Thermal Modification Research Articles

Effects of pH-varying thermal modification on sewage sludge: A focus on releasing nitrogen- and phosphorus-containing substances

Sewage sludge is promising for the recovery and utilisation of nutrient components, but its complex nature hinders the release of these components. The combination of pH and thermal modifications shows promise for the release of nutrient components from sludge. However, comprehensive studies on the full spectrum of pH levels and corresponding mechanisms of pH-varying thermal modification are lacking. In this study, the main nutrient components, physicochemical properties, molecular structure, and noncovalent interactions of sludge were comprehensively investigated through pH-varying thermal modification (within a pH range of 2.0 to 12.0 under the same thermal condition). The experimental results showed that the release of main organics, particularly nitrogen (N)-containing organics, was well-fitted, with a tick-like function (R2: 0.74–0.96). The thermal protons exhibited a notable accumulative mutagenic effect on the N-containing organics release, while the thermal hydroxyl ions had a more direct effect, as revealed by the changes in multivalent metals and molecular structures with the protonation–deprotonation of carboxyl groups. The driving force for the release of N-containing organics was identified as the fluctuation of electrostatic interactions at the solid–liquid interface of the sludge. However, the release of phosphorus (P)-containing substances exhibited a contrasting response to that of N-containing substances with varying pH, likely because the reaction sites of thermal protons and thermal hydroxyl ions for P-containing substances were different. Moreover, high concentrations of thermal protons and hydroxyl ions collapsed the Lifshitz–van der Waals interactions of sludge, resulting in a decrease in viscoelasticity and binding strength. These propositions were further confirmed through statistical analyses of the main indicators of the main nutrient components, physicochemical properties, and noncovalent interactions of sludge. These findings can provide a basis for optimising characteristic-specific methods to recovery nutrient components (N/P) from sludge.

Enhancing the fire resistance properties of thermally modified Robinia pseudoacacia wood with natural and synthetic flame retardants: chemical characterisation and fire behaviour

The increasing demand for wood with enhanced flame retardant characteristics in construction applications necessitates strategic interventions. This study explores the fire behaviour and chemical characterisation of Robinia pseudoacacia wood subjected to thermal modification and flame retardant treatments. Thermal modification was carried out at three different temperatures (160 °C, 180 °C and 240 °C). The fire properties of wood coated with Flame Gard (F), a commercial flame retardant, arabinogalactan (A), a natural flame retardant, melamine adhesive (MF) with ammonium polyphosphate (AP), nanosilica (NS), nanoclay (NC) (MF-AP-NS and MF-AP-NC) and arabinogalactan with AP, NS and NC (A-AP-NS and A-AP-NC), were assessed using cone calorimetry in terms of the weight loss rate, ignition time and heat release rate. The commercial flame retardant Flame Gard outperformed the natural and fortified flame retardants in terms of the weight loss rate, heat release rate (HRR) and ignition time (tig). Unmodified samples exhibited superior fire properties in terms of tig and HRR compared to thermally modified samples. The peak heat release rate (kW.m− 2) and time to peak heat release rate (s) showed a moderate degree of dependency on the chemical constituents of the wood.

How thermal treatment affects the chemical composition and the physical, mechanical and swelling properties of Scots pine juvenile and mature wood

High variations in juvenile wood properties in the radial direction and its worse performance than mature wood make it less suitable for some applications and often treated as waste material. This study aimed to assess how thermal modification affects the chemical composition and the physical, mechanical and swelling properties of Scots pine juvenile and mature wood. An additional goal was to evaluate if the modification can equalise the differences in selected properties of juvenile wood to those of mature wood so that from waste material, juvenile wood can become a fully-fledged raw material for various industrial applications. Thermal treatment at 220 °C influenced wood chemical composition, degrading mainly hemicelluloses but also affecting cellulose and lignin, which resulted in a reduction of hydroxyls and carbonyl/carboxyl groups. These changes were more pronounced for mature than juvenile wood. It reduced mass loss and swelling rate, and increased swelling pressure in the tangential and radial directions to a higher degree for juvenile than mature wood. Changes in mechanical properties in compression were statistically significant only for mature wood, while wood hardness remained unaffected. Although the applied heat treatment improved the performance of juvenile wood by reducing its swelling rate, it did not equalise the examined properties between juvenile and mature wood. Since higher juvenile wood proportion is expected in the wood supply from the future intensively managed forests, there is still a need to find suitable modification methods or better processing techniques so that instead of being thrown away as waste, it could be used broadly in various industrial applications.

