Low-density Fiberboard Research Articles

Effects of different flame-retardant treatments on the sound absorption properties of low-density fiberboard

Effects of different flame-retardant treatments on the sound absorption properties of low-density fiberboard

Latest advancements in high-performance bio-based wood adhesives: A critical review

Over the last 50 years, the use of wood adhesives in the manufacturing of wood-based panel goods has increased the efficiency of wood resources. Wood adhesives are becoming more popular as the need for wood-based panels grows. By 2028, the global market for wood adhesives is expected to reach 21.8 billion dollars. Even though urea-formaldehyde (UF), phenol-formaldehyde (PF), melamine-formaldehyde (MF), phenol-resorcinol-formaldehyde (PRF), and resorcinol-formaldehyde (RF) resins are excellent in terms of bonding performance, workability, quality, and economy, they consist of harmful or toxic chemical agents derived from fossil resources, which make their application severely limited. This review aims to go through the most significant ‘green’ wood adhesives for manufacturing high-performance wood-based panels, such as lignin, tannin, protein, natural rubber, emulsion polymer isocyanate (EPI), 1C PUR polyurethane (for glue-laminated wood and cross-laminated timber), PMDI (for particleboards, medium-density and low-density fiberboards), carboxylic acid, and vegetable oil. The physical and mechanical characteristics of bio-based wood adhesives, as well as the development of sustainable, greener, and high-performance bio-based wood adhesives, are discussed in this work. Original research papers and review articles are among the most important sources since they provide complete information on the most recent developments in sustainable, eco-friendly, and high-performance bio-based wood adhesives.

Multiscale analysis of water vapor diffusion in low density fiberboard: Implications as a building material

This work is devoted to diffusion mechanisms in low-density fiberboard (255 kg m−3). Experiments were performed under unsteady state conditions (relative humidity step from 37% to 71%) with different thicknesses (half thickness ranging from 1 mm to 20 mm). The mass diffusivity was determined by inverse analysis from the experimental moisture content evolution, using a comprehensive macroscopic model of coupled heat and mass transfer. A clear failure of Fickian’s law becomes evident regarding the effect of thickness. A dual-scale model, based on the concept of distributed microstructure models with coupled heat and mass transfer at both scales, was used to simulate the experiments. The large number of dual-scale simulations proposed in this work were also analyzed by the inverse method. These dual-scale simulation results were successfully confronted to the experiment. The good fit with the experimental data is obtained for a diffusivity of the microscopic phase (the storage phase) equal to 1.10−13m2 s−1 for a fiber radius of 20μm. As the main recommendation, we advise that the dual scale effect can be neglected for this kind of fiberboard for a total thickness larger than some centimeters, depending on the panel density. This also means that this effect must be considered in material characterization or when capturing the buffering effect of the surface layers of the envelope.

Potential new tracers and their mass fraction in the emitted PM<sub>10</sub> from the burning of household waste in stoves

Abstract. The production and use of plastics is increasing rapidly as they are widely used in packaging, construction materials, furniture, foils, etc. As a consequence of their widespread use and often disposable nature, vast streams of plastic waste are continuously generated, a considerable fraction of which are combusted in households worldwide. In this paper, various types of commonly used plastics (PE, PET, PP, PU, PVC, PS, ABS) as well as treated wood samples (LDF, low-density fibreboard) and firewood were combusted separately in a test stove under controlled conditions. The particulates emitted during the combustion test were collected on filters, potential tracers for each waste type were identified by GC-MS, and their relative abundances were determined. The emission factor of 1,3,5-triphenylbenzene was found to be higher for polymers containing aromatic rings in their structure. The application of terphenyls and quaterphenyls as tracer compounds has also been investigated. The trimer of styrene was found to be a potential tracer for the combustion of polystyrene and/or styrene-containing copolymers. Novel tracers were proposed for the burning of PET and furniture plates (LDF), which are among the most widely used waste types burned in households.

