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The purpose of this study is the development of sustainable and low-formaldehyde emission wood adhesive formulations.

Three-step urea formaldehyde (UF) resin has been in situ modified with calcium lignosulfonate (LS) and/or 1,4 butanediol diglycidyl ether (GE). The structural, chemical, thermal and morphological characterizations were carried out on resin samples. These resins have been applied for particleboard pressing, and UF, UF-LS and UF-GE were evaluated as P2 classes according to EN 312.

The results show that the improved LS- or diglycidyl ether-modified UF wood adhesives were successful in their adhesive capacity, and the formaldehyde content of the final product was obtained as low as 8 mg/100 g. This paper highlights that the presented adhesive formulations could be a potential eco-friendly and cost-effective alternative to formaldehyde-based wood adhesives for interior particleboard production.

Combination of LS and GE resulted in weaker mechanical properties and fulfilled P1 class particleboards due to temperature and duration conditions. Therefore, in situ usage of LS or GE in UF resins is highly recommended for particleboard pressing. Formaldehyde content of particleboards was determined with the perforator method according to EN 12460-5 and all of the particleboards exhibited E1 class. LS was more efficient in decreasing formaldehyde content than GE.

This study provides the application of particleboards with low formaldehyde emission.

The developed LS- and diglycidyl ether-modified UF resins made it possible to obtain boards with significantly low formaldehyde content compared with commercial resins.

The developed formaldehyde-based resin formulation made it possible to produce laboratory-scale board prototypes using LS or GE without sacrificing of press factors and panel quality.

In industrial applications, formaldehyde-based wood adhesives have been used extensively because of their low costs and high reactivity. However, their real-world applications are hindered by some main bottlenecks, especially the formaldehyde emission and usage of nonrenewable raw materials. The purpose of this study is the development of sustainable and formaldehyde-free wood adhesive formulation.

In this study, starch and tannin-based wood adhesive were synthesized. Chemical structures and thermal properties of the prepared bio-based resin formulations were elucidated by using Fourier transform infrared and differential scanning calorimetry analysis, respectively. Laboratory scale particleboard production was carried out to determine the performance of the developed resin formulations. Obtained results were evaluated in dry medium (P2) according to European norms EN 312 (2010). Furthermore, the board formaldehyde content was determined by using the perforator method according to the European Norm EN 12460-5.

The results show that the improved starch and tannin-based wood adhesives were successful in their adhesive capacity, and the formaldehyde content of the final product was obtained as low as 0.75 mg/100 g. This paper highlights that the presented adhesive formulations could be a potential eco-friendly and cost-effective alternative to the formaldehyde-based wood adhesives for interior particleboard production.

Starch-based resins in the liquid form needed to be continuously mixed throughout their shelf life to prevent the starch from settling because it was not possible to dissolve the precipitated starch again after a while. For this reason, starch was given to the chips in powder form while preparing the particleboard.

In conclusion, this study shows that the developed bio-based resin formulations have a high potential to be used for producing interior-grade particleboards instead of commercial formaldehyde-based wood adhesives because the obtained results generally satisfied the interior grade particleboard requirements according to European norms EN 312, P2 class (2010). In addition, it was determined that the produced boards had significantly low formaldehyde content. The low formaldehyde content of the final boards was not because of the resin but because of the natural structure of the wood raw material, press parameters and environmental factors.

The developed bio-based resin system made it possible to obtain boards with significantly low formaldehyde content compared to commercial resins.

The developed bio-based resin formulation made it possible to produce laboratory-scale board prototypes at lower press factors and board densities compared to their counterparts.

This paper aims to analyze general waste handling in Hungarian particleboard production and give solutions based on experimental researches. During our research reuse of waste in Hungarian particleboard production was studied. A wood industrial branch, which can be considered as both a waste “producer” and a waste “re‐user”, recycler was mapped. This allowed an examination and analysis of both sides of waste handling. In the experimental work the effect of recycling dried impregnated décor paper in particleboard production was evaluated. The primary goal was to work out technologies for recycling non‐dangerous materials such as washing water, production and process waste from the cutting of boards. With these technologies general techniques for waste handling in the particleboard industry can be developed. The results of the experiments with impregnated paper showed that by adding crushed impregnated paper the strength of the particleboards can be increased or the same board properties can be achieved with reduced amounts of applied adhesive (UF). Based on this case study the waste handling in Hungarian particleboard companies can be worked out. More experimental researches should be made to give solutions on every waste handling needs. Solutions and advices for the particleboard industry to work in an environmental friendly and economical way are practical implications of the research. This paper was created based on a case study and researches at the University of West Hungary and Hungarian particleboard companies.

