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Coated Particleboards based on Castor Stalk Waste as an Alternative to Artificial Wood: (Part II)
Abstract
The coating of the particleboard often challenges researchers in the wood industry, and only a small portion of the literature focuses on particleboard coating, practically and academically. This study focuses on the properties of pigmented coatings that mix acrylic-styrene latex with alkyd latex on the particleboards made from castor stalk. By testing abrasion resistance, UV resistance, hardness, adhesion, pull-off test, water, and chemical resistance, the performance of the blends in pigmented coatings was assessed. The performance of the surface qualities of coated caster particleboard was improved due to pigmented coatings. Coating, moreover, significantly enhances gloss and abrasion resistance further.
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Wood-based industry is one of the main drivers of economic growth in Malaysia. Forest being the source of various lignocellulosic materials has many untapped potentials that could be exploited to produce sustainable and biodegradable nanosized material that possesses very interesting features for use in wood-based industry itself or across many different application fields. Wood-based products sector could also utilise various readily available nanomaterials to enhance the performance of existing products or to create new value added products from the forest. This review highlights recent developments in nanotechnology application in the wood-based products industry.
Sumatran elephants (Elephas maximus sumatranus) are the world’s largest living land mammals. The elephant’s digestive system can only absorb 40% of the nutrients in digested feed, and the remainder is excreted as dung. Elephant dung waste can be used as a particleboard material due to its high fiber content. The objectives of this study are: (i) to prepare elephant dung waste as raw material for particleboard, (ii) to improve elephant dung particleboard’s physical and mechanical properties using wood shavings, and (iii) to study the influence of several parameters on the physical and mechanical properties of particleboard. The particleboard dimensions and density were set at 20 cm × 20 cm × 1 cm and 0.8 g/cm3, respectively. The mixture ratio of elephant dung and wood shavings was 100/0, 90/10, 80/20, 70/30, 60/40, and 50/50 (% w/w). This mixture ratio of particles was sprayed with 7% isocyanate adhesive. The pressing at a pressure of 30 kg/cm2 for 5 min and 160 ◦C was used in this study. The physical and mechanical properties of particleboard were tested according to JIS A 5908 (2003) standard. The result shows that the addition of wood shaving improved the elephant dung particleboard’s physical and mechanical properties. Except for moisture content and water absorption, the addition of wood shavings has a significant effect on elephant dung particleboard’s physical and mechanical properties. The best ratio of elephant dung and wood-shaving for this research is 50/50 and has fulfilled the JIS A 5908-2003 standard, except for thickness swelling.
The depletion of natural resources and increased demand for wood and wood-based materials have directed researchers and the industry towards alternative raw materials for composite manufacturing, such as agricultural waste and wood residues as substitutes of traditional wood. The potential of reusing walnut (Juglans regia L.) wood residues as an alternative raw material in particleboard manufacturing is investigated in this work. Three-layer particleboard was manufactured in the laboratory with a thickness of 16 mm, target density of 650 kg•m −3 and three different levels (0%, 25% and 50%) of walnut wood particles, bonded with urea-formaldehyde (UF) resin. The physical properties (thickness swelling after 24 h) and mechanical properties (bending strength, modulus of elasticity and internal bond strength) were evaluated in accordance with the European standards. The effect of UF resin content and nominal applied pressure on the properties of the particleboard was also investigated. Markedly, the laboratory panels, manufactured with 50% walnut wood residues, exhibited flexural properties and internal bond strength, fulfilling the European standard requirements to particleboards used in load-bearing applications. However, none of the boards met the technical standard requirements for thickness swelling (24 h). Conclusively, walnut wood residues as a waste or by-product of the wood-processing industry can be efficiently utilized in the production of particleboard in terms of enhancing its mechanical properties.
