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Analysis of briquettes and pellets obtained from two types of Paulownia (Paulownia tomentosa and Paulownia elongata) sawdust
Abstract
Sawdust specimens of two Paulownia species, namely Paulownia tomentosa and Paulownia elongata, were evaluated in order to obtain briquettes and pellets. Briquettes and pellets were manufactured from the sawdust, and their physical properties (density), mechanical properties (the resistance of the briquettes to breaking, and the shear resistance of the pellets), and energetic properties (caloric value, black ash content, and calcined ash content) were determined. The densities of the P. elongata and P. tomentosa briquettes were 790 kg/m3 and 934 kg/m3, respectively, while the pellets had densities of 1268 kg/m3 and 1266 kg/m3, respectively. These values were within the standardized limits, and the ash content had good values. The high calorific value of 16815 kJ/kg and the low calorific value of 16669 kJ/kg was acceptable, since they were greater than other vegetable resources. In conclusion, it was found that the two types of wood biomass are suitable for the production of briquettes and pellets, due to their good physical, mechanical, and energetic properties.
... According to European standards, a comparison of P. elongata × P. fortunei pellets from young plantations revealed that they were of inferior quality than those made from Pinus radiata and Eucalyptus nitens (Pegoretti Leite de Souza et al., 2021). In a distinct investigation, P.tomentosa and P.elongate showed the proper findings while assessing the production of briquettes and pellets from sawdust (Spirchez et al., 2021). Paulownia wood is currently the subject of extensive study to support its use in the creation of biopolymers (Rodríguez-Seoane et al., 2020) as well as wood plastics and composites (Ebrahimi et al., 2021). ...
... The diameter of the lumen was 25.3 μm and the mean cell wall thickness was 5.25 μm. Spirchez et al. (2021) analysed briquettes and pellets obtained from paulownia. Kalaycioglu et al. (2005), Nelis et al. (2018) and Salari et al. (2013) studied the potential of this wood species for particleboard (PB) and oriented strand board (OSB) production, respectively. ...
In Austria, paulownia (Paulownia spp.) has not been approved as a forest species. Because of the enormous annual growth and the promising mechanical and physical properties of this tree species, it is grown in short-rotation and value timber plantations in Central Europe. Previous studies have addressed the forestry and silvicultural aspects of different plant materials and issues in wood technology and wood physics based on small sample collections. Broad material screening for the technological evaluation of paulownia, samples obtained in large quantities from plantations, has not been conducted thus far. Therefore, this study aimed to provide a general overview of the technological, physical and mechanical properties of this wood species, in addition to basic forestry considerations. The wood samples for the experiments were obtained from an Austrian experimental plantation. In addition to wood drying, natural durability, workability and gluing, density and swelling/shrinking behaviour were investigated, and a comprehensive characterisation of all strength and stiffness properties was performed. The results will enable the modelling of paulownia wood to determine its static and dynamic loads, as well as the crash behaviour, using the finite element method (FEM) and well-founded assessments of the material's workability.
... A comparison of pellets, in terms of European standards, produced from young P. elongata × P. fortunei plantations showed their poor quality compared to Pinus radiata and Eucalyptus nitens pellets [119]. In another study, however, evaluating the production of briquettes and pellets from sawdust, satisfactory energy effects were obtained for P. tomentosa and P. elongata [120]. It may be appropriate to first apply biomass torrefaction, as proposed byŚwiechowski et al. [121,122], in order to get a better starting quality for fuel production. ...
This review aimed to determine the current state of research on the growth conditions and use pertaining to paulownia wood, mainly in European countries where paulownia has been introduced only relatively recently. Several studies carried out on Paulownia hybrids have shown significant differences in the growth dynamics of individual clones in their response to local environmental and climatic conditions. For example, dry biomass production yields in the second year of cultivation range from 1.5 t ha−1 to as much as 14 t ha−1. This diversity has manifested itself not only in growth characteristics but also in the properties of the wood and the possibilities for its use. Despite having clear similarities to the genus Paulownia, the cultivation of species and hybrids under different conditions has produced varying results. The best growing conditions for this wood (that make economic sense) are in the Middle East and Southern Europe. These regions have accumulated the most experience because of the earlier establishment of the crop. Today, paulownia cultivation is dominated by hybrids with selected traits that are propagated mainly in vitro. The most commonly planted hybrids include the clones in vitro 112, Cotevisa 2 and Shan Tong. The growth results and production capacity in central European countries are lower compared to Southern Europe. Experiments on paulownia cultivation are still relatively young, mainly consisting of replicating the cultivation of hybrids developed in Asia or Southern Europe. However, agronomic procedures are being developed and reactions to local climatic conditions are being studied. It is likely that, in the next few years, the profitability of growing paulownia in these regions will become apparent.