Cooked or discarded? Experimental distinction of rabbit burnt bones and its application to the archaeological record

Leporid bones from Middle Palaeolithic assemblages may result from the contributions of various predators, including humans, or natural processes. Although the acquisition, processing, and consumption of small mammals by Neanderthal groups has been widely demonstrated, there are still some unresolved issues. Cut marks are typically the most reliable indicators of human processing of carcasses. However, animals the size of rabbits often pose a challenge in this regard, as the use of stone tools is not always necessary for their consumption, particularly for meat or marrow extraction. Consequently, the quantity of these types of marks, such as cuts or hammer-stone percussion damage, indicating human processing, may be limited. Burning is another type of bone damage that could be indicative of human action, although both intentional and accidental processes could lead to the thermal alteration of remains without necessarily linking them to consumption. Therefore, efforts to distinguish the processes resulting in bone burning are of vital importance in determining the origin of these animals in archaeological assemblages. In this work, the results of several experimental series designed to characterise the roasting and subsequent cleaning of waste on rabbit bones are presented. These results confirm most of the characteristics described in previous experimental works on burnt bones, highlighting the differential damage between bones with and without meat. The current study aims to contribute new data for characterising burned rabbit bones resulting from human actions, which can then be applied to Middle Palaeolithic assemblages with this type of thermal alteration bone modifications.

Recent Advances in Catalytic Compounds Developed by Thermal Treatment of (Zr-Based) Metal–Organic Frameworks

Metal–organic frameworks (MOFs) have been the subject of extensive scientific investigation in the last three decades and, currently, they make up one of the types of compounds most studied for their potential application in a wide range of distinct catalytic processes. Pristine MOF compounds provide several intriguing benefits for catalytic applications, including large interior surface areas and high densities of active sites; high catalytic reaction rates per volume; post-synthesis modifications with complementary catalytic groups; and the ability for multiple functional groups to catalyze the reaction. For most large-scale catalytic applications, including those in fuel processing, gas emission reduction, and chemical synthesis, pristine MOFs often show limited stabilities and opportunities for regeneration at high temperatures. As a result, the real applications of MOFs in these technologies are likely to be constrained, and a controlled thermal modification to prepare MOF-derivative compounds has been applied to induce crystalline structural changes and increase the structural stability of the MOFs, enhancing their potential applicability in more severe catalytic processes. Recent advances concerning the use of this strategy to boost the catalytic potential of MOF-derivative compounds, particularly for stable Zr-based MOFs, are outlined in this short review article.

Cellulose-Based Waste in a Close Loop as an Adsorbent for Removing Dyes from Textile Industry Wastewater

In an attempt to reuse fibrous textile waste and, at the same time, to address dye pollution in textile wastewater, waste cotton-based yarn was utilized as a cheap and sustainable adsorbent, as well as a row material for carbon adsorbent production. Unmodified yarn and cotton-based carbon adsorbents were used as adsorbents for dye removal from water. Cotton and cotton/polyester yarn samples underwent thermal modification through carbonization followed by chemical activation with KOH. Various techniques, including scanning electron microscopy, Fourier transform infrared spectroscopy, nitrogen adsorption–desorption isotherms, and surface charge determination, were employed to analyze the morphological and surface characteristics of the cotton-based adsorbents. Adsorption properties were evaluated by testing the removal of selected cationic and anionic dyes from water. The impact of temperature, initial pH and concentration of the dye solution, and contact time on adsorption were investigated, and experimentally obtained data were analyzed using theoretical models. While carbonization alone did not significantly enhance adsorption properties, activated samples exhibited high efficacy in removing both cationic and anionic dyes from water. Despite the negative influence of the polyester component in the carbon precursor on the efficiency of activated samples in removing methyl orange, the results indicated that activated cotton and cotton/polyester yarn could be used to prepare highly efficient adsorbents for the rapid removal of methylene blue from real wastewater samples.

