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Article
Publication date: 3 May 2016

Altaf H. Basta, Houssni El-Saied and Emad M. Deffallah

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…

Abstract

Purpose

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.

Design/methodology/approach

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.

Findings

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.

Research limitations/implications

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.

Practical implications

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.

Social implications

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.

Originality/value

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).

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Article
Publication date: 18 September 2007

Z.H. Gao, J.L. Yuan and X.M. Wang

This paper aims to evaluate the effect of multiple additions of sodium hydroxide (NaOH) on the properties of bark‐phenol‐formaldehyde (BPF) adhesives, and to lay the…

Abstract

Purpose

This paper aims to evaluate the effect of multiple additions of sodium hydroxide (NaOH) on the properties of bark‐phenol‐formaldehyde (BPF) adhesives, and to lay the foundations for further studies on bark utilisation.

Design/methodology/approach

Synthetic technologies that used multiple additions of NaOH were developed for the production of BPF adhesives. Differential scanning calorimetry (DSC), gel permeation chromatography (GPC) and plywood bond were used to evaluate properties of the PF and BPF adhesives.

Findings

The number of NaOH additions had an important effect on many BPF adhesive properties, such as gel time, free formaldehyde content in adhesive, thermosetting peak temperature, molecular weight distribution, as well as the wet shear strength and free formaldehyde release of the bonded plywood panels. The study determined that a two‐step process for adding NaOH offers a prospective synthetic technology for BPF adhesive production. This technology made it possible to use 28.6 per cent bark by weight and resulted in plywood with properties comparable with those of plywood bonded with a commercial PF adhesive. However, BPF adhesives prepared with more than two NaOH additions were fast‐curing.

Research limitations/implications

BPF adhesives are very complex systems with many unknown variables, such as the chemical structures of bark derivatives from phenolation and adhesive synthesis. To further improve the curing rate and adhesion of BPF, future investigations should be based on a two‐addition process or attempt to increase the amount of NaOH in the second addition.

Practical implications

The BPF adhesive prepared with two NaOH additions and 28.6 per cent bark was comparable with a commercial PF adhesive in terms of adhesive properties and plywood bond quality. These results indicate that this technology shows potential for commercial applications.

Originality/value

Synthetic technologies using multiple additions of NaOH were developed to produce BPF adhesives. The BPF with two additions of NaOH seemed to be comparable with a commercial PF adhesive.

Details

Pigment & Resin Technology, vol. 36 no. 5
Type: Research Article
ISSN: 0369-9420

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Article
Publication date: 7 September 2012

S. Jahanshaei, T. Tabarsa and J. Asghari

The purpose of this paper is to describe the development of an eco‐friendly tannin‐phenol formaldehyde resin (PFT) applicable in the wood composite industry.

Abstract

Purpose

The purpose of this paper is to describe the development of an eco‐friendly tannin‐phenol formaldehyde resin (PFT) applicable in the wood composite industry.

Design/methodology/approach

The bark of oak (Quercus castaneifolia) contains a large amount of condensed tannin. Condensed tannin, with a large amount of Catechol groups was considered for reducing the formaldehyde emission level on the adhesive system. Physical characteristics of synthesized PFT resin were evaluated.

Findings

For optimal extraction, three solvents were used in the extraction process. The results showed that a mixture of water‐methanol (1:1 v/v) as extracting solvent is the best solvent and yields about 14 per cent tannin based on dry weight of bark. For producing tannin phenol formaldehyde adhesive, 10 per cent, 20 per cent and 30 per cent (based on PF dry weight) of PF, substituted with natural extracted tannin. For evaluating PFT performance effects of percentage amount of substitution tannin content on the gel time, viscosity, pH, and density of adhesives were evaluated. Based on emission test (JIS A 1460‐2001) formaldehyde emission of PFT 10 per cent, 20 per cent and 30 per cent were 1.13, 1.12 and 0.4 mg/100 g, which is very low compared with tannin‐free PF.

Research limitations/implications

Tannin‐PF adhesive compared to PF adhesive had lower PH, higher viscosity and shorter gel time.

Practical implications

The method developed provides a simple and excellent renewable resource “tannin” which can be used or partially substituted in phenol formaldehyde adhesive.

