| 1. |
- Backman, A.C., et al.
(författare)
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Differences in wood material responses for radial and tangential direction as measured by dynamic mechanical thermal analysis
- 2001
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Ingår i: Journal of Materials Science. - 0022-2461 .- 1573-4803. ; 36:15, s. 3777-3783
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Tidskriftsartikel (refereegranskat)abstract
- Wood is a complex cellular structure with different properties in the radial and tangential direction. Many researchers have measured dynamic properties in the longitudinal direction and a few in the radial direction but very little data can be found in the literature on dynamic mechanical properties in the tangential direction. The purpose of the work presented in this paper was to investigate the dynamic mechanical behaviour in the radial and tangential directions of wood (Pinus sylvestris). Testing was done in tension at 1 Hz with a Dynamic Mechanical Thermal Analyser. Properties in radial and tangential direction were different. The radial direction showed a higher elastic modulus and lower loss factor levels at temperatures between -120°C and 80°C. The tangential direction had on average a higher peak temperature than the radial direction for a loss factor peak around -80°C. It is the opposite of synthetic composites where the stiffer direction has a higher peak temperature. A loss factor peak at around 0°C was seen, most significantly in the tangential direction. This peak has scarcely been reported in the literature before. The distance between annual rings did not significantly affect the dynamic behaviour in the tangential direction.
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| 2. |
- Carlsson, Mats, et al.
(författare)
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Synthesis of LaxCe1-xB6 whiskers
- 2004
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Ingår i: Journal of Materials Science. - : Springer Science and Business Media LLC. - 0022-2461 .- 1573-4803. ; 40:11, s. 2991-2994
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Tidskriftsartikel (refereegranskat)
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| 3. |
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| 4. |
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| 5. |
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| 6. |
- Fahlén, Jesper, et al.
(författare)
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Cross-sectional structure of the secondary wall of wood fibers as affected by processing
- 2003
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Ingår i: Journal of Materials Science. - 0022-2461 .- 1573-4803. ; 38:1, s. 119-126
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Tidskriftsartikel (refereegranskat)abstract
- Understanding the arrangement of wood polymers within the fiber wall is important for understanding the mechanical properties of the fibers themselves. Due to their high load bearing ability, the arrangement of cellulose fibrils within the cell wall are of special interest. In this work AFM-Atomic Force Microscopy-in combination with image processing has been used to obtain more information about the arrangement of cellulose aggregates (fibrils) in the secondary cell wall layer of spruce wood. The effects of chemical processing on the arrangement of these cellulose aggregates were also studied. Enlargement of cellulose aggregates was found in the initial phase of the kraft cook. This increase in cellulose aggregate dimensions depended mostly on temperature for treatment temperatures above 140degreesC, regardless of the amount of alkali present. Although hemicelluloses are lost to various degrees under alkaline conditions, the increase in cellulose aggregate size was mainly related to thermally induced rearrangement of the cellulose molecules. The mean side length of cellulose aggregates was found to be around 18 nm in unprocessed wood and 23 nm in processed wood. The cellulose aggregates were assumed to be square shaped in cross section in both cases.
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| 7. |
- He, Ming, et al.
(författare)
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A controllable approach for the synthesis of titanate derivatives of potassium tetratitanate fiber
- 2004
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Ingår i: Journal of Materials Science. - 0022-2461 .- 1573-4803. ; 39, s. 3745-3750
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Tidskriftsartikel (refereegranskat)abstract
- Three types titanate derivatives, K2Ti6O13 fiber, K2Ti8O17 fiber and anatase TiO2 fiber, were synthesized by ion-exchange reaction from potassium tetratitanate fiber (K2Ti4O9) based on the hydrate conditions predicted by a thermodynamic model. These products were formed by a heat treatment of the corresponding hydrate intermediates K1.33H0.67Ti4O9·H2O, KHTi4O9·0.5H2O and H2Ti4O9·1.2H2O which were quantitatively obtained by controlling the pH value and the equilibrium concentration of potassium ion. The mole ratio of Ti/K in solid phase (R) of the target products was taken as the controlling aim in the hydrate process. The temperature for heat treatment of hydrate intermediates was determined by thermogravimetry (TG) and differential scanning calorimetry (DSC). All products retained fibrous morphology similar to that of K2Ti4O9 used as the starting material.
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| 8. |
- Larsson, P, et al.
(författare)
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Improvements of the microstructure and erosion resistance of boron carbide with additives
- 2000
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Ingår i: JOURNAL OF MATERIALS SCIENCE. - : KLUWER ACADEMIC PUBL. - 0022-2461. ; 35:14, s. 3433-3440
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Tidskriftsartikel (refereegranskat)abstract
- A series of test materials were produced from boron carbide (B4C) powders with additions of either boron in amounts up to 60 wt.%, silicon (4 wt.%) or silicon and silicon carbide (4 wt.% and 30 wt.%, respectively). The powder mixtures were densified by en
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| 9. |
- Li, JG, et al.
(författare)
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High-strength aluminate cement produced by cold isostatic pressing
- 2000
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Ingår i: JOURNAL OF MATERIALS SCIENCE. - : KLUWER ACADEMIC PUBL. - 0022-2461. ; 35:23, s. 5879-5883
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Tidskriftsartikel (refereegranskat)abstract
- High-strength cement was obtained by a simple process technique. Powders of Secar 71 were cold isostatically pressed (CIP) into green bodies with a relative density of 66 vol%. The green bodies were then immersed in water or kept in humid air for curing a
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