Internal Bond Research Articles

Fabrication of a new bamboo composite with large-size high-quality flattened surface

Bamboo is a highly lignified grass with a thin wall and hollow interior. Recombination technology is commonly used to realize its scaling utilization. In this study, a high-quality flattened bamboo recombination panel (BRP) was fabricated based on the full utilization of bamboo. The BRP was designed with sandwich structure and a core layer composed of a mixture of bamboo skin strips and bamboo pith particles upon hot pressing, resembling a reinforced bar-concrete structure. The surface layer was made from densified bamboo slices through thermal-flattening (TF) to achieve stress relief and realize deformation resistant, surface modified resulted in decreased hydrophilicity. The performance of the flattened bamboo slices and BRP was analyzed, the results showed that the TF treatment was successfully modified the bamboo mid-slices, which were compressed and densified during the process. The TF treatment realized stress relief and increased surface hardness and hydrophobicity, because of a reduction in the number of free hydroxyl groups in hemicellulose. The vascular bundles and parenchyma cells of the bamboo mid-slices underwent different extents of contraction. Further, the initial moisture content was negatively correlated with the compression rate. Dynamic mechanical analysis results showed that through the TF treatment conducted at an initial moisture content (MC) of 30%, temperature of 160 ℃ and time of 4 min (30%−160 ℃−4 min) the storage elastic modulus of bamboo mid-slices increased from 5133 to 8867 MPa. The average internal bond strength, surface bond strength, and thickness swelling of the BRP bonded by phenol formaldehyde (PF) and urea-formaldehyde (UF) resins were 0.71, 0.6 MPa; 0.89, 0.82 MPa; and 9.1%, 14.7%, respectively, which meet national standards. The BRP had a high-quality flattening effect, and the flattened width could reach 2–5 times the circumference of the bamboo culm, and the performance matched that of oriented strand boards, confirming to be an upgraded product of bamboo-flattening boards and bamboo- oriented strand boards.

Highly Adhesive and Self-Healing Zwitterionic Hydrogels as Antibacterial Coatings for Medical Devices.

Bacterial infection of medical devices has caused incalculable losses to maintenance costs and health care. A single coating with antibacterial function cannot guarantee the long-term use of the device, because the coating will be damaged and fall off during reuse. To solve this problem, the development of coatings with high adhesion and self-healing ability is a wise direction. In this paper, a multifunctional polyzwitterionic antibacterial hydrogel coating (PZG) composed of amphozwitterion monomer, anionic monomer, and quaternary ammonium cationic monomer was synthesized by dipping UV photoinitiated polymerization. The structure of PZGs was characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. Ascribing to the hydrogel internal electrostatic interaction, hydrogen bond, and cation-π interaction, the obtained PZGs exhibited high ductility (>1200% strain) and appropriate strength (>189 kPa). Remarkably, PZGs could also adhere firmly on different substrates through noncovalent interaction, and their adhesion could be controlled by adjusting the amount of zwitterionic. Reversible physical interactions in polymer networks endowed hydrogels with excellent self-healing properties. In addition, PZGs exhibit good antibacterial activity and biocompatibility due to the synergistic effect of quaternary ammonium cation and amphozwitterion monomer. This work provides a multifunctional antibacterial coating for medical equipment and has broad application prospects in the biomedical field.

Heterogeneous Phosphine-Containing Hydroformylation Catalysts Based on Modified Porous Organic Framework

A series of heterogeneous phosphine-containing rhodium hydroformylation catalysts based on porous aromatic frameworks (PAFs) were prepared. The catalysts PAF30-MDEA-TPPTS-Rh (TPPTS is trisodium triphenylphosphine-3,3',3''-trisulfonate, MDEA is methyldiethanolamine fragment) and PAF-30-Im-TPPTS-Rh (Im is imidazole fragment) showed the highest stability in repeated use in 1-hexene hydroformylation. The catalyst PAF-30-MDEA-TPPTS-Rh before and after use in hydroformylation was characterized by elemental C,N,H,S analysis, inductively coupled plasma atomic absorption spectroscopy, low-temperature nitrogen adsorption–desorption, transmission electron microscopy, IR spectroscopy, and X-ray photoelectron spectroscopy. The effect of temperature, pressure, and solvent on the course of hydroformylation in the presence of PAF-30-MDEA-TPPTS-Rh was studied. The catalyst is active in hydroformylation of a series of unsaturated compounds, including functionalized substrates and olefins with internal double bond.

