| 1. |
- Bardage, Stig, et al.
(author)
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The effect of natural product treatment of southern yellow pine on fungi causing blue stain and mold
- 2014
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In: International Biodeterioration & Biodegradation. - : Elsevier BV. - 0964-8305 .- 1879-0208. ; 86:B, s. 54-59
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Journal article (peer-reviewed)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.
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| 2. |
- Claudino, Mauro, et al.
(author)
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Photoinduced thiol-ene cross-linking of globalide/ε-caprolactone copolymers : curing performance and resulting thermoset properties
- 2012
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In: Journal of Polymer Science Part A. - : Wiley. - 0887-624X .- 1099-0518. ; 50:1, s. 16-24
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Journal article (peer-reviewed)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.
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| 3. |
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| 4. |
- Eriksson, Magnus, et al.
(author)
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Enzymatic One-Pot Route to Telechelic Polypentadecalactone Epoxide : Synthesis, UV Curing, and Characterization
- 2009
-
In: Biomacromolecules. - : American Chemical Society (ACS). - 1525-7797 .- 1526-4602. ; 10:11, s. 3108-3113
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Journal article (peer-reviewed)abstract
- In an enzymatic one-pot procedure immobilized lipase B from Candida antarctica was used to synthesize semicrystalline diepoxy functional macromonomers based on glycidol, pentadecalactone, and adipic acid. By changing the stoichiometry of the building blocks. macromonomers of controlled molecular weight front 1400 to 2700 g mol(-1) could be afforded. The enzyme-catalyzed reaction went to completion (conversion >= 95%) within 24 h at 60 degrees C. After removal of the enzyme, the produced macromonomers were used for photopolymerization without any purification. The macromonomers readily copolymerized cationically with a cycloaliphatic diepoxide (Cyracure UVR-6110; CA-dE) to high conversion. The cross-linked copolymers formed a durable film with a degree of crystallinity depending on the macromonomer size and amount of CA-dE used, without CA-dE the macromonomers homopolymerized only to a low degree. Combined with CA-dE conversions of 85-90% were determined by FT-Raman spectroscopy. The films became more durable once reinforced with CA-dE, increasing the cross-link density and reducing the crystallinity of the PDL segments in the films.
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| 5. |
- Eriksson, Magnus G., et al.
(author)
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One-pot enzymatic polycondensation to telechelic methacrylate-functional oligoesters used for film formation
- 2011
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In: POLYM CHEM. - Cambridge : ROYAL SOC CHEMISTRY. - 1759-9954 .- 1759-9962. ; 2:3, s. 714-719
-
Journal article (peer-reviewed)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.
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| 6. |
- Eriksson, Magnus, et al.
(author)
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One-Pot Enzymatic Route to Tetraallyl Ether Functional Oligoesters : Synthesis, UV Curing, and Characterization
- 2010
-
In: Journal of Polymer Science Part A. - : Wiley. - 0887-624X .- 1099-0518. ; 48:23, s. 5289-5297
-
Journal article (peer-reviewed)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.
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| 7. |
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| 8. |
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| 9. |
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| 10. |
- Hassel, Beatriz I., et al.
(author)
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A Study on the Morphology, Mechanical, and Electrical Performance of Polyaniline-modified Wood - A Semiconducting Composite Material
- 2014
-
In: BioResources. - : BioResources. - 1930-2126. ; 9:3, s. 5007-5023
-
Journal article (peer-reviewed)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.
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| 11. |
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| 12. |
- Nilsson, Camilla, et al.
(author)
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Dendrimers in Thiol-ene Crosslinked Networks and the Effect on Subsequent Generations on Thermoset Properties
- 2009
-
In: Journal of Polymer Science Part A. - : Wiley. - 0887-624X .- 1099-0518. ; 47:2, s. 589-601
-
Journal article (peer-reviewed)abstract
- A series of well-defined allyl-ether functionalized polyester dendrimers has been synthesized via the divergent approach using traditional esterification reactions. Two commercially available trifunctional thiols, trimethylolpropane tri(3-mercaptopropanoate) (TRIS) and ethoxylated trimethylolpropane tri(3-mercaptopropanoate) (ETTMP), were incorporated with the dendrimers into the thiol-ene polymer networks. The thiol-ene reactions were conducted at room temperature and cured by UV light without the addition of photoinitiatior. Highly crosslinked films were obtained and characterized with respect to mechanical (DMA) and thermal (DSC and TGA) properties.