The purpose of this paper is to develop an environmental adhesive from defatted rice bran (RB) to increase its economic value and provide environmentally friendly products for the wood industry.

The powder was mixed with water in a flask. After pH adjustment, potassium permanganate (KMnO₄) solution was added. Then the mixture was heated in a shaking water bath. After maintaining the mixture at 70°C for 1 h, poly(vinyl alcohol) (PVA) powder was added to the slurry and heated at the same temperature for a further 0.5 h. The adhesive thus prepared was used to bond veneers to evaluate its bonding strength and analysed by IR. The optimised RB adhesive was mixed with phenol formaldehyde resin in a ratio of 8:8 to bond straw particleboard. Silane was used to improve the properties of the straw particleboard.

As an economically renewable resource, RB has potential use in the preparation of adhesives. When RB powder was treated with KMnO₄ and PVA at pH 6, the resulting adhesive was able to produce a bonding strength of 1.29 MPa. Silane was found to be a useful coupling agent in the bonding of straw particleboard. Once the board had been bonded with the mixed adhesive, it was found to have a bending strength of 11.9 MPa and a modulus of elasticity of 2.2 GPa.

Chemical change was not obvious during RB modification, which led to a low water resistance. Further research is needed to modify the method.

RB adhesive was dark in colour, which limits its use for light‐coloured wood. Because of its lower water resistance, this adhesive has to be mixed with other synthetic resins to meet requirements.

A new adhesive product was developed for the wood industry from economic RB. This will contribute to environmentally friendly wood products and the effective utilisation of agricultural residues.

This paper aims to focus on the liquefaction of soybean protein to obtain a homogeneous protein solution with a high solid/protein content but low viscosity, which may improve the bond properties and technological applicability of soybean protein adhesive.

The liquefactions of soybean protein in the presence of various amounts of sodium sulphite, urea and sodium dodecyl sulphate (SDS) are investigated, and their effects on the main properties of liquefied soybean protein and soybean protein adhesives are characterized by Fourier transform infrared spectroscopy (FT-IR), gel permeation chromatography (GPC), viscosity tracing and plywood evaluation. Meanwhile, the applicability of soybean protein adhesive composed of liquefied protein for particleboard is also investigated.

Soybean protein can be effectively liquefied to form a homogeneous protein solution with a soybean protein content of 25 per cent and viscosity as low as 772 mPa.s; the addition of sodium sulphite, urea and SDS are beneficial for the liquefaction of soybean protein and have important effects on the technological applicability and water resistance of the obtained adhesive. The optimal liquefying technology of soybean protein is obtained in the presence of 1.5 Wt.% of sodium sulphite, 5 Wt.% of urea, 1.5 Wt.% of SDS and 3 Wt.% of sodium hydroxide. The optimal soybean protein adhesive has the desired water resistance in terms of the boiling-dry-boiling aged wet bond strength, which is up to 1.08 MPa higher than the required value (0.98 MPa) for structural use according to the commercial standard JIS K6806-2003. The optimal liquefied protein has the great potential to prepare particleboard.

The protein content of liquefied soybean protein is expected to further increase from 25 to 40 Wt.% or even higher to further reduce the hot-pressing cycle or energy consumption of wood composites bonded by soybean protein adhesives.

The soybean protein adhesive composed of optimal liquefied protein has potential use in the manufacturing of structural-use plywood and has comparable applicability as a commercial urea-formaldehyde resin for the manufacturing of common particleboard.

Soybean protein adhesive is an environmentally safe bio-adhesive that does not lead to the release of toxic formaldehyde, and the renewable and abundant soybean protein can be used with higher value added by the application as wood adhesive.

A novel liquefaction approach of soybean protein is proposed, and the soybean protein adhesive based on the liquefied protein is obtained with good technological applicability and desired bond properties that extend the applications of the soybean protein adhesive from interior plywood to particleboard and exterior or structural plywood.