The utilization of sawdust waste in East Nusa Tenggara has not been utilized optimally. This waste is only burned, so it sometimes causes air pollution. So there needs to be an effort to overcome these problems by making alternative energy in the form of briquettes. Analytical description method with observation, literature study and economic and energy analysis is used in this research. Sources of data in this observation came from direct observations in the field through questionnaires and interviews. Based on the data of sawdust waste produced can reach 20-60 kg per day and can be used as other forms of energy. This energy can be used as a source of electrical energy to replace conventional energy which is less environmentally friendly and fuel for burning fishery products in East Nusa Tenggara. Based on the value of the benefit-cost ratio (BCR) and payback period, good results were obtained with a value of 2.13 with a return on investment of 0.82 years. The generated electricity biomass can replace conventional electrical energy and provide cost savings of 19.2% per kWh. In addition, the utilization of this energy can have a positive impact on regional income, health, schools, and transportation as well as agriculture.
Paulownia tomentosa (Princess tree, Empress tree) is a deciduous tree in the family Paulowniaceae, native to central and western China. It is an extremely fast-growing tree, and is a persistent exotic invasive in North America. This tree grows 10–25 m tall, with large heart-shaped to five-lobed leaves 15–40 cm across, arranged in opposite pairs on the stem. The very fragrant flowers are produced before the leaves in early spring, on panicles 10–30 cm long, with a tubular purple corolla 4–6 cm long resembling a foxglove flower. The fruit is a dry egg-shaped capsule 3–4 cm long, containing numerous tiny seeds. The seeds are winged and disperse by wind and water. Paulownia tomentosa can survive wildfire because the roots can regenerate new, very fast-growing stems. It is tolerant of pollution and it is not fussy about soil type. For this reason, it functions ecologically as a pioneer plant. Its nitrogen-rich leaves provide good fodder and its roots prevent soil erosion. It is able to grow from small cracks in pavements and walls. Paulownia tomentosa is cultivated as an ornamental tree in parks and gardens and is cultivated in all continents. All in all, this tree has popularity all over the world and needs to more attention. In this research, the ecophysiology of this plant has been studied. In first step, all related data were collected and then, after assessing their validity, the related data were extracted and combined and finally some suggestions are offered to improve and protect of this tree.
Differences in the densities of bed material and—especially biogenic—solid fuels prevent an ideal mixture within bubbling fluidised bed (BFB) combustors. So, the presence of fuel particles is usually observed mainly near the surface of the fluidised bed. During their thermal conversion, this leads to a release of unburnt pyrolysis products to the freeboard of the combustion chamber. Within the further oxidation, these species will not transfer their heat-of-reaction to the inert bed material in the way of a convective heat transfer, but rather increase the gas phase temperature providing probably some additional radiative heat transfer to the dense bed. In this case, the so-called heat release efficiency to the fluidised bed, being the ratio of transferred heat to the fuel input, will be reduced. This paper presents a methodology to quantify this heat release efficiency with lab-scale experiments and the observed effects of common operating parameters like bed temperature, fluidisation ratio and fuel-to-air ratio. Experimental results show that the air-to-fuel ratio dominates the heat release efficiency, while bed temperature and fluidisation ratio have minor influences.
The thermal conductivity properties of wood of Paulownia Clones in Vitro 112 were investigated after heat treatment at temperatures of 180 °C, 200 °C and 220 °C. After the treatment, the density decreased by 5.6, 8.9, and 14.1% for the samples heat-treated at 180 °C, 200 °C and 220 °C, respectively. The decrease in the thermal conductivity was 0, 2.6 and 15.7%, respectively. The thermal conductivity of kiri wood after thermal treatment at 220 °C was 0.064 W/mK, which is almost the same as that of thermal insulation materials.