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| 13. |
- Nilsson, Camilla, et al.
(author)
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Methacrylated Dendrimers in Thiol-Methacrylate Networks and the Effect of Conversion on the Thermoset Properties
- 2009
-
In: Journal of Polymer Science Part A. - : Wiley. - 0887-624X .- 1099-0518. ; 47:21, s. 5815-5826
-
Journal article (peer-reviewed)abstract
- A series of well-defined methacrylate-functionalized polyester dendrimers based on 2,2-bis(methylol)propionic acid (bis-MPA) has been synthesized divergently. The thermal properties and conversion of the methacrylate functional dendrimers are investigated along with the structure-property relationship of networks composed of the methacrylate dendrimers and two commercially available trifunctional thiols, trimethylolpropane tri(3-mercaptopropanoate) (TRIS) and ethoxylated trimethylolpropane tri(3-mercaptopropanoate) (ETTMP). The thiol-methacrylate reactions were conducted at room temperature, under ambient conditions, and triggered by UV light in the presence of a photoinitiator. Crosslinked films were obtained and characterized with respect to conversion (FT-Raman) and thermal (DSC and TGA) properties.
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| 14. |
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| 15. |
- Rüdiger, Arne, et al.
(author)
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Chemoenzymatic Route to Renewable Thermosets Based on a Suberin Monomer
- 2013
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In: Journal of renewable materials. - : Scrivener Publishing LLC. - 2164-6341 .- 2164-6325. ; 1:2, s. 124-140
-
Journal article (peer-reviewed)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.
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| 16. |
- Salehi Movahed, Alireza, et al.
(author)
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Effect of model lignin structures on the oxidation of unsaturated fatty acids
- 2010
-
In: Polymers from Renewable Resources. - : SAGE Publications. - 2041-2479 .- 2045-1377. ; 1:2
-
Journal article (peer-reviewed)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.
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| 17. |
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| 18. |
- Sepehri, Sobhan, et al.
(author)
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Non-Destructive Evaluation of Thermal Aging in EPDM Rubber Using Electromagnetic Techniques
- 2023
-
In: Materials. - 1996-1944. ; 16:15, s. 5471-5471
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Journal article (peer-reviewed)abstract
- This study investigates the use of eddy-current technology and impedance spectroscopy in sensing the change in rubber properties after it is exposed to accelerated thermal aging. The thermal aging process, by application of temperature and pressure over time, of ethylene propylene diene monomer (EPDM) rubbers containing both carbon black (CB) and graphene are investigated. Both eddy-current sensing and electrical impedance measurement techniques were used for electromagnetic analysis. Both methods measure the in- and out-of-phase responses as a function of excitation frequency at room temperature. The measurements were performed before and after the aging process. The electrical percolation threshold was detected in the rubber samples by varying the CB content from 0 to 40 wt%. In the rubber sample containing 30 wt% CB, 0–5 wt% of the CB was replaced with graphene flakes. The substitution of graphene for CB in the EPDM rubber formulation provided an enhanced eddy-current and electrical impedance response. The findings demonstrate the feasibility of employing electromagnetic analysis techniques to investigate the extent of aging.
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| 19. |
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| 20. |
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| 21. |
- Tondi, Gianluca, et al.
(author)
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Tannin based foams modified to be semi-conductive : Synthesis and characterization
- 2015
-
In: Progress in organic coatings. - : Elsevier BV. - 0300-9440 .- 1873-331X. ; 78, s. 488-493
-
Journal article (peer-reviewed)abstract
- The objective of this study was to modify highly insulative and lightweight biorenewable foam thermosets to be semi-conductive for primarily building material applications. The foams were formed and then posttreated with in-situ polymerization of polyaniline, both doped and undoped, adsorbing and possibly absorbing (observed by SEM-EDX) to the foam structure at levels of 100-120 wt%. The modified tannin foams were shown to be semi-conductive in comparison to the highly insulative structure prior to polyaniline modification. While the 50% protonated polyaniline modified foams, or doped foams, had a higher conductivity than the undoped polyaniline modified foams, the acid used in fabrication of the foams provided some degree of conductivity to the undoped PANI modified foams. Moreover, the modified foams had an increased volume of 15% after modification, were more sensitive to moisture, and the polyaniline did not affect the degradation temperature of the foams.
