Ultra-low Density Fiberboard Research Articles

Optimizing properties of ultra-low-density fiberboard via response surface methodology and evaluating the addition of a coupling agent

The main production process parameters of ultra-low-density fiberboard (UDF) were selected by use of response surface methodology, and then the properties of UDF were improved by adding a coupling agent. Microstructures and chemical bonding in UDF were analyzed by scanning electron microscopy and infrared spectroscopy. The results showed that the desirable process parameters for UDF production were the amount of urea-formaldehyde resin adhesive (18%), the hot pressing temperature (170 °C), the hot pressing time (200 s), and the amount of KH560 coupling agent added (1%). The main physical and mechanical properties of UDF obtained included internal bond strength (0.59 MPa), modulus of rupture (19.8 MPa), and 24h thickness swelling (10.0%). These properties exceeded the requirements of ISO 16895 (2016).

Manufacturing and properties of ultra-low density fiberboards with an unsaturated polyester resin by a dry process

Although ultra-low density fiberboards (ULDFs) have good sound and thermal insulation performance, formaldehyde emission in the manufacturing process and in the subsequent use of the products limits their field of application. The objective of this study was to employ an unsaturated polyester resin (UPR) in the manufacturing of the boards as a substitute of formaldehyde-based adhesives in order to develop environment-friendly ULDFs. The effects of UPR dosage, fiber treatment agent, press time and fiber consumption on the properties of fiberboards were studied. Sound absorption and thermal conductivity were also measured to ensure sound and thermal insulation properties of the fiberboards. Board density, modulus of rupture and thickness swelling in 2 h were 320 kg/m3, 4.14 MPa and 3.75%, respectively, under optimal conditions such as 12% UPR dosage, 1% fiber treatment agent, 400 g fiber consumption and 210 s press time. Noise reduction coefficient and thermal conductivity of the boards were found within a range of 0.68–0.58 and 0.038–0.048 W/(m K), respectively, while the density of boards ranged from 150 to 400 kg/m3. Therefore, sound absorption property of the fiberboards developed in this study satisfies the requirement of high-efficiency sound absorption materials, which is close to the value (0.67) of ULDF having a density of 56.3 kg/m3 obtained by a wet process. Thermal insulation property of boards was close to that of commonly used insulation materials such as rock wool [0.036 W/(m K)] and glass fiber [0.045 W/(m K)]. In conclusion, fiberboards can be used for non-structural furniture materials, sound and thermal insulation materials in buildings because of their environmental friendliness, good mechanical properties, and excellent sound and thermal insulation properties.

Optimization for Fire Performance of Ultra-low Density Fiberboards Using Response Surface Methodology

The optimization of the process conditions for fire retardant ultra-low density fiberboards (ULDFs) was investigated using response surface methodology (RSM). Three parameters, namely those of Borax-Zinc-Silicate-Aluminum (B-Zn-Si-Al), chlorinated paraffin (CP), and chloride-vinyl chloride emulsions (PVDC) were chosen as variables. The considerably high R2 value (99.98%) indicated the statistical significance of the model. The optimal process conditions for the limiting oxygen index (LOI) were determined by analyzing the response surface’s three-dimensional surface plot and contour plot, and by solving the regression model equation with Design Expert software. The Box-Behnken design (BBD) was used to optimize the process conditions, which showed that the most favorable dosages of B-Zn-Si-Al, CP, and PVDC were 800 mL, 46.47 mL, and 35.64 g, respectively. Under the optimized conditions, the maximum LOI was 48.4.

Fire Performance of Ultra-Low Density Fiberboard (ULDF) with Complex Fire-Retardants

To clarify how the fire performance of ultra-low density fiberboard (ULDF) can be improved by complex fire-retardants, the limiting oxygen index (LOI) and microstructure of ULDFs with different additive amounts of complex fire-retardants was analyzed. The char yield, chemical bonding, and thermostability of ULDFs treated by different temperatures were also tested. Results showed that the LOI values and compactness of ULDFs were increased with increased amounts of fire-retardants. Three steps of char yield curves in control fiberboard (CF) and mixed fiberboard (MF) were apparent. The preliminary degradation in lignin and cellulose of CF occurred at 300 °C. The cellulose had completely decomposed at 400 °C, but in the case of MF, the lignin and cellulose were not completely decomposed at 400 °C. It was shown that there are different ways to improve the fire resistance of ULDF using boron, nitrogen-phosphorus, silica, and halogen-based fire-retardants. The fiberboard with silicium compounds had the lowest mass loss in three stages and total mass loss. Compared with CF, MF had a lower mass loss. Furthermore, the exothermic peak for MF at around 400.0 °C was decreased, indicating that the fire resistance of ULDF was improved by the complex fire-retardants.