Synthesis and properties of (+)-ketopinic and (-)-camphanic acids esters bearing a nitrogen-containing heterocycle

A three-stage method was proposed for the synthesis of (1 S )-(+)-camphor-10-sulfonic acid, (+)-ketopinic and (-)-camphanic acids esters containing a saturated nitrogen-containing heterocycle. It was found that (1 S )-(+)camphor-10-sulfonic acid esters undergo destruction with elimination of the sulfonic acid group in substitution reactions involving nitrogen-containing heterocycles. Esters of (+)-ketopinic and (-)-camphanic acids were formed during the proposed synthetic route, but undergo transesterification under column chromatography conditions. Quantum chemical calculations showed that the destruction of the ester bond in the case of (+)-ketopinic and (-)-camphanic acids requires less energy than the breaking of a similar bond in (-)-borneol esters. It was revealed that the internal bond strength index (IBSI) for the alkyl C-O bond in (-)-borneol esters is higher than in (+)-ketopinic and (-)-camphanic acid esters. Antiviral properties against the H1N1 influenza virus were studied for derivatives of (+)-ketopinic and (-)-camphanic acids.

Experimental investigation on mechanical properties and fire performance of innovative wheat straw-gypsum composites as building sheathing panels

An innovative and high-performance wheat straw-gypsum composite (SGC) was developed to solve the problem of cracking and separation caused by water release when exposed to high temperature of gypsum board (GB) on the fire side of a wall. Compatibility between wheat straw and gypsum crystal was improved by combined pretreatment (i.e., sodium hydroxide and coupling agent) and adding magnesite. The mechanical properties of SGC were investigated and its fire performance determined by cone calorimetry and fire tests. The results indicated that the modulus of rupture, modulus of elasticity, and internal bond strength of SGC were 53.7%, 115.9%, and 173.9%, respectively higher than the traditional GB. The improvement in strength was attributed to the fact that alkali-treated wheat straw was well combined with gypsum crystals through magnesite to form a compact structure, as evidenced by scanning electron microscopy. SGC had extremely low heat and smoke release rate, ignition point at > 1200 s, and mass retention increased by 17.1%, compared with the literature results of gypsum-based bio-composites. Under a 60-min duration exposure, the charring depth of the wood studs of light frame walls sheathed with GB was 27 mm higher than that of SGC wall, and the bearing capacity retention rate of SGC wall 65.4%, while that of GB wall was lost. Errors between the calculation of bearing capacity proposed in this study and test values were < 6%. SGC with superior thermal insulation and mechanical properties could beneficially replace GB as fire-resistant panels in buildings.

Optimisation of particle distribution and performance in three-layer tubular particleboards using response surface methodology

