| 1. |
- Lindberg, Siv M, et al.
(författare)
-
A product semantic study of the influence of the sense of touch on the evaluation of wood-based materials
- 2013
-
Ingår i: Materials & design. - : Elsevier BV. - 0264-1275 .- 1873-4197 .- 0261-3069. ; 52, s. 300-307
-
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.
|
|
| 2. |
- Cho, Sung-Woo, et al.
(författare)
-
Injection-molded nanocomposites and materials based on wheat gluten
- 2011
-
Ingår i: International Journal of Biological Macromolecules. - : Elsevier BV. - 0141-8130 .- 1879-0003. ; 48:1, s. 146-152
-
Tidskriftsartikel (refereegranskat)abstract
- This is, to our knowledge, the first study of the injection molding of materials where wheat gluten (WG) is the main component. In addition to a plasticizer (glycerol), 5 wt.% natural montmorillonite clay was added. X-ray indicated intercalated clay and transmission electron microscopy indicated locally good clay platelet dispersion. Prior to feeding into the injection molder, the material was first compression molded into plates and pelletized. The filling of the circular mold via the central gate was characterized by a divergent flow yielding, in general, a stronger and stiffer material in the circumferential direction. It was observed that 20–30 wt.% glycerol yielded the best combination of processability and mechanical properties. The clay yielded improved processability, plate homogeneity and tensile stiffness. IR spectroscopy and protein solubility indicated that the injection molding process yielded a highly aggregated structure. The overall conclusion was that injection molding is a very promising method for producing WG objects.
|
|
| 3. |
- Muneer, Faraz, et al.
(författare)
-
Preparation, Properties, Protein Cross-Linking and Biodegradability of Plasticizer-Solvent Free Hemp Fibre Reinforced Wheat Gluten, Glutenin, and Gliadin Composites
- 2014
-
Ingår i: BioResources. - : BioResources. - 1930-2126. ; 9:3, s. 5246-5261
-
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.
|
|
| 4. |
- Kessler, Vadim, et al.
(författare)
-
Rhenium Nanochemistry for Catalyst Preparation
- 2012
-
Ingår i: Minerals. - : MDPI AG. - 2075-163X. ; 2, s. 244-257
-
Tidskriftsartikel (refereegranskat)abstract
- The review presents synthetic approaches to modern rhenium-based catalysts. Creation of an active center is considered as a process of obtaining a nanoparticle or a molecule, immobilized within a matrix of the substrate. Selective chemical routes to preparation of particles of rhenium alloys, rhenium oxides and the molecules of alkyltrioxorhenium, and their insertion into porous structure of zeolites, ordered mesoporous MCM matrices, anodic mesoporous alumina, and porous transition metal oxides are considered. Structure-property relationships are traced for these catalysts in relation to such processes as alkylation and isomerization, olefin metathesis, selective oxidation of olefins, methanol to formaldehyde conversion,etc.
|
|
| 5. |
- Kessler, Vadim
(författare)
-
The Synthesis and Solution Stability of Alkoxide Precursors
- 2016
-
Ingår i: Handbook of Sol-Gel Science and Technology. - Cham : Springer International Publishing. - 9783319194547 ; , s. 1-50
-
Bokkapitel (refereegranskat)abstract
- The aim of this chapter is to serve as a guide in understanding the principles in thechemical approaches to and stability of the metal and silicon alkoxide precursors.The major accent is made on the overview of the accessible precursor compoundsapplicable in solgel technology, focusing on their synthesis and reactivity includingthe chemistry behind the solgel process. The chapter provides an insight intothe synthesis of homometallic precursors (see section “Synthesis ofHomometallic Precursors”), synthesis of heterometallic precursors (see section“Synthesis of Heterometallic Alkoxide Precursors”), solution stability withrespect to formation of oxoalkoxides (see section “Solution Stability with Respectto Formation of Oxoalkoxides”), solution stability with respect to solvolysis (seesection “Solution Stability with Respect to Solvolysis”), and, finally, a shortreview summarizing the literature data on individual alkoxide complexes appliedas precursors (see section “Individual Alkoxide Complexes Applied as Precursors”)considering separately the homometallic species (see section“Homometallic Precursors”) and the heterometallic ones – so-called singlesourceprecursors (see section “Heterometallic Precursors”). Finally, a briefoverview of the modern concepts treating the transformation of precursors intomaterials is also provided (see section “The Chemistry of Alkoxide Precursors’Transformation into Oxide Materials in Sol-Gel Technology”).
|
|
| 6. |
- Seisenbaeva, Gulaim, et al.