Effect of PVDC on the Fire Performance of Ultra-Low Density Fiberboards (ULDFs)

Poly vinylidene chloride-vinyl chloride emulsions (PVDC) were added as a substitute for chlorinated paraffin (CP) in the preparation of ultra-low density fiberboards (ULDFs). The micromorphology and fire performance of ULDFs were investigated using a scanning electron microscope, limiting oxygen index instrument, and cone calorimeter. The results showed that PVDC specimens were coated with a regularly smooth film, while the distribution of CP inside CP specimens was uneven. The limiting oxygen index increased with the dosage of PVDC, then reached a plateau at 50 mL and 28%, slightly higher than CP specimens (27.3%). The peak of heat release rate, mean heat release rate, mean CO, and total smoke release of PVDC specimens was reduced 43.3%, 13.5%, 38.5%, and 51.5% lower than respective CP specimens, and with nearly the same total heat release (only 0.04 MJ/m2 higher). Thus, PVDC exhibited excellent heat-reducing and smoke-suppressing properties and could replace CP in ULDFs.

Effect of Boron-Zinc-Aluminum-Silicium Compounds on the Fire Performance of Ultra-Low Density Fiberboards (ULDFs)

B-Zn-Si-Al compounds, as a modification of Si-Al compounds, is made of sodium silicate, zinc sulfate, borax and aluminum sulfate, acting as a fire retardant during the preparation of ultra-low density fiberboards (ULDFs). An orthogonal experiment was used to optimize the amount of the four compounds, according to the results of limiting oxygen index. Fourier transform infrared spectra was employed to preliminarily make sure chemical structure of the compounds. Cone calorimeter was used measure fire performance of ULDFs. The results suggested that the optimized sodium silicate solution, aluminum sulfate solution, zinc sulfate and borax were 27.0 mL, 27.0 mL, 3.0 g and 6.5 g, respectively, corresponding to oxygen index of 29.5%. Al-O-B and Si-O-Zn bonds were detected at 1397, 796 cm-1 and 867 cm-1, respectively. The heat release rate, total heat release, and total smoke release obviously decreased and mass residual ratio increased. Conclusively, B-Zn-Si-Al compounds effectively protect fibers from fire hazard.

Effect of Chlorinated Paraffin Nanoemulsion on the Microstructure and Water Repellency of Ultra-Low Density Fiberboard

This work describes a water repellent ultra-low density fiberboard (ULDF) prepared by chlorinated paraffin nanoemulsion (CPNE). Compared with the untreated ULDF, the contact angle of ULDF treated with 150 mL of CPNE increased from 40° to 134°, while its apparent surface free energy decreased from 24.19 mN/m to 10.06 mN/m. Moreover, the water absorbance of ULDF treated with CPNE decreased from 88.2% to 24% in the first hour. The improved hydrophobicity and hygroscopicity of ULDF was supported by the presence of a film on the surface of fibers, as observed by environmental scanning electron microscopy. The occurrence of chlorine and the chemical structure changes in ULDF before and after CPNE treatment were also confirmed by X-ray photoelectron spectroscopy analysis and Fourier transform infrared spectroscopy respectively. This ULDF with enhanced water repellency is a promising insulation material.

Evaluating the Effectiveness of Complex Fire-Retardants on the Fire Properties of Ultra-low Density Fiberboard (ULDF)

The preparation conditions of complex fire-retardant (FR) agents containing boron compounds (BF, X1), nitrogen-phosphorus compounds (NPF, X2), silicon compounds (SF, X3), and halogen compounds (HF, X4) for ultra-low density fiberboard (ULDF) were optimized using a response surface methodology. The effects and interactions of X1, X2, X3, and X4 on the fire properties of ULDF were investigated. An optimum char yield of 61.4% was obtained when the complex fire-retardant agents contained 33.9% boron, 27.2% nitrogen-phosphorus, 15.0% silicon, and 28.6% halogen. Compared with control fiberboard (CF), the heat release rate (HRR) profiles of all fiberboards with FRs were reduced. The peak HRR reduction in BF and NPF was more pronounced than for SF and HF at this stage. And the mixed fiberboard (MF) had the lowest pkHRR of 75.02 kW m−2. In total heat release (THR) profiles, all fiberboards with FRs were lower than the CF. Unlike the HRR profiles, HF had the lowest THR profile of 15.33 MJ m−2. Additionally, Si compounds showed greater effectiveness in preventing ULDF mass loss than BF, NPF, and HF. MF showed the highest residual mass (40.94%). Furthermore, the synergistic effect between four FR agents showed more significant results in ULDFs.