Originality/value

Results showed that replacing PF for tannin reduces modulus of rupture (MOR) and modulus of elasticity (MOE) slightly but has significant effects on IB, water absorption and thickness swelling.

Details

Pigment & Resin Technology, vol. 41 no. 5
Type: Research Article
ISSN: 0369-9420

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Article
Publication date: 11 September 2009

Jianlong Yuan, Zhenhua Gao and Xiang‐Ming Wang

The purpose of this paper is to evaluate the effect of different amounts of sodium hydroxide (NaOH) introduced during the resin synthesis on the properties of bark‐phenol…

Abstract

Purpose

The purpose of this paper is to evaluate the effect of different amounts of sodium hydroxide (NaOH) introduced during the resin synthesis on the properties of bark‐phenol‐formaldehyde (BPF) adhesives aims at achieving a balance between storage life and other properties of BPF adhesives.

Design/methodology/approach

Based on the best synthetic technologies for the production of BPF adhesives obtained in a previous study, a new synthetic technology is developed for the production of BPF adhesives that involve a three‐step addition of NaOH using different amounts of NaOH in the third charge. Gel permeation chromatography is used to evaluate properties of the phenol‐formaldehyde (PF) and BPF adhesives.

Findings

The amount of NaOH in the third charge has an important influence on many BPF adhesive properties. The paper determines that the synthetic technology involving three‐step NaOH additions with only water introduced in the third charge of NaOH produces a BPF adhesive with the longest storage life and best bonding strength.

Research limitations/implications

BPF adhesives are very complex systems with many unknown variables.

Practical implications

The improved storage life of the BPF adhesive prepared with the new synthetic technology is comparable to that of a commercial PF adhesive, which indicates that this new technology shows greater potential for commercial applications.

Originality/value

A new synthetic technology is developed to produce a BPF adhesive that is more comparable to commercial PF adhesives than other BPF adhesives in terms of storage life and other resin properties.

Details

Pigment & Resin Technology, vol. 38 no. 5
Type: Research Article
ISSN: 0369-9420

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Article
Publication date: 1 July 2014

Altaf H. Basta, Houssni El-Saied and Emad M. Deffallah

The purpose of this paper is to prepare high-performance agro-based composites from the non-toxic rice bran-urea-formaldehyde (RB-UF) adhesive system. Investigations have…

Abstract

Purpose

The purpose of this paper is to prepare high-performance agro-based composites from the non-toxic rice bran-urea-formaldehyde (RB-UF) adhesive system. Investigations have continued for production high performance agro-based composites using environmentally acceptable approaches. The utilisation of such system with the available used local agro-based wood products (sugar-cane bagasse, SCB) adds economic value and helps reducing the environmental impact of commercial urea-formaldehyde (UF) adhesive, and most importantly, provides a potentially inexpensive alternative to the existing commercial artificial wood-panel mills.

Design/methodology/approach

Optimising the process for incorporating the RB in UF, as wood adhesive for binding the bagasse fibres, was carried out, by partially replacing commercial UF by denaturalised RB in slurry (wet) and dry form or through synthesis of UF. The denaturalisation of RB was carried out at different pHs (10-11) and at temperature 60°C for two hours. While incorporating the RB during synthesis of UF, it was carried out according to the method reported elsewhere. The formulation of adhesive components, pH value of the denaturalisation stage and the process of incorporating the RB were optimised. Assessment of the role of RB adhesive was specified from its free-formaldehyde (HCHO) content, as well as the properties (mechanical and physical properties) of the produced composites of bagasse particle board type, in comparison with the environmental impact of commercial thermosetting resin (UF).

Findings

The promising adhesive system exhibits improvement in the environmental performance (as E1 type) over a commercially UF adhesive (as E2 type), besides providing boards fulfill the requirements of grade H-3 (according to ANSI A208.1 (NPA1993). This adhesive system was resulted from replacing 30 per cent of UF by denalturalised RB (at pH 10) in slurry form. Where, its reduction in free-HCHO reached 53 per cent, as well as modulus of rupture (MOR), modulus of elasticity (MOE), internal bond (IB) and TS of the produced boards were approximately 24.2 N/mm2, approximately 3753 N/mm2, approximately 0.84 N/mm2 and approximately 11.4 per cent, respectively.

