| 1. |
- Bardage, Stig, et al.
(författare)
-
The effect of natural product treatment of southern yellow pine on fungi causing blue stain and mold
- 2014
-
Ingår i: International Biodeterioration & Biodegradation. - : Elsevier BV. - 0964-8305 .- 1879-0208. ; 86:B, s. 54-59
-
Tidskriftsartikel (refereegranskat)abstract
- Blue stain and mold growth on wood can be aesthetically unappealing, but mold growth can also potentially trigger health related issues. In this study, a screening of the effect of selected natural products and derivatives of natural products including essential oils, plant based monomers, and shellfish exoskeleton compounds on the inhibition of blue stain fungi and mold fungi in southern yellow pine veneers and cellulose filter paper. The treatment of the substrates, the weight percent gain of the natural products, and the inhibition effect is presented. The natural products have been investigated previously, but most have not been applied to wood or investigated with regards to blue stain or mold growth. The specimens were treated by dipping, wrapping in foil, and then heating at 105°C for 24h in order to encourage reaction or grafting of the natural products to the wood. A selection of seven additives each exhibited significant protection against blue stain colonization in Petri dish tests and these were studied more in-depth. These included tea tree oil, propyl gallate, hydrogenated gum oil, salicylic acid, cinnamon bark oil, butylene oxide, and furfural. The salicylic acid, tea tree oil, and cinnamon bark oil had the least amount of mold growth after four weeks in the mold chamber test, and have been previously reported to have a mechanism of antifungal activity resulting from their ability to disrupt the fungal cell wall. Propyl gallate veneer was the only specimen that had a lower pH and that would be considered unfavorable to mold growth. While furfural, salicylic acid, and cinnamon bark oil treated veneers all had more hydrophobic surfaces when compared to untreated wood.
|
|
| 2. |
- Claudino, Mauro, et al.
(författare)
-
Photoinduced thiol-ene cross-linking of globalide/ε-caprolactone copolymers : curing performance and resulting thermoset properties
- 2012
-
Ingår i: Journal of Polymer Science Part A. - : Wiley. - 0887-624X .- 1099-0518. ; 50:1, s. 16-24
-
Tidskriftsartikel (refereegranskat)abstract
- The increasing demand for bioderived polymers led us to investigate the potential use of the macrolactone globalide in thermoset synthesis via the photoinduced thiolene reaction. A series of six lipase-catalyzed poly(globalide-caprolactone) copolyesters bearing internal main-chain unsaturations ranging from 10 to 50 and 100 mol % were successfully crosslinked in the melt with equal amounts of thiol groups from trimethylolpropane-trimercapto propionate affording fully transparent amorphous elastomeric materials with different thermal and viscoelastic properties. Three major conclusions can be drawn from this study: (i) high thiol-ene conversions (> 80%) were easily attained for all cases, while maintaining the cure behavior, and irrespective of functionality at reasonable reaction rates; (ii) parallel chain-growth homopropagation of the ene monomer is insignificant when compared with the main thiolene coupling route; and (iii) high ene-density copolymers result in much lower extracted sol fractions and high T(g) values as a result of a more dense and homogeneous crosslinked network. The thiol-ene system evaluated in this contribution serve as model example for the sustainable use of naturally occurring 1,2-disubstituted alkenes in making semisynthetic polymeric materials in high conversions with a range of properties.
|
|
| 3. |
|
|
| 4. |
- Eriksson, Magnus G., et al.
(författare)
-
One-pot enzymatic polycondensation to telechelic methacrylate-functional oligoesters used for film formation
- 2011
-
Ingår i: POLYM CHEM. - Cambridge : ROYAL SOC CHEMISTRY. - 1759-9954 .- 1759-9962. ; 2:3, s. 714-719
-
Tidskriftsartikel (refereegranskat)abstract
- Based on largely renewable monomers, an enzymatic one-pot polycondensation route towards functional oligomers with targeted molecular weights and end-groups was developed. This one-pot synthesis was performed by combining Candida antarctica lipase B (CALB), 2-hydroxyethyl methacrylate (HEMA), ethylene glycol, and divinyl adipate under reduced pressure (72 mbar) at 60 degrees C. The polymerization went to completion (>95% conversion for all monomers) within 24 h and the fraction of methacrylate end-groups was >90%. Three targeted dimethacrylate functional oligomers with molecular weights of 920, 1700 and 2500 g mol(-1) (degrees of polymerization 4, 8, and 13 respectively) were synthesized. The oligomer products were characterized by NMR, MALDI-TOF MS and SEC. The dimethacrylate functional oligomers were further UV homopolymerized or combined with a tetrathiol crosslinker to demonstrate the potential to produce novel networks with tunable thermal properties dependent on chain length of the telechelic building blocks. This research is the first to demonstrate methacrylate functionalization and condensation polymerization in a one step process, which expands the growing toolbox for polymer/material chemists towards an increased throughput in available macromonomers used in material design.
|
|
| 5. |
- Eriksson, Magnus, et al.
