Effect of press cycle time and resin content on physical and mechanical properties of particleboard panels made from the underutilized low-quality raw materials

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 6 min). Other parameters such as type of resin (UF), hardener content (2%), type of hardener (NH₄Cl), press-closing time (4.5 mm/s), board density (0.75 g/cm³), press pressure (30 kg/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 5 min 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 5 min is adequate for general uses while eucalyptus with a resin content of 11% and pressed for 6 min is suitable for interior decoration.     

Properties of medium-density particleboard from saline Athel wood

The Athel tree, Tamarix aphylla (L), can potentially be used as a biomass crop to help manage saline subsurface drainage water in arid land irrigated agriculture. In this study, Athel wood was used to manufacture medium-density particleboard with an aim of developing new applications for the saline wood. The research investigated the effects of different types of adhesives, particle sizes, bark content (BC), resin content (RC), and hot water pretreatment on the mechanical and water resistance properties of the Athel-derived, medium-density particleboards. The measured mechanical properties included tensile strength (TS), modulus of rupture (MOR), modulus of elasticity (MOE), and internal bond strength (IB) of the finished particleboards. Water absorption and thickness swell were used to evaluate the water resistance. Polymeric methane diphenyl diisocyanate (PMDI) resin made particleboard of better mechanical properties and water resistance than urea formaldehyde (UF). The medium size (20–40 mesh) particles gave the best mechanical properties and water resistance than of the particleboard when evaluated against the smaller size (40–60 mesh) and larger size (10–20 mesh) particles. The mechanical properties of particleboard were improved as the resin content of the UF-board increased from 7 to 16%, but deteriorated as the bark content increased from 0 to 16.2%. The particleboard made from the wood particles that had undergone hot water pretreatment had poor mechanical properties and water resistance compared with the particleboard made from the untreated particles. Saline Athel wood is an appropriate material for manufacturing particleboards.     

Effect of resin content and pressure on the performance properties of rubberwood-kenaf composite Board Panel

The possibility of manufacturing rubberwood and kenaf (Hibiscus cannabinus L.) stem medium density fibreboard (MDF) panels at different pressure and resin content were investigated. The effect of mechanisms of interacted independent variables (resin content and pressure) on MDF properties was analyzed. The board performance was evaluated by measuring internal bond (IB) strength, modulus of rupture (MOR), modulus of elasticity (MOE), water absorption (WA) and thickness swell (TS). The test results were statistically analyzed by using response surface method (RSM) to determine the significant independent variables that influenced MDF properties. A mathematical simulation or response surface models were developed to predict the MDF properties (MOR, MOE, IB, WA and TS). The obtained results showed that MDF density and all interactions between the experimental variables were significant factors that influenced the mechanical properties of MDF. At 8 bar and 14 % resin content, the MDF recorded WA of 83.12 % and TS of 20.2 %. It can be inferred that two parameters (resin content and pressure) had positive effect on physical and mechanical properties of MDF. We concluded that resin content show more significant effects on MDF manufacturing as compared to pressure parameters.     

The influence of wax-sizing on dimension stability and mechanical properties of bagasse particleboard

Bagasse particleboards (BPBs) were made using polymeric methylene diphenyl diisocyanate (pMDI) resin as binder and wax emulsion as dimension stabilizer. A factorial experiment was conducted to measure the effects of wax and pMDI resin content on particleboard dimension stability and mechanical properties. The data were compared with respective properties specified in the ANSI A208.1 standard for commercial M3 grade wood-based particleboard.Wax-sizing improved the linear expansion (LE) of the particleboards under both pMDI resin contents used in this research and all LE values were controlled under the critical value of 0.35%. The use of wax significantly reduced 24-h water absorption and thickness swelling compared to the control panels without wax. Wax-sizing at the moderate levels also showed positive influence on long-term water absorption and thickness swelling properties. Wax content levels, however, did not significantly influence water absorption and thickness swelling behavior. Wax-sizing had no evident negative effects on the bending properties of MDI-bonded bagasse particleboards under both resin contents, while it caused slightly negative effect on internal bond strength. Mechanical properties of all boards far exceeded the minimum values specified in ANSI A208.1 standard. The entire properties of the 5% pMDI BPBs were better than those of the 3% pMDI panels as expected.     