Research limitations/implications

The eco-adhesive with relatively high percentage of low-cost commercial UF (70 per cent) and 30 per cent RB, as oil production by-product, in slurry form provides good board strength and is environmentally friendly compared to SCB-based composite properties, with that produced from commercial UF. The mechanical (MOR, MOE and IB) and water-resistance properties of the produced composite comply with the standard values.

Practical implications

The approach provided low HCHO-free UF adhesive with good comparative board strength and water resistance and reasonable working life. Replacing 30 per cent of UF by RB in slurry form and denaturalised at pH 10 is considered a promising inexpensive alternate adhesive (as E1) in the wood industry based on SCB wastes.

Social implications

Incorporating the RB by-product of oil production to commercial UF will be beneficial for saving the health of wood co-workers and motivating the wood mill to export its wood products.

Originality/value

It provided a potentially simple way to improve both the utilisation of commercial UF and SCB as industrial substrates for particle-board production. This will benefit farmers, local wood mills in Upper Egypt, significantly. Meanwhile, incorporating low percentage of RB, as oil-mill by-products, is promising to partly replace UF resin in the wood industry, minimising formaldehyde emission or toxic gasses during board formation.

Details

Pigment & Resin Technology, vol. 43 no. 4
Type: Research Article
ISSN: 0369-9420

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Article
Publication date: 4 January 2013

Altaf H. Basta, Houssni El‐Saied and Vivian F. Lotfy

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…

Abstract

Purpose

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.

Design/methodology/approach

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.

Findings

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.

Research limitations/implications

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.

Practical implications

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.

Originality/value

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.

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Article
Publication date: 6 March 2017

Altaf Halim Basta, Houssni El-Saied, Amin Mahmoud Baraka and Vivian Fayez Lotfy

The purpose of this research paper focused on studying the role of activated carbons (ACs), which were synthesized from long-chain aldehyde-based xerogels (Xs-AC), as…

Abstract

Purpose

The purpose of this research paper focused on studying the role of activated carbons (ACs), which were synthesized from long-chain aldehyde-based xerogels (Xs-AC), as benefit additives to enhance the application of a low-cost urea formaldehyde (UF) adhesive for production of rice straw (RS) composites complying with both the standard specifications of particle-board type and the board produced from using conventional adhesive of RS fibers (methylene diphenyl diisocyanate, MDI). The results are supported by differential scanning calorimetry (DSC) analysis, which indicated the curing and interaction of RS fibers with the adhesive systems.

Design/methodology/approach

RS-based composites of particle-board type were prepared from applying new Xs-AC–UF adhesive systems to RS particles. For comparison, particle boards by using commercial UF and 4 per cent MDI were also prepared. To clear the beneficial effect of X-ACs as new HCHO (formaldehyde)-scavengers, the properties of the resulted boards were compared with those produced from the previous investigated scavenger: amide-containing starch-UF (AM/St–UF), and treated RS. DSC analysis was performed on the RS adhesive system, to follow the curing and the interaction behavior of UF with fibers in the presence of Xs-ACs.

Findings

The promising results obtained of RS particle boards from using the investigated new HCHO-scavenger are modulus of rupture (MOR) = 17.2 MPa, modulus of elasticity (MOE) = 4,689 MPa and internal bond (IB) strength = 0.49 MPa. While, the thickness swelling (TS) and maximum reduction in free-HCHO are 48.5 and 44.6 per cent, respectively; this reduction value specified the particle-board of E1-E2 type.

Research limitations/implications

The X-AC-UF adhesive systems and treated RS provided particle boards with mechanical properties (MOR, MOE and IB) that met the standard specification values (class M-2 according to ANSI standard and P-2 according to EN standard requirements), together with maximum reduction in toxicity of UF. However, the resistance in water swelling property is weak and needs further study to be solved.

Practical implications

The incorporation of small percentage of new HCHO-scavenger (X-AC) to UF is an effective way to improve its thermal behavior. Moreover, the mechanical properties of agro-based composites based on the treated RS waste together with the X-AC-UF system exceeded those values of panels produced from (AM/St-UF) and also from (4 per cent MDI).

Social implications

Incorporating the Xs-AC to commercial UF will be of benefit for saving the health of wood co-workers and motivating the wood mill to export its wood products, as well as minimizing the export of MDI.