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| 22. |
- Treu, Andreas, et al.
(author)
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Fungal durability of polyaniline modified wood and the impact of a low pulsed electric field
- 2014
-
In: International Biodeterioration & Biodegradation. - : Elsevier BV. - 0964-8305 .- 1879-0208. ; 87, s. 26-33
-
Journal article (peer-reviewed)abstract
- New wood protection technologies should be effective against biodeterioration and at the same time minimize environmental impact. The present study investigates the effect of polyaniline modification of wood and the effect of a pulsed electric field on fungal protection. The effect of fungi and a pulsed electric field on the conductivity of the modified wood was also measured. It was found that it is possible to polymerize polyaniline particles in-situ homogeneously throughout the wood specimens. The polyaniline particles themselves were not found to be anti-fungal, however when in contact with water they affected the pH drastically and inhibited fungal growth. The wood treatment with polyaniline and the connection to a pulsed electric field were found to be effective in protecting the wood from deterioration when exposed to Postia placenta. The unmodified samples that were connected to a pulsed electric field lost under 10 wt% due to fungal degradation. The combination of polyaniline treatment with the connection to a pulsed electric field showed a slight synergistic effect which resulted in less weight loss due to fungal degradation. However, a more brittle wood structure was observed. Leached and fungal exposed samples showed a significant drop in the conductivity, indicating that the network has broken down slightly.
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| 23. |
- Trey, Stacy, et al.
(author)
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Controlled deposition of magnetic particles within the 3-D template of wood : making use of the natural hierarchical structure of wood
- 2014
-
In: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 4:67, s. 35678-35685
-
Journal article (peer-reviewed)abstract
- This study presents a promising method to make three-dimensional lattices of structured nanomaterials by using wood templates for in situ (confined) directed growth of inorganic material in the ordered cell walls. The wood was impregnated by transition metal ion precursors (iron, manganese and cobalt) at 5 bars pressure that were further transformed into magnetic particles (Fe3O4, MnFe2O4 and CoFe2O4) by addition of alkaline solutions. It was found that by this method, it was possible to produce lightweight ferromagnetic functionalized wood materials in an inexpensive and environmentally friendly way. It was possible to functionalise the wood throughout the structure with a high weight percent of particles from 15-20 wt% as observed by TGA. These were not only adsorbed to the surface of the lumen, but also found by SEM-EDX throughout the cell wall and middle lamella and in higher amounts in early wood. The magnetic properties were nearly unaffected by the incorporation into the wood samples as compared to powder compacts obtained as particles that precipitated separately in the impregnation solution, both for soft and hard magnetic materials. Whereas the hard magnetic phase CoFe2O4 showed insignificant leaching, the soft magnetic Fe3O4, MnFe2O4 lost around 50 wt% during repeated washing in deionized water, suggesting that the CoFe2O4 particles were more readily attached in the structure of the wood. The crystal structure of the magnetic particles was determined to be the same in the wood structure as those formed in solution.
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| 24. |
- Trey, Stacy, et al.
