Density and humidity gradients in veneers of oil palm stems

Large variations in the stem of oil palm in terms of moisture content and density hinder its full utilization in the plywood industry. In this study, the density and moisture content (MC) pattern throughout the trunk of the oil palm tree were measured and established. The veneer samples were taken from various sections i.e., top, bottom, outer and inner parts of the trunk and the density and moisture content of each veneer were then measured. The results showed that there was a decrease of density and an increase of moisture content in the veneers as they were peeled progressively towards the inner portion of the trunk. It was also discovered that veneers taken from the top part of the stem had higher density but did not have a significant difference in MC compared to veneers taken from the bottom part of the stem.     

高含水率染色、固色桦木单板的胶合性能探讨

高含水率染色、固色单板的胶合质量是制造人造薄木的关键技术之一。试验比较、分析了不同含水率条件下,素板、染色、固色单板的胶合强度。结果表明：随着含水率的升高,素板、染色和固色桦木单板胶合强度均呈下降趋势,并且其湿状胶合强度均明显低于各自的干状胶合强度;素板的干湿状胶合强度均明显大于染色和固色单板。     

Ultrasound evaluation of lathe check depth in birch veneer

In this study, the lathe checks in birch veneer were examined with contact ultrasound and a preliminary study for the measurement with air-coupled ultrasound from green birch veneer (moisture content 60–75%) was carried out. The contact measurements were conducted from dry veneer and then from moistened veneer. Several ultrasound parameters measured from dry veneers were related with lathe check depth, e.g. correlation between ultrasound transit time and lathe check depth was 0.63 (p<0.001, N=30) when measuring perpendicular to grain from unchecked face of the veneer. The same correlation for moistened veneers was 0.74 (p <0.01, N=12). Furthermore, air-coupled reflection and through-transmission measurements were carried out with green veneer samples. In air-coupled through-transmission measurements, it seemed that moisture content dominated the measurement when measuring parallel to checks. There was also positive correlation between energy-related parameters in through-transmission and reflection measurement, which could be utilised to measure the properties of veneer with transducers on one side.     

Dimensional stability of heat oil-cured particleboard made with oil palm trunk and rubberwood

Dimensional stability of heat oil-cured particleboard made with admixture of oil palm trunk and rubberwood was evaluated. Particleboard made with oil palm trunk had better dimensional stability due to better compact ratio and lower hygroscopicity than rubberwood. Combination of repellent properties of oil and application of heat had greatly reduced the hygroscopicity of particleboard by decreasing its equilibrium moisture content, thickness swelling and water absorption.     

Ethanol and lactic acid production using sap squeezed from old oil palm trunks felled for replanting

Old oil palm trunks that had been felled for replanting were found to contain large quantities of high glucose content sap. Notably, the sap in the inner part of the trunk accounted for more than 80% of the whole trunk weight. The glucose concentration of the sap from the inner part was 85.2 g/L and decreased towards the outer part. Other sugars found in relatively low concentrations were sucrose, fructose, galactose, xylose, and rhamnose. In addition, oil palm sap was found to be rich in various kinds of amino acids, organic acids, minerals and vitamins. Based on these findings, we fermented the sap to produce ethanol using the sake brewing yeast strain, Saccharomyces cerevisiae Kyokai no.7. Ethanol was produced from the sap without the addition of nutrients, at a comparable rate and yield to the reference fermentation on YPD medium with glucose as a carbon source. Likewise, we produced lactic acid, a promising material for bio-plastics, poly-lactate, from the sap using the homolactic acid bacterium Lactobacillus lactis ATCC19435. We confirmed that sugars contained in the sap were readily converted to lactic acid with almost the same efficiency as the reference fermentation on MSR medium with glucose as a substrate. These results indicate that oil palm trunks felled for replanting are a significant resource for the production of fuel ethanol and lactic acid in palm oil-producing countries such as Malaysia and Indonesia.     

Cold tack of urea formaldehyde resins as an important factor in plywood production

The ability of urea formaldehyde (UF) resins to develop cold tack is needed in plywood production during pre-pressing in a cold press to ensure that the veneers stick together, can be transported, and fit into a multi-daylight hot press. The influence of defined factors on the cold tack was analyzed by determining the tensile shear strength of uncured birch veneers bonded with UF resin, and the statistically significant impact factors were determined. The factors tested were lay-up time, resin amount, resin age, moisture content, veneer temperature and pre-press time. Moisture content and veneer temperature had the highest impact on the cold tack of UF resins. A negative impact of high moisture content on the tensile shear strength and therefore on the cold tack of UF resins was proven as well as a positive impact of a comparably high (30 °C) veneer temperature. Lay-up time and pre-press time showed a minor impact on the tensile shear strength. Models were created using Design-Expert software to calculate the optimum operation conditions for cold tack.     

