1,720,962 research outputs found
Enhancing fire resistance in pine wood through DMDHEU resin and phosphate-nitrogen flame retardant synergies
No full textAbstract Wood modification with 1,3-dimethylol-4,5-dihydroxyethyleneurea (DMDHEU) has been widely demonstrated to enhance the biological durability and dimension stability of wood, thus it serves a predestined technology to equip wooden products for outdoor applications. However, such technology hardly affects the fire performance of wood, a parameter which gains increasing relevance in the construction sector. Recently, the combination of curing resins with flame retardants has been proposed as a potential approach to enhance the fire performance of wood in a permanent way, hence providing a durable fire protection system. Scots pine sapwood ( Pinus sylvestris L.) was impregnated with aqueous compositions of DMDHEU, a commercially available phosphate-nitrogen based fire retardant (adapted for wooden applications) and combinations thereof. The fixation of the flame retardant was assessed on the basis of a cold water leaching process according to EN 84 (2020). The fire performance of the treated wood was assessed through thermal gravimetry analysis (TGA), a Bunsen burner ignition test and mass loss calorimeter. Both wood treated with pure flame retardant and combination of a flame retardant and DMDHEU, demonstrated improvements in thermal stability, reduced flammability and decreased heat release after treatment. Notably, the THR 600s of wood treated with DMDHEU in combination with the flame retardant was reduced by 89.3% compared to wood treated solely with DMDHEU. However, after the leaching process, the flame retardant happened to leach out almost completely, which was assessed on the basis of a loss in its efficacy related to fire protection. On the contrary, DMDHEU seemed to partially fix the flame retardant inside the wood matrix, which was derived from a persistent enhancement in fire performance, even after wooden specimens passed a cold water leaching
Fire resistance of Scots pine modified with sorbitol, citric acid and fire retardants
No full textAbstract Sorbitol-citric acid (SorCA) modification is an eco-friendly wood treatment that demonstrates promising potential for enhancing dimensional stability and decay resistance of wood material. To improve the fire resistance property of SorCA (1:2; 30%) modified wood, fire retardants (FRs) such as diammonium hydrogen phosphate (DAP) and potassium carbonate (PC) were incorporated into the modification system at a rate of 10% and 15%, respectively. Scots pine wood modified with the combination of SorCA and FRs was subjected to mass loss calorimeter test to evaluate its flame retardancy. In addition, thermogravimetric analysis (TGA) was carried out for determining the thermal behaviour of modified wood at elevated temperatures. Fourier-transform infrared spectroscopy (FTIR) was used to identify the chemical bonds in the modified wood. The FTIR spectrum indicated an intensity enhancement at 1716 cm − 1 , resulting from the bonding with the cell wall or between the reagents. TGA analysis showed that the addition of DAP and PC to the SorCA system enhanced the thermal stability, yielding higher residual mass compared to SorCA alone and the untreated reference. The mass loss calorimeter revealed that SorCA with DAP 15% significantly improved flame retardancy, lowering the peak heat release rate by 65% and total heat release within 600 s by 82% compared to untreated wood. The combination of SorCA with DAP and PC contributed to the char formation and showed potential flame retardancy for modified Scots pine wood
Fire behavior of thermally modified pine ( Pinus sylvestris ) treated with DMDHEU and flame retardants: from small scale to SBI tests
No full textAbstract In this study, thermally modified Scots pine ( Pinus sylvestris L.) was impregnated with DMDHEU (1,3-dimethylol-4,5-dihydroxyethyleneurea) monomers combined with a flame retardant (FR) based on monoguanidine phosphate salt. Fire performance was assessed using ignitability tests (ISO 11925-2, 2020), mass loss calorimetry test (ISO 13927, 2015), and single burning item (SBI) tests (EN 13823, 2020). Results showed enhanced flame retardancy, reaching Class B in the SBI test. Small-scale ignitability tests revealed minor differences in flame spread across samples, unlike the SBI results. Fire growth rate and ignition time from mass loss calorimetry strongly correlated with burning suppression in the SBI test
Combined treatment of wood with thermosetting resins and phosphorous flame retardants
No full textAbstract Wood modification with thermosetting resins results in improved dimensional stability and durability. However, the treatment does not enhance fire resistance. To address this, Scots pine sapwood ( Pinus sylvestris L.) was impregnated with thermosetting resins such as 1,3-dimethylol-4,5-dihydroxyethyleneurea, phenol-formaldehyde resin and melamine-formaldehyde resin, along with a phosphorus polyol as the flame retardant. Both weight percent gain and cell wall bulking were measured to investigate the deposition of resin and phosphorus polyol. Fire resistance was assessed through thermogravimetric analysis, Bunsen burner test and mass loss calorimeter. The inclusion of a phosphate polyol improved thermal stability, reduced flammability and heat release. Melamine-formaldehyde resin combined with phosphorus polyol demonstrated self-extinguishing capability with the heat release rate comparable to non-combustible materials inside 400 s. Moreover, the total heat release within 600 s shows an 84% reduction compared to untreated wood
Fire-retardant properties of wood modified with sorbitol, citric acid and a phosphorous-based system
No full textAbstract
Scots pine sapwood (
Pinus sylvestris
L.) was modified with an aqueous solution of sorbitol and citric acid (SorCA) and a commercial phosphorus-based fire-retardant (FR). The aim of this study was to assess whether the fire behavior can be improved when the SorCA solution is supplemented by an FR and if this effect is resistant to leaching. The fire behavior of modified wood was investigated by a Bunsen burner ignition test, mass loss calorimetry (MLC) and thermogravimetric analysis (TGA). The results demonstrated a significantly improved fire-retardancy based on a decreased burning rate and a reduced mass loss in the Bunsen burner test. Also, the induced formation of a protective char barrier facilitated by the addition of a FR, reduced the heat release rate and delayed the ignition. The fire-retardant effect was still observed, to the less extent, after a cold-water (EN 84 2020) leaching of the specimens
Fire resistance of pine wood treated with phenol-formaldehyde resin and phosphate-based flame retardant
No full textChina Scholarship Council 10.13039/50110000454
Long-term durability and flame retardancy for outdoor wood : Multifunctional enhancement using phenol-formaldehyde resin and monoguanidine phosphate salt
No full textWood's flammability, low dimensional stability, and poor fungal resistance limit its application. In this study, Scots pine sapwood (Pinus sylvestris L.) was treated with a low-molecular-weight phenol–formaldehyde (PF) resin and a monoguanidine phosphate flame retardant (FR) to achieve multifunctional enhancement. Differential scanning calorimetry confirmed no interference of FR with PF curing, while SEM and cell wall bulking analysis demonstrated effective penetration. The treatment improved the modulus of elasticity and rupture, though impact bending strength slightly decreased. Fungal decay resistance reached durability class 1 (EN 350, 2016) based on white- and brown-rot tests (EN 113–2, 2021). Dynamic vapor sorption showed no increase in equilibrium moisture content below 70 % RH. Artificial and natural weathering tests confirmed good FR retention and weathering resistance. Thermogravimetric analysis showed enhanced thermal stability, with higher char residue than FR-only treatments. Cone calorimetry verified sustained flame retardancy even after weathering. This combined treatment offers a durable, multifunctional wood modification approach suitable for structural and outdoor applications
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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