The potential of using residual softwood fibers from the pulp and paper industry for producing eco-friendly, zero-formaldehyde fiberboard panels, bonded with calcium lignosulfonate (CLS) as a lignin-based, formaldehyde free adhesive, was investigated in this work. Fiberboard panels were manufactured in the laboratory by applying CLS addition content ranging from 8% to 14% (on the dry fibers). The physical and mechanical properties of the developed composites, i.e. water absorption (WA), thickness swelling (TS), modulus of elasticity (MOE), bending strength (MOR), as well as the free formaldehyde emission, were evaluated according to the European norms. In general, only the composites, developed with 14% CLS content, exhibited MOE and MOR values, comparable with the standard requirements for medium-density fiberboards (MDF) for use in dry conditions. All laboratory-produced composites demonstrated significantly deteriorated moisture-related properties, i.e. WA (24 h) and TS (24 h), which is a major drawback. Noticeably, the fiberboards produced had a close-to-zero formaldehyde content, reaching the super E0 class (≤1.5 mg/100 g), with values, ranging from 0.8 mg/100 g to 1.1 mg/100 g, i.e. equivalent to formaldehyde emission of natural wood. The amount of CLS adhesive had no significant effect on formaldehyde content.
This study aims to investigate the influence of atmospheric plasma treatment on the abrasion resistance of particleboards, as an example of a wood-based material, coated with a waterborne finish. The treatment of the substrate, prior to coating application, using a floating-electrode dielectric barrier discharge (FE-DBD) plasma, resulted in an enhanced abrasion resistance of the coated particleboards in comparison to the untreated ones during the abrasion test with a duration of 200 revolutions. This finding was related to lower contact angles of water and coating after treatment with plasma and greater hardness of the coating on the treated substrates. The micrographs of the sample cross sections recorded with scanning electron microscope showed differences in the amounts of remained coating on the abraded areas. Investigation with attenuated total reflection Fourier transform infrared spectroscopy revealed that treatment of the substrate with plasma did not affect the chemical composition nor the curing and structure of the later applied coating. Further studies should be performed to determine the resistance properties of such surface systems to other impacts.
Particleboard (PB) are woodbased composites with fine wood fibers bound together by a small amount of polymeric adhesive, widely used in furniture industry and civil engineering. PB plates can be painted, laminated or veneered, and have good dimensional stability and load bearing capacity when properly designed. However, the deformation and fracture of such elements create malfunctions of structures made of MDF. This paper presents experimental results obtained for three point bending (TPB) tests, mode I and mode II fracture toughness. The bending tests were carried on rectangular specimens, while the fracture toughness tests were performed on Single Edge Notched Bend (SENB) specimens for mode I, respectively on Compact Shear (CS) specimens for mode II loadings. Digital Image Correlation technique allows the determination of the Crack Relative Displacement Factor and estimation of the Energy Release Rate.
Coated papers have an excessive impact on the appearance and utility of printed materials with respect to the increase in mechanical strength, print gloss and print density. Styrene–butyl acrylate copolymers were synthesized utilizing different emulsifier systems and modified with acrylamide. These lattices were evaluated as paper coats in the presence of kaolin, calcium carbonate and a mixture of both as pigments. The evaluation aimed at employing these lattices on recycled white and brown paper substrates with respect to their mechanical properties and their printability. The tensile strength of coated papers was upgraded by ~ 20–30% in CD compared with that of uncoated papers. The improvement ratio was ~ 12–16% in bursting strength compared with that of the uncoated paper. The maximum gloss values (39 and 48) and the maximum print density values (2.51 and 2.44) were obtained for ground calcium carbonate “GCC” composites on white and brown bases, respectively. Formulas containing GCC had a uniform printed surface with high-quality ink distribution without any picking up of coated surface. This work is a promising one as efficient synthesized binders and a local pigment were employed besides achieving offset printing on recycled brown papers for the first time.
Purpose of Review
Although surface roughness can have a
huge impact on finishing costs and the perceived quality of
wood products, there is a lack of consensus on how to measure
and evaluate wood surface roughness. One reason for this is
that the presence of anatomical features can bias the measuring
and evaluation of surface data. Consequently, the methods
and recommendations given in general standards on measuring
surface roughness do not apply well to wood surfaces.
This review offers some recommendations on how to best
measure and evaluate surface roughness.