Resource utilization of gasified fine ash from entrained flow bed via thermal modification-melting combustion: A pilot study

China generates substantial quantities of gasified fine ash (GFA) annually through entrained flow bed coal gasification processes. These GFAs are laden with significant amounts of poorly reactive carbon and abundant ash resources, including silica, aluminum. Typically GFA represent not only a gross squandering of resources but also a potential source of environmental contamination. In order to use both ash and carbon of GFA, our team has developed the thermal modification -melting combustion method. The study conducted thermal modification-melting combustion experiments of GFA with auxiliary heating fuel and varying moisture content on a pilot-scale experimental platform. The aim was to ascertain the influence of operating conditions on the physical and chemical properties of GFA fuel, as well as the carbon conversion rate of GFA and the potential for reusing ash after melting combustion in the entire system. The results indicate that an increase in the moisture content of GFA allows the thermally modified fine ash (MFA) to possess smaller particle sizes and more reactive sites in carbon structures, along with higher combustible gas yield and calorific value. Post-melting combustion, the residual carbon conversion rate in GFA surpassed 96.88 %, indicative of a high recovery potential. Moreover, the ash slag, rich in inorganic non-metallic glassy phases, emerged as a promising candidate for material reuse and application.

Dimensional stability and mechanical strength of thermally modified giant bamboo [Dendrocalamus asper (Schult.) Backer] using steam and oil

Various thermal modification (TM) treatments using different media have been commercialized, including the commonly practiced TM via steam and hot oil using vegetable or mineral oils. To expand the range of oil treatment mediums, this study explored the use of spent cooking oil (used oil from food frying in restaurants), which was centrally collected by a certified hauler and treater of this waste liquid. The effects on the dimensional stability and mechanical strength of giant bamboo [Dendrocalamus asper (Schult.) Backer] poles subjected to 175°C and 200°C for 30 min and 60 min in steam and oil, respectively were determined. The data were analyzed using a factorial experiment in a completely randomized design with TM treatments, temperature, duration, and presence of nodes as factors.Results revealed significantly improved dimensional stability in modified bamboo as indicated by reduced moisture content, dimensional shrinkage/swelling, and water loss/absorption at higher temperatures. While treatment duration moderately affected dimensional stability, oil-treated samples exhibited greater enhancement.In terms of mechanical strength, bamboo treated at 175°C exhibited enhanced flexural (modulus of rupture or MOR, and modulus of elasticity or MOE) and compressive strength (CS). However, treatments at 200°C led to marked reductions in these properties. Node presence generally weakened bamboo, except for CS. Oil-treated samples demonstrated superior mechanical strength, although there was a slight reduction in MOR with extended exposure.In conclusion, steam and oil-based TM improve the dimensional stability and mechanical strength of giant bamboo at 175°C. For optimal properties, a 30-min treatment is recommended. This research underscores the viability of spent cooking oil in enhancing bamboo's physico-mechanical attributes, contributing to sustainable applications.

Green Approach and Thermal Modification for Nanoparticles Development of Alumina and Its Phases Using Aluminium Waste Cans as a Precursor

Green Approach and Thermal Modification for Nanoparticles Development of Alumina and Its Phases Using Aluminium Waste Cans as a Precursor

Thermal excitation-induced micro/nano fabrication and material modification of superconducting Nb films

We report the thermal excitation-induced material modification and micro/nano fabrication based on the interactions between nano laser direct writing (NLDW) and superconducting films experimentally and by simulation. The niobium (Nb) films with a critical temperature of 9 K were deposited on silicon substrate via sputtering with the thickness of around 50 nm. The boundary between material modification and micro/nano fabrication was verified by changing the interaction time and laser power continuously. Specifically, as the laser power was fixed at 250 mW and the interaction time below 440 ns, the interaction is material modification. With the increasing interaction time further, the Nb films were etched away. As the interaction time was fixed at 500 ns and the laser power below 200 mW, the interaction is material modification too. With the increasing of laser power further, the Nb films were etched away. In the experiment, the oxygen content and current–voltage characteristic (IVCs) before and after laser irradiation were displayed to verify the material modification, which is in line with the simulation results. Considering the 50 nm resolution of NLDW, in the material modification region, one could trim trilayer junctions, tune shunt resistors, or adjust critical currents, etc. In the micro/nano fabrication region, one could fabricate various devices and exploit the properties of high spatial resolution, high flexibility, and fast processing.