To explore the impact of manufacturing parameters on the modulus of rupture (MOR), internal bond strength (IB), and 24-h water absorption thickness swelling (24 h TS) of tubular particleboards, the geometry of the particles and the combination and distribution of the particles were investigated and integrated with response surface modeling (RSM). The results show that coarse particles with high aspect ratios form the network skeleton structure of tubular particleboards and provide the basic mechanical strength of the panels. The addition of an appropriate amount of fine particles can reduce the internal voids of the board and improve its mechanical strength. In addition, the surface fine particles flowed from the gaps of the coarse particles to the interior of the boards, making the boards more compact, which was conducive to improving the modulus of rupture and internal bond strength of the tubular particleboards. It was also found that the tube spacing limited the distribution of particles of different sizes, and regulating the tube spacing could lead to boards with good performance. According to the response surface data, the derived mathematical model of the second-order response function has an R2 of 0.954 for MOR, 0.956 for IB, and 0.923 for 24 h TS. The results predicted by the RSM are close to the experimental results when the fine particle content (FoC) in the core layer is 39.35 %, the surface particle content (Sf) is 37.45 %, the tube spacing (TD) is 18.81 mm, the MOR of the tubular particle board is 17.47 MPa, the IB is 0.70 MPa, and the 24 h Ts is 7.30 %. The optimized tubular particleboard has a thermal conductivity of 38.89 mW m−1K−1, which provides efficient thermal insulation. The RSM is important in the development and structural optimization field.

Locust bean gum as an adhesive for wood particleboards

Locust bean gum, derived from the carob tree, was evaluated as a biobased adhesive in particleboard manufacturing, investigating the effect of adhesive amount, mat moisture content, and process parameters such as temperature and time. Single-layer particleboards prepared with locust bean gum showed that effective hydration of the polymer chains is necessary to achieve satisfactory interactions with wood and thus yield a sufficient particleboard strength. A mat moisture content below 30 % resulted in weak particleboards, which easily broke immediately after pressing. With increasing mat moisture content, while keeping the adhesive amount constant, the internal bond strength was increased. Moreover, with constant mat moisture contents (40 %), the internal bond strength increased when the adhesive amount was increased, even though not proportionally. With an increase from 9 % to 18 % adhesive, the internal bond strength was increased by more than 100 %. However, with a further increase in adhesive content from 18 % to 36 %, the increase in internal bond strength was statistically insignificant. Even with high mat moisture contents (35–45 %), larger lab-scale particleboards had internal bond strength that fulfilled standard requirements for P2 boards, commonly used for furniture in dry conditions (SS EN 312), when the pressing time was long enough (75 s/mm) to allow for water and vapors to be removed before releasing the pressure. Using biopolymers as adhesives, without extensive chemical modification and hazardous crosslinkers, could lead to a more benign and sustainable particleboard production. Since the chemistry and setting/curing processes of biopolymer-based adhesives differ from those of the fossil-based adhesives used today, increased understanding of how production parameters affect the properties of the particleboards prepared with biopolymers may pave the way for their better utilization in this field.

Synthesis and Properties of (+)-Ketopinic and (–)-Camphanic Acids Esters Bearing a Nitrogen-Containing Heterocycle

A three-stage method was proposed for the synthesis of (1S)-(+)-camphor-10-sulfonic acid, (+)-ketopinic and (–)-camphanic acids esters containing a saturated nitrogen-containing heterocycle. It was found that (1S)-(+)-camphor-10-sulfonic acid esters undergo destruction with elimination of the sulfonic acid group in substitution reactions involving nitrogen-containing heterocycles. Esters of (+)-ketopinic and (–)-camphanic acids were formed during the proposed synthetic route, but undergo transesterification under column chromatography conditions. Quantum chemical calculations showed that the destruction of the ester bond in the case of (+)-ketopinic and (–)-camphanic acids requires less energy than the breaking of a similar bond in (–)-borneol esters. It was revealed that the internal bond strength index (IBSI) for the alkyl C–O bond in (–)-borneol esters is higher than in (+)-ketopinic and (–)-camphanic acid esters. Antiviral properties against the H1N1 influenza virus were studied for derivatives of (+)-ketopinic and (–)-camphanic acids.