Recent Findings
This review covers the measurement (instruments,
methods, profile measurements versus area measurements,
measuring length and resolution) and evaluation (form
error removal, filtering, the selection of the cut-off length,
removal of wood anatomy from the measured data, calculation
of roughness parameters) of surface roughness of wood
products.
Summary
A set of best practices in order to overcome the
biasing effect of wood anatomy is presented in this paper.
Specific recommendations are given regarding the selection
of the measuring instrument (stylus), the length of evaluation (at least 40 mm), the measuring resolution (5 μm), removal of form error (with or without prior removal of wood pores), the
use of the Robust Gaussian Regression Filter, appropriate
cut-off length (2.5 mm), the best roughness parameter for
describing the processing roughness (Rk) as well as a method
to separate the processing roughness from anatomical roughness
by using an Abbot-curve. These findings, if automated in
dedicated software can serve for optimisation of processing
parameters in industry applications.
Keywords:
Surface roughness .Wood products . Roughness
measurement . Roughness evaluation .Wood anatomy .
Push-up effect
Methanolic extracts of the leaves of Cajanus cajan (pigeon pea), Ricinus communis (castor bean) and Thymus vulgaris (thyme) were investigated for their medicinal, antimicrobial and toxicological properties. Phytochemical screening of the leaves revealed the presence of tannins, phlobatannins, flavonoids, steroids, terpenoids, saponins and cardiac glycosides which are the most important bioactive constituents of medicinal plants. Antimicrobial testing against eight pathogenic bacteria showed that all the extracts possess antimicrobial properties with Thymus vulgaris being the most effective as it inhibited seven out of the eight bacteria tested. Rats were given daily oral administration of methanolic extracts of the leaves at two different concentrations (100 mg and 200 mg/kg body weight) for a period of 14 days. Analysis of kidney and liver function parameters in the serum and tissues of the rats show no significant difference (P < 0.05) between treated and untreated rats. Measurement of organ: body weight ratio did not show any indication of kidney or liver enlargement. These results showed that the extracts are not toxic and also possess medicinal components which are inhibitory to bacteria.
"Wood Coatings" addresses the factors responsible for the performance of wood coatings in both domestic and industrial situations. The term 'wood coatings' covers a broad range of products including stains, varnishes, paints and supporting ancillary products that may be used indoors or outdoors. Techniques for coating wood go back many centuries but in recent decades there has been a move towards more environmentally-friendly materials, for example, the use of water-borne rather than solvent-borne chemicals. A major objective of "Wood Coatings" is to explain the underlying factors that influence selection, application and general operational issues. Basic information on the chemistry and technology of coatings is included for the benefit of students and laboratory technicians. Additionally, the book includes individual chapters of interest to architects, specifiers, and industrial users. It offers up-to-date guidance on current availability and usage of wood coatings. It provides the reader with a basic understanding of both coating and substrate interactions. It covers both architectural (trade and DIY) and industrial sectors.
This paper examined the effect of temperature of pressing on the strength of width glued elements during the process of production of solid wood panels. It has been used the polyvinylacetate D3 adhesive and solid beech wood (Fagus silvatica). Time of pressing has been determinate separately for each level of temperature of bonding, which amounted to (30o, 40°, 50°, 60°, 70o C). For each level has been formed 20 samples in order to determinate the value of the shear strength of bonded joint. The results were processed using the Student's t-test. This research showed that with increasing the temperature and pressing time increases the shear strength of the bonded joint, but non-linear.
The objective of this study is to evaluate the effect of decor paper and resin type on physical properties, mechanic properties, and surface quality properties of particleboards coated with decor papers impregnated by using different resin. White oak, New wenge and common maple pattern decor papers impregnated with urea formaldehyde (UF), melamine formaldehyde (MF) and urea-melamine formaldehyde (UF+MF) were used as coating materials. Particleboard surface was laminated with these coating materials by hydraulic press. As a result, specimens coated with MF-impregnated papers showed better performance than those coated with UF and UF+MF-impregnated papers. Resin type and paper pattern affected the physical, mechanical (with exception of tension strength), and surface properties (especially cigarette burn and abrasion) of coated particleboards. Physical and mechanical properties of coated particleboard were significantly improved compared to non-laminated particleboards. It was found that paper pattern affected the surface properties, such as impact, scratch, and abrasion, resistance to staining and cigarette burn. However, it did not change the cracking and steaming properties of the coated samples. After the coating process, it was determined that cigarette burn, abrasion, impact, and scratch performances were among 1 to 3 grade, lp: 10-35, Fp: 210-340/100-150, and 2 to 5 grade, respectively.