Water uptake and permeability in sapwood and heartwood of hydro-thermally proceed Turkey oak

ABSTRACT This study aimed to investigate the combined effect of steaming and heating on the equilibrium moisture content (EMC) of Turkey oak (Quercus cerris L.) wood over a nine-year period. The study also aimed to determine the impact of steaming on water absorption and water permeability, crucial for the durability of the species against environmental factors. The specimens underwent thermal modification with and without steaming, then were stored under laboratory conditions for ten years. The mass of the specimens was monitored throughout the ten-year period. To measure the water uptake capacity, the specimens were soaked in water for 120 hours. The water permeability of the specimens was assessed using a pressurised chamber. The results showed that the moisture content of thermally-modified oak was constant under laboratory conditions after nine years, further improved by steam treatment. The research also revealed that the steamed wood absorbed more water during water submersion compared to the unmodified wood. When the steaming treatment was applied, there was a significant increase in permeability in the sapwood compared to the heartwood, due to anatomical variations. Despite this, statistical noise, and material variability, alongside tylosis presence, underline the need for examining more specimens in future studies.

Древесно-композитные плиты с низким коэффициентом линейного теплового расширения

A number of industries require materials with a low coefficient of linear thermal expansion (CLTE), in particular, in the production of satellite spherical antennas. The latter are formed from composites containing carbon fibers and synthetic resins. The composition is cured by heating up to 180 °C. This leads to a thermal expansion of the mold and a change in the geometric characteristics of the product. Therefore, specific requirements are imposed on the materials for making molds. The high cost of special materials used for molds determines the need to search for other materials with a low CLTE. Wood is a possible solution to this problem. Its CLTE along the fibers is less than that of the vast majority of materials, and is approximately 3 ‧ 10-6 K–1, which is comparable to special materials. However, the expansion of wood across the fibers is much higher than the longitudinal one, which excludes the use of solid wood. Anisotropy can be reduced by creating a composite in which the fibers are uniformly oriented in all structural directions, bringing the value of wood expansion across the fibers closer to the value of expansion along the fibers. The traditional approach to producing wood composites, based on the use of synthetic adhesives, fails to achieve a noticeable reduction in thermal expansion due to the high CLTE of adhesives The use of boards made of hydrodynamically activated wood particles without binders is promising. Three series of experiments have been carried out: with varying the density of the boards, preliminary thermal modification of the original wood and the use of alkali during hydrodynamic processing. The thermal expansion study has been carried out using the NETZSCH DIL-402 C induction dilatometer in dynamic mode with a heating rate of 2 K/min. It has been established that thermal expansion increases with increasing density.The average CLTE at a density of 950 kg/m3 is 12 ‧10–6 K–1 and at a density of 1,100 kg/m3 it is 17‧10–6 K–1. At a comparable density, the thermal expansion of boards without binders is significantly lower than that of fiberboards (MDF). Preliminary thermal modification of wood does not significantly affect the CLTE of the boards. The use of alkali in the hydrodynamic treatment also has no effect.

Experimental investigation on thermal modification and burnout of residual carbon in coal gasification fine slag

Disposal of coal gasification fine slag (CGFS) has caused environmental pollution and resource waste. Its decarbonization is the bottleneck of aluminum and silicon resource utilization. A fluidization-melting combustion system is proposed in this study to realize the decarbonization. The fluidized thermal modification and burnout characters of residual carbon in CGFS were investigated experimentally on a bench-scale test rig. A two-stage decarburization path of CGFS was concluded and verified. The fluidized modification of CGFS is first conducted to decrease the particle size and improve the specific surface area and combustion reactivity. So, the modified exposed carbon in CGFS rapidly burns in the melting furnace to generate the condition above the fluid temperature of minerals. Then the mineral shell of the amorphous mineral covered carbon in CGFS is molten and damaged, and the carbon appears and burns out. The decrease in the thermal modification temperature induced deceases in melting combustion temperature and decarbonization efficiency. Efficient decarbonization of CGFS produced by three different entrained bed gasifiers was realized by the fluidization-melting combustion, the decarburization efficiencies are all above 95% and the comprehensive carbon contents of ash and slag are all below 5%.