Originality/value

This paper was based on enhancing the potential utilization of both undesirable RS agro wastes and environmentally unacceptable low-cost UF adhesive in the production of agro-composites that comply with the International Standard Specifications of particle board type. In this respect, a new HCHO-scavenger was synthesized and applied, based on AC from non-conventional xerogels. This study presents a solution to protect the environment from pollution, as a result of burning the undesirable RS, as well as to protect the workers and users of wood panels from exposure to the toxic and carcinogenic gas (formaldehyde). It also benefits in replacing the high cost of the RS adhesive (MDI) by using low-cost modified UF.

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Article
Publication date: 25 February 2014

Xiaofeng Zhang, Shuangying Wei and Zhenhua Gao

The purpose of this paper is to investigate the effects of multi-hydroxymethylated phenol (MHMP) on the properties of moisture-curing polyurethane (PU) resin, especially…

Abstract

Purpose

The purpose of this paper is to investigate the effects of multi-hydroxymethylated phenol (MHMP) on the properties of moisture-curing polyurethane (PU) resin, especially on the heat resistance.

Design/methodology/approach

The MHMPs with various active sites from 2.52 to 3.91 were synthesised and used as a modifier. The bond test (according to the JIS K6806-2003 standard) and thermogravimetric analysis (TGA) were used, respectively, to characterise the bond durability and heat resistance of MHMP-modified PU resin.

Findings

The MHMP with various F/P mole ratios had great effects on the properties of resultant PU resins. The increase of active sites of MHMP can improve the water resistance of resin due to the more cross-linking densities, while the decrease of active sites of MHMP can improve heat resistance of resin because more stable benzene ring introduced into the PU backbone.

Research limitations/implications

In cases where heat resistance of the PU resin is of primary concern, the use of MHMP with fewer active sites or a lower F/P ratio is recommended. In other cases where bond durability is focussed, the modifier MHMP shall be synthesised with higher F/P ratio.

Practical implications

MHMP as a modifier can be used to improve the heat resistance of PU resin.

Originality/value

The MHMPs with various hydroxymethyl groups were synthesised and used as modifier of moisture-curing PU resins to improve their heat resistance.

Details

Pigment & Resin Technology, vol. 43 no. 2
Type: Research Article
ISSN: 0369-9420

Keywords

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Article
Publication date: 8 February 2008

Sven Lamprecht, Günter Heinz, Neil Patton, Stephen Kenny and Patrick Brooks

The purpose of this paper is to show production process developments and innovations that resolve many of the issues faced with certain process steps for printed circuit…

Abstract

Purpose

The purpose of this paper is to show production process developments and innovations that resolve many of the issues faced with certain process steps for printed circuit board (PCB) manufacturing following “green” practices.

Design/methodology/approach

Several key PCB manufacturing processes have been developed or studied with respect to new environmental legislations and practises.

Findings

The introduction of new legislations designed to protect the environment require changes to laminate materials, solders, and PCB manufacturing techniques. The effect of new laminate materials on the desmearing and metallising processes have been assessed and recommendations given. The effect of increased thermal stress on plated copper has been assessed. Developments in adhesion enhancement for black oxide alternatives have been made and are presented with their suitability for the newer green laminate materials. The development of a new laminate manufacturing technique to reduce environmental impact is introduced. The capabilities of different surface finishes in relation to new lead‐free soldering techniques is investigated and presented.

Research limitations/implications

This is a short paper covering several major PCB processing steps and covers experiences and development results.

Originality/value

The paper details how “green” PCB manufacturing affects some key processes, developments to improve results and environmentally friendlier innovations in laminate manufacturing techniques.

Details

Circuit World, vol. 34 no. 1
Type: Research Article
ISSN: 0305-6120

Keywords

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Article
Publication date: 1 December 2001

George Stylios

Discusses the 6th ITCRR, its breadth of textile and clothing research activity, plus the encouragement given to workers in this field and its related areas. States that…

Abstract

Discusses the 6th ITCRR, its breadth of textile and clothing research activity, plus the encouragement given to workers in this field and its related areas. States that, within the newer research areas under the microscope of the community involved, technical textiles focuses on new, ‘smart’ garments and the initiatives in this field in both the UK and the international community at large. Covers this subject at length.

Details

International Journal of Clothing Science and Technology, vol. 13 no. 6
Type: Research Article
ISSN: 0955-6222

Keywords

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