Influence of environment, temperature and time of the thermal modification of ash wood (Fraxinus excelsior L.) on the cellulose weight average degree of polymerization

Thermal Modification ◽

Average Degree ◽

Fraxinus Excelsior ◽

Size Exclusion ◽

Wood Modification ◽

Degradation Reactions ◽

Environment Temperature ◽

Influence of environment, temperature and time of the thermal modification of ash wood (Fraxinus excelsior L.) on the cellulose weight average degree of polymerization . Using the size-exclusion chromatography (HPLC SEC) method, the weight average degree of cellulose polymerization was determined. The polymer was isolated by the Kürschner-Hoffer method from ash wood (Fraxinus excelsior L.). The wood was thermally modified in different environments (nitrogen, steam and air) at 190°C and modification times of 2, 6 and 10 hours. Depending on the anaerobic atmosphere used, the highest values of the weight average degree of cellulose polymerization were obtained for the nitrogen environment, followed by steam and air. The effect of modification time on the weight average degree of polymerization was observed. The highest values were obtained for wood modified at 2 hours, then 6 and 10 hours of modification. The native wood showed the highest degree of polymerization. On the basis of the results obtained, it can be concluded that for the material studied the oxidation and degradation reactions occurring depend on the environment and time for a given temperature of wood modification.

Structural Changes of Oak Wood Main Components Caused by Thermal Modification

Polymers ◽

10.3390/polym12020485 ◽

2020 ◽

Vol 12 (2) ◽

pp. 485 ◽

Cited By ~ 11

Author(s):

Ivan Kubovský ◽

Danica Kačíková ◽

František Kačík

Keyword(s):

Structural Changes ◽

Biological Properties ◽

Thermal Modification ◽

Size Exclusion ◽

Chemical Changes ◽

Oak Wood ◽

Degradation Reactions ◽

Exclusion Chromatography ◽

Main Components

Thermal modification of wood causes chemical changes that significantly affect the physical, mechanical and biological properties of wood; thus, it is essential to investigate these changes for better utilization of products. Fourier transform infrared spectroscopy and size exclusion chromatography were used for evaluation of chemical changes at thermal treatment of oak wood. Thermal modification was applied according to Thermowood process at the temperatures of 160, 180 and 210 °C, respectively. The results showed that hemicelluloses are less thermally stable than cellulose. Chains of polysaccharides split to shorter ones leading to a decrease of the degree of polymerization and an increase of polydispersity. At the highest temperature of the treatment (210 °C), also crosslinking reactions take place. At lower temperatures degradation reactions of lignin predominate, higher temperatures cause mainly condensation reactions and a molecular weight increase. Chemical changes in main components of thermally modified wood mainly affect its mechanical properties, which should be considered into account especially when designing various timber constructions.

Separation of proanthocyanidins by degree of polymerization by means of size-exclusion chromatography and related techniques

Journal of Biochemical and Biophysical Methods ◽

10.1016/s0165-022x(03)00068-x ◽

2003 ◽

Vol 56 (1-3) ◽

pp. 311-322 ◽

Cited By ~ 55

Author(s):

Akio Yanagida ◽

Toshihiko Shoji ◽

Yoichi Shibusawa

Keyword(s):

Size Exclusion ◽

Characterization of a Novel β-Galactosidase fromBifidobacterium adolescentis DSM 20083 Active towards Transgalactooligosaccharides

Applied and Environmental Microbiology ◽

10.1128/aem.66.4.1379-1384.2000 ◽

2000 ◽

Vol 66 (4) ◽

pp. 1379-1384 ◽

Cited By ~ 68

Author(s):

Katrien M. J. Van Laere ◽

Tjakko Abee ◽

Henk A. Schols ◽

Gerrit Beldman ◽

Alphons G. J. Voragen

Keyword(s):

Polyacrylamide Gel Electrophoresis ◽

Sodium Dodecyl ◽

Cell Extract ◽

Exchange Chromatography ◽

Size Exclusion ◽

Bifidobacterium Adolescentis ◽

ABSTRACT This paper reports on the effects of both reducing and nonreducing transgalactooligosaccharides (TOS) comprising 2 to 8 residues on the growth of Bifidobacterium adolescentis DSM 20083 and on the production of a novel β-galactosidase (β-Gal II). In cells grown on TOS, in addition to the lactose-degrading β-Gal (β-Gal I), another β-Gal (β-Gal II) was detected and it showed activity towards TOS but not towards lactose. β-Gal II activity was at least 20-fold higher when cells were grown on TOS than when cells were grown on galactose, glucose, and lactose. Subsequently, the enzyme was purified from the cell extract of TOS-grown B. adolescentis by anion-exchange chromatography, adsorption chromatography, and size-exclusion chromatography. β-Gal II has apparent molecular masses of 350 and 89 kDa as judged by size-exclusion chromatography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis, respectively, indicating that the enzyme is active in vivo as a tetramer. β-Gal II had an optimal activity at pH 6 and was not active below pH 5. Its optimum temperature was 35°C. The enzyme showed highestV max values towards galactooligosaccharides with a low degree of polymerization. This result is in agreement with the observation that during fermentation of TOS, the di- and trisaccharides were fermented first. β-Gal II was active towards β-galactosyl residues that were 1→4, 1→6, 1→3, and 1↔1 linked, signifying its role in the metabolism of galactooligosaccharides by B. adolescentis.

Characterization of the Micelle Formed by a Hydrophobically Modified Pullulan in Aqueous Solution: Size Exclusion Chromatography

Polymers ◽

10.3390/polym13081237 ◽

2021 ◽

Vol 13 (8) ◽

pp. 1237

Author(s):

Jia Yang ◽

Takahiro Sato

Keyword(s):

Size Exclusion ◽

Radius Of Gyration ◽

X Ray ◽

X Ray Scattering ◽

Hydrophobically Modified ◽

Tiny Amount ◽

Size exclusion chromatography equipped with a multi-angle, light-scattering online detector (SEC-MALS) measurements were carried out on a hydrophobically modified pullulan (PUL-OSA) with degrees of substitution (DS) of 0.14, 0.2, and 0.3 in 0.01 M aqueous NaCl to obtain the degree of polymerization (N0) dependence of the radius of gyration (⟨S2⟩1/2) for PUL-OSA in the aqueous NaCl. The result was consistent with the loose flower necklace model proposed in a previous study, and the increase in the chain size with introducing OSA groups was explained by the backbone stiffness of the loose flower necklace formed by PUL-OSA. For PUL-OSA samples with DS = 0.2 and 0.3, ⟨S2⟩1/2 obtained by SEC-MALS in a high N0 region deviated downward from ⟨S2⟩1/2 expected by the loose flower necklace model. This deviation came from a tiny amount of the aggregating component of PUL-OSA, taking a branched architecture composed of loose flower necklaces. Although the aggregating component of PUL-OSA was also detected by previous small angle X-ray scattering measurements, its conformation was revealed in this study by SEC-MALS.