Novel insulation panels development from multilayered coir short and long fiber reinforced phenol formaldehyde polymeric biocomposites

This study investigated about the developments of insulation panels from multilayered coir long and short fiber reinforced phenol formaldehyde polymeric (PF) resin. The lengths of coir long fibers (CLF) were within 3 mm, whereas the short fibers (CSF) ranged from 0.1 mm to 1.25 mm. Four composite panels of 360, 680, 800, and 1000 kg/m3 densities were developed by employing hot pressing technology. The thermal conductivity, microstructural, mechanical, and physical properties of the composite panels were investigated. Perceived thermal conductivity values ranged within 0.046280 (0.000494) to 0.062400 (0.001146) Wm‒1 k‒1of the composites demonstrating superior insulation properties. Moreover, the current study also found that mechanical and thermal properties showed improvement with the increase of density. Low-density fiberboards had the lowest performances compared to high-density composite panels, with the exception of the 1000 kg/m3 density, in which fiber agglomeration occurred. Furthermore, all the developed composite panels display superior potentiality for use as effective insulation materials. The FTIR (Fourier transform infrared spectroscopy) analysis also shows an efficient bonding between the cellulosic coir materials and PF resin. The overall characteristics of the composite panels, especially medium fiberboard, show prominent potential for industrial production units by fulfilling the consumer requirements.

Enhanced mechanical and thermal properties of hollow wood composites filled with phase-change material

To obtain lightweight wood building materials with good thermal insulation, energy-saving properties, and satisfying mechanical properties, low-density fiberboard and hollow wood composites (HWC) embedded polyvinyl chloride tubes were fabricated by hot-pressing. Polyethylene glycol was used as the phase-change material to fill polyvinyl chloride tubes and obtain phase-change hollow wood composite (PHWC). The physical and mechanical properties of HWC and PHWC were tested, and their thermal properties were analyzed and simulated. The results showed that the thermal conductivities of low-density fiberboard, HWC, and PHWC ranged from 0.06 to 0.07 W/(m·K), indicating they had sufficient physical and mechanical properties to be used as thermal insulation building materials. The combination of series and parallel models accurately predicted the thermal conductivity of HWC and PHWC, whose structures were similar to a series structure. The addition of polyethylene glycol into HWC allowed the PHWC to store latent heat and reduce indoor temperature fluctuations. Heat transfer simulations showed that when used as a non-structural building wall material, the PHWC wall had a better energy efficiency compared with a concrete wall. Thus, PHWC has potential applications as thermal insulation and phase-change building material.

Effects of kenaf core and bast fibers as dispersing phases on low density fiberboards (engineered wood)

Fiberboards are engineered woods made from a composition of wood chippings, wood fibers, sawdust etc., glued together with adhesives. Low density fiberboards (LDF) are part of the classes of fiberboards widely used in Nigeria because they are readily available, relatively cheap and offer good aesthetic values, compared to conventional woods. However, they possess low strength, durability and lifespan, thus making them susceptible to damage during service. The aim of this study was to determine the effect of kenaf core and bast fibers (Hibiscus cannabinus) as one of the dispersing phases in low density fiberboard production, also known as particleboards. The materials and methods employed in the study, followed procedures in established standards and literatures. The different composite materials were weighed and mixed properly for about 10 minutes to ensure homogeneity in the mixture. Thereafter, the materials were placed in a mould of uniform thickness and compressed to different fiber board samples using a compression press machine, for about 10mins. A series of physio-mechanical tests such as water absorption, density, tensile strength, modulus of elasticity and modulus of rupture were conducted on the developed fiberboard samples as well as the control samples. The results showed that the average values for water absorption and density of the developed samples enhanced with kenaf core and bast fibers were 5.480% and 0.027 g/cm3 respectively. These values compare well with that of the control samples. Also, the tensile strength, modulus of elasticity and modulus of rupture of samples enhanced with kenaf gave average values of 31.842 MPa, 2.920 GPa and 16.58 N/mm2 respectively. These values also compare well with that of the control samples. From the results gotten and all the properties determined, the study showed that kenaf core and bast fibers can be employed appreciably as dispersing phases for low density fiber board (LDF) composite production.

Non-Fickian diffusion in biosourced materials: Prediction of the delay between relative humidity and moisture content

This work focuses on non-Fickian diffusion in biosourced building materials. To study these memory effects in this kind of materials, an original and automatic device was conceived and built. It allows a series of samples to be submitted, simultaneously, to a perturbation of RH at its front face and to record the evolution of sample mass and of RH at its back face. When analyzed using a classical heat and mass transfer model, the experimental data depicts a delay between RH and moisture content, the RH evolution being too fast. To address this problem, a new formulation able to model those types of behaviors using memory functions was used. To test the predictive potential of the new formulation, these memory functions were not identified but taken from a previous work, where they were determined experimentally using minute samples. A full set of experiments performed with Low Density Fiberboard (LDF) and Medium Density Fiberboard (MDF) was simulated using this new formulation feed by the experimental memory functions. The good agreement found between simulated and experimental results proves the predictive potential of the new macroscopic formulation.