Investigation of physical and mechanical properties of oil palm wood core sandwich panels overlaid with a rubberwood veneer face

Low-density sandwich panels consisting of an oil palm wood core overlaid with a rubberwood veneer face were manufactured. Effects of two types of grain orientation of the oil palm wood core (parallel and perpendicular to board surface) and three different veneer thicknesses (0.7, 1.8 and 2.7 mm) and core densities (223 ± 14, 301 ± 35 and 418 ± 33 kg/m³) on some physical and mechanical properties of the boards were investigated. Results showed that higher core density increased the values of thermal conductivity, screw withdrawal resistance, modulus of rupture and modulus of elasticity but decreased the value of water absorption without effect on thickness swelling of the boards. Boards with the core grain direction oriented perpendicular to panel’s surface possessed lower value of thickness swelling but higher values of thermal conductivity and strain at fracture when the board failed in a mode of core shear under bending test than those of the others. Finally, the relationship between board density and the measured physical and mechanical properties of the oil palm wood core sandwich panels overlaid with a rubberwood veneer expressed as mathematical equations could be used to predict and design the expected properties of this type of sandwich board.     

Evaluation on some finishing properties of oil palm plywood

Oil palm is the largest and most important plantation crop in Malaysia. The oil palm generally lasts for 25–30 years before the next replantation is done. Substantial amount of biomass in the form of palm trunk results from plantation cycle. This resource is simply left on the ground to decay and is not used as raw material to manufacture any kind of value-added products. The objective of this study was to investigate the possibility of manufacturing plywood from oil palm trunks and to evaluate some of the finishing properties of such experimental panels in comparison to those from Shorea sp as control samples. Three-ply plywood samples were produced from 5 mm thick veneers of oil palm using urea formaldehyde adhesive. Three types of chemicals, namely nitrocellulose, pre-catalyzed lacquer and polyurethane were used to finish experimental panels. The surface finished with nitrocellulose had the lowest contact angle on raw surface of oil palm plywood and wood. The average cross cut tape index of oil palm plywood was comparable to Shorea sp. All finishing materials of oil palm plywood produced impact rating of 4 except for surface finished with nitrocellulose while finishing on wood indicated an impact rating of 3. Oil palm plywood had higher weight loss compared to Shorea sp. Based on results from contact angle, cross cut tape index, impact rate test, weathering, and soil burial test methods it appears that the samples showed acceptable finishing properties comparable to those of solid wood.     

泸型酒醅物理性质的实验研究

实验测定了酒醅含湿量、乙醇含量、真实密度、堆积密度、空隙率、堆积角和静摩擦系数在窖池中的分布规律.结果表明,随着窖池深度的增加,含湿量从60.2%升高到71.3%,乙醇含量先升高后降低,表层最低为4.1%,中下层最高为6.4%,底层为5.7%;真实密度、松散堆积密度和振实堆积密度随窖池深度增加而增大,其范围分别为747.5kg/m3～913.4kg/m3、374.7kg/m3～443.2kg/m3和529.8kg/m3～580.6kg/m3;堆积角的变化范围是42.8°～45.3°,表层最小、中下层最大;酒醅在生铁、玻璃和木板上的静摩擦系数均随窖池深度增加而增加,其范围分别为0.54～0.58、0.58～0.66和0.69～0.85.研究结果为酒醅混合搅拌及输运设备的设计和蒸馏工艺优化提供了重要参考.     

Fatigue life of oil palm wood (OPW) for furniture applications

Oil palm wood (OPW) from different portions of the trunk was tested on edge to evaluate its fatigue life, a criterion necessary for furniture application. It was found that as the stress levels increased, as a percentage of its MOR, a reduction in fatigue life was observed. Further, the phenol–formaldehyde resin impregnated OPW from the middle and center portion of the oil palm trunk showed comparable fatigue life with those untreated samples from the periphery of the trunk, and hence, the allowable design stress for the OPW for furniture applications could be set at 40 % of its MOR. The results show oil palm wood of acceptable density can be successfully used for furniture applications.     

A study of the deformation behaviour of veneers resulting from water storage (A methodological approach for determining the swelling characteristic using the example of European beech veneer)

This article discusses the swelling-induced deformation behaviour of veneers. Impregnation tests were performed to assess the influences on the unrestrained deformation of veneers. Among others, the tests focused on a comparison of the swelling-induced deformation in consideration of influences caused by the manufacturing process for different anatomical orientations (tangential or radial veneer). For this, samples of European beech veneer (Fagus sylvatica L.) were measured under a microscope and categorised into groups of tangentially or radially sampled veneers based on the anatomical characteristics. In addition, manufacture-specific damage was documented during the slicing process and also considered for the assessment. As a result of these tests, it was proven that the influence of near-surface damage caused by the manufacture on the unrestrained deformation of veneers was significantly dominant.     