Influence of impregnating wood particles with mimosa bark extract on some properties of particleboard

In this study, influence of impregnating wood particles with mimosa bark extract on the some properties of particleboard was investigated. Properties evaluated were modulus of rupture (MOR), modulus of elasticity (MOE), internal bond (IB), thickness swelling (TS), and formaldehyde emission (FE). The results showed that particleboards made from particles impregnated with mimosa bark extract had significantly lower mechanical, physical and formaldehyde emission values than those of the boards made from unimpregnated particles. Brushing of mimosa bark extract to the surfaces and edges of the particleboards did not affect the mechanical properties, statistically. However, this application caused a significant improvement in the thickness swelling and formaldehyde emission.     

Moisture-dependent physical properties of Karanja (Pongamia pinnata) kernel

The moisture-dependent physical properties are important to design post harvest equipments of the product. The physical properties of Karanja kernel were evaluated as a function of moisture content in the range of 8.56–22.22% d.b. The average length, width, thickness and 1000 kernel mass were 25.29 mm, 15.58 mm, 7.88 mm and 1036.45 g, respectively, at moisture content of 8.56% d.b. The geometric mean diameter and sphericity increased from 14.55 to 15.97 mm and 0.57 to 0.6 as moisture content increased from 8.56 to 22.22% d.b., respectively. In the same moisture range, the bulk density decreased from 663 to 616 kg/m³, whereas the corresponding true density and porosity increased from 967 to 1081 kg/m³ and 31.44 to 43.02%, respectively. As the moisture content increased from 8.56 to 22.22% d.b., the angle of repose and surface areas were found to increase from 27.69 to 37.33° and 665.74 to 801.63 mm², respectively. The static coefficient of friction of Karanja kernel increased linearly against the surfaces of three structural materials, namely plywood (28.72%), mild steel sheet (29.88%) and aluminium (18.86%) as the moisture content increased from 8.56 to 22.22% d.b.     

Impregnation modification of sugar palm fibres with phenol formaldehyde and unsaturated polyester

This study investigated the effects of impregnation modification via vacuum resin impregnation on physical and mechanical properties of sugar palm (Arenga pinnata) fibres. The fibre was evacuated at a constant impregnation pressure of 1000 mmHg impregnation times (0, 5, 10, 15, 20 and 25 min) with two different impregnation agents: phenol formaldehyde (PF) and unsaturated polyester (UP). A notable improvement in the physical properties of sugar palm fibres was observed after they were impregnated with PF and UP for 5 min, shown by the reduction of their moisture content (91 % and 89 %, respectively) and water absorption (43 % and 41 %, respectively) compared to the control sample. However, no significant improvement (p≤0.05) in the physical properties of fibre was observed when the impregnation time was extended (from 10 to 25 min) using both impregnation agents. As for the mechanical properties of the fibre, significant improvement was observed after they were impregnated for 5 min. The fibres impregnated with UP resulted in better fibre toughness and improved mechanical properties as shown in their higher tensile strength and elongation at break compared to the fibres impregnated with PF. Both the physical and mechanical properties showed no significant improvement (p≤0.05) after time for impregnation was extended (from 10 to 25 min) using both impregnation agents. Therefore, it can be concluded that the physical and mechanical properties of sugar palm fibre could be enhanced by impregnating the fibre with thermosetting polymer (PF and UP) for 5 min. It was shown that impregnation with unsaturated polyester (UP) showed better improvement than phenol formaldehyde (PF). In addition, this study also concluded that the unsatisfactory enhancement of the properties of sugar palm fibre even after the impregnation time was extended from 10 to 25 min was due to the use of low impregnation pressure of 1000 mmHg.     

密植夏玉米穗部脱水及力学特性研究

以仲玉3号和正红6号玉米为试材,设置6.75×10⁴、8.25×10⁴株/hm²两个种植密度,研究密植条件下夏玉米子粒、穗轴脱水及力学特性的变化规律,探明二者之间的关系。结果表明,随着种植密度的增加,穗部器官脱水减慢、含水率增加,力学强度呈下降趋势。品种间穗部脱水及力学强度存在显著差异,且远大于种植密度及二者交互作用的影响。与正红6号(ZH6)相比,仲玉3号(ZY3)脱水较快,到达适宜机械粒收含水率时所需吐丝后积温较少,收获时ZY3子粒压碎强度与穿刺强度大,穗轴抗折断力小,茎秆倒伏率低,机收性能更好。相关性分析显示,子粒与穗轴力学强度与含水率均呈显著负相关;穗轴抗折断力与干重、单位长度干重及单位体积干重呈极显著正相关,与穗轴长、长粗比呈极显著负相关。密度与品种对子粒产量存在无显著差异,随着种植密度的提高,茎秆倒伏率显著增大,ZY3生理成熟后脱水速率显著降低,达到宜机收子粒含水率所需积温增多。     