Non-Fickian diffusion in biosourced materials: Experimental determination of the memory function using minute samples

Focusing on non-Fickian diffusion in biosourced materials, we have recently developed a new formulation that can model this behavior using memory functions. To identify those memory functions, an experimental device based on a magnetic suspension balance is used. Very thin samples of low-density fiberboard, medium-density fiberboard, and Spruce in the longitudinal direction are subjected to variations in ambient relative humidity (RH) while their mass is recorded. The imposed RH and temperature are used as boundary conditions in a comprehensive model to solve the heat and mass transfer equations in porous media. A computational code solving the new formulation was used to determine the memory functions by inverse analysis. The use of very thin samples enables macroscopic parameters to be considered as negligible compared to microscopic effects.

On the importance of heat and mass transfer coupling for the characterization of hygroscopic insulation materials

This work is focused on mass transfer characterization of hygroscopic materials used for insulation, such as low density fiberboards (LDF). Due to their particular morphology, these panels present a very high mass diffusivity due to the connected gaseous phase together with a very low thermal conductivity. This combination of properties exacerbates the coupling between heat and mass transfer in transient state. Based on experimental data obtained with an original set-up and relevant simulations performed using a comprehensive physical formulation, a throughout vision of this question is proposed in the present study. In particular, we emphasize on:•The impressive change in core temperature in terms of magnitude and duration,•The great impact of the internal temperature gradient, which slows down mass diffusion,•The dramatic error on mass diffusivity value if the coupling is ignored,•The possible determination of thermal conductivity during transient sorption tests.A dimensionless number Nc was derived to quantify the intensity of this coupling. Finally, a practical example is proposed that confirms the importance of heat and mass transfer coupling in the case of LDF, and at the same time, proves that this effect can be controlled and corrected by using a relevant physical formulation.

Mass diffusivity determination of various building materials based on inverse analysis of relative humidity evolution at the back face of a sample

In this study, we use a novel method to determine the mass diffusion coefficients of hygroscopic materials. The experiment involves subjecting one face of the sample to relative humidity (RH) variations over time and measuring the RH at the back face. The imposed RH and temperature are measured during the experiment, and they are used as boundary conditions in a comprehensive computational code to address heat and mass transfer in porous media. This new method is utilized to characterize the following building materials: autoclave aerated concrete, plaster, poplar wood, pine wood, medium-density fiberboard and low-density fiberboard. This paper provides the details regarding the determination of the sorption isotherms of the selected materials that are required for the determination of mass diffusivity. The obtained electrical tortuosity values are compared with geometrical tortuosity values determined via microtomography and three-dimensional image processing. The agreement between the two tortuosity values is applicable only for porous media with narrow pore size distribution.

Epoxidized sucrose soyate—A novel green resin for crop straw based low density fiberboards

A study was conducted to evaluate the mechanical properties of low density fiberboard produced with combinations of two fibers soybean straw (Glycine max), and wheat straw (Triticum aestivum) and two resins methylene diphenyl diisocyanate (MDI) and epoxidized sucrose soyate (ESS) resin as binders. ESS is a high performance, soybean oil based epoxy that has shown promise as a highly biobased adhesive. Six formulations of panels were produced using various combinations of straw and resin binder. Mechanical testing of sample boards was conducted using ASTM standard D1037-12. Test results showed that type of resin did not influence soy straw or wheat straw board’s stiffness and strength properties but had a major impact on water resistance, screw withdrawal strength and internal bond strength. The study demonstrated the potential of ESS as a novel binder for fiberboard system if a suitable crosslinker and catalyst is utilized. It also showed that increasing ESS content over 50% in a MDI blend lowered the performance characteristics of boards. However, analytical testing of the resin systems showed limited reactivity between ESS soyate and MDI, indicating other compatible resin chemistries should be explored for achieving superior board properties. Overall, a resin blend with 25–50% ESS in MDI appears favorable for low density fiberboards. ESS can be a promising bio-based resin as it has the potential to meet California Air and Resources Board (CARB) standards while providing acceptable properties as an adhesive.

Thermal properties of wood-based panels: specific heat determination

Ensuring reliability of data on thermal properties of wood-based panels is important for manufacturing processes, especially when it is recommended to shorten the cooling phase and stack the panels in hot conditions. Prediction of the heat transfer during cooling phase and normal or hot stacking based on accurate data is essentially important for attaining panels of required properties. The thermal properties are also required when designing houses, especially low-energy or passive ones. Therefore, a water calorimeter was adequately designed and constructed to ensure improvement in the accuracy of the specific heat measurements. The calorimeter was used to determine the specific heat. The attained accuracy estimated by the relative error was significantly increased, and the error values were less than 2 % for all types of the investigated particleboard and OSB. In case of low-density fiberboard (LDF), the maximum value of the relative error did not exceed 4 %. It was also shown that high accuracy required for the specific heat measurements was achieved for experiments in which high-mass samples were used, in contrast to measurements for such samples in traditional DSC systems. The results for the specific heat were within the range from 1420 to 1450 J/kg K for LDF and all types of particleboard. The effect of the investigated material density on the specific heat was not found. The only exception was in case of OSB for which the specific heat was ca. 1550 J/kg K, and it was approximately 100 J/kg K higher when compared to other panels.