Hybrid composites of polyvinyl alcohol (PVA)/Si–Al for improving the properties of ultra-low density fiberboard (ULDF)

The hybrid composites of polyvinyl alcohol (PVA)/Si–Al were synthesized to improve the thermostability and mechanical properties of ultra-low density fiberboard (ULDF).

Effect of Si–Al molar ratio on microstructure and mechanical properties of ultra-low density fiberboard

Si–Al compounds represent the substances having silicium (Si) and aluminum (Al) in the mixed aqueous solution of sodium silicate and aluminum silicate. Their chemical structure depends on Si–Al molar ratio. In this study, several Si–Al molar ratios were used to prepare different Si–Al compounds. These Si–Al compounds were added in the manufacturing process of ultra-low density fiberboards (ULDFs) to examine the effects of Si–Al molar ratio on the microstructure and the mechanical properties of ULDFs. Scanning electron microscope-energy dispersive spectroscopy, X-ray photoelectron spectrometer, infrared spectrometer, X-ray diffractometer and electronic universal testing machine were used to analyze the microstructure and mechanical properties of ULDFs. The results showed that the microstructure and bulk density of ULDFs were affected by Si–Al molar ratios. The mechanical properties of ULDFs were also significantly affected because of Si and Al components being uniformly distributed on the fibers’ surface and formation of Si–O–C bond. When Si–Al molar ratio was 2:1, the modulus of elasticity, modulus of rupture and internal bond strength of the ULDF was up to 20.78, 0.17, and 0.025 MPa, respectively.

Morphology of Burned Ultra-low Density Fiberboards

The synergistic effect of two fire retardants, a Si-Al compound and chlorinated paraffin, was tested on ultra-low density fiberboards (ULDFs). To further understand the mechanism of fire retardancy ...

Fire Performance of Si-Al Ultra-Low Density Fiberboards Evaluated by Cone Calorimetry

To clarify how the fire resistance of ultra-low density fiberboards (ULDFs) was improved by the Si-Al compounds and to compare the effect of fire resistance between Si-Al compounds and fire retardant (chlorinated paraffin), the fire performance of ULDFs was evaluated by cone calorimetry. Comparing Si-Al compounds to chlorinated paraffin, the heat release rate (HRR), total heat release (THR), mass loss, total smoke release, and off-gases (CO and CO2) release of ULDFs treated with Si-Al compounds significantly decreased. However, when Si-Al compounds and chlorinated paraffins were simultaneously added, the mixed fiberboards showed the best results for peak of HRR (100.76 kW m-2), time to flameout (336s), THR (21.36 MJ m-2), and residual mass (34.26%). These results indicated that the Si-Al compounds had a significant effect on improving the fire resistance of ULDFs, and the Si-Al compounds and chlorinated paraffins have a synergistic effect in ULDFs.

Microstructure of Burned Ultra-Low-Density Fiberboards using Plant Fiber as the Matrix and Si-Al compounds as the Filler

Ultra-low-density fiberboards (ULDFs) were prepared by a liquid frothing technique using plant fibers as the matrix and Si-Al compounds as the filler to be used as a versatile bio-based composite. Si-Al compounds played an important role in the fire properties of ULDFs. Fire intensity and the amount of volatiles were significantly restrained because of the Si-Al compounds. To determine the combustion mechanism of ULDFs treated by Si-Al compounds, the microstructure of burned specimens was tested by chemical analysis, X-ray diffractometer (XRD), and infrared spectrometer (IR). According to the results from gas chromatography, glucose, xylose, and mannose disappeared in the bottom ashes. After combustion, the XRD profiles of the two ashes became weaker and broader; the sharpest peaks at 18.6o (2) that represented Si-Al compounds remained; the obvious peaks at 22o (2) from cellulose were gone. The results from IR suggested the characteristic functional groups OH, CH, and C=O from carbohydrate also disappeared, and absorbance at 1200 to 400 cm-1, which attributed to the vibration of Si-O, Al-O, and Si-O-Si bonds, increased. In conclusion, fibers are almost completely pyrolyzed at 780 °C. The crystalline structure of Si-Al compounds is rearranged and more amorphous silicon oxide and aluminum oxide are generated.