Arundo donax chipboard based on urea-formaldehyde resin using under 4 mm particles size meets the standard criteria for indoor use

Common reed (Arundo donax) is a fast growing perennial plant, considered in many countries as a weed or invasive plant. New material developments in recent years have led to common cane proliferation and an invasion in crops and water channels, significantly increasing elimination and control costs. In this study, it is proposed that particleboard be manufactured of common reed (A. donax). The objective is twofold. On the one hand it allows control of a weed, and secondly, it helps reduce the high dependence of imported wood timber and boards by using a readily and annually renewable resource.The fibers of common reed A. donax, possess high tensile strength (200 N/mm² between knots), providing much higher values than wood. This fact together with an important moisture and aging resistance, encourage us to propose it as a suitable raw material for the production of particleboards. In this study we propose the manufacture of particle board with urea formaldehyde resin, which is currently used in the wood chipboard industry.To perform this study, A. donax fibers obtained from a shredding hammer, were classified attending to size and slenderness. Following the standard industrial chipboard manufacturing processes, boards were developed to compare their behaviour against wood chipboards. Fifteen test-tube batches with different proportions of pre-selected fibers were manufactured. New boards were subjected to a mechanical stress test, and other physical properties were also measured. UNE EN—specific wood chipboard regulations were applied.Results showed that particleboard could be manufactured using A. donax adjusting the particle size to a maximum of 4 mm sieves. Finally it can be stated that making common reed panels also involves the reuse of a plant actually considered a weed, to become a raw material for industrial applications, leaving a door open to future development and research areas.     

Thermal and mechanical properties of environment-friendly ‘green’ plastics from stearic acid modified-soy protein isolate

Most plastics, at present, are petroleum-based and do not degrade over many decades under normal environmental conditions. As a result, efforts towards developing environment-friendly and biodegradable ‘green’ plastics for various commercial applications have gained significant momentum in recent years. Soy protein isolate (SPI)-based ‘green’ plastics have been shown to suffer from high moisture sensitivity and low strength. These properties have limited their use in most commercial applications. They are also difficult to process into sheets without any plasticizer. The commonly used plasticizer, glycerol, tends to leach out over time producing time-dependent properties, which is highly undesirable for commercial applications. The objectives of the current research are to reduce the moisture sensitivity and simultaneously improve the tensile properties of SPI by incorporation of stearic acid without affecting its biodegradability. The effect of stearic acid and glycerol on the tensile and thermal properties of SPI has been characterized using various techniques to determine the interaction mechanisms between stearic acid and soy protein. Mechanical properties were characterized using Instron tensile tester. Attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, differential scanning calorimetry (DSC), thermo-gravimetric analysis (TGA) and X-ray diffraction (XRD) techniques have been used to determine the effects of stearic acid and glycerol on the surface chemistry, thermal transitions and thermal degradation of the stearic acid modified SPI plastic (resin). The tensile test results show that Young’s modulus increased on increasing the stearic acid content, reaching the maximum value at about 25% (by weight of SPI powder) stearic acid. Further increase in stearic acid content from 25 to 30% led to a reduction in Young’s modulus. The moisture content, fracture stress, strain, and energy at break decreased steadily on increasing the stearic acid from 0 to 30% for SPI containing 30% glycerol. At 25% stearic acid content, the modulus and the fracture stress increased significantly, whereas the fracture strain, energy at break and the moisture content decreased on reducing glycerol content. Scanning electron microscopy photomicrographs of fractured surfaces showed a layered structure for stearic acid modified-SPI resin. TGA measurements showed that the thermal degradation of stearic acid modified-SPI resin initiated at higher temperature than the SPI resin. DSC scans indicated that stearic acid modified-SPI resin had a small degree of crystallinity, which was confirmed by X-ray diffraction patterns. Modifying SPI resin with stearic acid has been successful in obtaining better tensile and thermal properties as well as reduced moisture sensitivity without any processing problems.     