(författare)
-
One-Pot Enzymatic Route to Tetraallyl Ether Functional Oligoesters : Synthesis, UV Curing, and Characterization
- 2010
-
Ingår i: Journal of Polymer Science Part A. - : Wiley. - 0887-624X .- 1099-0518. ; 48:23, s. 5289-5297
-
Tidskriftsartikel (refereegranskat)abstract
- An enzymatic one-pot route in bulk was used to synthesize tetraallyl ether (tAE) functional oligomers based on divinyl adipate, 1,4-butanediol and trimethylolpropane diallyl ether. By using lipase B from Candida antarctica as catalyst and varying the stoichiometric ratio of monomers, it was possible to reach targeted molecular weights (from 1300 to 3300 g mol(-1)) of allyl-ether functional polyesters. The enzyme catalyzed reaction reached completion (>98% conversion based on all monomers) within 24 h at 60 degrees C, under reduced pressure (72 mbar) resulting in similar to 90% yield after filtration. The tAE-functional oligoesters were photopolymerized, without any purification other than removal of the enzyme by filtration, with thiol functional monomers (dithiol, tetrathiol) in a 1: 1 ratio thiol-ene reaction. The photo-initiator, 2,2-dimethoxy-2-phenylacetophenone, was used to improve the rate of reaction under UV light. High conversions (96-99% within detection limits) were found for all thiol-ene films as determined by FT-Raman spectroscopy. The tAE-functional oligoesters were characterized by NMR, MALDI, and SEC. The UV-cured homopolymerized films and the thiol-ene films properties were characterized utilizing DSC and DMTA.
|
|
| 6. |
|
|
| 7. |
- Hassel, Beatriz I., et al.
(författare)
-
A Study on the Morphology, Mechanical, and Electrical Performance of Polyaniline-modified Wood - A Semiconducting Composite Material
- 2014
-
Ingår i: BioResources. - : BioResources. - 1930-2126. ; 9:3, s. 5007-5023
-
Tidskriftsartikel (refereegranskat)abstract
- This study investigated the morphology, electrochemical modification with respect to the wood fiber direction, and mechanical properties of wood modified by in situ polymerization with polyaniline (PANI). This polymerization formed a composite material with applications as an antistatic, electromagnetic, anti-corrosion, and heavy metal purifying materials. The polymer was found throughout the entire structure of the wood and was quantified within the wood cell wall and middle lamella by SEM-EDX. The presence of PANI affected the conductivity of the composite specimens, which was found to be higher in the fiber direction, indicating a more intact percolation pathway of connected PANI particles in this direction. The PANI modification resulted in a small reduction of the storage modulus, the maximum strength, and the ductility of the wood, with decreases in the properties of specimens conditioned in an environment above 66% relative humidity. The in situ-polymerized PANI strongly interacted with the lignin component of the veneers, according to the decrease in the lignin glass transition temperature (T-g) noted in DMA studies.
|
|
| 8. |
|
|
| 9. |
- Rüdiger, Arne, et al.
(författare)
-
Chemoenzymatic Route to Renewable Thermosets Based on a Suberin Monomer
- 2013
-
Ingår i: Journal of renewable materials. - : Scrivener Publishing LLC. - 2164-6341 .- 2164-6325. ; 1:2, s. 124-140
-
Tidskriftsartikel (refereegranskat)abstract
- The present study describes the use of an epoxy functional fatty acid, 9,10-epoxy-18-hydroxyoctadecanoic acid (EFA), extracted from birch (Betula pendula) outer bark to produce thermosets. The purified epoxy fatty acid was polymerized by enzyme-catalyzed polycondensation utilizing Candida antarctica lipase B (CalB) to form oligomers with targeted degrees of polymerization (DP) of 3, 6, and 9 and obtained DPs of 2.3, 5.9 and 7.3, respectively. It was determined that it is possible to first enzymatically polymerize and aliphatically endcap the epoxy functional fatty acid resulting in controlled oligomer lengths while also maintaining the epoxy functionality for further reaction by main-chain homo-epoxy cationic photopolymerization. The enzymatic polymerized oligomers were characterized in terms of conversion of the residual epoxy groups (FT-IR), the thermal properties (DSC, TGA) and the purity by MALDI-TOF and 1H-NMR. The amorphous thermoset films with varying degrees of crosslinking resulting from the cationically photopolymerized oligomers, were characterized in terms of their thermal properties and residual epoxy content (FT-IR ATR). The crosslinked polyesters formed insoluble, amorphous, and transparent films. This work demonstrates that thermoset films with designed properties can be effectively made with the use of forest products to reduce the petroleum-based plastics market.
|
|
| 10. |
- Salehi Movahed, Alireza, et al.
(författare)
-
Effect of model lignin structures on the oxidation of unsaturated fatty acids
- 2010
-
Ingår i: Polymers from Renewable Resources. - : SAGE Publications. - 2041-2479 .- 2045-1377. ; 1:2
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of this study is to better understand vegetable oils as raw materials in the application of wood protection in order to obtain improved durability of exterior wood materials in an environmentally friendly way. This was done by studying the effect of lignin model compounds on the auto-oxidation rate of methyl linoleate. The auto-oxidation process of methyl linoleate was measured by itself and in combination with 1 wt% phenolic and non-phenolic lignin model compounds at 70°C. The effect of lignin compounds on the methyl linoleate auto-oxidation process was monitored by 1H-NMR, size exclusion chromatography (SEC), and real-time infrared spectroscopy (RT-IR). It was observed that phenolic groups and radical conjugation are the main contributors to an antioxidant effect of lignin compounds on the oxidation rate of the methyl linoleate. Ferulic acid, which is phenolic and contains a carboxylic group, has the largest antioxidant effect on methyl linoleate. It was also found that the antioxidant effect existed, despite the low solubility of ferulic acid in methyl linoleate. This research demonstrates that it is possible to follow the auto-oxidation process in real time to uncover the effects of wood constituents on the fatty acid auto-oxidation process. Additionally, this knowledge that drying rate of oil can be tuned with the addition of lignin compounds can be used to predict drying times when this oil is applied to different species of wood.
|
|