To investigate environmentally friendly alternatives for sludge disposal, three proportions of secondary sludge (SS) from two pulping processes (Kraft and TMP) were incorporated in the formulation of particleboard manufacturing. A 3² factorial design was used where the factors were Urea-formaldehyde (UF) content (5%, 7%, and 9% dry weight of resin per dry weight of particles) and secondary sludge percentage (75%, 100%, and 125% dry weight of SS per dry weight of resin). For each pulping process, 27 panels with SS and 3 control panels (without SS for each resin content) were made for a total of 63 panels. All panels were tested for thickness swell, linear expansion, internal bond strength (IB), flexural modulus of elasticity (MOE) and flexural modulus of rupture (MOR). Results indicated that particleboards made with SS from both pulping processes met the ANSI standards for linear expansion, IB, MOE and MOR. However, none of the tested panels met the standard for thickness swell and adding SS to the formulation affected negatively this property. It was concluded that SS from TMP and Kraft mills can be used to manufacture particleboard panels. However, its' percentage along with other additives' content should be optimized.

The purpose of this paper is to examine the effects of denaturised rice bran (RB) and route of its incorporation during synthesis of urea-formaldehyde adhesive, on the performance of the resulting adhesive, especially viscosity, free-formaldehyde (HCHO) and quality of the produced bagasse-based composites, in comparison with those produced from commercial urea formaldehyde (UF) and RB-added UF.

The experiments were carried out using different denaturised RB at different percentages (1-5 per cent) and pH’s (9-11 per cent). These denaturised RB were incorporated at the last synthesis stage of UF synthesis process. The assessment was carried out on both the viscosity and environmental safety of the adhesive system, as well as the quality of the manufactured bagasse-based composites, of the particleboards (static bending, internal bond (IB) strength and water resistance properties), in comparison to commercial UF and RB added to UF. The performance of the adhesive system was evidenced by the thermogravimetric analysis and differential scanning calorimetry analyses.

The results showed that maximum static bending [modulus of rupture (MOR) and modulus of elasticity (MOE)], IB strength and water resistance properties of the resulted wood product accompanied the incorporating 5 per cent of the denaturised RB (pH = 9.0), at the last synthesised stage of UF synthesis process. Where, this synthesis process provided adhesive with viscosity nearly approaching to commercial UF adhesive, and reduced the free-HCHO of adhesive and board by approximately 56 and 49 per cent, respectively. For mechanical and water resistance properties, it provided board with 24.5 MPa MOR, 3,029 MPa MOE, 0.64 MPa IB, 11 per cent swelling (SW) and 20.5 per cent absorption. These properties fulfil the requirements of high grade particleboards American National Standard Institute (ANSI) A208.1, especially with respect to static bending values and water swelling property.

Incorporating 5 per cent of pre-denaturised RB, at pH 9.0, in wet form, and in the last stage of synthesis UF, provided adhesive system with convenient viscosity together with lower free-HCHO and acceptable board properties, compared with that produced from commercial UF, or adding denaturised RB to already synthesised UF. For the mechanical (MOR, MOE and IB) and water resistance properties (SW per cent and absorption per cent) of the produced composite are complied the standard values of H-3 grade of particleboard.

Promising adhesive system is resulted from incorporating 5 per cent of pre-denaturised RB at pH 9.0, in wet form, during last stage of UF synthesis process.

Incorporating the RB by-product of oil production to commercial UF or during synthesis of UF will be benefit for saving the healthy of wood co-workers, and motivating the wood mill to export its wood products.

The article provides a potential simple way to solve the drawback of increasing the viscosity of UF, as a result of adding RB, via incorporating the RB during synthesis process. The viscosity of the synthesised RB-modified UF approaches RB-free UF, and consequently the adhesive system easily penetrates through agro-fibres, and provides good bonding behaviour and high performance wood product (both quality and environmental by minimising formaldehyde emission or toxic gasses during board formation).

China is not only the biggest importing country of the raw materials of forest products, but also the biggest exporting country of intermediate and final forest products. The paper aims to discuss these issues.

The authors use the Khandelwal (2010) method and trade data from 2000 to 2014 of bilateral forest products between China and ten main developed countries to evaluate the quality of China’s forestry imports and exports. Subsequently, the influencing factors of product quality are analyzed.

The results show that the current export quality of plywood and fiberboard is decreasing, and the export quality of particleboard and paper products is on the rise. A further study finds that several factors have the positive effects on the quality of forestry exports, including gross domestic product of the importing country, forestry export value of the importing country as well as the number of forestry higher education graduates of the exporting country. Moreover, the study also finds that the status of an Asia-Pacific Economic Cooperation member has a negative effect on the quality of forestry exports, while the distance cost has a negative influence on fiberboard, paper and paperboard.