(author)
-
Electron beam initiated polymerization of poly(ethylene glycol) based wood impregnants
- 2010
-
In: ACS Applied Materials and Interfaces. - 1944-8244 .- 1944-8252. ; 2:11, s. 3352–3362-
-
Journal article (peer-reviewed)abstract
- The current study demonstrates that methacrylate and acrylate poly(ethylene glycol) (PEG) functional oligomers can be effectively impregnated into wood blocks, and cured efficiently to high conversions without catalyst by e-beam radiation, allowing for less susceptibility to leaching, and favourable properties including higher Brinell hardness values. PEG based monomers were chosen because there is a long history of this water soluble monomer being able to penetrate the cell wall, thus bulking it and decreasing the uptake of water which further protects the wood from fungal attack. Diacrylate, dimethacrylate, and dihydroxyl functional PEG of Mw 550-575, of concentrations 0, 30, 60, and 100 wt% in water, were vacuum pressure impregnated into Scots Pine blocks of 15 x 25 x 50 mm in an effort to bulk the cell wall. The samples were then irradiated and compared with non-irradiated samples. It was shown by IR, DSC that the acrylate polymers were fully cured to much higher conversions than can be reached with conventional methods. Leaching studies indicated a much lower amount of oligomer loss from the cured vinyl functional PEG chains in comparison to hydroxyl functional PEG indicating a high degree of fastening of the polymer in the wood. The Brinell hardness indicated a significant increase in hardness to hardwood levels in the modified samples compared to the samples of hydroxyl functional PEG and un-cured vinyl PEG samples which actually became softer than the untreated Scots Pine. By monitoring the dimensions of the sample it was found by weight percent gain calculations (WPG %) that water helps to swell the wood structure and allow better access of the oligomers into the cell wall. Further, the cure shrinkage of the wood samples demonstrated infiltration of the oligomers into the cell wall as this was not observed for methyl methacrylate which is well documented to remain in the lumen. However, dimensional stability of the vinyl polymer modified blocks when placed in water was not observed to the same extent as PEG.
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| 25. |
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| 26. |
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| 27. |
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| 28. |
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| 29. |
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| 30. |
- Trey, Stacy, et al.
(author)
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In situ polymerization of polyaniline in wood veneers
- 2012
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In: NWBC 2012 - 4th Nordic Wood Biorefinery Conference. - : VTT Technical Research Centre of Finland. ; 4:3, s. 1760-1769
-
Conference paper (peer-reviewed)abstract
- The present study describes the possibility to polymerize aniline within wood veneers to obtain a semi-conducting material with solid wood acting as the base template. It was determined that it is possible to synthesize the intrinsically conductive polymer (ICP) polyaniline in situ within the wood structure of Southern yellow pine veneers, combining the strength of the natural wood structure with the conductivity of the impregnated polymer. It was found that polyaniline is uniformly dispersed within the wood structure by light microscopy and FT-IR imaging. A weight percent gain in the range of 3−12 wt % was obtained with a preferential formation in the wood structure and cell wall, rather than in the lumen. The modified wood was found to be less hydrophilic with the addition of phosphate doped polyaniline as observed by equilibrium water swelling studies. While wood itself is insulating, the modified veneers had conductivities of 1 × 10−4 to 1 × 10−9 S cm−1, demonstrating the ability to tune the conductivity and allowing for materials with a wide range of applications, from anti-static to charge-dispersing materials. Furthermore, the modified veneers had lower total and peak heat releases, as determined by cone calorimetry, because of the char properties of the ICP. This is of interest if these materials are to be used in building and furniture applications where flame retardance is of importance.
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| 31. |
- Trey, Stacy M., et al.
(author)
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Dual cure (UV/thermal) primers for composite substrates-Effect of surface treatment and primer composition on adhesion
- 2009
-
In: Progress in organic coatings. - : Elsevier BV. - 0300-9440 .- 1873-331X. ; 64:4, s. 489-496
-
Journal article (peer-reviewed)abstract
- It can be concluded by the Study of UV primer formulations on sheet molding compound (SMC) substrates that all studied formulation parameters affect adhesion. Moreover, the dual cure approach can result in acceptable adhesion of UV primers on SMC substrates if the coating procedure and composition are well designed. Adhesion of UV cure primers as determined by the cross-cut test is significantly improved in formulations containing solvent. This is a result of enhanced wetting and interaction of the solvent with the SMC Substrate, confirmed by contact angle and gravimetric swelling studies. Furthermore, sanded SMC surfaces demonstrated superior UV primer adhesion. This results from the increased surface area of the topography, confirmed by CSLM and the exposure of more oxygen moieties such as pigments and silanols at the air-substrate interface as confirmed by AFM and XPS, The UV films have a higher modulus with increasing resin functionality and resulting cross-link density which correlated with reduced adhesion in formulations without an added isocyanate functional UV monomer. This indicates that cure shrinkage may play a role in the adhesion of UV cure primers and will be investigated further. Also, the added adhesion that an isocyanate functional UV monomer provides results in a significant increase in the glass transition temperature (T-g) giving a glassier film at room temperature.