This paper firstly introduces different views about discoloration of paulownia wood. Secondly, it summarizes treatment methods to prevent and remove stains on surface of paulownia wood. Finally, it analyzes the trend of paulownia wood discoloration treatment technology.
The paper presents some aspects regarding the use of certain bark biomass as sustainable and renewable fuel. The main bark uses are listed exhaustively, emphasizing the fact that they are parts of the forestry biomass. The main problems arising from the ecological burning of bark are highlighted, namely the amount of ash and the resulting gases, especially carbon dioxide, but the emphasis is placed on the amount of heat and ash that bark produces during combustion. Accordingly, the high and low calorific value and ash content are determined experimentally, but they are also estimated according to the relationships of prediction. Other calorific characteristics of bark for the four analyzed species and a mixture of them as calorific density, rate of energy release, limitative moisture content and so on are presented. The influence of ash content on the calorific value of bark use is also evaluated. The main conclusions of the paper refer to the net calorific value of the bark to be used for domestic purposes, in natural shredded form, or in the form of briquettes or pellets. © 2017, Gh. Asachi Technical University of Iasi. All rights reserved.
Kiri trees are fast-growing species, which are increasingly cultivated on plantations in Europe. This study assesses the application of kiri wood (Paulownia tomentosa) for the production of particleboards. Single-layer particleboards (PBs) were produced from kiri particles (KPs), industrial particles (IPs) and various mixtures of both materials with target densities of 350, 500 and 650 kg m⁻³, respectively. The composition of the PBs was 100% KPs, 66% KPs, 33% KPs and 0% KPs (100% IPs). PBs based on 100% IPs exhibited the lowest mechanical strength properties, which increased with increasing proportions of KPs within the same density range. The swelling properties of the boards were similar within one density range. The formaldehyde contents of PBs made of KPs were higher compared to PBs based on IPs, but all values were below the threshold value given in EN 13986 (Wood-based panels for use in construction—characteristics, evaluation of conformity and marking, German version. European Committee for Standardisation, Brussels, Belgium, 2004). X-ray micro-computed tomography (XµCT) revealed differences in the structure and compression of the PBs based on KPs and IPs resulting in smaller and more evenly distributed voids between the particles in PBs based on KPs. This study shows that kiri wood is a promising raw material for the PB industry, both alone and in mixtures with other particles.
The fast growing woody crops are a very important source for the generation of the bioenergetics biomass. Paulownia sp. Is a plant part of this group, and because of its fast growth, multiple values and high adaptability with climate conditions, is set recently in the centre of the intention. Paulownia is one of the fastest growing species in the world with low concentration of ash, sulphur and nitrogen and high calorific energy from its wood. It is considered as an energetic crop adequate for the production of the solid biocarburants and the bioethanol. The cultivation of the Paulownia because of the high absorption of CO
Paulownia is one of the most useful and sought after trees, in China and elsewhere, due to its multipurpose status. Though not regarded as a regular medicinal plant species, various plant parts (leaves, flowers, fruits, wood, bark, roots and seeds) of Paulownia have been used for treating a variety of ailments and diseases. Each of these parts has been shown to contain one or more bioactive components, such as ursolic acid and matteucinol in the leaves; paulownin and d-sesamin in the wood/xylem; syringin and catalpinoside in the bark. The fruits contain fatty oils, alkaloids, flavonones as well as flavonoids with antioxidant properties. The flavonoid contents and TROLOX Equivalent Antioxidant Capacity (TEAC) value in fresh and dry leaf extracts of Paulownia elongata suggest that this species has potential for advanced medicinal use. In vitro grown Paulownia fortunei Hemsl. seedlings, inoculated with Agrobacterium rhizogenes have a potential to produce hairy roots and synthesize bioactive compounds such as acteosides (verbascosides). With various new studies describing isolation of therapeutic compounds and their probable application in human health, it is an opportune moment to revisit medicinal potential of this tree. In this review, the usage of Paulownia in traditional medicine has been revisited and current advances in various fields of research in the genus Paulownia are summarized.
