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- Mikkonen, K. S., et al.
(author)
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Glucomannan composite films with cellulose nanowhiskers
- 2010
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In: Cellulose. - : Springer Science and Business Media LLC. - 0969-0239 .- 1572-882X. ; 17:1, s. 69-81
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Journal article (peer-reviewed)abstract
- Spruce galactoglucomannans (GGM) and konjac glucomannan (KGM) were mixed with cellulose nanowhiskers (CNW) to form composite films. Remarkable effects of CNW on the appearance of the films were detected when viewed with regular and polarizing optical microscopes and with a scanning electron microscope. Addition of CNW to KGM-based films induced the formation of fiberlike structures with lengths of several millimeters. In GGM-based films, rodlike structures with lengths of several tens of micrometers were formed. The degree of crystallinity of mannan in the plasticized KGM-based films increased slightly when CNW were added, from 25 to 30%. The tensile strength of the KGM-based films not containing glycerol increased with increasing CNW content from 57 to 74 MPa, but that of glycerol-plasticized KGM and GGM films was not affected. Interestingly, the notable differences in the film structure did not appear to be related to the thermal properties of the films.
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- Stevanic, J. S., et al.
(author)
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Bacterial Nanocellulose-Reinforced Arabinoxylan Films MELL TE, 1964, V19, P247
- 2011
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In: Journal of Applied Polymer Science. - : Wiley. - 1097-4628 .- 0021-8995. ; 122:2, s. 1030-1039
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Journal article (peer-reviewed)abstract
- There is an increasing interest in substituting today's films for food packaging applications with films based on renewable resources. For this purpose, rye arabinoxylans, unmodified and enzymatically debranched, were studied for the preparation of neat films and composite films reinforced with bacterial cellulose (BC). Mixing in a homogenizer produced optically transparent, uniform films. Physical and mechanical characteristics of such films are here reported. Debranching of the arabinoxylan caused an increase in its crystallinity of 20%. Debranching as well as reinforcement with BC resulted in a decrease of the moisture sorption of the films. The debranching also resulted in a reduced breaking strain while the reinforcement with BC increased stiffness and strength of the films. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 122: 1030-1039, 2011
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- Stevanic, Jasna S., et al.
(author)
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Wood cell wall mimicking for composite films of spruce nanofibrillated cellulose with spruce galactoglucomannan and arabinoglucuronoxylan
- 2014
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In: Journal of Materials Science. - : Springer Science and Business Media LLC. - 0022-2461 .- 1573-4803. ; 49:14, s. 5043-5055
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Journal article (peer-reviewed)abstract
- Two hemicelluloses (HCs), galactoglucomannan (GGM) and arabinoglucuronoxylan (AGX), and nanofibrillated cellulose (NFC) were isolated from spruce wood and used for the preparation of composite films containing high amounts of cellulose, i.e. 85 and 80 wt% of NFC, respectively. The films were prepared in two ways: (i) by the pre-sorption of HCs on NFC and (ii) by the mixing of components in the usual way. Pre-sorption was applied in an attempt to mimic the carbohydrate biosynthesis pattern during wood cell wall development, where HCs were deposited on the cellulose fibrils prior to lignification taking place. It was assumed that pre-sorption would result in a better film-forming as well as stronger and denser composite films. The mechanical, thermal, structural, moisture sorption and oxygen barrier characteristics of such composite films were tested in order to examine whether the performance of composite films prepared by pre-sorption was better, when compared to the performance of composite films prepared by mixing. The performance of composite films was also tested with respect to the HCs used. All the films showed quite similar barrier and mechanical properties. In general, stiff, strong and quite ductile films were produced. The moisture sorption of the films was comparably low. The oxygen barrier properties of the films were in the range of commercially used poly ethylene vinyl alcohol films. However, the pre-sorption procedure for the preparation of composite films resulted in no additional improvement in the performance of the films compared to the corresponding composite films that had been prepared using the mixing process. Almost certainly, the applied mixing process led to an optimal mixing of components for the film performance achieved. The GGM contributed to a somewhat better film performance than the AGX did. Indications were observed for stronger interactions between the GGM and NFC than that for the AGX and NFC.
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| 7. |
- Liu, Jun, et al.
(author)
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Nanofibrillated cellulose originated from birch sawdust after sequential extractions : a promising polymeric material from waste to films
- 2014
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In: Cellulose. - : Springer Science and Business Media LLC. - 0969-0239 .- 1572-882X. ; 21:4, s. 2587-2598
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Journal article (peer-reviewed)abstract
- The residual cellulose of wood processing waste, sawdust, which was leftover after sequential hot-water extraction processes to isolate hemicelluloses and lignin in a novel forest biorefinery concept, was explored as the starting material for preparation of a highly value-added polymeric material, nanofibrillated cellulose (NFC) also widely termed as cellulose nanofiber, which has provided an alternative efficient way to upgrade sawdust waste. The residual cellulose in sawdust was converted to a transparent NFC suspension in water through the 2,2,6,6-tetramethylpiperidine-1-oxyl radical/NaClO/NaBr oxidization approach. The resultant NFC with a dimension of ca. 5 nm in width and hundreds of nanometers in length were further processed into NFC films. The morphological features of the NFC suspension and its films were assessed by transmission electron microscopy and scanning electron microscopy. Highly even dispersion of NFC fibrils in the films originated from sawdust feasibly contributes to the outstanding mechanical performance of the films. NFC suspension with higher carboxylate content and its resultant NFC films were found to show higher transmission of light.
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