Effect of laminated structure design on the mechanical properties of bamboo-wood hybrid laminated veneer lumber

The effects of veneer orientation and loading direction on the mechanical properties of bamboo-bundle/poplar veneer laminated veneer lumber (BWLVL) were investigated by a statistical analysis method. Eight types of laminated structure were designed for the BWLVL aiming to explore the feasibility of manufacturing high-performance bamboo-based composites. A specific type of bamboo species named Cizhu bamboo (Neosinocalamus affinis) with a thickness of 6 mm and diameter of 65 mm was used. The wood veneers were from fast-growing poplar tree (Populus ussuriensis Kom.) in China. The bamboo bundles were obtained by a mechanical process. They were then formed into uniform veneers using a one-piece veneer technology. Bamboo bundle and poplar veneer were immersed in water-soluble phenol formaldehyde (PF) resin with low molecular weight for 7 min and dried to MC of 8–12 % under the ambient environment. All specimens were prepared through hand lay-up using compressing molding method. The density and mechanical properties including modulus of elasticity (MOE), modulus of rupture (MOR), and shearing strength (SS) of samples were characterized under loading parallel and perpendicular to the glue line. The results indicated that as the contribution of bamboo bundle increased in laminated structure, especially laminated on the surface layers, the MOE, MOR and SS increased. A lay-up BBPBPBB (B-bamboo, P-poplar) had the highest properties due to the cooperation of bamboo bundle and poplar veneer. A higher value of MOE and MOR was found for the perpendicular loading test than that for the parallel test, while a slightly higher SS was observed parallel to the glue line compared with perpendicular loading. Any lay-up within the homogeneous group can be used to replace others for obtaining the same mechanical properties in applications. These findings suggested that the laminated structure with high stiffness laid-up on the surface layers could improve the performance of natural fiber reinforced composites.     

Effect of palm oil replacement with monoglyceride organogel and hydrogel on sweet bread properties

The potentialities of monoglyceride (MG) organogel and hydrogel containing sunflower oil in replacing palm oil were studied in sweet breads. This substitution was addressed to reduce the total saturated fat content of the product. The effects of the palm oil substitution were determined by assessing bread specific volume, moisture, crumb grain, firmness, and proton density/mobility by magnetic resonance imaging (MRI).Sweet bread prepared with hydrogel has quality characteristics comparable to that of control palm oil sample. This result was attributed to the capacity of MG crystallized lamellas to favor oil spreading over flour, replacing the typical functionality of triacylglycerol crystal networks. On the contrary, when oil was embedded in the organogel structure, less leavened and firmer bread with inhomogeneous lipid distribution was obtained. In this case, monoglycerides were probably engaged in oil networking and were less available to interact with other ingredients and exert their softening and anti-staling activities.     

Effect of differential maturity of paddy grains in a panicle on their milling quality

Branches of paddy panicles were divided into four equal parts and grains collected from each part separately. Moisture content at harvest and milling breakage after shade drying of grains to 12 to 13% moisture were determined. Average moisture content of grains gradually increased while milling quality generally suffered in grains from the top first quarter to the last quarter at the bottom. The same trend was found when the grains in the “top” quarter were compared with those from the “rest” of the panicle. The proportion of sun-checked grains was highest in the “top” fractions at all stages of maturity. The grains at the “top” also had a tendency to shed easily from the panicle. At early stages of maturity milling breakage of grains in lower portions of panicles was high perhaps due to immaturity and softness.     

Natural decay resistance of LVL made of veneers from durable and non-durable wood species

Laminated veneer lumber (LVL) was laboratory manufactured using veneers from decay and non decay resistant species in order to evaluate changes in the durability as a result of the LVL manufacturing process, and to test if the mixing of decay resistant species and non decay resistant species can improve durability. Laboratory soil block test and field test were conducted. The durability of solid wood was comparable to that of LVL made using the same species. For LVL made using veneer from durable and non-durable wood species, durability was improved when two faces and one core veneers were from decay resistant species.     

Moisture Content Adjustment to Modify Texture of Reduced-Oil Pecans

Reducing oil content has produced pecans with extended shelf-life and less calories, but poor texture. Adjusting final moisture content may restore texture of reduced-oil pecans. Texture Profile Analysis (TPA) was performed using an Instron on cylinders taken from full-oil and reduced-oil pecans sprayed with water or with a water-based flavoring, then dried to 15 final moisture contents ranging from 2.43 to 19.85%. Wetting and partial drying increased hardness to 87%, Area 1 to 89%, and fracturability to 79% of the value for full-oil pecans. Springiness and Area 2 were practically fully restored after redrying to 5% MC.     