Evaluation of rice husk composite boards prepared using different adhesives and processing methods

Rice husks, a byproduct of rice milling, were used to develop composite boards. Different processing methods, grinding, and treating with sodium hydroxide (NaOH), were adopted to improve the bonding and mechanical performance. NaOH solution was prepared at 5% (wt/v) concentration. The effect of different adhesives, phenol formaldehyde (PF), and polymeric diphenylmethane diisocyanate (pMDI), was evaluated. Rice husks mixed with resin were hot pressed to the target density of 768 kg/m3 and thickness of 12.7 mm. Specimens cut from these flat panels were submitted to bending, internal bond, water absorption, and thickness swelling tests. Results revealed that chemical treatment with NaOH significantly improved fiber-to-fiber bonding of rice husks. Internal bond strength of specimens made from chemically treated rice husks increased at least 1000% compared to others. Considering the mechanical properties and water uptake, rice husk boards fabricated with unprocessed rice husks and pMDI showed a better performance.

Development and investigation on physical and mechanical properties of mahogany sawdust particleboards made with tannic powder of Indian tamarind (Pithecellobium Dulce Benth)

The recycling of forest residues was investigated in the present study. It arms to determine the physical and mechanical properties of particleboards from mahogany sawdust bonded by pearls bone glue or tannic powder of peel of Indian tamarind (Pithecellobium Dulce). The influence of the size of particles on the physical and mechanical properties of the particleboards is studied. Five different granulometries (raw sawdust; 2.5 &lt; g £ 5; 1.6 &lt; g £ 2.5 and 0.8 &lt; g £ 1.6, and g £ 0.8) were investigated. The rate of the adhesives used were 5; 6.5; 7; 7.5; 8; 10, 12.5 and 15 percent. Physically, the density, thickness swelling (TS) and water absorption (WA) were evaluated. Mechanically, the modulus of elasticity (MOE), the modulus of rupture (MOR), the modulus of Young E, the tensile modulus of rupture (MOT) and the internal bond (IB) were determined. The results obtained showed that the granulometry has a great influence on the physical as well as the mechanical properties of the Mahogany sawdust particleboards. The pressing temperature is 160 °C. The threshold fixed by the American standard ANSI A208.1-2016 for the MOE and the MOR are widely reached. The values of the density classified the particleboards from sawdust of Mahogany wood in the categories of low and mean density. The thickness swelling and water absorption has not respectful to the American standard ANSI A208.1–2016 [1]. So, the manufactured boards can only be used in dry conditions.

Development of electrically conductive wood‐based composites using carbon nets

AbstractA novel conductive composite material was developed using woven carbon nets. For this purpose, carbon nets with different mesh sizes of 25, 100, 225, and 400 mm2 were woven, using two different carbon yarns with widths of 2 and 0.5 mm. The woven carbon nets were used before and after the core layer formation during mat forming of the particleboard. It was found that the insertion of carbon nets into the panel structure not only transforms insulated particleboard into a highly conductive composite but also significantly improves the flexural properties of the composite. However, the internal bond strength and physical properties of the composites were negatively affected by the presence of carbon nets in the panel structure, although their values were still above the minimum requirements of the standard values. Increasing the mesh area of the carbon nets and using thinner carbon yarns to weave the nets had a negative effect on the electrical and mechanical properties of the composites. In addition, a demonstration object was made of conductive composites to integrate lighting and a smartphone charging port into the object and prove the applicability of the developed composites for the furniture industry.Highlights Composites with carbon nets with smaller mesh area showed higher conductivity. The smaller the width of the carbon yarn, the higher the electrical resistance. The carbon net in the composites led to a decrease in internal bond strength. The carbon nets improved the flexural properties of the composites. Thickness swelling was significantly reduced by the use of carbon nets.

Basalt grid reinforcement of cement-bonded particleboards

This study focuses on the effect of basalt fiber reinforcement of cement-bonded particleboards (CBPB) with a target density of 1200 kg m-³ in terms of the compatibility with cement and the change in mechanical properties compared to conventionally produced boards. The modulus of rupture (MOR) and modulus of elasticity (MOE) were increased for all wood-cement ratios compared to the corresponding boards without basalt grid. Reinforcement with basalt grids significantly increased the strength-to-weight ratio (SWR) of the CBPB with various wood-cement ratios, due to the high tensile strength of the basalt grid. Simultaneously, the addition of the basalt reinforcement layer did not reduce the internal bond strength (IB). By using a basalt grid as reinforcement material, it is possible to counteract the negative effects of a higher wood particle content and even produce boards with increased bending properties. Basalt reinforcement could therefore be a good way to produce higher-strength panels and counteract the loss of strength due to the addition of wood particles.