We investigated the effect of genotype and culture medium on the in vitro germination and development of plantlets from seeds of 6 different Paulownia genotypes (P. tomentosa, hybrid lines P. tomentosa × P. fortunei (Mega, Ganter and Caroline), P. elongata and hybrid line P. elongata × P. fortunei). Nodal and shoot tip explants were used for micropropagation of Paulownia genotypes by manipulating plant growth regulators. The highest germination percentage for all genotypes was obtained for seeds inoculated on medium supplemented with 50 mg*L GA3(MSG2). On Thidiazuron containing media, the explants of hybrid line P. elongata × P. fortunei exhibited the highest frequency of axillary shoot proliferation following by P. tomentosa × P. fortunei. The results are discussed with the perspective of applying an improved protocol for in vitro seed germination and plantlet formation in several economically valuable Paulownia genotypes. ©2014 University of Zagreb - Faculty of Agriculture.All rights reserved.
The measuring has proved that the energy herbs can be pressed into the form of compact briquettes. It regards 9 varieties of the energy crops, i.e. coriander, crambe, saphlor, sorrel, sorghum, reed canary grass, knotweed, barley straw and rapeseed straw. These energy crops are disintegrated by the grinding mill ŠV 15 (manufacturer Stoza, Ltd.) before the pressing. The fraction size is given by the mesh size of circular cross section of diameter 15 mm. All the crops have constant moisture content during the measuring and uniform diameter 65 mm of the resulting briquettes. The biomass moisture ranges from 9 to 11%. The pressing is conducted by the briquette press HLS 50 (manufacturer Briklis, Ltd.). The measuring results have shown the highest volume weight in following energy herbs: coriander, saphlor, rapeseed straw, sorghum, sorrel and knotweed. The lowest volume weight was found in these crops: reed canary grass, crambe and barley straw. The measuring proved that the highest force for the briquette disintegration is necessary for knotweed, saphlor, sorrel, sorghum and coriander. The lowest force for the briquette disintegration needs the reed canary grass, barley and rapeseed straw and crambe. Crambe contains a high level of oil in its seeds and this fact causes difficulties during their pressing as good mechanical parameters regards, thus they cannot be pressed into the briquette form.
Paulownia witches’ broom (PaWB) is a fatal disease of Paulownia caused by a phytoplasma. In previous studies, we found that plants with PaWB symptoms would revert to a healthy morphology after methyl methane sulfonate (MMS) treatment. To completely understand the gene expression profiles of the Paulownia-phytoplasma interaction, three high-throughput sequencing technologies were used to investigate changes of gene expression and microRNAs (miRNAs) in healthy Paulownia tomentosa plantlets, PaWB-infected plantlets, and PaWB-infected plantlets treated with 60 mg · L −1 MMS.
Transcriptome, miRNAs and degradome sequencing were performed to explore the global gene expression profiles in the process of Paulownia tomentosa with phytoplasma infection.
A total of 98,714 all-unigenes, 62 conserved miRNAs, and 35 novel miRNAs were obtained, among which 902 differentially expressed genes (DEGs) and 24 miRNAs were found to be associated with PaWB disease. Subsequently, the target genes of these miRNAs were predicted by degradome sequencing. Interestingly, we found that 19 target genes of these differentially expressed miRNAs were among the 902 DEGs. The targets of pau-miR156g, pau-miR403, and pau-miR166c were significantly up-regulated in the P. tomentosa plantlets infected with phytoplasma. Interaction of miRNA -target genes mediated gene expression related to PaWB were identified.
The results elucidated the possible roles of the regulation of genes and miRNAs in the Paulownia-phytoplasma interaction, which will enrich our understanding of the mechanisms of PaWB disease in this plant.
