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| 2. |
- Kim, Injeong, et al.
(författare)
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Characterisation of Moisture in Scots Pine (Pinus sylvestris L.) Sapwood Modified with Maleic Anhydride and Sodium Hypophosphite
- 2021
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Ingår i: Forests. - : MDPI. - 1999-4907. ; 12:10
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Tidskriftsartikel (refereegranskat)abstract
- In this study, the wood–water interactions in Scots pine sapwood modified with maleic anhydride (MA) and sodium hypophosphite (SHP) was studied in the water-saturated state. The water in wood was studied with low field nuclear magnetic resonance (LFNMR) and the hydrophilicity of cell walls was studied by infrared spectroscopy after deuteration using liquid D2O. The results of LFNMR showed that the spin–spin relaxation (T2) time of cell wall water decreased by modification, while T2 of capillary water increased. Furthermore, the moisture content and the amount of water in cell walls of modified wood were lower than for unmodified samples at the water-saturated state. Although the amount of accessible hydroxyl groups in modified wood did not show any significant difference compared with unmodified wood, the increase in T2 of capillary water indicates a decreased affinity of the wood cell wall to water. However, for the cell wall water, the physical confinement within the cell walls seemed to overrule the weaker wood–water interactions.
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| 3. |
- Kim, Injeong, et al.
(författare)
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Dimensional stabilisation of Scots pine (Pinus sylvestris L.) sapwood by reaction with maleic anhydride and sodium hypophosphite
- 2021
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Ingår i: European Journal of Wood and Wood Products. - : Springer. - 0018-3768 .- 1436-736X. ; 79:3, s. 589-596
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Tidskriftsartikel (refereegranskat)abstract
- Wood has the ability to absorb and desorb moisture, which can affect its dimensional size when in use. Limiting this can provide products with greater shape stability and less stresses on external coatings. One method that has been investigated for achieving this has been through chemical modification. In this work, the dimensional stabilisation imparted to Scots pine sapwood by chemical modification with maleic anhydride (MA) combined with sodium hypophosphite (SHP) was investigated. The influence of concentration of MA, treatment temperature and treatment period on weight percent gain (WPG) and bulking coefficient (BC) during treatment with MA and SHP of wood was studied. Furthermore, dimensional stability was determined by the water soak/oven dry method (wet-dry cycle) through five cycles in order to determine the hydrolytic stability of the ester bond and any potential cross-linking reactions. Wood blocks (20 × 20 × 10 mm) modified with MA combined with SHP exhibited lower weight loss following water soaking than unmodified blocks or MA-treated blocks. Wood blocks modified with MA and SHP showed the best anti-swelling efficiency and minimum wet-volume (water-saturated). However, as the concentration of SHP increased, dimensional stability was diminished without any increase in weight percentage gain after water soaking. When combined with FTIR results, it appeared that the modification with MA and SHP seemed to form cross-linking between wood constituents, though high concentration of SHP did not seem to result in additional cross-linking.
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| 5. |
- Lin, Chia-feng, et al.
(författare)
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A new wood-modification process based on in situ grafting of urethane groups: biological resistance and dimensional stability of carbamylated Scots pine wood
- 2023
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Ingår i: Wood Material Science & Engineering. - : Taylor & Francis. - 1748-0272 .- 1748-0280. ; 18:3, s. 1160-1162
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Tidskriftsartikel (refereegranskat)abstract
- Chemical modification of wood typically requires the impregnation of wood with reactive compounds capable of undergoing covalent bonding to functional groups present in the cell wall. Creating such reactive agents in situ, with the use of low-priced chemicals, would prove more attractive for commercial applications. In this study, Scots pine (Pinus sylvestris L.) sapwood was impregnated with an aqueous solution of urea (30%), dried at 40°C for 24 h, and subsequently heat treated in an oven at 150°C for 24 h to produce the reactive isocyanic acid. By using accelerated fungal tests under laboratory conditions, provisional tests demonstrated a high biological resistance against selected moulds and rots. Migration of urea into the wood structure and grafting to its polymers during subsequent heat treatment, led to a bulked cell wall and enhanced resistance to water swelling, even after cycling water treatments. The bending strength (MOR) of modified pine wood was reduced by the treatment applied, while its modulus of elasticity (MOE) remained unchanged.
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| 6. |
- Lin, Chia-Feng, et al.
(författare)
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Approaching Highly Leaching-Resistant Fire-Retardant Wood by In Situ Polymerization with Melamine Formaldehyde Resin
- 2021
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Ingår i: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 6:19, s. 12733-12745
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Tidskriftsartikel (refereegranskat)abstract
- The objective of the work was to improve the leaching resistance of fire-retardant (FR) modified wood by the incorporation of a thermoset resin. Here, Scots pine (Pinus sylvestris L.) sapwood was impregnated with melamine formaldehyde (MF) resin and hydrophilic FRs guanyl-urea phosphate/boric acid by a vacuum-pressure treatment. Resistance to leaching of FR-modified wood was evaluated, after conducting an accelerated aging test according to European standard EN 84. Inductively coupled plasma analysis showed that the incorporation of MF resin significantly reduced the leachability of FRs. Scanning electron microscopy/energy-dispersive X-ray spectrometry revealed that the mechanism of water resistance was by doping the FRs into MF resin microspheres. Fourier transform infrared spectra showed the chemical functionality changes of FR-modified wood such as the formation of methylene bridges by drying the modified wood specimens. An increase in the thermal stability of FR-modified wood was confirmed by thermal gravimetric analysis. Excellent fire performance of FR-modified wood after leaching was affirmed by the limiting oxygen index and cone calorimeter tests.