Renewable resources used in the preparation of polymers are falling in the class of biomaterials which are rich in hydrocarbons and most of the times obtained from parts of profusely available agriculture feedstock. Use of non-edible vegetable oils and their fatty acids are currently the raw materials focused in synthesizing polymeric materials as renewable sources due to increasing economic and environmental concerns of petroleums. The current oil based polymers are prepared by consuming petroleum based anhydrides and dicarboxylic acids. With this investigation, we tried to substitute almost all components of petroleum feed stock by renewable sources in preparation of polyol. Initially palmitic acid was used as a renewable source to prepare palmitamide by amidation reaction. Further amide was converted into the polyesteramide resin (PEPAD) by reacting it with another renewable resource, i.e. dimer fatty acid which is the dimerized product of unsaturated fatty acids of vegetable oils. Structure of the prepared resin was confirmed by spectroscopic techniques and resin was also characterized by end group analysis like hydroxyl and acid values. The molecular weight of PEPAD was ranged between 2590 and 2760 g mol(-1). Palmitic acid based polyesteramide was used to prepare polyurethanes by varying amount of diisocyanate. The transparent polyurethane films and coatings were obtained and examined for water absorption, contact angle, hardness, coating properties, solvent, acid and alkali resistances. The thermal properties of the polyurethane films were estimated by TGA and discussed. It was found that change in NCO content affected on transparency as well flexibility of the prepared films. It also noticed that thermal stability was shifted toward higher range by increasing mole (NCO/OH) ratios due to formation of urea linkages.
The present study examines the suitability of particleboard made from ground macadamia nut shells bonded with castor oil derived resin as an environmentally sustainable substitute for conventional wood fiber/urea formaldehyde particleboards. The properties of the macadamia shell castor oil resin particleboard were compared with those of a wood fiber/castor oil resin particleboard and a conventional wood fiber/urea formaldehyde particleboard.The density of the macadamia shell particleboard was 43% higher than that of its wood fiber counterpart, in keeping with the higher density of the macadamia shells. Water absorption and water-induced swelling were much lower in the macadamia shell particleboard, being only one quarter of the value obtained for the wood fiber particleboard. This is consistent with the lower moisture absorption reported previously for macadamia shells.The internal bond strength was similar for the macadamia shell and wood fiber particleboards bonded with castor oil based polyurethane. The modulus of rupture and modulus of elasticity were however about 50% lower for the macadamia shell particleboard than for its wood fiber counterpart. This is considered to be due, at least in part, to the lower cellulose content of macadamia shells.Formaldehyde emissions from the castor oil resin particleboards were less than 5% of those typical of urea formaldehyde particleboards.Based on these findings it is considered that macadamia shell/castor oil particleboards have acceptable properties for use in the built environment. Their good moisture resistance makes them particularly attractive for use in humid environments, such as in bathroom and kitchen applications. Moreover, they have much lower environmental impact than conventional particleboards.