Our paper presents an effective micropropagation protocol for Paulownia sp. (P. elongata, P. fortunei
and a P. elongata x P. fortunei hybrid). For in vitro culture initiation, axillary buds as well as seeds were
used. For the multiplication stage, modified Murashige & Skoog (MS) was tested, supplemented with
0.5 mg/l BAP (6-benzilaminopurine) and mT (meta-topoline) at the concentrations of 0.5, 0.7 and 1
mg/l. The media supplemented with BAP ensured intense proliferation of axillary buds but they also
caused negative physiological effects (abundant callus growth at the plantlets’ base). In the P. elongata x
P. fortunei hybrid as well as in P. elongata 1 mg/l mT ensured the highest proliferation and multiplication
rates, but the plantlets that resulted from the media supplemented with 0.5 and 0.7 mg/l mT were more
vigorous and well developed. In P. fortunei 1 mg/l mT ensured average proliferation rates of 9.28 and
average multiplication rates of 12.92. Wheat starch proved to be a cheap and very effective alternative
gelling agent. Ex vitro rooting and acclimatization was very successful by using Jiffy7 pellets and floating
perlite, the latter being a technique elaborated at the Fruit Research Station Cluj, with acclimatization
percentages of more than 80 % in the 3-5 cm long shoots and more than 60 % in the 2-2.5 cm long
shoots. The protocol developed allowed eliminating the in vitro rooting stage in the commonly used
processes in the industry.
The objective of this study was to investigate some mechanical (modulus of rupture, modulus of elasticity and internal bond) and physical (thickness swelling and water absorption) properties of wood-based three-layer particleboard containing different cotton (Gossypium hirsutum L.) stalks and underutilized paulownia (paulownia fortunie) wood particle ratios (30, 50 and 70%) using urea formaldehyde resin. Addition of cotton stalk and paulownia wood in particleboard improved mechanical properties of resulting composites boards significantly. However, the water resistance decreased with increasing cotton stalk and paulownia wood particle contents. The highest mechanical properties were obtained at cotton stalk and paulownia wood particle loading of 50 and 70%, respectively. Conclusively, valuable underutilized natural resources, cotton stalk and paulownia wood can be used with the mixture of industrial wood particles in the production of particleboards with high mechanical properties.
The objective of this study was to determine some of the properties of experimental particleboard panels made from low-quality paulownia (Paulownia tomentosa). Chemical properties including holocellulose, cellulose, lignin contents, water solubility, and pH level of the wood were also analyzed. Three-layer experimental panels were manufactured with two density levels using urea–formaldehyde as a binder. Modulus of elasticity (MOE), modulus of rupture (MOR), internal bond strength (IB), screw-holding strength, thickness swelling, and surface roughness of the specimens were evaluated. Panels with densities of 0.65 g/cm3 and manufactured using a 7-min press time resulted in higher mechanical properties than those of made with densities of 0.55 g/cm3 and press times of 5 min. Based on the initial findings of this study, it appears that higher values of solubility and lignin content of the raw material contributed to better physical and mechanical properties of the experimental panels. All types of strength characteristics of the samples manufactured from underutilized low-quality paulownia wood met the minimum strength requirements of the European Standards for general uses.
In the present work, chemical and morphological characteristics of Iranian cultivated paulownia (Paulownia
fortunei L.) fibers were investigated.
Chemical properties including holocellulose (81.2%), alpha-cellulose (52.6%), lignin (24.6%) and extractives
(1% NaOH 14.7%) contents were determined. Fiber length, width, width of lumen and cell wall thickness
were 1002, 35.44, 26.49 and 6.47 µm, respectively. The paulownia wood contains a significant
portion of parenchyma cells and vessel elements compared to the hardwoods being mainly fibrous. The short
length and thin-walled fibers may be expected to give relatively dense papers which are weak in tearing
strength, but are superior in burst and tensile properties. Paulownia has acceptable Runkel ratio and flexibility
coefficient are in the range of hard and softwoods, respectively. In general, results based on chemical
and morphological analysis indicated that Iranian cultivated paulownia fibers are promising fibrous raw
material for the paper production.