The study suggests that China needs to strengthen the research and development investment on forest products, and improve the quality of forest products to promote the trade development of forestry exports.

The existing literature has not shown much research regarding the quality of China’s forestry exports through econometric analysis. Therefore, the research results provide new perspective about the influencing factors on China’s forestry trade activities.

The purpose of this paper is to investigate the effects of various catalyst contents, resin solid contents, catalyst species and wood extract on urea‐formaldehyde (UF) curing by differential scanning calorimetry (DSC) technique. The finding obtained would benefit the manufacturers of UF‐bonded composite panels.

The UF curing rate under each condition in terms of DSC peak temperature was measured by high‐pressure DSC at a heating rate of 15°C/min; the correlations of peak temperature with catalyst content, resin solid content, catalyst species and wood extract, respectively, were regressed via a model equation, which described the curing characteristics of the UF bonding system.

A model equation, T_p=A · EXP(−B · CC per cent)+D, was proposed to characterise the DSC peak temperatures or the rate of UF curing with regressing coefficients greater than 0.97 (commonly greater than 0.99). The constants A and B in the model equation were found to correspond to kinetic characteristics of UF resin curing reaction. The constant D in the model equation is believed to be associated with the utmost peak temperature, which implies that the DSC peak temperature will finally reach a maximum with catalyst content increasing. It was also found that the wood extracts having higher pH value and base buffer capacity had stronger catalyses on UF curing.

The catalysts commonly used in medium density fibreboard plants or particleboard plants are those having the utmost peak temperature of about 90‐95°C; the catalyses of wood extracts were much weaker than that of catalyst NH₄Cl.

The model equation could be used to predict the peak temperature or the curing rate of UF resin, and to quantify the effects of wood extracts on UF curing.

The study developed a model equation that can well characterise the UF curing, and quantified the effects of wood extracts on UF curing.

The purpose of this paper is to study the possibility of preparing high performance, agro‐based composites from rice straw, using eco‐polyalcohol polymers‐based adhesive system. The utilization of rice straw (undesirable biowastes) for the production of high quality biocomposite products, will add economic value, help to reduce the environmental impact of waste disposal and, most importantly, provide a potentially inexpensive alternative to the existing commercial artificial wood‐panels.

Simple synthesizing and optimizing the polyalcohol polymers‐based non‐toxic adhesive system were carried out, by blending corn starch, as natural polyalcohol polymer with polyvinyl alcohol, as synthetic polyalcohol polymers‐based adhesive (St/PV adhesive), at temperature ∼75°C. The percentages of adhesive components, type of starch, bonding temperature and time were optimized. Assessment of the synthesized adhesive was performed from its adhesion behavior (bond strength), in comparison with commercial thermosetting resin (urea‐formaldehyde), as well as the properties (mechanical and physical properties) of the composites produced. The effects of amount and type of water resistance co‐additives (paraffin wax and polyester), on mechanical properties of RS‐based composite were also optimized.

The promising adhesive system exhibits improved performance over a previously commercially HCHO‐based adhesive (UF), and results bonding strength 9.8 N/mm2, as well as MOR, IB and TS of RS‐based composites up to 31 N/mm2, 0.49 N/mm2 and 20%, respectively.

Through the studied eco‐adhesive with relatively high natural polyalcohol polymer (starch) in presence of water‐resistance additive (PE) provided a good bonding strength and comparative RS‐based composite properties, with that produced from commercial UF. For the mechanical properties (MOR and IB) are complied the standard values; while water resistance is still higher. Further study is needed to solve this problem.

The approach provided a HCHO‐free adhesive with good bonding strength, comparative board strength and water resistance, reasonable working life, and without formaldehyde emission. Starch‐based adhesive with low percentages of polyvinyl alcohol is considered a promising inexpensive alternate adhesive in wood industry based on rice straw wastes, which traditionally required expensive pMDI.

The paper provides a potential way to utilise undesirable rice by‐product (RS), corn starch as industrial raw material. This will benefit farmers significantly. Meanwhile, the modified starch adhesive with low percentage of PVA is promising to partly or completely replace urea formaldehyde resin and pMDI that are mainly used in wood industry, or pMDI in RS‐based artificial wood, avoiding formaldehyde emission or toxic gases during exposed to burning, and reducing the dependence on petroleum products.