| 1. |
- Lindberg, Siv M, et al.
(författare)
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A product semantic study of the influence of the sense of touch on the evaluation of wood-based materials
- 2013
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Ingår i: Materials & design. - : Elsevier BV. - 0264-1275 .- 1873-4197 .- 0261-3069. ; 52, s. 300-307
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Tidskriftsartikel (refereegranskat)abstract
- Based on product semantics, this study investigated how the tactile attributes of wood and wood-based composites are perceived and interpreted semantically. The wood-based samples included ash, birch, elm, oak, pine, OSB (oriented strand board), two wood pulp-reinforced polylactide composites, Comp A and B and one wood-fiber reinforced polypropene composite, Comp C. The subjects rated the samples by the descriptive words natural, exclusive, eco-. friendly, rough, inexpensive, reliable, warm, modern, snug and solid. The most significant differences between the samples were found for roughness and for the descriptors, reliable, natural and solid. A principal component analysis yielded three attributes based on the tactile perceptions: reliable, old-. fashioned and smooth. The solid wood pieces were perceived as natural and oak was perceived as being exclusive. The composite materials presented a greater variation in terms of perceived attributes than the wood specimens.
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| 2. |
- Chen, Zhe, et al.
(författare)
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Nano-scale characterization of white layer in broached Inconel 718
- 2017
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Ingår i: Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing. - Amsterdam : Elsevier BV. - 0921-5093 .- 1873-4936. ; 684, s. 373-384
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Tidskriftsartikel (refereegranskat)abstract
- The formation mechanism of white layers during broaching and their mechanical properties are not well investigated and understood to date. In the present study, multiple advanced characterization techniques with nano-scale resolution, including transmission electron microscopy (TEM), transmission Kikuchi diffraction (TKD), atom probe tomography (APT) as well as nano-indentation, have been used to systematically examine the microstructural evolution and corresponding mechanical properties of a surface white layer formed when broaching the nickel-based superalloy Inconel 718.TEM observations showed that the broached white layer consists of nano-sized grains, mostly in the range of 20–50 nm. The crystallographic texture detected by TKD further revealed that the refined microstructure is primarily caused by strong shear deformation. Co-located Al-rich and Nb-rich fine clusters have been identified by APT, which are most likely to be γ′ and γ′′ clusters in a form of co-precipitates, where the clusters showed elongated and aligned appearance associated with the severe shearing history. The microstructural characteristics and crystallography of the broached white layer suggest that it was essentially formed by adiabatic shear localization in which the dominant metallurgical process is rotational dynamic recrystallization based on mechanically-driven subgrain rotations. The grain refinement within the white layer led to an increase of the surface nano-hardness by 14% and a reduction in elastic modulus by nearly 10% compared to that of the bulk material. This is primarily due to the greatly increased volume fraction of grain boundaries, when the grain size was reduced down to the nanoscale.
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| 3. |
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| 4. |
- Muneer, Faraz, et al.
(författare)
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Preparation, Properties, Protein Cross-Linking and Biodegradability of Plasticizer-Solvent Free Hemp Fibre Reinforced Wheat Gluten, Glutenin, and Gliadin Composites
- 2014
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Ingår i: BioResources. - : BioResources. - 1930-2126 .- 1930-2126. ; 9:3, s. 5246-5261
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Tidskriftsartikel (refereegranskat)abstract
- The present study is aimed at evaluating the use of plant-based polymers and fibres for the production of sustainable biocomposites. For the first time, plasticiser/solvent-free hemp fibre-reinforced wheat gluten and hemp-gliadin and glutenin composites were obtained by compression moulding at different temperatures. The plasticiser/solvent-free sample preparation method developed in this study facilitated the use of a powdered protein matrix with a mat of randomly oriented hemp fibres. The tensile and protein cross-linking properties, as well as the biodegradability, were investigated. The addition of hemp fibre to the protein matrix increased the E-modulus by 20 to 60% at 130 degrees C. An increase in moulding temperature from 110 to 130 degrees C resulted in an increase in maximum stress due to the formation of intermolecular bonds between protein chains. The gliadin composites had higher E-modulus and maximum stress and showed a larger increase in protein polymerisation with increased temperature compared to the gluten in composites. A comparison of tensile properties revealed that the composites were stiffer and stronger compared to several similarly produced biobased composites. The composites were found to be fully biodegradable under a simulated soil environment after 180 days. Biocomposites produced in the present study were found to be environmentally friendly with fairly good mechanical properties.
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| 5. |
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| 6. |
- Almgren, Karin M., et al.