Paulownia elongota, one of the most fast growing species of the world, was evaluated as raw material for pulp and paper prodn. The chem., morphol. and anatomical aspects of paulownia wood were detd. The lignin, holocellulose and α-cellulose contents in P. elongota wood were comparable to those of some common non-wood and hardwood raw materials. Different chem. pulping procedures were applied to P. elongota wood to evaluate its pulping potential. Paper strength properties and acidic group content bound to the cell wall were detd. The alkali soly., water soly. and alc.-benzene extractive content were higher than those from wood and most non-woods. The fiber length of 0.83 mm was obsd., which is close to low end of the hardwoods but fiber diam. was very wide, similar to that of softwoods. The pulpability of paulownia wood was also studied. The pulp yield and viscosity were very low and the kappa nos. were high. The strength properties were comparable to those of some wood and non-wood pulps. Although, paulownia pulps are considered as low quality materials, it can be used for paper prodn. when mixed with long fibrous materials. [on SciFinder(R)]
The aim of this study is to determine some physical and mechanical properties of Paulownia tomentosa wood grown in Turkey. The samples trees harvested from Kargi in Corum. Physical properties including air-dry density oven-dry density basic density swelling, shrinkage and oven-dry and air-dry thermal conductivity coefficients; mechanical properties including bending strength, modulus of elasticity in bending, compression strength parallel to grain, hardness, bonding strength were analyzed. Paulownia tomentosa wood's air dry and oven dry densities were determined as 0.317 and 0.294 g cm(-3); basic density was determined as 0.272 g cm(-3); volumetric shrinkage and swelling were determined as 7.78 and 8.41%; tangential, radial and longitudinal air-dry thermal conductivity coefficients were determined as 0.089, 0.090 and 0.133 kcal/mh degrees C, respectively. Fiber saturation point (FSP) was found 28.79%; bending strength, Modulus of elasticity in bending, compression strength parallel to grain and Brinell hardness values (parallel and perpendicular to grain) were determined as 43.56 N mm(-2), 4281.32 N mm(-2), 25.55 N mm(-2), 2.01 kgf mm(-2) and 0.88 kgf mm(-2), respectively. Consequently paulownia wood can be widely used for various purposes such as house construction, furniture making, pulp and paper and handicrafts.
In the industrial processing of logs, large amounts of bark can be utilized as pellets. This study sought to establish conditions for the efficient use of bark, in the form of pellets, as a solid, renewable fuel. First, the physical properties of the bark (10% moisture content, 618-kg/m3densityfor aspen, and 749-kg/m3 density for birch) and pellets obtained from the shredded bark were determined. Then, the calorific properties (calorific value, calorific density, and ash content) of the shredded native bark and bark treated at 180 °C, 200 °C, and 220 °C for 1h, 2h, and 3 h were determined. The sawdust samples that underwent the torrefaction treatment were analyzed to find the mass loss. The mass losses of the birch bark were 20.0% (native bark) to 39.0% after a heat treatment at 220 °C for 3 h. An increased calorific value, up to 9.6%, showed that both the temperature and duration of the treatment improved the calorific properties of the bark. The findings of this paper highlighted the fact that bark can be used as a fuel source in log processing factories.
This paper presents a methodology for determining the shear and crushing strengths of four types of wood pellets. Wood pellets are renewable and sustainable products that are obtained from wood biomass and used in combustion. Their mechanical characteristics are not well defined. To characterize wood pellets, their shear and crushing strengths should be measured along with their size, moisture content, density, abrasion, and chemical contents. The shear and crushing strengths were analysed for their dependence on density, considering if these strengths remain as independent properties or only an additional option for the producers. All results showed that the shear and crushing strengths were individual properties of wood pellets and that density greatly influenced these properties. Based on theoretical research, the admittance values of breaking and shear strengths were also estimated. These results can be used in wood combustion for creating fuels from waste wood.
The paper deals with a method for assessing the quality of briquettes as solid fuel, made from wheat straw biomass. There are presented the advantages of biomass from wheat straw used at a burning process, especially when straws are used in the form of briquettes. Method makes an aggregate of main properties of briquettes and proposes an appreciation of the importance of each property separately. As referencing values of briquette properties resulted from biomass were used some European standards, especially ÖNORM M7135, 2012 from Austria, which contains a specific part only for briquettes. Finally, an aggregated property, defined as value of quality obtained for wheat straw briquettes is compared with the values of woody briquettes obtained from beech and spruce biomass. A better value of aggregated property for straw briquettes quality is put in evidence.