Physical and mechanical properties of particleboard mixed with waste ACQ-treated wood

In this study, we recycle alkaline copper quaternary (ACQ) -treated wood used as a material for pyrolysis and gasification. The physical and mechanical properties of particleboards manufactured according to the mixing ratio and resin type (phenol–formaldehyde resin; PF, urea–melamine formaldehyde resin; UMF) were compared as materials for particleboard, which are used for wood recycling. According to the increase of ACQ particle input ratio, the PF particleboard did not differ in density; however, the thickness welling rate (TSR) and water absorption rate (WAR) decreased. The density of the UMF particleboard increased and the TSR and WAR also decreased. Although the bending strength (BS) of the PF particleboard increased, the internal bond strength (IB) did not show a difference. The UMF showed no difference in BS, but the IB improved. Through physical and mechanical properties, the mixing ratio of ACQ particle and untreated particles was 70:30 as the optimal mixing ratio. The surface was activated by the copper ions of the ACQ treated, which affected the improvement of adhesion and physical and mechanical properties. When ACQ-treated wood, which is classified as waste, was reused as a particleboard, its properties were superior to that of a board manufactured with untreated particles.

New particleboards for food-packaging from poplar peeling by-products using a circular economy approach

Poplar (Populus x canadenses Moench.) veneers (PWV) are a sustainable raw material traditionally used for producing food-packaging containers. However, the poplar log peeling process, to obtain veneers with a thickness of 0.8–2 mm, generates a large amount of waste, mostly consisting of bark and clippings from veneer sheets. The current work is focused on using these by-products to produce a new material, in the form of thin particleboards, that can be used for package production. The clippings from veneer sheets were dried and milled, and then sieved to obtain different particle size fractions. A bioadhesive, based on poplar bark extract combined with citric acid, was combined with the particles to produce single layer 210 mm × 210 mm x 2 mm particleboards by heat-pressing (press temperature = 160 °C, pressing time = 10 min, resin load = 10 wt%). It was possible to produce 100 % biobased particleboards in which the internal bond resistance and the moisture-resistance properties surpass the EN 312 requirements for boards type P3 for non load-bearing boards used in humid conditions, without the addition paraffin or any other additive. This work shows that the valorisation of by-products of poplar wood veneer production allows manufacturing high-performance particleboards, that can be used by the same industry to manufacture food-packaging containers. The viability of recycling used particleboards was demonstrated, yielding products with enough performance to be used in the production of new packaging products, and an alternative to the possible composting of these particleboards.

BINDER RATE AND GRANULOMETRY EFFECTON THE PHYSICALAND MECHANICALPROPERTIES OF MAHOGANYSAWDUST PARTICLEBOARDS MADE WITH PEARLS BONE GLUE

This work armtovalorizethesawdustofmahogany wood and the pearlsbone glue for environmental purposes.First, sawdust was sifted with three sieves respectively 0.8 1.6 and 2.5mm diameter. So, we have four granulometries (g) g ≤ 0.8 (G1), 0.8 &lt; g ≤ 1.6 (G2), 1.6 &lt; g ≤ 2.5 (G3), 2.5 &lt; g ≤ 5 (G4) and the raw sawdust. particleboards are manufactured from sawdust by varyingsuchthebinder rate (5 6.5 7 7.5 8 10 12.5 and 15) and the granulometry. Second,physical properties such asthe density, thickness swelling (TS) Water absorption (WA) were searched. The mechanical properties (Modulus of Elasticity (MOE), the Modulus of Rupture (MOR) in flexion, and Internal Bond (IB)) are determined according to the standard ANSI A208.1 – 2016[1]. The threshold fixed by the standard fortheMOE andtheMORarewidelyreached.Themanufactured particleboards are classified in the categoriesofmeandensity and can only be used in dry conditions.