Sound Absorption and Physical Properties of Carbonized Fiberboards with Three Different Densities

Characteristics of carbonized fiberboard such as chemical materials absorption, electromagnetic shielding, and electrical and mechanical performance were determined in previous studies. The carbonized board therefore confirmed that having excellent abilities of these characteristics. In this study, the effect of density on physical properties and sound absorption properties of carbonized fiberboards at <TEX>$800^{\circ}C$</TEX> were investigated for the potential use of carbonized fiberboards as a replacement of conventional sound absorbing material. The thickness of fiberboards after carbonization was reduced 49.9%, 40.7%, and 43.3% in low density fiberboard (LDF), medium density fiberboard (MDF), and high density fiberboard (HDF), respectively. Based on SEM images, porosity of carbonized fiberboard increased by carbonization due to removing adhesives. Moreover, carbonization did not destroy structure of wood fiber based on SEM results. Carbonization process influenced contraction of fiberboard. The sound absorption coefficient of carbonized low density fiberboard (c-LDF) was higher than those of carbonized medium density fiberboard (c-MDF) and carbonized high density fiberboard (c-HDF). This result was similar with original fiberboards, which indicated sound absorbing ability was not significantly changed by carbonization compared to that of original fiberboards. Therefore, the sound absorbing coefficient may depend on source, texture, and density of fiberboard rather than carbonization.

Mass diffusivity of low-density fibreboard determined under steady- and unsteady-state conditions: Evidence of dual-scale mechanisms in the diffusion

The mass diffusivity of low-density fibreboard (<300 kg m−3) was measured under steady-state conditions (cup method) and under unsteady-state conditions (sorption in the relative humidity range 37–71%). The diffusivity was measured parallel and perpendicular to the sheet plan, for different sample thicknesses (~24, 20, 10, 4 and 2 mm) and different densities (160 and 270 kg m−3). The change in mass was measured with a conventional balance for thick samples and a magnetic suspension balance for thin samples. The results indicated that the diffusivity of fibreboard thicker than 20 mm was similar in steady- and unsteady-state measurements. For boards less than this dimension, diffusivity in transient sorption (unsteady state) depended on the sample thickness. In this case, the simplified continuum representation of the physical medium must be discarded. The discussion emphasizes the effect of the double porosity of the material to explain this diffusion behaviour.

Elastic moduli and stiffness optimization in four-point bending of wood-based sandwich panel for use as structural insulated walls and floors

Several wood-based sandwich panels with low-density fiberboard core were developed for structural insulated walls and floors, with different face material, panel thickness, and core density. The elastic moduli with and without shear effect (E L, E 0) and shear modulus (Gb) were evaluated in four-point bending. Generally, the stiffer face, thicker panel, and higher core density were advantageous in flexural and shear rigidity for structural use, but the weight control was critical for insulation. Therefore, optimum designs of some virtual sandwich structures were analyzed for bending stiffness in relation to weight for fixed core densities, considering the manufactured-panel designs. As a result, the plywood-faced sandwich panel with a panel thickness of 95 mm (PSW-T100), with insulation performance that had been previously confirmed, was most advantageous at a panel density of 430 kg/m3, showing the highest flexural rigidity (E L I = 13 × 10−6 GNm2) among these panels, where E L, E 0, and G b were 3.5, 5.5, and 0.038 GN/m2, respectively. The panel was found to be closest to the optimum design, which meant that its core and face thickness were optimum for stiffness with minimum density. The panel also provided enough internal bond strength and an excellent dimensional stability. The panel was the most feasible for structural insulation use with the weight-saving structure.