Business models for symbiosis between the alumina and cement industries

Global alumina production generates approximately 150–170 million tonnes of bauxite residue (BR), predominately landfilled. The cement industry is looking for new supplementary cementitious materials (SCMs) to replace additional clinker volumes and reduce their carbon footprint. Symbiosis between the alumina and cement industries presents an opportunity to conserve resources and produce low-carbon cements by thermally modifying BR into novel SCMs. This research uses the Horizon 2020 ReActiv project as a case study to evaluate the suitability of different modified BRs for use as SCMs using evidence from project documentation and participant observations from progress meetings. It also explores symbiotic business model configurations between alumina and cement industries through semi-structured interviews with ReActiv project participants. Results indicate that thermal modification of BR significantly increases its cementitious value, and should optimally be carried out in alumina plants, with the cement industry then grinding and mixing the resulting SCM with other cement components.

Impact of Heat Treatment on Dimensional Stability of Salix tetrasperma Roxb. Wood

The present investigation was carried out during the years October, 2021–September, 2022 in the Laboratory of the Department of Forest Products, Dr. Y S Parmar University of Horticulture and Forestry Nauni, Solan. Thermal modification was performed on the samples of Salix tetrasperma at various temperatures 60, 80, 100, 120, 140, 160 and 200°C for 2, 4 and 6h under stability oven, to asses its impact on wood dimensional stability. The data pertaining on maximum moisture content, swelling coefficient and shrinkage coefficient shows significant variation. The maximum moisture content at different temperature treatment, was recorded to be maximum (192.03%) in control and minimum (140.09%) at 200°C, whereas for durations the maximum moisture content (164.77%) was observed at 2 h while minimum (161.77%) at 6 h. Among interactions, the maximum value (192.03%) was observed in control and minimum (139.42%) was found at 200°C (6 h). In volumetric swelling and shrinkage coefficient, maximum values (8.03%) and (7.42%) among temperatures were found in control and minimum values (3.85%) and (3.42%) were observed at 200°C (6 h). Among durations, the highest values (5.94%) and (5.73%) were found at 2 h and the lowest values (5.60%) and (5.50%) were observed at 6h. The interactions in volumetric swelling coefficient showed significant results and the highest value (8.03%) was noticed in control and the lowest value (3.74%) at 200°C (6 h), However, interactions in volumetric shrinkage coefficient were found to be non-significant. This indicated that after thermal treatment, wood becomes less hygroscopic and exhibits less wear and tear, even in a harsh environment.

Chemical Composition and Mechanical Properties of Wood after Thermal Modification in Closed Process under Pressure in Nitrogen.

In this study, silver birch (Betula pendula) and Scots pine (Pinus sylvestris) wood planks (1000 × 100 × 25 mm) were thermally modified in pilot-scale equipment. Research extended our knowledge of the thermal modification (TM) process in a closed system under nitrogen pressure, as well as how process parameters affect the chemical composition and mechanical strength of wood. Various TM regimes were selected-maximum temperature (150-180 °C), modification time (30-180 min), and initial nitrogen pressure (3-6 bar). Chemical analyses were performed to assess the amount of extractives, lignin, polysaccharides and acetyl group content following the TM process. The mechanical properties of TM wood were characterized using the modulus of rupture (MOR), modulus of elasticity (MOE), and Brinell hardness. The MOR of both studied wood species following TM in nitrogen was reduced, but MOE changes were insignificant. The Brinell hardness of TM birch wood's tangential surface was much higher than that of the radial surface, although Scots pine wood showed the opposite pattern. TM birch and pine wood specimens with the highest mass loss, acetone soluble extractive amount, and the lowest xylan and acetyl group content had the lowest MOR and Brinell hardness.

Construction of thermally-modified wood surface with superstrong UV-resistance by in-situ modification of lignin

Ultraviolet (UV)-induced discoloration and cracking pose formidable challenges for thermally modified wood (TMW) when used in outdoor applications. Herein, we propose a novel pretreatment strategy using deep eutectic solvent (DES) to enhance the weathering resistance of TMW. DES-assisted TMW (DES-TMW) was prepared by coating wood with choline chloride/citric acid (CA) DES, followed by thermal modification. During the DES-assisted thermal modification process, the cross-linking of the lignin network in DES-TMW was increased as a result of lignin self-polymerization, cross-linking with autologous molecules and furfural, as well as esterified connections caused by CA. This in-situ modification reduces the quantity of photosensitive phenolic hydroxyl groups within lignin by forming cross-linked structures, reducing phenoxy free radical generation during the weathering and obstructing chromophores production pathways, thus enhancing the photostability of lignin. Consequently, the DES-TMW exhibited remarkable resistance to discoloration and cracking compared to TMW. These findings provide evidence that our strategy can effectively enhance the photostability of wood, thereby contributing to the development and production of sustainable outdoor wood products capable of withstanding changing weather conditions.