Evaluation of the Oriented Strand Board Properties Produced Using Tropical Wood Mixtures

The objective of this study was to evaluate the composition of OSB panels created using the Amazonian species Caryocar villosum Aubl., Erisma uncinatum Warm., and Hymenolobium excelsum Ducke. The OSB was produced using a phenol–formaldehyde adhesive at a ratio of 30:40:30 for each layer. Different mixtures of Amazonian wood and Pinus caribaea var. caribaea. were tested. Physical (water absorption and thickness swelling after 2 and 24 h of immersion in water and non-return rate in thickness) and mechanical (internal bond and parallel and perpendicular static bending) tests were performed. The OSB panels composed of wood mixtures absorbed less water after 2 and 24 h of immersion when compared to the OSB produced using pine wood. After 24 h of immersion in water, the T3 panel (40% Pinus caribaea + 40% Hymenolobium excelsum + 20% Caryocar villosum) presented the lowest absorption value. In terms of swelling in thickness at 2 h and 24 h, the panel composed of 100% pine strands showed the highest swelling value, while the T3 treatment exhibited the lowest swelling value at 2 and 24 h, as well as for the rate of non-return in thickness. Regarding mechanical properties, we observed that all panels exhibited similar resistance for both parallel and perpendicular Modulus of Rupture, as well as parallel and perpendicular Modulus of Elasticity, except for the internal bond, where T3 demonstrated the highest resistance. Additionally, some OSB panels met the requirements of the EN 300 standard for OSB panels.

Triple reaction centers Vo-Ce-CuO nanosheets with single Ce atom for the Fenton-like degradation of niflumic acid

Vo (oxygen vacancy)-Ce-CuO nanosheet catalysts were studied for degrading niflumic acid (NFA) by the heterogeneous Fenton-like process (HFLP). NFA removal percentage of optimal Vo-Ce0.05-CuO reached 92% after 60 min of Fenton-like reactions and dropped only 0.28% after five times of recycles. Synergetic effects of triple reaction centers with electron-rich Vo centers, single Ce atom centers, and electron-deficient Cu centers have been demonstrated for generating hydroxyl radicals (OH) by H2O2 decomposition. The electrons from the organic pollutants adsorbed at the electron-deficient Cu centers could be transferred to Vo and Ce via the internal bridge bond to balance the electron transfer. H2O2 could directly obtain electrons from electron-rich Vo and single Ce atom centers to produce OH with a high H2O2 utilization efficiency instead of reducing metal ions by consuming H2O2. For the first time, we demonstrate that triple reaction centers with single Ce atom could improve the conversion percentage of H2O2 to OH with 71.1%. OH, HO2/O2− and 1O2 were the primary oxidants in the HFLP, in which OH played the dominant role.