(författare)
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Characterization of interfacial stress transfer ability by dynamic mechanical analysis of cellulose fiber based composite materials
- 2010
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Ingår i: Composite interfaces (Print). - 0927-6440 .- 1568-5543. ; 17:9, s. 845-861
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Tidskriftsartikel (refereegranskat)abstract
- The stress transfer ability at the fiber-matrix interface of wood fiber composites is known to affect the mechanical properties of the composite. The evaluation of interface properties at the level of individual fibers is however difficult due to the small dimensions and variability of the fibers. The dynamical mechanical properties of composite and constituents, in this case wood fibers and polylactide matrix, was here used together with micromechanical modeling to quantify the stress transfer efficiency at the fiber-matrix interface. To illustrate the methodology, a parameter quantifying the degree of imperfection at the interface was identified by inverse modeling using a micromechanical viscoelastic general self-consistent model with an imperfect interface together with laminate analogy on the composite level. The effect of moisture was assessed by comparison with experimental data from dynamic mechanical analysis in dry and moist state. For the wood fiber reinforced polylactide, the model shows that moisture absorption led to softening and mechanical dissipation in the hydrophilic wood fibers and biothermoplastic matrix, rather than loss of interfacial stress transfer ability.
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| 7. |
- Guo, Zengwei, et al.
(författare)
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Preparation of polypropylene/nanoclay composite fibers
- 2013
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Ingår i: Polymer Engineering and Science. - : Wiley. - 0032-3888 .- 1548-2634. ; 53:10, s. 2035-2044
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Tidskriftsartikel (refereegranskat)abstract
- Melt spinning of nanoclay (NA)/polypropylene (PP) composites into textile fibers is studied. The synthetic NA Perkalite F100 is prone to be exfoliated in PP matrix. With the help of a maleic anhydride-grafted low-molecular-weight PP as compatibilizer (Epolene E43), a highly exfoliated PP/NA composite was successfully prepared. However, the prepared PP/NA composite shows a poor spinnability because of the phase separation between Epolene E43 and PP matrix. The combination of two different groups of compatibilizers, which are Polybond 1001 (acrylic acid-grafted PP) for the dispersion of NA and Epolene G3216 (maleic anhydride-grafted PP-based copolymer) for the exfoliation of NA, can solve this problem. The PP/NA composite prepared by these two compatibilizers can be smoothly spun into fiber at the NA concentration below 1.9 wt%, which is found to be the percolation concentration of formation of NA network structure in PP matrix.
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| 8. |
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| 9. |
- Lobov, Gleb, et al.
(författare)
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Dynamic manipulation of optical anisotropy of suspended Poly-3-hexylthiophene nanofibers
- 2016
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Ingår i: Advanced Optical Materials. - : Wiley. - 2162-7568 .- 2195-1071. ; 4:10, s. 1651-1656
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Tidskriftsartikel (refereegranskat)abstract
- Poly-3-hexylthiophene (P3HT) nanofibers are 1D crystalline semiconducting nanostructures, which are known for their application in photovoltaics. Due to the internal arrangement, P3HT nanofibers possess optical anisotropy, which can be enhanced on a macroscale if nanofibers are aligned. Alternating electric field, applied to a solution with dispersed nanofibers, causes their alignment and serves as a method to produce solid layers with ordered nanofibers. The transmission ellipsometry measurements demonstrate the dichroic absorption and birefringence of ordered nanofibers in a wide spectral range of 400–1700 nm. Moreover, the length of nanofibers has a crucial impact on their degree of alignment. Using electric birefringence technique, it is shown that external electric field applied to the solution with P3HT nanofibers can cause direct birefringence modulation. Dynamic alignment of dispersed nanofibers changes the refractive index of the solution and, therefore, the polarization of transmitted light. A reversible reorientation of nanofibers is organized by using a quadrupole configuration of poling electrodes. With further development, the described method can be used in the area of active optical fiber components, lab-on-chip or sensors. It also reveals the potential of 1D conducting polymeric structures as objects whose highly anisotropic properties can be implemented in electro-optical applications..
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| 10. |
- Lund, Anja, et al.
(författare)
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Piezoelectric polymeric bicomponent fibers produced by melt spinning
- 2012
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Ingår i: Journal of Applied Polymer Science. - : Wiley Periodicals, Inc.. - 0021-8995 .- 1097-4628. ; 126:2, s. 490-500
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Tidskriftsartikel (refereegranskat)abstract
- Melt spinning of a novel piezoelectric bicomponent fiber, with poly(vinylidene fluoride) as the electroactive sheath component, has been demonstrated. An electrically conductive compound of carbon black (CB) and high density polyethylene was used as core material, working as an inner electrode. A force sensor consisting of a number of fibers embedded in a soft CB/polyolefin elastomer matrix was manufactured for characterization. The fibers showed a clear piezoelectric effect, with a voltage output (peak-to-peak) of up to 40 mV under lateral compression. This continuous all-polymer piezoelectric fiber introduces new possibilities toward minimal single fiber sensors as well as large area sensors produced in standard industrial weaving machines.
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