| 1. |
- Bexell, Ulf, et al.
(författare)
-
Bonding of vegetable oils to mercapto silane treated metal surfaces : Surface engineering on the nano scale
- 2006
-
Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 515:2, s. 838-841
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper the bonding of thin vegetable oil films on mercapto silane treated aluminium surfaces has been studied. The silane molecules are attached to the surface by metal-oxygen-silicon bonds. The coupling between the unsaturated bonds of the vegetable oil and the thiol functionalised surface was obtained through a photoinduced thiol-ene reaction. The surfaces were characterised by X-ray photoelectron spectroscopy (XPS). Vegetable oil contains both saturated and unsaturated carbon chains. For the reactions investigated in this study it is the unsaturated carbon chains that can react by a thiol-ene reaction and the results indicate that it is possible to attach a vegetable oil to a metal surface pre-treated with a thiol functionalised silane.
|
|
| 2. |
- Antonsson, Stefan, et al.
(författare)
-
Biomimetic synthesis of suberin for new biomaterials
- 2005
-
Ingår i: Appita Annual Conference. ; , s. 561-564
-
Konferensbidrag (refereegranskat)abstract
- Suberin is the biopolymer giving cork (oak bark) its hydrophobic and resistant characteristics. It acts as a diffusion barrier in bark and roots of plants. Similarly to lignin, it is a phenolic polymer with good affinity to cellulose and other wood polysaccharides, but it also contains polyaliphatic and strongly hydrophobic elements. In order to produce a lignin derivative similar to suberin, a desired lignin starting material should be of low molecular weight and have a high content of hydroxylic phenolic groups. By means of cross flow nanofiltration of softwood kraft pulping black liquor and pH-precipitation with diluted sulphuric acid, such a lignin has been obtained. Due to the fact that too much organics entering the recovery boiler frequently is the bottleneck for pulp production increases, a removal of part of the lignin can be economically very favourable. By using this lignin together with linola oil, a linseed oil with a large amount of unsaturated structures, an attempt was made to create a new hydrophobic lignin derivative similar tosuberin. The product was analysed with FT-IR, Fourier Transformed Infra Red Spectroscopy and GPC, Gel Permeation Chromatography. The suberin like material obtained from this lignin could be polymerised on thermo mechanical pulp fibres by means of Mn(III)-driven phenolic coupling. The ability of the suberin monomers to act as a hydrophobic paper coating was evaluated with contact angle measurements and the results indicate that this lignin derivative was potentially of interest due to its capability to interact well with wood fibres and make paper hydrophobic.
|
|
| 3. |
- Antonsson, Stefan, et al.
(författare)
-
Low Mw-lignin fractions together with vegetable oils as available oligomers for novel paper-coating applications as hydrophobic barrier
- 2008
-
Ingår i: Industrial crops and products (Print). - : Elsevier BV. - 0926-6690 .- 1872-633X. ; 27:1, s. 98-103
-
Tidskriftsartikel (refereegranskat)abstract
- Lignin residues are available in large amounts as kraft lignin from chemical pulping processes. This lignin is mainly incinerated in recovery boilers. The recovery boilers are often the bottle-necks in the overall pulping process when pulp production increases are desired. Through cross-flow nano-filtration of the black liquor from kraft pulping, a low-molecular weight lignin fraction can be removed thus decreasing the organic load on the recovery boilers. The low-molecular weight lignin fraction furthermore exhibit different characteristics compared to other commercial kraft lignins and represents a new raw material source in novel applications. The low-molecular weight lignin was used together with a vegetable oil to produce a new hydrophobic lignin derivative similar to suberin. The lignin and the lignin derivative was analysed with FT-IR, UV-vis and SEC. The ability of the product to make paper surfaces hydrophobic was also evaluated. The results demonstrate the possibility to make a suberin-like lignin derivative that is potentially of interest in paper-coating applications due to its capability to interact well with wood fibres and make paper hydrophobic.
|
|
| 4. |
- Antonsson, Stefan, 1979-
(författare)
-
Strategies for improving kraftliner pulp properties
- 2008
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A large part of the world paper manufacturing consists of production of corrugated board components, kraftliner and fluting, that are used in many different types of corrugated boxes. Because these boxes are stored and transported, they are often subjected to changes in relative humidity. These changes together with mechanical loads will increase the deformation of the boxes compared to the case where the same loads are applied in a static environment. This enlarged creep due to the changes in relative humidity is called mechano-sorptive or accelerated creep. Mechano-sorptive creep forces producers to use high safety factors when designing boxes, and therefore, this is one of the key properties of kraftliner boards. Different strategies to decrease mechano-sorptive creep, and to simultaneously gain more knowledge about the causes for this phenomenon in paper, are the aim of this work. Derivatised and underivatised black liquor lignins, a by-product produced in pulp mills in large quantities, have been used together with biomimetic methods, to modify the properties of kraftliner pulp. Furthermore, the properties of kraftliner pulp have been compared to other pulps in order to evaluate the influence of fibre morphological factors, such as fibre width and shape factor, on the mechano-sorptive creep. In addition the influence of the chemical composition of the kraftliner pulp has been evaluated both by means of treating a kraftliner pulp with chlorite and xylanase and by producing pulps with different chemical composition. By using lignin and biomimetic methods, to create radical coupling reactions, it has been shown that it is possible to increase the wet strength of kraftliner pulp sheets. This method of treating the pulp showed, however, no significant effects on the mechano-sorptive creep. The addition of an apolar suberin-like lignin derivative, which has been shown to be possible to produce from natural resources, did show a positive effect on mechano-sorptive creep properties, but at the expense of stiffness properties in constant climate. Different pulps were compared with a kraftliner pulp and it was observed that the ratio between tensile stiffness and hygroexpansion can be used to estimate the mechano-sorptive creep properties. The hardwood kraft pulps investigated had lower hygroexpansion, probably due to more slender and straighter fibres, and higher tensile stiffness, probably due to lower lignin content. As the lignin content was varied by different methods in kraft pulps, it was observed that increased lignin content gives an increased hygroexpansion and decreased tensile stiffness as well as an increased mechano-sorptive creep. There were also indications of increased mechano-sorptive creep due to higher xylan content.