烟草托盘育苗钵苗力学性能试验

为设计机械化取苗机构,以山东农业大学温室大棚培育的“革新一号”移栽期烟草钵苗为试验材料,在万能试验机上对烟苗进行了钵苗拔取、烟苗茎秆拉伸、压缩、弯曲和剪切力学性能试验。结果表明,营养基质含水率为（52.70±6.50）%时,烟苗拔取力为（2.09±1.28）N;烟苗茎秆含水率为（85.15±2.21）%时,烟苗茎秆抗拉强度为（1.96±0.68）MPa;烟苗茎秆径向抗压强度以及底部、中部的轴向抗压强度分别为（0.096±0.043）、（1.20±0.34）、（1.28±0.28）MPa;简支梁、悬臂梁弹性模量分别为（0.0042±0.0018）、（0.0130±0.0062）MPa;剪切强度为（1.64±0.39）MPa。此结果为机械化取苗机构的设计提供了理论依据。     

The potential of phenol–formaldehyde as plasticizing agent for moulding applications of wood veneer: two-dimensional and three-dimensional moulding

Two phenol–formaldehyde resols, namely a low and a medium molecular weight phenol–formaldehyde, were investigated for their applicability as plasticizers in moulding of European beech veneer (Fagus sylvatica L.). Therefore, beech veneers specimens were impregnated with both phenol–formaldehyde resol types in various concentrations. Subsequently, two-dimensional mouldability of the veneer was tested in a three-point-bending test along and perpendicular to the grain. Additionally, three-dimensional moulding of the phenol–formaldehyde impregnated veneer was tested throughout a modified Erichsen cupping test, where the veneer is pressed through a circular shaped coining die. The obtained results indicate a significantly improved mouldability of the treated beech veneers compared to untreated, water-saturated control specimens. Even at low phenol–formaldehyde concentrations plasticizing effects were detected in longitudinal direction and perpendicular to the grain. These findings are substantiated by results from three-dimensional moulding. Furthermore, the low molecular weight phenol–formaldehyde treated veneers displayed a higher mouldability than medium molecular weight phenol–formaldehyde specimens at similar phenol–formaldehyde concentration.     

Lipid profile of foods fried in thermally polymerized palm oil

Lipids extracted from foods fried in thermally polymerized palm oil were evaluated in papads, French fries and fish fry (Bombay duck) with moisture content ranging between 10% and 75%, in an attempt to investigate the effect of moisture content on lipid quality indices such as free fatty acids, conjugated dienes, p-anisidine value, viscosity, total polar materials and colour values. The quality of lipids in products with high moisture content (50% or more) was found to be inferior to that of the oil left after frying, as evidenced in Bombay duck and French fries from potatoes with initial moisture content of 52–77%. A reverse trend was observed in papads and French fries prepared from dehydrated potatoes with moisture content of 12% or less. The results indicate the moisture content of food plays a definite role in the distribution of the lipid constituents during frying in thermally polymerized oil.     

Variation of certain chemical properties within the stemwood of black locust (Robinia pseudoacacia L.)

From the bottom, middle, and top of three mature 35 to 37-year old black locust tree discs were cut and analysed to determine the variation within the stem of certain chemical properties. Hot-water extractive content was greater in heartwood than in sapwood, while the reverse occurred for the dichloromethane extractive content. Vertical stem analysis of hot-water extractives showed that they increased in heartwood but decreasedin sapwood from the bottom to the top of the stems while the reversal occurred for dichloromethane extractive content of sapwood. At the bottom and the middle of the stems, ash content was greater in sapwood than in heartwood, but at the top no difference was found between heartwood and sapwood. Ash content of both heartwood and sapwood was found to increase in the axial direction with respective values of 0.36% (bottom) and 0.76% (top) for heartwood and of 0.65% (bottom) and 0.76% (top) for sapwood. Ash analysis showed that considerable variations were found for the inorganic elements K and P being greater in sapwood than in heartwood. Heartwood was more acid than sapwood except for the top of the stems. Acidity mean values were found to increase from the bottom to the top of the stems in heartwood while they slightly decreased in sapwood. Total buffering capacity of heartwood was greater than that of sapwood and total buffering capacity of sapwood exhibited an inverse relationship to height. Very small acid equivalent values were determined only in sapwood. At the bottom, lignin content in heartwood (25.73%) was greater than in sapwood (18.13%). Lignin content of heartwood decreased from 25.73% at the bottom to 18.33% at the top, while that of sapwood was 18.13% at the bottom, 21.42% at the middle and 19.64% at the top.