Castor (Ricinus communis L.) stalks, which are a readily available by-product of this plant mainly cultivated for seed production, derived from experimental plantations grown in Northern Greece during the period April–October 1996 were assessed for their suitability as feed stocks for direct substitution of wood in particleboard. The average stalk yield of castor reached about 10 dry t/ha, which is higher than the average yield of forest in temperate zones. After harvesting, castor stalks were dried in a greenhouse to about 12% moisture content, and chipped by an automobile chipper and re-chipped in a hammermill. Castor particles and industrial wood particles mixed in various proportions were used as raw material for one-layer and for the middle layer of three-layer particleboards. A commercial E2 grade UF-resin was used as binder. Castor particles were characterized by a lower slenderness ratio and lower bulk density than industrial wood particles. The evaluation of the mechanical and hygroscopic properties of panels showed the following results: Partial substitution of wood by castor stalks resulted in the deterioration of all board properties. The presence of the unlignified pith and the configuration of castor particles seem to be responsible for the deleterious effect of castor stalks on board properties. However, comparing the properties of the boards produced in this study to relevant European and American Standards, it was found that, with the exception of screwholding strength for three-layer boards, the experimental one layer-, and three-layer boards containing up to 25% and 75% castor particles respectively meet or exceed the Standards requirements for interior boards.
One way to reduce the use of wood resources and simultaneously to manage wastes in the form of forest and agricultural biomass, as well as biomass originating from the food processing industry, is to use those wastes in particleboard production as an alternative raw material to wood chips. This article highlights the potential of woody biomass from non-forest sources. Based on a review of the current scientific literature, an attempt is made to identify the raw materials with the greatest potential, considering their availability and the quality of boards made from them. Suggestions are also made regarding the search for new raw materials, based on their production potential.
Because the timber market is more and more competitive, the particleboard manufacturers are looking for new sources of plant raw material. In the same time, the use of healthier, safer and more environmentally friendly materials becomes a priority in the building sector. In this context, using bio-based adhesives to bond the particles instead of the synthetic ones is an interesting alternative. In the same time agricultural byproducts as annual plant stems can be a sustainable alternative raw material. These resources are abundant, renewable and safe raw material. Moreover, their porous structure gives them interesting properties for building materials such as lightness and thermal insulation capacity. Two agricultural byproducts abundant in France have been studied: flax shives and sunflower bark. Particleboards were made at laboratory scale by thermocompression of the plant raw particles to a target density of 500 kg.m⁻³. The plant particles were bond by different methods:
- * without addition of any adhesive. In that case water was sprayed on the plant particles before the forming process and was evaporated during the thermocompression. It leads to extraction of soluble and lignocellulosic compounds from the agroresources that can act as adhesives.
- * with addition of a biobased adhesive based on casein, the protein from bovine milk, or based on a commercial caseinate, added at different ratios to the plant particles.
- The effect of the type of agroresources, the particle size, the formulation of the biosourced adhesive, and its application are evaluated testing the physico-chemical properties of the particleboards: mechanical properties (bending test and internal bond), thermal properties, and behavior towards water and fire. Using a biobased adhesive improves the mechanical properties of the particleboards significantly compared to the version without added adhesive. Panels made with flax shives generally showed better properties than with sunflower bark, so flax shives seem more suitable for particleboard manufacturing. But after optimization of the formulation and the process, both raw materials could be used with casein-based adhesive yielding efficient and fully biobased particleboards for applications such as furniture or door panels.
This paper presents the results of experimental study on the production of particle boards from wastes of wood and expanded polystyrene foam (EPS). Two different particle sizes of wood wastes and two different dosages of EPS resin were used as binders in the boards (WPP). Modulus of rupture (MOR), modulus of elasticity (MOE) and physical properties were analysed. Effects of long-term immersion in water for 7–28 days on the properties of the particleboards were similarly evaluated. SEM and FTIR were used to analyse the specimens. The results showed that water absorption decreased as EPS content was increased from 1.5 to 2.0 and thickness swelling indicated that WPP with 0.85 mm particle sizes and 1.5 resin dosages had the least value between 2.38 and 3.51% after 7–28 days of prolonged immersion in water. MOR and MOE indicated that the optimum performances of the WPP boards were recorded before the prolonged immersion in water at 4.3 MPa and 187.8 MPa. WPP with 0.85 and 1.75 mm particle sizes with 2.0 resin dosage had good post immersion performance. This study demonstrated that wood and EPS wastes are sustainable materials for producing composite wood based panels that are still durable in moist environment.