(författare)
-
Precursor directed synthesis - "molecular" mechanisms in the Soft Chemistry approaches and their use for template-free synthesis of metal, metal oxide and metal chalcogenide nanoparticles and nanostructures
- 2014
-
Ingår i: Nanoscale. - : Royal Society of Chemistry (RSC). - 2040-3364 .- 2040-3372. ; 6, s. 6229-6244
-
Forskningsöversikt (refereegranskat)abstract
- This review provides an insight into the common reaction mechanisms in Soft Chemistry processes involved in nucleation, growth and aggregation of metal, metal oxide and chalcogenide nanoparticles starting from metal-organic precursors such as metal alkoxides, beta-diketonates, carboxylates and their chalcogene analogues and demonstrates how mastering the precursor chemistry permits us to control the chemical and phase composition, crystallinity, morphology, porosity and surface characteristics of produced nanomaterials.
|
|
| 7. |
- Muneer, Faraz
(författare)
-
Biocomposites from natural polymers and fibers
- 2015
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Alternative resources to petroleum resources to produce environmentally friendly and sustainable plastics and composites are discussed. Such plant based resources are abundantly available at low prices being side stream products from bioethanol and food industries. The review begins with a short introduction to plant based polymers and their potential use for making plastics. Wheat gluten proteins and starch have shown attractive functional properties which are potentially suitable for making plastics with reduced carbon foot print. The structure and function of wheat gluten and potato starch and their use in different polymer blends to produce composites with improved functional properties are also discussed. The use of natural fibers and their advantage over synthetic fibers for making composites are also examined in this review.
|
|
| 8. |
- Rogers, Patrick, et al.
(författare)
-
Chloride Ion Diffusion Resistance of Bulk Hydrophobic Concrete : Comparison of w/c and Dosages
- 2023
-
Ingår i: Nordic Concrete Research. - : Walter de Gruyter GmbH. - 0800-6377 .- 2545-2819. ; 68:1, s. 17-38
-
Tidskriftsartikel (refereegranskat)abstract
- Post-cast application of hydrophobic agents onto hardened concrete is successful at reducing external ion diffusion into cement paste, this work examines pre-cast application of hydrophobic admixtures in fresh concrete. Concretes, with water to cement ratios (w/c) 0.45 and 0.50 (CEM I; low C3A), were mixed. Adding alkyltrialkoxysilane or triacylglycerol admixtures ranging from 1 to 3 wt%cem in these concretes were evaluated. Increasing the dosage of hydrophobic admixtures decreased the compressive strength. The usage of these admixtures did not hinder the further development of the microstructure as all concretes gained strength after one year, but not in the same percentage increase as the reference concrete. Chloride ion diffusion, after exposure to 3 wt% NaCl solution at 20 °C for 91 days, in concretes with 1 wt%cem admixture showed slight reductions in diffusion rate (8-17%) compared to the reference. At 3 wt%cem, triacylglycerol admixtures showed better hindering effects of inward chloride diffusion, this was especially evident in w/c = 0.45. Equivalent addition of alkyltrialkoxysilane-based admixtures increased the diffusion of chloride ions transferred into the cement matrix.
|
|
| 9. |
- Wu, Qiong, et al.
(författare)
-
Flexible strength-improved and crack-resistant biocomposites based on plasticised wheat gluten reinforced with a flax-fibre-weave
- 2017
-
Ingår i: Composites Part A: Applied Science and Manufacturing. - : Elsevier. - 1359-835X. ; 94, s. 61-69
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents strength-improved and crack-resistant wheat gluten biocomposites, using flax-fibre-weaves as reinforcement. The composites were produced by dip-coating of the weave into a wheat gluten/glycerol (WGG) solution, or by compression moulding. The most extensive coverage and wetting of the flax yarns occurred during the compression moulding, and the adhesion between the fibres and the matrix increased with increasing glycerol content. The compression-moulded sheets were, at a comparable flax content, stiffer than those produced by dipping, whereas their strength was similar and their extensibility slightly lower. Tensile tests on notched samples showed that the flax yarn improved the crack-resistant properties significantly; the maximum stress increased from 2 to 29 MPa using a content of 19 wt.% flax fibres. A clear advantage of this novel mechanically flexible biocomposite is that it can be shaped plastically under ambient conditions, while at the same time providing in-plane stiffness, strength and crack-resistance.
|
|
| 10. |
- Afshar, Reza, et al.
(författare)
-
Creep in oak material from the Vasa ship: : verification of linear viscoelasticity and identification of stress thresholds
- 2020
-
Ingår i: European Journal of Wood and Wood Products. - : Springer Nature. - 0018-3768 .- 1436-736X. ; 78:6, s. 1095-1103
-
Tidskriftsartikel (refereegranskat)abstract
- Creep deformation is a general problem for large wooden structures, and in particular for shipwrecks in museums. In this study, experimental creep data on the wooden cubic samples from the Vasa ship have been analysed to confrm the linearity of the viscoelastic response in the directions where creep was detectable (T and R directions). Isochronous stress–strain curves were derived for relevant uniaxial compressive stresses within reasonable time spans. These curves and the associated creep compliance values justify that it is reasonable to assume a linear viscoelastic behaviour within the tested ranges, given the high degree of general variability. Furthermore, the creep curves were ftted with a one-dimensional standard linear solid model, and although the rheological parameters show a fair amount of scatter, they are candidates as input parameters in a numerical model to predict creep deformations. The isochronous stress–strain relationships were used to defne a creep threshold stress below which only negligible creep is expected. These thresholds ranges were 0.3–0.5 MPa in the R direction and 0.05–0.2 MPa in the T direction.
|
|