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| 32. |
- Trey, Stacy. M., et al.
(author)
-
Effects of dual cure and surface treatments on coating adhesion to different SMC substrates
- 2009
-
In: Plastics, rubber and composites. - : Informa UK Limited. - 1465-8011 .- 1743-2898. ; 38:2-4, s. 131-137
-
Journal article (peer-reviewed)abstract
- Sheet moulded compound (SMC) is a highly filled, glass fibre 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. The present study investigates a series of UVPs, showing the effect of resin functionality and isocyanate additive content on the adhesion of the coatings to SMC substrates. The SMC formulation is also considered regarding how variables such as surface chemistry, morphology, surface area and degree of post-mould emissions affect UVP adhesion. The present study reveals the crucial factors involved in achieving adhesion including the importance of low post-mould emissions, high surface areas, glass fibre and other oxygen moieties on the surface, and improved wetting of the surface.
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| 33. |
- Trey, Stacy M., et al.
(author)
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Effects of thiol additives on urethane acrylate UV primers for SMC applications
- 2009
-
In: Progress in organic coatings. - : Elsevier BV. - 0300-9440 .- 1873-331X. ; 64:2-3, s. 238-246
-
Journal article (peer-reviewed)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.
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| 34. |
- Trey, Stacy M., et al.
(author)
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Electron-Beam-Initiated Polymerization of Poly(ethylene glycol)-Based Wood Impregnants
- 2010
-
In: ACS APPL MATER INTERFACES. - : American Chemical Society (ACS). - 1944-8244. ; 2:11, s. 3352-3362
-
Journal article (peer-reviewed)abstract
- The current study demonstrates that methacrylate and acrylate poly(ethylene glycol) (PEG) functional oligomers can be effectively impregnated into wood blocks and cured efficiently to high conversions without catalyst by e-beam radiation, allowing for less susceptibility to leaching, and favorable properties including higher Brinell hardness values. PEG based monomers were chosen because there is a long history of this water-soluble monomer being able to penetrate the cell wall, thus bulking it and decreasing the uptake of water which further protects the wood from fungal attack. Diacrylate dimethacrylate and dihydroxyl functional PEG of M-v, 550-575 of concentration 0-30, 60 and 100 wt % in water, were vacuum pressure impregnated into Scots Pine blocks of 15 x 25 x 50 mm in an effort to bulk the cell wall. The samples were then irradiated and compared with nonirradiated samples it was shown by IR, DSC that the acrylate polymers were fully cured to much higher conversions than can be reached with conventional methods Leaching studies indicated a much lower amount of oligomer loss from the cured to much higher conversions than can be reached with conventional methods functional PEG indication a high degree of fastening of the polymer in the wood. The Brinell hardness indicated a significant increase in hardness to hardwood levels in the modified samples compared to the samples of hydroxyl functional PEG and uncured vinyl PEC samples, which actually became softer than the untreated Scots Pine. By monitoring the dimensions of the sample it was found by weight percent gain calculations WPC %) that water helps to swell the wood structure and allow better access of the oligomers into the cell wall as this was not observed for methyl methacrylate which is well-cocumented to remain in the lumen. However dimensional stability of the viny ploymer modified blocks when placed in water was not observed to the same extent as PEG.
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| 35. |
- Trey, Stacy M., et al.
(author)
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Glass fiber reinforced high glass transition temperature thiol-ene networks
- 2011
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In: Composites. Part A, Applied science and manufacturing. - : Elsevier BV. - 1359-835X .- 1878-5840. ; 42:11, s. 1800-1808
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Journal article (peer-reviewed)abstract
- Although thiol-ene polymers have highly desirable processing properties the networks usually are limited to having characteristically low glass transition temperatures with low strength. This study is one of the first studies to examine a thiol-ene polymer thermoset matrix, having many industrial advantages compared to conventional polymer matrices, reinforced with continuous E-glass fibers. In order to control the interphase, a mercapto functional sizing of 1 wt% is applied to the glass fibers. The resulting composites of 12 vol% fibers are comparable to glass fiber reinforced polyesters in terms of strength with Young's modulus. This work contributes to the furthering of thiol-ene ultra-violet cure systems, with their range of advantageous properties, for use in a broader scope of applications by way of creating a stronger material based on a novel class of thermoset matrix.