In order to replace wood in particleboard manufacturing, two agricultural by-products were studied: the flax shives and the sunflower bark, which are abundant, renewable and little valorized raw materials. Sunflower bark in particular is very few studied. This study will demonstrate the possibility of using sunflower bark in particleboards and how to modulate the manufacturing process to take the benefits of both studied agroresources. These plant based particles present interesting porous structures for using as materials for building insulation or as furniture. To obtain totally biosourced materials, the plant based particles were self-bound by a thermocompression process with water. The properties of these materials were compared with particleboards made of the same plant based particles with a classical urea-formaldehyde binder. Particleboards of two target densities are compared: 350 and 500 kg m⁻³. Both agroresource materials do not present the same behavior to self-binding or classical binding. Flax shives are more adapted to self-binding process thanks to their biochemical composition and their morphological structure. These different boards were characterized according to mechanical and thermal properties, resistance to water and to fire. The type of agroresource or of binder does not influence the thermal conductivity. The denser binderless boards show better resistance to fire. The main defect of binderless boards is their too low resistance to water compared to boards made with a synthetic binder.
The hybridisation of wood-based panels has gained interest in recent years. Lightweight hybrid panels consisting of wood fibres as faces and a mixture of wood particles with expandable polystyrene (EPS) granules as core layer were manufactured in this study. The effects of initial compression and different face-to-core-layer weight ratios were investigated. Results showed that both variables significantly influence panel properties. The initial compression enhanced the surface layer quality while negatively affecting the core layer. Adding EPS influenced the core layer quality, which improved the panel properties. The weight ratio of the face-to-core-layer also enhanced the bending properties and thickness swelling. The internal bond was weakened by increasing the face-to-core-layer ratio.
Abbreviations: WBPs: wood-based panels; EPS: expandable polystyrene; MOR: modulus of rupture; MOE: modulus of elasticity; IB: internal bond; SS: surface soundness; SWR: screw withdrawal resistance; TS: thickness swelling; WA: water absorption
This paper presents the findings from comprehensive studies for enhancing efficiency and competitiveness of wood based panels for uses in furniture and other building construction industries. Five stress modes, which are encountered in the design and applications of wood based panels, were investigated, i.e. flat-bending, edgewise-bending, panel shear, planar shear and concentrated load stresses. Four commercial board types, namely plywood (PW), particleboard (PB), medium density fibreboard (MDF) and oriented strand board (OSB), were examined to evaluate the different responses to the various stresses. Results showed that stress modes had a significant effect on both short- and long-term performance of wood based panels: 1) wood based panels had a much higher capability to carry the stresses applied along the edge than plane of the panels, 2) the maximum failure load under planar shear was 10–16 times that under flat bending load and 2–3 times that under concentrated load, and the maximum failure load under panel shear was 3–9 times that under pure edgewise bending load, 3) for the materials tested, PW had a higher capability to carry both pure edgewise bending load and concentrated load, and MDF had a higher capability to carry pure flat bending load, and panel and planar shear load, 4) stress modes had a more significant effect on deflection under creep loading than short term test, with the ratio of deflection under flat bending, concentrated load and planar shear being 23:6:1 for PW under short term test, while 205:20:1 for PW and 507:72:1 for PB under creep loads, 5) theoretically calculated deflection was higher than the measured for short term tests but lower than the measured for creep tests, 6) the effect of stress modes on relative creep varied among the materials tested. These findings provide most constructive database for designing and using wood based panels in various industrial sectors.
A new linear saturated terminal diisocyanate was synthesized from castor oil-derived undecylenic acid by thiol-ene coupling (TEC) and Curtius rearrangement. The structure of the diisocyanate was carefully examined using Fourier transform infrared spectroscopy, 1H nuclear magnetic resonance (NMR), and 13C NMR. This diisocyanate was used as a starting material for the preparation of a fully bio-based waterborne polyurethane dispersion (BPUD) by reacting with castor oil and castor oil-based carboxylic acid-type hydrophilic chain extender, which was prepared from castor oil by using 3-mercaptopropionic acid via TEC. The thermal/mechanical properties of the formed BPUD film were characterized via differential scanning calorimetry, thermogravimetric analysis, tensile test, hardness test, and water resistance test. The fatty acid-derived diisocyanate and the castor oil-based hydrophilic chain extender were used to produce BPUD with favorable properties.