Effect of Silica Sol Content on Thermostability and Mechanical Properties of Ultra-low Density Fiberboards

The thermostability and mechanical properties of ultra-low density fiberboard (ULDF) were improved with the different content of silica sol. Microstructure and properties of ULDF were tested using scanning electron microscope (SEM), thermogravimetric analyzer (TGA), and microcomputer control electronic universal testing machine. The microstructures and the relative density of ULDFs were different with changes in Si sol content. The TGA results showed that the residual weight of ULDF was increased with the increasing content of silica sol and that the thermostability of ULDFs was improved. The modulus of rupture (MOR), modulus of elasticity (MOE), and the internal bond strength (IB) of ULDF were significantly improved from 0.12, 10.86, and 0.020 MPa to their maximum values of 0.23, 23.36, and 0.031 MPa while 4% silica sol was added.

Synthesis and characterization of poly-aluminum silicate sulphate (PASS) for ultra-low density fiberboard (ULDF)

Poly-aluminum silicate sulphate (PASS) was synthesized in a mixed aqueous solution of sodium silicate and aluminum silicate via a sol–gel method for use in ultra-low density fiberboard (ULDF).

Modification of Ultra-Low Density Fiberboards by an Inorganic Film Formed by Si-Al Deposition and their Mechanical Properties

To improve mechanical properties of ultra-low density fiberboards (ULDFs), Si-Al compounds were mixed together with fibers during preparation of ULDFs, forming a thin film on the surface of the fibers via hydrogen bonding. This work mainly optimized two proposed methods in which the inorganic thin film was assembled on the surface of fibers, in terms of its effect on the mechanical properties of fibers. Microstructural characterization (such as micromorphology and elemental distribution, chemical bonding, and crystalline phase) of Si-Al compounds and ULDFs was done to evaluate the effects. The results revealed that an inorganic thin film (probably Al2O3-SiO2) covered the surface of the fibers. Compared with the control specimen, the modulus of elasticity, modulus of rupture, and internal bond strength of the specimen treated by the sol-gel process increased from 3.87 MPa to 13.19 MPa, 0.05 MPa to 0.16 MPa, and 0.010 MPa to 0.025 MPa, respectively. Based on its higher mechanical properties, a combined sol-gel method was judged to be better for enhancement of fibers than a separate deposition method.

Effect of Si-Al Compounds on Fire Properties of Ultra-low Density Fiberboard

An ultra-low density fiberboard was made of plant fiber using a liquid frothing approach. The inflammability of the plant fiber limited its application as a candidate for building insulation materials and packaging buffering materials. Si-Al compounds were introduced into the foaming system because of the high temperature resistance of Si and Al compounds. The results from energy-dispersive spectroscopy suggested that the Si and Al relatively evenly covered the surface of the fibers, and their weight ratios in the material increased as a function of the amount of Si-Al compounds. The increasing weight ratios of Si and Al affected the fire properties of the material, reducing the released amount of heat, smoke, and off-gases such as CO and CO2, as well as decreasing the mass loss percentage, shown through the use of a Cone Calorimeter. It follows that Si-Al compounds have an evident collaborative effect on the halogen fire retardant. The system can effectively restrain the fire hazard intensity and the yields of solid and gas volatiles.

Manufacture and properties of ultra-low density fibreboard from wood fibre

This study described a process of making ultra-low density fiberboard (ULDF) and investigated the properties of samples of ultra-low density fibreboard made from wood fiber using a liquid frothing approach. The fiberboard had a density of 56.3 kg/m3 and a layered cross-linked interior structure. Density profiles showed a relatively high density in the surface layers and low density in the core layer. The results showed that the fiberboard had an internal bond strength of 0.15 MPa, a modulus of rupture of 0.70 MPa, a modulus of elasticity of 8.91 MPa, and a compressive strength of 0.17 MPa at 10% deformation. Thickness swelling after 24 hours water immersion was 0.57%. It had a low thermal conductivity of 0.035 W/mK, and a high sound reduction coefficient of 0.67. Resin was uniformly distributed on the fiber surface. The fiberboard can be used as buffer material for packaging and insulation material for building.