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Elena Kokoliou - One of the best experts on this subject based on the ideXlab platform.

  • Product needs
    internal, 2017
    Co-Authors: Elena Kokoliou
    Abstract:

    structure for containing a consumer product comprising a. a cellulose based substrate comprising: i. from about 50% to about 75% of a bamboo derived pulp; ii … coating said cellulosic base substrate having a thickness of from about 0.02 mm to about 0.1 mm, said laminate structure forming a tub having a base and a perimeter

  • Composition
    internal, 2017
    Co-Authors: Elena Kokoliou
    Abstract:

    while wet shaving are: Polyethylene oxide (PEO) Polyethylene glycol (PEG) Polyvinyl pyrrolidone (PVP) Polyacrylamide Modified hydroxyalkyl cellulose … the biodegradation of such polymers. Biodegradable polymers may be made from biosources like corn, wood cellulose etc. or can also be synthesized by bacteria from small

  • Coating Properties
    internal, 2017
    Co-Authors: Elena Kokoliou
    Abstract:

    in a physical blend with fibers such as cellulose and thermoplastic binder fibers. The resulting structure is called the absorbent core. The absorbent core relies

Nikos Chatzigrigoriou - One of the best experts on this subject based on the ideXlab platform.

Luiz Junior - One of the best experts on this subject based on the ideXlab platform.

Panagiotis Giannopoulos - One of the best experts on this subject based on the ideXlab platform.

Arnulf Kai Mahler - One of the best experts on this subject based on the ideXlab platform.

  • Chromophores in Cellulosics, XVIII. Degradation of the cellulosic key chromophore 5,8-dihydroxy-[1,4]-naphthoquinone under conditions of chlorine dioxide pulp bleaching: a combined experimental and theoretical study
    Cellulose, 2018
    Co-Authors: Takashi Hosoya, Klaus Eibinger, Heidemarie Reiter, Martin Spitzbart, Wolfgang Kreiner, Arnulf Kai Mahler, Thomas Dietz, Nele Sophie Zwirchmayr, Karl Michael Klinger, Heribert Winter
    Abstract:

    5,8-Dihydroxy-[1,4]-naphthoquinone (DHNQ) is one of the key chromophores occurring in all types of aged Cellulosics. This study investigates the degradation of DHNQ by chlorine dioxide at moderately acidic (pH 3) conditions, corresponding to the conditions of industrial bleaching (“D stage”). The degradation involves three major pathways. As initial reaction, a hydrogen transfer from DHNQ to chlorine dioxide via a PCET mechanism occurs to form a radical DHNQ^· and chlorous acid. DHNQ^· is then attacked by water to give a pentahydroxynaphthalene radical PHN^· that is stabilized by strong delocalization of the non-paired electron into its aromatic ring. PHN^· immediately disproportionates to give the observable intermediate 1,2,4,5,8-pentahydroxynapththalene ( I ), which was comprehensively confirmed by NMR and MS (path A). In the presence of excess ClO_2, I is immediately further oxidized into acetic acid, glycolic acid, oxalic acid and CO_2 as the final, stable, and non-colored products (path C). In the absence of excess ClO_2, elimination of water from I regenerates DHNQ (path B), so that at roughly equimolar DHNQ/ClO_2 ratios ClO_2 is fully consumed while a major part of DHNQ is recovered. To avoid such DHNQ “recycling” under ClO_2 consumption—and to completely degrade DHNQ to colorless degradation products instead—ClO_2 must be applied in at least fivefold molar excess relative to DHNQ. Graphical Abstract

  • degradation of the cellulosic key chromophores 2 5 and 2 6 dihydroxyacetophenone by hydrogen peroxide under alkaline conditions chromophores in Cellulosics xvii
    Cellulose, 2018
    Co-Authors: Nele Sophie Zwirchmayr, Klaus Eibinger, Heidemarie Reiter, Martin Spitzbart, Wolfgang Kreiner, Thomas Dietz, Takashi Hosoya, Ute Henniges, Markus Bacher, Arnulf Kai Mahler
    Abstract:

    The dihydroxyacetophenones 2,5-dihydroxyacetophenone (2,5-DHAP) and 2,6-dihydroxy-acetophenone (2,6-DHAP) belong to the key chromophores in cellulosic materials. The pulp and paper industry targets these key chromophores in their bleaching sequences to obtain brighter products. 2,5-DHAP and 2,6-DHAP were degraded with hydrogen peroxide in alkaline media, similar to conditions of peroxide bleaching (P stage) in industrial pulp bleaching. Degradation product analyses were performed by GC–MS and NMR. The degradation reaction starts by loss of acetic acid originating from the acetyl moiety of the dihydroxyacetophenones (Baeyer–Villiger rearrangement). Further reaction steps involve introduction of another hydroxyl group at C-1 (previously acetyl bearing), and further oxidation of the resulting trihydroxybenzene to quinone intermediates which are ultimately degraded to a mixture of low-molecular weight carboxylic acids.

  • Chromophores in lignin-free cellulosic materials belong to three compound classes. Chromophores in Cellulosics, XII
    Cellulose, 2015
    Co-Authors: Philipp Korntner, Klaus Eibinger, Heidemarie Reiter, Martin Spitzbart, Thomas Röder, Andrea Borgards, Wolfgang Kreiner, Thomas Dietz, Takashi Hosoya, Arnulf Kai Mahler
    Abstract:

    The chromophore release and identification method isolates well-defined chromophoric substances from different cellulosic matrices, such as highly bleached pulps, cotton linters, bacterial cellulose, viscose or lyocell fibers, and cellulose acetates. The chromophores are present only in extremely low (ppm to ppb) concentrations. The concept of primary and secondary chromophores is introduced, with primary chromophores arising only from the polysaccharides inherent to cellulosic materials. Secondary chromophores also include atoms from the chemicals used to process the cellulose. Most primary chromophores belong to one of three compound classes: hydroxy-[1,4]-benzoquinones, hydroxy-[1,4]-naphthoquinones, and hydroxyacetophenones. Among them, three individual compounds dominate: 2,5-dihydroxy-[1,4]-benzoquinone, 5,8-hydroxy-[1,4]-naphthoquinone, and 2,5-dihydroxyacetophenones, amounting to more than 80 % of the total isolated chromophores in most cases. In lignin-free Cellulosics, these three compounds can thus be regarded as key chromophores. The prevalence of these molecules is due to both exceptionally strong resonance stabilization, as reflected in delocalized double bonds, and their ready reformation from carbohydrate degradation products by recondensation reactions. The findings that (a) most chromophores in lignin-free cellulosic materials belong to only three compound classes and that (b) three chromophore compounds make up the bulk of the chromophore mixtures are foundational for future bleaching research: Based on this knowledge, specific searches for optimized bleaching conditions can now concentrate on these compounds and still cover the vast majority of chromophores.