Degree of surface quality of wood plastic composites (WPCs) is a function of both raw material characteristics and the manufacturing variables. The WPC panels comprised of different panel densities (800, 950, 1000, and 1080kg/m3), wood flour contents (50, 60, 70, and 80wt.%), wood flour sizes (1mm), and hot-pressing temperatures (190 and 210°C) were manufactured using a dry blend/flat-pressing method under laboratory conditions. The surface smoothness of the WPC panels improved with increasing WPC density, plastic content, and hot-pressing temperature while it deteriorated with increasing wood flour size. The reduction in the particle size of the WF resulted in a more compact structure on the WPC surface. In general, the wettability of the samples increased by increasing surface roughness.
The recently promulgated ASTM D7522 Standard Test Method for Pull-Off Strength for FRP Bonded to Concrete Substrate provides a method for quality control and acceptance testing of fiber reinforced polymer (FRP) systems adhesively bonded to a concrete substrate. In the process of developingASTM D7522, a number of comments and questions were received - some were incorporated as best practices and some were tabled, requiring further investigation. The present study addresses the latter issues and thereby directs future amendments of the ASTM D7522 standard method. Specifically, this study addresses the effects of specimen shape, the effects of variation in specimen cut depth, methods of cutting square specimens, and the impact of retesting specimens that do not fail during their initial test. It is shown that square specimens should be permitted although their results may not be directly compared with round specimens and they may have some other practical considerations affecting their use. Additionally, it is shown that cutting too deeply into the concrete substrate results in lower values of pull-off strength.
In this study, the influence of press cycle time and resin content (RC) on some of the physical and mechanical properties of single-layer particleboard manufactured from the low-quality raw materials were determined. Eucalyptus (Eucalyptus camaldulensis), mesquite (Prosopis juliflora), saltcedar (Tamarix stricta) and date palm (Phoenix dactylifera) wood, which is underutilized invasive species in southern parts of Iran, were used as alternative raw materials for particleboard manufacturing. Variable factors were as resin content (9, 10 and 11%) and press time (PT) (4, 5 and 6min). Other parameters such as type of resin (UF), hardener content (2%), type of hardener (NH4Cl), press-closing time (4.5mm/s), board density (0.75g/cm3), press pressure (30kg/m2) and press temperature (160°C) were held constant. The experimental panels were tested for their mechanical strength including modulus of elasticity (MOE), modulus of rupture (MOR), internal bonding (IB) and physical stability properties (thickness swelling) according to the procedures defined by European Union (EN) Standard. Overall results showed that most panels made from above-mentioned materials exceed the EN Standards for IB, MOE and MOR. The mechanical properties of particleboard were improved as the resin content increased from 9 to 11%. The results indicated that the polymerization of resin and wood is better at 11% resin content and 5min of press time. However, thickness-swelling (TS) values were higher (poor) than requirements. Panels made of mesquite, saltcedar and date palm with a resin content of 11% and pressed for 5min is adequate for general uses while eucalyptus with a resin content of 11% and pressed for 6min is suitable for interior decoration.
The paper analyses changes of the properties of particleboard furniture panels depending on the type and thickness of the coating material. As far as there is no standard regulating the structure and properties of differently coated construction panels, it is important to study the bending strength of panel details on the type and thickness of the coating material. The obtained results allow to ascertain rational type, structure and thickness of the coating material for panels (produced from the most often used for furniture manufacture 18 mm thick particleboard). Particleboard furniture panels were coated using paper-based film, compensatory paper, laminated plastics, 0.6 mm thick mahogany veneer (1 to 8 outer layers) and coated with acrylic paint. The specimens were constructed from the particleboard 18 mm thickness, produced at J/V "Girių Bizonas". The studies have ascertained changes in the modulus of elasticity and bending strength of particleboards covered by different coating materials, depending on the type and thickness of the coating material.