Polymer-mediated vacancy defects of graphene sheets as high-performance cathode materials for aqueous zinc-ion hybrid supercapacitors

The electrochemical behavior of graphene sheets in energy storage system is closely related to its electronic structures. Specifically, structural vacancy defects can expose more active sites and enhance the electrochemical performance. However, it is still a challenging problem to realize valid defect regulation on improving the reaction kinetics of electrode materials. Herein, vacancy-defective graphene sheets were constructed through the thermal mediated method via intercalation of polyacrylonitrile nanofibers. The vacancy defects were generated from the NH3 gas resulting from polymer decomposition at gradient carbonization temperature. The obtained composites of the graphene sheets and carbon nanofibers demonstrate that the vacancy defects benefit to charge transport, allowing more electrons to pass through the interlayered structure, and enhance the adsorption capacitance during the reversible electrochemical process. In addition, the as-assembled Zn ion hybrid supercapacitors exhibit a high energy density of 129.9 Wh kg−1 and outstanding cyclic stability (99.8 % after 10,000 cycling). The confined polymer-mediated thermal modification strategy can afford abundant vacancy defective sites and exhibit promising outlook for constructing high-performance graphene-based electrode materials for Zn ion hybrid supercapacitors.

Efficient Alkyne Semihydrogenation Catalysis Enabled by Synergistic Chemical and Thermal Modifications of a PdIn MOF.

Recently, there has been a growing interest in using MOF templating to synthesize heterogeneous catalysts based on metal nanoparticles on carbonaceous supports. Unlike the common approach of direct pyrolysis of PdIn-MOFs at high temperatures, this work proposes a reductive chemical treatment under mild conditions before pyrolysis (resulting in PdIn-QT). The resulting material (PdIn-QT) underwent comprehensive characterization via state-of-the-art aberration-corrected electron microscopy, N2 physisorption, X-ray absorption spectroscopy, Raman, X-ray photoelectron spectroscopy, and X-ray diffraction. These analyses have proven the existence of PdIn bimetallic nanoparticles supported on N-doped carbon. In situ DRIFT spectroscopy reveals the advantageous role of indium (In) in regulating Pd activity in alkyne semihydrogenation. Notably, incorporating a soft nucleation step before pyrolysis enhances surface area, porosity, and nitrogen content compared to direct MOF pyrolysis. The optimized material exhibits outstanding catalytic performance with 96% phenylacetylene conversion and 96% selectivity to phenylethylene in the fifth cycle under mild conditions (5 mmol phenylacetylene, 7 mg cat, 5 mL EtOH, R.T., 1 H2 bar).

Dimensional Stability and Mechanical Properties of Gmelina arborea Roxb. Wood Thermally Modified through Open Reactor and Low-Pressure Closed Reactor Systems

This study focused on the thermal modification of Gmelina arborea Roxb. wood following processes using the open reactor and low-pressure closed reactor systems. The aim is to determine the optimum treatment conditions suitable for gmelina wood due to its poor drying characteristics using the low-pressure closed reactor thermal modification. Subsequent to thermal modification under both processes, the dimensional stability and mechanical properties of gmelina wood were investigated. Effects of the thermal modifications under the open and low-pressure closed reactor systems on mechanical properties were additionally reported. The outcome of this investigation revealed that mass loss increased with increasing treatment temperatures, but minimal mass losses were observed for samples modified in the low-pressure closed reactor system. Due to the low-pressure regime used in the closed reactor system, a lesser improvement was found in volumetric shrinkage, fibre saturation point and tangential-to-radial swelling compared to the improvement in these properties in the open reactor system. Results further revealed that the mechanical properties of gmelina wood deteriorated more rapidly after modification in the open reactor system. Since the properties of modified gmelina wood are comparable at 180 °C under both systems, the closed reactor system will be investigated further to arrive at a suitable treatment condition under higher pressure variations. The thermal modification of gmelina wood with the closed reactor system is more promising in delivering a better quality of modified gmelina wood.