Restoring important hair properties with wool keratin proteins and peptides

In this work the effect on hair of two types of keratin samples obtained from wool, was investigated. Fiber surface changes were evaluated by contact angle measurements. The effectiveness of these keratin ingredients to restore the mechanical properties and the moisture content of the fibers was also determined. Modifications of hair properties due to some conventional chemical treatments were demonstrated with lower values of contact angle and detrimental effects on the mechanical properties. Application of keratin peptides and proteins to pretreated hair improved the fibers’ moisture content and their mechanical properties.     

Condensed tannins extraction from grape pomace: Characterization and utilization as wood adhesives for wood particleboard

The extraction of condensed tannins from grape pomace was examined using water medium in the presence of NaOH, Na₂CO₃, NaHCO₃ eventually in the presence of Na₂SO₃. The tannin fractions reactivity towards formaldehyde was studied by gel time analysis and thermomechanical analysis in bending and it was demonstrated that despite of their lower phenolic contents, some of these extracts displayed promising properties for adhesive applications. A resin formulation in which the total content of tannin is 75% of the total resin solids content gave good results and was employed for the elaboration of the first grape pomace based-wood particleboard which passed relevant international standard specifications for interior-grade panels.     

Feasibility of using eggplant (Solanum melongena) stalks in the production of experimental particleboard

This study examined possible feasibility of eggplant (Solanum melongena) stalks in the production of particleboard. Three-layer experimental particleboards with density of 0.53, 0.63, 0.73 and 0.78 g/cm³ were manufactured from eggplant stalks using certain ratios of urea formaldehyde (UF) and melamine urea formaldehyde (MUF) adhesives. Modulus of elasticity (MOE), modulus of rupture (MOR), internal bond strength (IB), thickness swelling (TS) properties of the boards were evaluated and a statistical analysis was performed in order to examine possible feasibility of these stalks in commercial particleboard manufacturing. The experimental results have shown that production of general purpose and furniture grade particleboard used in dry conditions using eggplant stalks is technically viable. The results of the study demonstrate that eggplant stalks can be an alternative raw material source for particleboard industry.     

Pulp from oil palm fronds by chemical processes

To enhance the use of the abundant biomass generated by the palm oil industry in Malaysia a study was conducted in view of exploring the papermaking potential of this industrial byproduct. Fiber strands from the frond of oil palm trees were examined relative to their physical and chemical characteristics and their response to chemical pulping such as sulfite, soda-sulfite and soda processes. Morphologically, the frond fibers are comparable to those of hardwood. They contain high content of holocellulose but low in lignin. Chemical pulps of 45–50% yield produced either by soda-sulfite or soda process exhibit acceptable papermaking properties comparable to those of hardwood kraft pulps. The study showed that frond pulp might be used as a reinforcement component in newsprint production using softwood thermomechanical fibers.     

The use of lignocellulosic hybrid filler in alternative FGRP configurations

The aim of this study was to develop an alternative fiberglass-reinforced plastic (FGRP) configuration. A hybrid composite, composed of a polyester-based matrix reinforced with fiberglass was conceived, in both continuous strand (roving) and mats forms, along with an alternative hybrid filler, derived from two different types of industrial residue: from the furniture industry and from the Cocos nucifera Linn (coconut palm) food derivative industry. The initial aim was to determine the feasibility of using residues, mainly of dry endocarp, without the need of prior selection, because it is more resistant and harder than wood residues. To that end, the following tests were performed: X-ray diffraction, differential thermal analysis (DTA), thermogravimetric analysis (TGA) and microstructural analysis of micrographic studies. The mechanical properties of strength and stiffness were studied using tensile uniaxial and three-point bending tests in dry and saturated moisture states. The graphics were obtained using Microsoft Oringin 6.0 software.     