Research on Gluing Properties of Thick Bamboo–Wood-Oriented Strand Boards

This study investigated the effects of adhesive resination and bamboo strand content on the physical and mechanical properties of thick bamboo–wood-oriented strand board (BWOSB), such as the air dry density (ADD), internal bond strength (IB), water absorption thickness swelling (TS), modulus of rupture (MOR), modulus of elasticity (MOE), and gluing properties. The raw materials used included large strands prepared from Chinese fir (Cunninghamia lanceolata), bamboo (Phyllostachys edulis), and modified isocyanate resin (PMDI). In this study, BWOSB specimens with different adhesive resination and bamboo strand content were fabricated, and their physical–mechanical properties were examined. It was found that the physical and mechanical properties of BWOSB with 8% PMDI resination were better than those with 5%, and their gluing damage was mostly in the form of the tearing of the raised vascular bundles of bamboo strands and the wood-breaking damage of wood strands. With the increase in the proportion of bamboo strands, the internal bonding strength and the short-span shear strength of BWOSB showed a tendency to decrease at first and then increase. The swelling rate of the water absorption thickness showed a tendency to decrease, and the other properties of BWOSB did not show a clear correlation with the change in the proportion of bamboo strands. The unique gluing interface between the bamboo and wood strands, which either used the “keyway” type of gluing effect or the “nail” type of gluing effect, determined the gluing performance of BWOSB, and the proportion of bamboo and wood strands influenced the gluing interface and gluing type of BWOSB, which ultimately affected the gluing performance of BWOSBs. The proportion of bamboo and wood strands also affected the gluing properties of BWOSBs by influencing the gluing interface and gluing type. This study provides a reference for the development of the production process of thick BWOSB and its application in the field of heavy load construction.

Theoretical investigation on the mechanism and kinetics of the OH•‒initiated atmospheric degradation of p-chloroaniline: Addition of [formula omitted] and isomerization of peroxy radicals

Atmospheric oxidation of the p-chloroaniline-OH• adduct [C6H4ClNH2–OH]• (AD-C2) by ∑g−3O2 and internal isomerization processes of peroxy radical [C6H4ClNH2–OH]•-O2 are theoretically investigated at the M06-2X/aug-cc-pVTZ and CBS-QB3//M06-2X/aug-cc-pVTZ level of theories. Potential energy surfaces (PESs) for the most efficient pathways indicated that the oxidation process begins via the complexation of individual reactants in syn mode forming PRCy-iOO-syn (y = 2,5) in an exothermic and endogenic step. The syn mode addition is favored over the anti one due to the formation of internal hydrogen bond between the hydroxyl and peroxy groups. Formation of new C5–OO bond in PRCy-iOO-syn complex is an unimolecular process which is exothermic and exoergic. This pathway is predominated over other internal conversions due to the presence of stronger intramolecular hydrogen bond. Cyclization of the produced [C6H4ClNH2–OH]•-O2 peroxy radical AD-C2-5OO-syn into the bicyclic peroxy radical AD-C2-5,6OO-syn is the last step which is strongly endothermic and endogenic. The rate coefficients are calculated by means of the RRKM theory over the temperature range 250–350 K and at a pressure range of 0.1 bar to the high-pressure limit. The RRKM rate coefficients at the M06-2X/aug-cc-pVTZ level for the first bimolecular and last unimolecular steps are in order of 10−16 cm3 molecule−1 s−1 and 10−7 s−1, respectively, while the obtained rate coefficients at the CBS-QB3//M06-2X/aug-cc-pVTZ are overestimated about two order of magnitude.

The effect of impregnation with fire retardant on the properties of particleboard bonded with PF/pMDI adhesive

ABSTRACT The application of commonly used flame retardants in most cases causes reduction in strength characteristic of particleboard. Therefore, it was decided to carry out research aimed at determining possibility of using pMDI-reinforced PF adhesive to produce board with increased fire resistance. The effect of different shares of particles impregnated with a mixture of potassium carbonate and urea on the particleboard properties such as density, density profile, bending strength, modulus of elasticity, internal bond and internal bond after boiling was investigated. Presented work also determined the effect of fire retardant on the performance of particleboards after ageing test and their reaction to fire. Studies demonstrated that PF adhesive modified with 20% pMDI is suitable for gluing impregnated wood particles. Regardless of their share, resultant panels showed no changes in strength and density. In the case of boards consisting of impregnated particles in the amount of 75% and 100%, lower values of swelling were demonstrated. The boards were classified as load-bearing boards for use in humid conditions. Fire retarding efficiency was confirmed by lowered mass loss, prolonged time needed to reach maximal burning rate, decreased gross calorific value and reduced ignitability when exposed to both radiant heat source and small flame source.