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A homologous series of partially hydrolyzed celluloses (level-off-DP cellulose) with weight-average molecular weight (DPw) < 150 were peracetylated and characterized by 1H-NMR spectroscopy. The results demonstrate the utility of 1H-NMR spectroscopy to assign the chemical shifts of all end groups of the peracetylated cellulose. On the one hand, the chemical shifts of all methine and methylene protons...
Apart from the reducing end groups, most celluloses contain small amounts of carbonyl groups in the μmol/g range, which are introduced into the material by a variety of preparation, processing and purification steps. By a combination of carbonyl-selective fluorescence labeling (CCOA method) and UV resonance Raman spectroscopy it was demonstrated that carbonyls in celluloses are not only present as...
The research presented herein is the first attempt to probe the chemical nature of lignocellulosic samples by the application of carbon near edge X-ray absorption fine structure spectroscopy (C-NEXAFS). C-NEXAFS is a soft X-ray technique that principally provides selective interrogation of discrete atomic moieties using photoelectrons of variable energies. The X1A beam line of the National Synchrotron...
The kinetics of the TEMPO-mediated oxidation of regenerated celluloses has been studied. It is revealed that the oxidation reaction of the regenerated celluloses by the 2,2,6,6-tetramethyl-piperidine-1-oxyl radical (TEMPO)–NaBr–NaOCl system can be approximately described by first-order kinetics with respect to substrate. In the concentration range used the rate constant k is directly proportional...
N-Methylmorpholine-N-oxide monohydrate (NMMO) is used as solvent for cellulose in the Lyocell process as a modern industrial fiber-making technology. Undesired chemical side reactions and byproduct formation in the system cellulose/NMMO/water are known to cause detrimental effects, such as chromophore formation and discoloration of the resulting fibers. A detailed kinetic study on the influence of...
To develop low-cost and environmentally friendly polymeric materials for enrichment, separation and remediation of metal ions from water, novel reactive graft copolymers based on cellulose extracted from pine needles were synthesized by grafting of poly(glycidyl methacrylate) alone and with comonomers acrylic acid, acrylamide and acrylonitrile by benzoyl peroxide initiation. Structural aspects of...
The chemical shift anisotropies (CSAs) of cellulose Iα and Iβ, the two crystalline constituents of bacterial cellulose produced by Acetobacter xylinum (DSM 14666), and regenerated cellulose II are reported for each of the spectroscopically resolved carbon resonances using the phase adjusted spinning sideband (PASS) experiment. The data are compared with experimental results using the recoupling of...
Within the framework of our studies on enzyme-compatible support matrix structures, we succeeded in making further derivatives of the new aminocellulose type ‘P–CH2–NH–(X)–NH2’ (P = cellulose); (X) = –(CH2)2– (EDA), –(CH2)2–NH–(CH2)2– (DETA), –(CH2)3–NH–(CH2)3– (DPTA), –(CH2)2–NH–(CH2)2–NH–(CH2)2– (TETA) accessible by nucleophilic substitution reaction with ethylenediamine (EDA) and selected oligoamines...
The chemical shift anisotropies (CSAs) of cellulose Iα and Iβ, the two crystalline constituents of bacterial cellulose produced by Acetobacter xylinum (DSM 14666), and regenerated cellulose II are reported for each of the spectroscopically resolved carbon resonances using the phase adjusted spinning sideband (PASS) experiment. The data are compared with experimental results using the recoupling of...
Functional thiomethyl and thiosulfate derivatives of carboxymethylcellulose (CMC, DS = 0.9) were synthesized by nucleophilic displacement reactions. Alkylation of CMC by allyl glycidyl ether took mainly place at the primary positions of the cellulose backbone and yielded a 6-O-(3′-allyloxy-2′-hydroxypropyl)-CMC 1 with a partial DS of 3′-allyloxy-2′-hydroxypropyl substituents DSallyl of up to 0.43...
To develop low-cost and environmentally friendly polymeric materials for enrichment, separation and remediation of metal ions from water, novel reactive graft copolymers based on cellulose extracted from pine needles were synthesized by grafting of poly(glycidyl methacrylate) alone and with comonomers acrylic acid, acrylamide and acrylonitrile by benzoyl peroxide initiation. Structural aspects of...
N-Methylmorpholine-N-oxide monohydrate (NMMO) is used as solvent for cellulose in the Lyocell process as a modern industrial fiber-making technology. Undesired chemical side reactions and byproduct formation in the system cellulose/NMMO/water are known to cause detrimental effects, such as chromophore formation and discoloration of the resulting fibers. A detailed kinetic study on the influence of...
The structure and morphology of cellulose extracted from wheat were studied. It was found that the extraction process is effective and hemicelluloses and lignin can be extracted completely. Cellulose in wheat straw was identified as cellulose I allomorph with low crystallinity and the crystallinity of cellulose from different parts of the wheat straw has little difference. There was no metastable...
The kinetics of the TEMPO-mediated oxidation of regenerated celluloses has been studied. It is revealed that the oxidation reaction of the regenerated celluloses by the 2,2,6,6-tetramethyl-piperidine-1-oxyl radical (TEMPO)–NaBr–NaOCl system can be approximately described by first-order kinetics with respect to substrate. In the concentration range used the rate constant k is directly proportional...
Within the framework of our studies on enzyme-compatible support matrix structures, we succeeded in making further derivatives of the new aminocellulose type ‘P–CH2–NH–(X)–NH2’ (P = cellulose); (X) = –(CH2)2– (EDA), –(CH2)2–NH–(CH2)2– (DETA), –(CH2)3–NH–(CH2)3– (DPTA), –(CH2)2–NH–(CH2)2–NH–(CH2)2– (TETA) accessible by nucleophilic substitution reaction with ethylenediamine (EDA) and selected oligoamines...
A homologous series of partially hydrolyzed celluloses (level-off-DP cellulose) with weight-average molecular weight (DPw) < 150 were peracetylated and characterized by 1H-NMR spectroscopy. The results demonstrate the utility of 1H-NMR spectroscopy to assign the chemical shifts of all end groups of the peracetylated cellulose. On the one hand, the chemical shifts of all methine and methylene...
The structure and morphology of cellulose extracted from wheat were studied. It was found that the extraction process is effective and hemicelluloses and lignin can be extracted completely. Cellulose in wheat straw was identified as cellulose I allomorph with low crystallinity and the crystallinity of cellulose from different parts of the wheat straw has little difference. There was no metastable...
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