cellulose, presumably owing to hydrolytic cleavage caused by hydrochloric acid occurring as an impurity in pMDI. Yarn twist, fibre moisture content and, most significantly, the chemical composition of the isocyanate matrix were identified as critical process parameters strongly affecting the extent of reduction in mechanical performance. To cope with the problem of degradative reactions an additional step using calcium carbonate to trap hydrogen ions is proposed.


Physchem ◽  
2021 ◽  
Vol 1 (2) ◽  
pp. 163-175
Author(s):  
Philipp Hawe ◽  
Vitor R. R. Silveira ◽  
Robert Bericat Vadell ◽  
Erik Lewin ◽  
Jacinto Sá

More sustainable solutions are needed to produce chemicals and fuels, mainly to face rising demands and mitigate climate change. Light, as a reagent, has emerged as a route to activate small molecules, e.g., H2O, CO2, N2, and make complex chemicals in a process called photocatalysis. Several photosystems have been proposed, with plasmonic technology emerging as one the most promising technologies due to its high optical absorption and hot-carrier formation. However, the lifetime of hot carriers is unsuitable for direct use; therefore, they are normally coupled with suitable charge-accepting materials, such as semiconductors. Herein, a system is reported consisting of Au supported in p-Cu2O. The combination of p-Cu2O intrinsic photoactivity with the plasmonic properties of Au extended the system’s optical absorption range, increasing photocatalytic efficiency. More importantly, the system enabled us to study the underlying processes responsible for hot-hole transfer to p-Cu2O. Based on photocatalytic studies, it was concluded that most of the holes involved in aniline photo-oxidation come from hot-carrier injections, not from the PIRET process.


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