The Paulownia tree is one of the most important fast growing species in the World and is an ideal multipurpose tree. In this study, the potential use of Paulownia wood (Paulownia elongata) as a raw material for the pencil manufacturing industry is investigated. Currently, poplar, cedar, and juniper species are most commonly used in this industry. However, Paulownia wood is a fast growing species that can be used in the industry after 5 years on the plantation. Paulownia (Paulownia elongata), poplar (Populus tremula), and juniper (Juniperus excelsa) wood specimens were used in this study. The specimens were prepared according to related standards, and physical, mechanical, and technological properties were investigated. The data obtained from these measurements were compared statistically using ANOVA and Duncan's Multiple Range Test. As a result, Paulownia wood exhibited favorable properties, suggesting that it would be a useful alternative raw material for the pencil manufacturing industry.
The effects of screw type, moisture content, and grain direction on the screw and nail withdrawal strength and bonding strength were investigated for paulownia (Paulownia tomentosa Steud.) wood grown in Turkey. The withdrawal strength was carried out according to the ASTM-D 143 and ASTM-D 1761 and Turkish Standard 6094 in three directions (tangential, radial, and longitudinal) on 60 samples. The moisture content of half of the samples was 12 % and that of the other half 28 %.The experiment of bonding strength (BS EN 205) was applied to both sanded surfaces jointed by poly-vinly acetate and Desmodur-VTKA adhesives. Results of the tests indicate that, the withdrawal strength values at 12 % moisture content were higher than the 28 % for screws whereas the withdrawal strength for 28 % moisture content was higher than 12 % for nails. The maximum withdrawal strength value was found in the chipboard screw. In the case of directions, the withdrawal strength values of radial direction were found to be higher than the others for all parameters. The lowest withdrawal strength values were found in the longitudinal directions for both nails and screws. For adhesive types, the highest bonding strength of D-VTKA was found to be 5.64 N mm−2 and it was higher than the bonding strength with PVAc (5.33 N mm−2). However, there were no significant statistical differences between the two adhesive types. The results show that paulownia wood can be used for different purposes such as house construction, roof systems, and box cases as it possesses enough strength.
The goal of this study was to investigate the effects of thermal modification by hot-pressing on the performance properties of paulownia wood boards. The boards were thermally modified by hot-pressing method under different pressure and temperature levels. As two boards for each modification group plus two for unmodified, totally 10 experimental wood boards were prepared in this study. Main density, vertical density profile (VDP), thickness swell (TS), water absorption (WA), moisture content (MC), and hardness tests were carried out to evaluate the performance properties of the thermally modified or unmodified wood boards. The results obtained in this study indicated that surface density of the boards increased with increasing press pressure. The thermal modification negatively affected the TS and WA values of the boards. Hardness values of the wood boards were significantly improved by the thermal modification. The results of this research revealed that the thermally compressing method could be used to improve end-use properties of low-density wood materials made from fast-growing tree species such as paulownia, poplar, eucalyptus etc. Thus low-value wood materials could be converted to value-added products. In addition, sustainable management of natural resources could be achieved by using the thermal modification method.
Paulownia, a naturalized Asiatic species, has been widely planted in the southeastern United States as a shade and ornamental tree because of its rapid growth and beautiful flowers. Although its multiple-use properties have made it an important commercial wood in Japan, it has not been used commercially in the United States. Recently, increased demand for paulownia from Japanese wood industries has created a potential new market for U.S. production of the species. The botanical characteristics, habitat conditions, forestation techniques, and economic potential of paulownia are reported. Also discussed is its utilization in reclamation efforts on surface-mined lands.¹
The aim of this study was to determine the changes in physical properties of Paulownia (Paulownia elongata) wood, a fast-growing species, during heat treatment at three different temperatures (160, 180, and 200°C) and durations (3, 5, and 7 h). After heat treatment, changes in swelling, density, color, and equilibrium moisture content at 35, 65, and 85% RH were investigated. The results indicated that the minimum and maximum decrease swelling ratios were 6–46% for tangential, 4–32% for radial, and 12–64% for longitudinal. The equilibrium moisture contents were 1–26% for 35% RH, 1–33% for 65% RH, and 1–38% for 85 RH, respectively; the density of air-dried and oven-dried samples decreased by 1–16% and 1.5–15%, respectively, and color changes values (L) were 10–40%.
Physico-mechanical Characterization of Paulownia elongata Wood
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