Particleboard (PB) is a widely used panelboard in value-added applications. Unfortunately, machining problems sometimes occur in practice when PB is used as a raw material that can be time consuming and costly to resolve. The wide availability and variety of substitutes, like medium density fiberboard (MDF), plywood, and orientated strandboard (OSB), have created a highly competitive marketplace for panelboards. That being the case, a survey of Canadian secondary wood products manufacturers was conducted to examine the perceived differences between PB vs. MDF, plywood, and OSB as a means of identifying the performance requirements of PB and other panelboard products. Very few respondents used OSB in high-value applications, and consequently it was excluded from the analysis. Survey respondents perceived MDF to have better properties than PB, rating it higher in 16 of 20 properties. PB's main advantages were its lower weight and lower cost. The comparison of PB and plywood was more balanced. Plywood was rated better than PB in fastening strength, moisture resistance and resistance to sagging, while PB's main advantages were its lower cost, lower warpage, and more uniform thickness. In general, the PB properties that rated the highest were edgeband peel/delamination, melamine edge chipping, and flatness/warp. These properties also tended to be common sources of problems for manufacturers. Surprisingly, fastening properties rated lower in importance, but at the same time, were selected to be the highest priorities for improvement in panelboards. Cost was ranked as the second most important priority for improvement. The survey highlighted means of better positioning PB in the marketplace; properties which rated highly in importance and were also identified as being sources of problems to secondary manufacturers are clear areas for improvement. The comparatively poor perceptions of PB relative to MDF can be addressed by improving the PB properties that are inherently similar to those of MDF. Finally, quality-control methods should be developed for secondary wood producers using PB to test important and problematic properties and to reduce the occurrence of problems common in manufacturing.
Bending strength and modulus of elasticity of phenol-formaldehyde (PF)-bonded particleboards were
studied at temperatures between -40 °C and +40 °C. These conditions may occur, for
example, during exterior use of boards. Bending strength and modulus of elasticity are significantly
affected by the temperature. Moreover, positive temperatures cause higher reduction of strength properties
than negative temperatures. The bending strength of boards in the temperature range from -40 °C
to 0 °C, for example, is reduced by 15% and in the temperature range from 0 °C to
40 °C by 28%.
Physical and mechanical properties of medium density fiberboards (MDF) made from various mixtures of wood fibers and stone pine (Pinus pinea L.) cones were evaluated using European standards. MDF panels were manufactured using standardized procedures that simulated industrial production at the laboratory. Six panel types were made from mixtures of wood fiber/cone flour, 100/0, 90/10, 80/20, 70/30, 60/40, and 50/50 percents, respectively. Addition of the cone flour into the MDF significantly reduced formaldehyde emission from the panel. In addition, the addition of 10% cone flour also improved water resistance of the MDF panels made using urea–formaldehyde (UF) resin. However, further addition of the cone flour into the panel negatively influenced their water resistance. Flexural properties and internal bond strength decreased with the increase of cone flour content in the panel. The UF resin is the main source of formaldehyde emission from the UF-bonded wood-based panels. Depending on addition of the cone flour in the panels, the formaldehyde emission values ranged from 2.6% to 55.3% lower than the panels made from 100% wood fiber. Based on the findings obtained from this study, pine cone can be used as a renewable biological formaldehyde catcher as an alternative to the traditional formaldehyde catchers for E1 Class MDF manufacture.
Wood-based panels and glues: technology and influencing factors, Woodbased panels and glues: technology and influencing factors
- M Dunky
- P Niemz
M. Dunky, P. Niemz, Wood-based panels and
glues: technology and influencing factors, Woodbased panels and glues: technology and influencing
factors. (2002).
Evaluating the warping of laminated particleboard panels, 7th Pacific Rim Bio-Based Composites Symposium: proceedings
- Z Cai
Z. Cai, Evaluating the warping of laminated
particleboard panels, 7th Pacific Rim Bio-Based
Composites Symposium: proceedings, volume II,
Nanjing, China, October 31-November 2, 2004.[Sl:
sn], 2004: Pages 69-79., 2004.
- W A Elkhateeb
- S Morsi
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