Thermal insulation properties of wood-based sandwich panel for use as structural insulated walls and floors

Thermal insulation and warmth-keeping properties of thick plywood-faced sandwich panels with low-density fiberboard (plywood-faced sandwich, PSW), which were developed as wood-based structural insulation materials for walls and floors, are comprehensively clarified. The properties focused on were thermal conductivity (λ), thermal resistance (R), and thermal diffusivity (D). The results for PSW panels were compared with those for commercial wood-based boards, solid wood, and commercial insulators. The λ values were measured for PSW panels and their core and face elements. As a result, the composite theory of λ was found to be appropriate for PSW composites, because the calculated/experimental λ ratios were approximately 90%. The λ values for PSW panels with densities of 340 kg/m3 (PSW350) and 410kg/m3 (PSW400) were 0.070 and 0.077W/mK, respectively. The R values for PSW350 and PSW400 were 1.4 and 1.2m2K/W, and the D values were 0.00050 and 0.00046m2/h, respectively. Consequently, the PSW provided thermal insulation properties superior to those of the boards and in terms of warmth-keeping properties were greatly advantageous over the insulators. These advantages were due to the moderate densities of PSW panels. The PSW panel with sufficient thickness showed remarkably improved thermal resistance compared with those of the boards.

Temperature measurements of combustible and non-combustible surfaces using laser induced phosphorescence

In recent years, thermographic phosphors used for surface temperature measurements have been developed to suit combustion applications. Pulsed ultraviolet laser radiation at 266 nm and 7 ns duration was used to excite a thermographic phosphor, Mg 4FGeO 6:Mn, which was adapted to the surface of the investigated material. The laser-induced emission from the phosphor was recorded. A calibration of the phosphorescence lifetime and spectral properties against temperature allowed surface temperature measurements between 298 and 873 K. The techniques were successfully used in a flame spread scenario for two-dimensional measurements of surface temperature on a low-density fiber board. The phosphorescence images were obtained with eight consecutively gated CCD detectors enable pixel by pixel-lifetime evaluation of the phosphorescence by interpolating an exponential–decay curve to the counts of the corresponding pixel positions of the sequential CCD images. The best precision, better than ±5 K, was obtained at these temperatures. The technique was also applied to temperature measurements of decomposing materials in a pyrolysis oven. The material investigated was birch particles. Recent development of the technique has allowed other applications, e.g., to such as engine valve and droplets temperature measurements.

In-plane shear properties of the wood-based sandwich panel as a small shear wall evaluated by the shear test method using tie-rods

The fundamental in-plane shear properties were investigated for the wood-based sandwich panel of plywood-overlaid low-density fiberboard (SW) manufactured at a pilot scale to develop it as a shear wall. The shear test method using tie-rods standardized for shear walls was applied to SW with dimensions of 260 mm square and 96 mm thick as a small shear wall and to plywood (PW) and thick low-density fiberboard (FB). The shear modulus and shear strength of PW, FB, and SW were determined. To measure the shear deformation angle, a displacement meter and strain-gauge were used. The shear moduli of PW (0.68 g/cm3) and FB (0.25–0.35 g/cm3) were 460 and 21–58 MPa/rad, respectively. The shear modulus of SW as a composite was analyzed. Some experimental models of SW were proposed (i.e., rigid-α, rigid-β, flexible, and semirigid models). The shear modulus of SW (0.35–0.40 g/cm3) evaluated based on the rigid-α and semirigid models were 73–89 and 109–125 MPa/rad, respectively. The theoretical shear modulus of SW was calculated to be 110–129 MPa/rad.

Two-dimensional surface temperature measurements of burning materials

A new technique for two-dimensional temperature measurements of burning surfaces is presented. Laser-induced phosphorescence from a thermographic phosphor material applied to a surface of investigation was measured with a fast framing camera. The phosphor was excited by the 4th harmonic from a pulsed Nd:YAG operating at 10 Hz. The phosphorescence images measured by eight consecutively gated CCD detectors enable pixel-by-pixel lifetime evaluation of the phosphorescence by interpolating an exponential decay curve to the counts of the corresponding pixel positions of the sequential CCD images. The temperature at each pixel position was evaluated using a calibration procedure of temperature against lifetime. These measurement procedures were used for surface temperature measurements of the evolution of flame spread on low-density fiber boards. The results from experiments showed the possibility of measuring surface temperature during all phases of the flame spread. The total time window used for each two-dimensional temperature measurement was 800 μs to obtain high accuracy and precision at high temperatures, 680–780 K, temperatures characteristic of burning surfaces. The best precision, better than ±5 K, was obtained at these temperatures. In this region, evaluation by the lifetime method shows a higher sensitivity to temperature than what can be expected from methods based on spectral line intensities. The results of the experiments were in accordance with those reproted from previous one-point measurements. In the low-temperature region close to room temperature, the accuracy deteriorated considerably. The results obtained from the two-dimensional imaging experiments are presented and discussed.