Physical properties of pellets made from sorghum stalk, corn stover, wheat straw, and big bluestem

Densification of biomass feedstocks, such as pelleting, can increase bulk density, improve storability, reduce transportation costs, and make these materials easier to handle using existing handling and storage equipment for grains. The objectives of this research were to study (1) the physical properties of pellets made from corn stover, sorghum stalk, wheat straw, and big bluestem, (2) the effect of moisture content on bulk density, true density, and durability of the biomass pellets, and (3) the effect of hammer mill screen size and die thickness on bulk density, true density, and durability of the pellets. Biomass pelleting can significantly improve the bulk density from 47 to 60 kg/m³ for biomass grinds to 360 to 500 kg/m³ for biomass pellets. Of the four types of biomass pellets, wheat straw pellets had the highest bulk density value of 495.8 kg/m³, and sorghum stalk pellets had the lowest bulk density value of 365.2 kg/m³. An increase in moisture level resulted in a decrease in bulk density and true density of the pellets. The effect of moisture content on durability of the pellets made from corn stover, wheat straw, and big bluestem showed a similar trend; the maximum durability value was 96.8% at the equilibrium moisture content (EMC) range of 9% (d.b.) to 14% (d.b.) for corn stover and wheat straw, and 9% (d.b.) to 11% (d.b.) for big bluestem. A further increase in EMC value resulted in a decrease in pellet durability. For sorghum stalk pellets, the durability value increased initially with increased EMC and reached a maximum of 89.5% at EMC values between 14% (d.b.) and 16% (d.b.). Use of a larger hammer mill screen size (from 3.2 mm to 6.5 mm screen openings) resulted in increases of bulk density, true density, and durability of biomass pellets, but not in significant levels. Use of a thicker die size (from 31.8 mm to 44.5 mm in thickness) resulted in significant increase of bulk density, true density, and durability of biomass pellets.     

Properties of starch-based foam formed by compression/explosion processing

Single-use foam packaging is used by manufacturers to protect and preserve a wide array of food and industrial products. Starch is one possible alternative material for making foam products. Starch-based foam was made using a compression/explosion process to study its properties and potential for single-use packaging. A feedstock was first prepared which consisted of wheat (WS), corn (CS) or potato starch (PS) that was formed into aggregates (1–3 mm) and conditioned to moisture levels ranging from 8 to 20%. The conditioned aggregates were loaded in an aluminum compression mold heated to 230°C and compressed for 10 s with 3.5 MPa force. The force was instantaneously released resulting in an explosive release of steam as the starch feedstock expanded and filled the mold. The moisture content of the feedstock influenced the density and compressive properties of the foam. Wheat, corn and potato starch feedstock with 17, 17 and 14% moisture content, respectively, produced foam with some physical and mechanical properties similar to those of commercial food containers. The starch foam had the general shape of the mold and appeared similar to polystyrene. The microstructure of the foam revealed a cellular structure with mostly closed cells less than 1 mm in diameter. However, some regions of the foam had a microstructure similar to that of expanded polystyrene except that the cells were much smaller (<0.1 mm).     

The potential use of Ricinus communis L. (Castor) stalks as a lignocellulosic resource for 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.     

硅溶胶浸注-热处理改性橡胶木物理性能初探

采用硅溶胶作为浸注改性液，分析橡胶木经过浸注及浸注-热处理改性后物理性能的变化。结果表明：浸注改性使橡胶木增重率提高约20%，气干密度提高15%，平衡含水率降低6%，径向及弦向气干湿胀率均降低20%左右；而橡胶木浸注-热处理材与热处理材相比，质量损失率降低15%，气干密度提升约15%，平衡含水率降低8%，径向及弦向气干湿胀率则分别降低约5%和20%。     

Long term performance study of glass reinforced composites with different resins under marine environment

For marine structural applications which poses significant challenges to the choice of materials due to presence of corrosive seawater, polymer matrix based fiber reinforced composites are increasingly becoming the material of choice. However the performance properties of composites are greatly influenced by the moisture absorbed by the composite. In the current study, the long term performance is assessed by determining the amount of moisture absorbed and the reduction of mechanical properties over 12 months in a simulated sea-water environment at different temperatures. Three commonly used thermoset resins with different chemistry such as unsaturated polyester (USP), epoxy resin (EP) and vinylester (VE) are chosen. The effect of fiber reinforcement on the long term performance is investigated. A suitable method for manufacturing glass reinforced composite with good interfacial bonding and high volume fraction is also developed in current study. It is observed that vinylester plaques and composites absorb lesser moisture compared to USP and Epoxy systems resulting in lesser reduction in flexural strength and making the best performing among polymers studied. It is also found that sea-water diffusion into the composite follows non-Fickian behaviour and diffusion relaxation model fits well with the experimental data and corresponding model parameters are evaluated.