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| 7. |
- Lin, Chia-Feng, et al.
(författare)
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Fire performance and leach resistance of pine wood impregnated with guanyl-urea phosphate/boric acid and a melamine-formaldehyde resin
- 2020
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Ingår i: European Journal of Wood and Wood Products. - : Springer. - 0018-3768 .- 1436-736X. ; 78:1, s. 107-111
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Tidskriftsartikel (refereegranskat)abstract
- Scots pine (Pinus sylvestris L.) wood impregnated with guanyl-urea phosphate/boric acid and a melamine-formaldehyde resin exhibited considerably increased resistance to leaching, while sustaining superior fire retardancy as tested by the limiting oxygen index (LOI) method. It was found that guanyl-urea phosphate has been well trapped in the wood structure by the cured resin network as evidenced by FTIR spectroscopy. Markedly, weight percentage gain (WPG) losses of fire retardant as low as 7.4% were achieved after excessive leaching of treated wood (EN 84). This was attributed to the effect of melamine-formaldehyde resin. Overall, this type of treatment could be a reliable method for producing fire-resistant pine wood for exterior uses.
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| 8. |
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| 9. |
- Lin, Chia-Feng, et al.
(författare)
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Fire Retardancy and Leaching Resistance of Furfurylated Pine Wood (Pinus sylvestris L.) Treated with Guanyl-Urea Phosphate
- 2022
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Ingår i: Polymers. - : MDPI. - 2073-4360. ; 14:9
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Tidskriftsartikel (refereegranskat)abstract
- Guanyl-urea phosphate (GUP) was introduced into furfurylated wood in order to improve fire retardancy. Modified wood was produced via vacuum-pressure impregnation of the GUP–furfuryl alcohol (FA) aqueous solution, which was then polymerized at elevated temperature. The water leaching resistance of the treated wood was tested according to European standard EN 84, while the leached water was analyzed using ultra-performance liquid chromatography (UPLC) and inductively coupled plasma–sector field mass spectrometry (ICP-SFMS). This new type of furfurylated wood was further characterized in the laboratory by evaluating its morphology and elemental composition using optical microscopy and electron microscopy coupled with energy-dispersive X-ray spectrometry (SEM-EDX). The chemical functionality was detected using infrared spectroscopy (FTIR), and the fire resistance was tested using cone calorimetry. The dimensional stability was evaluated in wet–dry soaking cycle tests, along with the mechanical properties, such as the Brinell hardness and bending strength. The fire retardancy of the modified furfurylated wood indicated that the flammability of wood can be depressed to some extent by introducing GUP. This was reflected in an observed reduction in heat release rate (HRR2) from 454.8 to 264.9 kW/m2, without a reduction in the material properties. In addition, this leaching-resistant furfurylated wood exhibited higher fire retardancy compared to conventional furfurylated wood. A potential method for producing fire-retardant treated furfurylated wood stable to water exposure has been suggested.
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| 10. |
- Lin, Chia-Feng, et al.
(författare)
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Fire Retardancy and Leaching Resistance of Pine Wood Impregnated with Melamine Formaldehyde Resin in-Situ with Guanyl-Urea Phosphate/Boric Acid
- 2020
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Ingår i: Wood & Fire Safety. - Cham : Springer. ; , s. 83-89
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Konferensbidrag (refereegranskat)abstract
- This work aimed at finding ways to improve the leaching resistance of Scots pine (Pinus sylvestris L.) wood impregnated with water soluble fire retardant (FR). Sapwood specimens of Scots pine (10 × 10 × 50 mm) were impregnated with aqueous solution of guanyl-urea phosphate (GUP)/boric acid (BA). Limiting oxygen index (LOI) revealed that treatment could improve the fire performance. At the same time, thermogravimetric analysis (TGA) illustrated increased thermal stability after the treatment. However, since the FR itself was not fixed within the wood cell wall, it was extracted during water leaching (EN 84), and the wood lost its fire retarding property. The resistance to leaching of FR from the treated wood can be primarily improved while maintaining high fire retarding performance and thermal stability of treated wood by mixing melamine-formaldehyde (MF) resin with GUP/BA before impregnation to the wood. To mix GUP/BA to MF solution, due to the acidic nature of GUP/BA, the condensation/polymerisation reaction would be accelerated in an undesired way even if the solution was adjusted to non-acidic by NaOH. The resulting solution would not penetrate deeply into the wood structure, whilst it would be difficult to re-use the FR solution. In order to avoid the reaction proceeding in an undesired way, introducing 0.5 wt% of pentaerythritol to the GUP/BA/MF solution can decrease the reaction rate. Additionally, it improved the weight percentage gain (WPG) and fire retarding performance, without significantly influencing the leaching resistance and thermal stability. Overall, it is suggested that such a treatment could be a suitable methodology for producing exterior-use fire-retardant pine wood.
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