|
|
| 5. |
- Antonsson, Stefan, 1979-
(författare)
-
The Use of Lignin Derivatives to Improve Selected Paper Properties
- 2007
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Ved består huvudsakligen av tre typer av polymerer, cellulosa, hemicellulosa och lignin. Lignin bildas i naturen genom enzymatiskt initierad oxidativ koppling av tre olika typer av fenylpropan-enheter. Dessa bygger genom olika kol-kol- och kol-syre-bindningar upp en amorf tredimensionell polymer. När kemisk massa tillverkas bryts lignin ner och löses ut i kokluten. Luten innehåller de förbrukade kokkemikalierna och bränns generellt i en sodapanna för att regenerera kemikalierna och producera ånga. Sodapannan är emellertid dyr. Därför har den blivit produktionsbegränsande på många massabruk. Att avlägsna en del av ligninet från avluten vore därför önskvärt och att finna ekonomiskt intressanta produkter baserade på lignin från svartlut är därför ett viktigt forskningsområde . Ett lämpligt område för ligninprodukter vore som tillsatts i oblekt massa. Oblekt massa används till stor del för tillverkning av kraftliner, topp- och bottenskikten på wellpapp. När lådor av wellpapp lagras i containrar som färdas över haven, förändras den relativa luftfuktigheten. Detta gör att lådorna kollapsar lättare än om de skulle ha lagrats vid konstant luftfuktighet, även en hög sådan. Detta är på grund av det så kallade mekanosorptiva- eller accelererade krypfenomenet. Genom tillsatts av våtstyrkemedel till kraftliner eller behandla den med hydrofoba ämnen, finns indikatoner på att mekanosorptiva effekten skulle kunna minska. För att försöka minska den effekten har ett lågmolekylärt kraftlignin, som utvunnits med hjälp av tvärsflödesfiltrering av svartlut och svavelsyrafällning, använts. Genom derivatisering av detta lignin med linolja erhölls ett hydrofobt ligninderivat som uppvisar strukturella likheter med biopolymeren suberin. När detta suberinlika ligninderivat tillsätts till massa verkar det mekanosorptiva krypet minska. När lågmolekylärt lignin används tillsammans med ligninradikalinitiatorerna lackas eller mangan(III) i kraftlinermassa erhålls dessutom en våtstyrka på ca 5% av torrstyrkan. Efter aminering av detta lignin gav en tillsatts till kraftlinermassan en våtstyrka på upp till 10% av torrstyrkan. Det finns indikationer på att det mekanosorptiva krypet samtidigt minskar när dessa behandlingar görs som ger upphov till ökad våtstyrka.
|
|
| 6. |
- Kristensen, Ingrid, et al.
(författare)
-
Barnradioterapi på distans
- 2006
-
Ingår i: Läkartidningen. ; 103:15-16, s. 1188-1190
-
Tidskriftsartikel (refereegranskat)
|
|
| 7. |
- Trey, Stacy M., et al.
(författare)
-
Effects of thiol additives on urethane acrylate UV primers for SMC applications
- 2009
-
Ingår i: Progress in organic coatings. - : Elsevier BV. - 0300-9440 .- 1873-331X. ; 64:2-3, s. 238-246
-
Tidskriftsartikel (refereegranskat)abstract
- Sheet molded compound (SMC) is a highly filled, glass fiber reinforced, thermoset material used in trim and body panel automotive parts. When SMC-substrates are coated with conventional thermally cured paints, inherent porosity and entrapped volatiles of the substrate result in popping ("paint pops") defects. UV-curable primers (UVP) provide an order of magnitude reduction of paint defects in SMC coatings, but typically have poor adhesion. Mercaptan polymers have a long history, dating back to 1928. of use in adhesives and sealant applications. The present study investigates a series of UVPs, showing the effect of resin functionality and thiol functional additive content on the adhesion of the coatings to SMC substrates. The SMC formulation is also considered when evaluating UVP adhesion, regarding variables such as surface chemistry, morphology, and surface area. The present study brings to light how adhesion of acrylate UVP can be enhanced with mercaptan moieties in additive amounts. The effect is most apparent on SMC substrates that have been treated to expose inorganic fillers as opposed to untreated surfaces of polyester. Additionally annealing the films boosts adhesion, but only in thiol containing formulations. This is a result of the decrease in T(g)s and modulus of the films with the addition of mercaptans, thus providing better contact with the substrate in comparison to non-thiol containing formulations.
|
|