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| 36. |
- Trey, Stacy M., et al.
(author)
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Thiol-ene networks and reactive surfaces via photoinduced polymerization of allyl ether functional hyperbranched polymers
- 2010
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In: Progress in organic coatings. - : Elsevier BV. - 0300-9440 .- 1873-331X. ; 67:3, s. 348-355
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Journal article (peer-reviewed)abstract
- A series of allyl ether functionalized hyperbranched (HB) polyester of three generations was synthesized from commercially available Boltorn (R). These modified HB polymers were homopolymerized to form films with a large number of residual allyl ether groups available for post film formation reactions. Additionally, the polyester Multifunctional molecules were cured with a di and tetrathiol monomer in a one to one molar ratio to determine the effect of conversion on the resulting network thermal and physical properties. The same UV-cure chemistries were carried out with a similar second generation polyester dendrimer for comparison. This was in an effort to determine if there is any significant difference in the film chemical conversion and properties with dendrimers in comparison to HB molecules. The highly crosslinked films were obtained and characterized with respect to physical (DMTA) and thermal (DSC and TGA) properties. (C) 2009 Elsevier B.V. All rights reserved.
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| 37. |
- Trey, Stacy M., et al.
(author)
-
Thiol-ene networks and reactive surfaces via photoinduced polymerization of allyl ether functional hyperbranched polymers
- 2010
-
In: Progress in organic coatings. - : Elsevier BV. - 0300-9440 .- 1873-331X. ; 68:1-2, s. 151-158
-
Journal article (peer-reviewed)abstract
- A series of allyl ether functionalized hyperbranched (HB) polyester of three generations was synthesized from commercially available Boltorn (R). These modified HB polymers were homopolymerized to form films with a large number of residual allyl ether groups available for post-film formation reactions. Additionally, the polyester multifunctional molecules were cured with a di and tetrathiol monomer in a one to one molar ratio to determine the effect of conversion on the resulting network thermal and physical properties. The same UV-cure chemistries were carried out with a similar second generation polyester dendrimer for comparison. This was in an effort to determine if there is any significant difference in the film chemical conversion and properties with dendrimers in comparison to HB molecules. The highly crosslinked films were obtained and characterized with respect to physical (DMTA) and thermal (DSC and TGA) properties.
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| 38. |
- Yucel, Yasemin Duygu, et al.
(author)
-
Enhancing Structural Battery Performance : Investigating the Role of Conductive Carbon Additives in LiFePO4-Impregnated Carbon Fiber Electrodes
-
Other publication (other academic/artistic)abstract
- This study centers on investigating the influence of conductive additives, carbon black (Super P) and graphene, within the context of LiFePO4 (LFP)-impregnated carbon fibers (CFs) produced using the powder impregnation method. The performance of these additives was subject to an electrochemical evaluation. The findings reveal that there are no substantial disparities between the two additives at lower cycling rates, highlighting their adaptability in conventional energy storage scenarios. However, as cycling rates increase, graphene emerges as the better performer. At a rate of 1.5C in a half-cell versus lithium, electrodes containing graphene exhibited a discharge capacity of 83 mAh g-1LFP ; those with Super P and without any additional conductive additive showed a capacity of 65 mAh g-1LFP and 48 mAh g-1LFP , respectively. This distinction is attributed to the structural and conductivity advantages inherent to graphene, showing its potential to enhance the electrochemical performance of structural batteries. Furthermore, LFP-impregnated CFs were evaluated in full cells versus pristine CFs, yielding relatively similar results, though with a slightly improved outcome observed with the graphene additive. These results provide valuable insights into the role of conductive additives in structural batteries and their responsiveness to varying operational conditions, underlining the potential for versatile energy storage solutions.
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| 39. |
- Yucel, Yasemin Duygu, et al.
(author)
-
Enhancing structural battery performance: Investigating the role of conductive carbon additives in LiFePO4-Impregnated carbon fiber electrodes
- 2024
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In: Composites Science And Technology. - : Elsevier BV. - 0266-3538 .- 1879-1050. ; 251
-
Journal article (peer-reviewed)abstract
- This study centers on investigating the influence of conductive additives, carbon black (Super P) and graphene, within the context of LiFePO4 (LFP)-impregnated carbon fibers (CFs) produced using the powder impregnation method. The performance of these additives was subject to an electrochemical evaluation. The findings reveal that there are no substantial disparities between the two additives at lower cycling rates, highlighting their adaptability in conventional energy storage scenarios. However, as cycling rates increase, graphene emerges as the better performer. At a rate of 1.5C in a half-cell versus lithium, electrodes containing graphene exhibited a discharge capacity of 83 mAhgLFP−1; those with Super P and without any additional conductive additive showed a capacity of 65 mAhgLFP−1 and 48 mAhgLFP−1, respectively. This distinction is attributed to the structural and conductivity advantages inherent to graphene, showing its potential to enhance the electrochemical performance of structural batteries. Furthermore, LFP-impregnated CFs were evaluated in full cells versus pristine CFs, yielding relatively similar results, though with a slightly improved outcome observed with the graphene additive. These results provide valuable insights into the role of conductive additives in structural batteries and their responsiveness to varying operational conditions, underlining the potential for versatile energy storage solutions.
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| 40. |
- Yucel, Yasemin Duygu, et al.
(author)
-
Powder-impregnated carbon fibers with lithium iron phosphate as positive electrodes in structural batteries
- 2023
-
In: Composites Science And Technology. - : Elsevier Ltd. - 0266-3538 .- 1879-1050. ; 241
-
Journal article (peer-reviewed)abstract
- A structural battery is a multifunctional battery that can carry a load while storing energy. Structural batteries have been a cutting-edge research focus in the last decade and are mainly based on polyacrylonitrile (PAN)-carbon fibers (CFs). In this work, positive electrodes based on PAN-carbon fibers were manufactured with powder impregnation (siphon impregnation) technique using a water-based slurry containing lithium iron phosphate (LFP) as the active electrode material and the water-soluble binder polyethylene glycol (PEG). Different coating compositions, electrode-drying temperatures, and coating parameters were investigated to optimize the coating uniformity and the electrochemical performances. Scanning electron microscopy results showed that the electrode materials coat the CFs uniformly, conformably, and individually. Electrochemical characterization of pouch cells shows that the electrodes containing 6 wt% PEG dried at 140 °C have the best battery performance, delivering a first discharge capacity of 151 mAh g−1 and capacity retention higher than 80% after 100 cycles. Moreover, excellent capacity reversibility was achieved when the electrodes were cycled at multiple C-rates attesting to their stability. The results demonstrate that CFs perform excellently as current collectors in positive electrodes.
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| 41. |
- Yucel, Yasemin Duygu, et al.
(author)
-
Structural Batteries with LiFePO4-Impregnated Carbon Fibers
-
Other publication (other academic/artistic)abstract
- This study focuses on the fabrication and evaluation of structural batteries, emphasizing their electrochemical performance. LiFePO4 (LFP)-impregnated carbon fibers (CFs), produced via the powder impregnation method, were employed as positive electrodes. These electrodes underwent infusion with structural battery electrolyte (SBE) and curing to yield positive structural battery electrodes. A structural battery fully based on CFs was constructed and subjected to electrochemical testing, with positive electrodes assembled versus pristine CF of T800S as negative electrodes. The results revealed specific discharge capacities of 123 mAh g-1LFP for the structural positive electrode and 178 mAh g-1T800S for the structural battery, both at similar current densities. Both the half and full structural cells maintained capacities of 94% and 96%, respectively, during rate capability tests when reverting to their initial current densities. The electrochemical impedance spectroscopy (EIS) results revealed that, the structural battery demonstrated a relatively improved surface impedance, with the values ranging between 186 Ω cm² and 2000 Ω cm². Additionally, similar comparative studies were conducted on full cells in a commercial liquid electrolyte consisting of 1M LiPF6 in EC: DEC (1:1 vol.%). The research introduces a prototype of laminated composite batteries, showing their potential, especially when utilizing fully carbon fiber-based electrodes.
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