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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.

The purpose of the study was to prepare melamine-urea-formaldehyde (MUF) resin that would be resistant to boiling water and high temperature and exhibit low formaldehyde emission.

The authors prepared MUF resin with different F/(M + U) and changed the amount of melamine added, through the analysis of MUF resin properties to get the best reaction parameters, and used different amino acid cure systems including NH₄Cl cured the resin.

Resin’s heat resistance and water resistance are mainly determined by the amount of melamine added, and formaldehyde emission of the plywood can be changed by adjusting F/(M + U). The peak temperature of the curing agent-cured resin increases as compared with the self-curing resin. Stronger the acidity of curing agent, faster the viscosity increased in probation period and lower the bonding strength and heat resistance of the resin.

Melamine improves the heat resistance and water resistance of the resin. When the amount of melamine is more than a certain value, water resistance of the resin decreased.

MUF resin that is resistant to boiling water and exhibits low formaldehyde emission can be used in high temperature, high humidity and strict formaldehyde emission environment and can also be combined with other materials.

It was helpful to reduce the effect of formaldehyde emission on people’s health and environmental pollution and is also beneficial for the expansion of the application range of aldehyde resin.

The originality is twofold: the influence of the acid strength of curing agent on the bonding strength of the resin adhesive and the method for preparing high performance MUF resin by following the traditional process.

The purpose of the research was as follows. In situ modified urea formaldehyde resins were prepared from clay (montmorillonite) and organoclay in the presence of base catalyst. Different clay contents (1 wt%, 3 wt%, 6 wt%) were used to produce clay modified nanocomposite resins. These nanocomposites were characterized with FT‐IR, XRD as structural analysis and DSC as thermal analysis and their hardness was evaluated as mechanical analysis. The thermal results was compatible with hardness measurements and showed that using clay/organoclay added resin as a surface coating material provides significant improvement.

During synthesis of the resin, modification was carried out using urea/formaldehyde with molar ratio of 1/1.6, under basic medium with pH=10 and with temperature of 70°C by loading pristine and organomodified layered silicates.

X‐ray diffraction (XRD) results indicate that the interlayer space of pristine clay was increased significantly by one step, seeing that one step processes are crucial for industrial applications.

The reaction mixture must be stirred continuously. Temperature should be controlled in order to prevent the thermal curing of urea formaldehyde resin.

This study provides technical information for the synthesis of nanocomposite resins. The clay or organoclay modified resins may also promote the adhesive strength of coating and also inhibit corrosion effects to metal surfaces of the coated area.

This resin will be used for the coating material.

As T_g‐T_m region of some nanocomposites is enhanced, and by assessing the results of hardness measurements, it is concluded that these samples have further improved mechanical properties as a coating material than urea formaldehyde resin has.

The paper deals with the mode of film formation from urea–formaldehyde and melamine–formaldehyde resins combined with alkyd resin based on castor oil‐modified alkyd. The properties of hardened coatings (such as hardness, chemical stability, and adhesion to substrate) were followed in dependence on the ratios of reaction components. An apparatus was built for measuring the formaldehyde emissions escaping from the solid coating films. The determination was performed by the pararosaniline method. The addition of imidazolidine in a concentration up to 10 per cent can reduce the emissions of formaldehyde escaping from the solid films to a considerable amount.

The purpose of this paper is to study the corrosion protective properties of modified urea and/or thiourea formaldehyde resins for steel surface.

Three butyl alcohol modified amino resins were laboratory prepared. The three modified resins were characterized using thermal gravimetric analysis and infrared; the solid content and refractive index of each were also measured.

The resins that contain both nitrogen and sulphur have excellent corrosion inhibitive activity compared with that containing nitrogen only.

The modified resins were based on urea formaldehyde resin, mixed urea and thiourea formaldehyde resin and thiourea formaldehyde resin, respectively.

The prepared resins were introduced in different coating formulations based on short‐oil alkyd resin, medium‐oil alkyd resin and plasticized chlorinated rubber. They were then tested and evaluated for corrosion protection of steel surfaces.

All the prepared resins show promising results for corrosion protection of steel surfaces.

Modern glues are manufactured with high moisture and water resistance; urea‐formaldehyde resins for gluing purposes are based on the fact that excellent control of the condensation reaction is possible by variation of pH, which can be applied easily at the production process. Among conclusions is that the shear stress of these resins is twice that of the unmodified type.

This study aims to prepare a low-formaldehyde and environmentally friendly glucose-lignin-based phenolic resin.

The authors directly used lignin to substitute formaldehyde to prepare lignin-based phenolic resin (LPF) with urea as formaldehyde absorbent. To improve the performance of the adhesive, the biobased glucose was introduced and the modified glucose-LPF (GLPF) was obtained.

The results showed that when the replacing amount of lignin to formaldehyde reached 15 Wt.%, the physical properties of the prepared LPF met the Chinese national standard, and the bonding strength increased by 21.9%, from 0.75 to 0.96 MPa, compared with PF. The addition of glucose boost the performance of wood adhesive, for example, the free phenol content of the obtained GLPF was significantly reduced by 79.11%, from 5.60% to 1.17%, the bonding strength (1.19 MPa) of GLPF increased by 19.3% in comparison to LPF and the curing temperature of GLPF decreased by 13.08%.

The low-formaldehyde and environmentally friendly GLPF has higher bonding strength and lower curing temperature, which is profitable to industrial application.

The prepared GLPF has lower free formaldehyde and formaldehyde emission, which is cost-effective and beneficial to human health.

The joint work of lignin and glucose provides the wood adhesive with increased bonding strength, decreased free phenol content and reduced curing temperature.

The interaction between formaldehyde and urea or thiourea has been reported by Richard and Gourdenne who used G.P.C. columns packed with reticular polystyrene gel of pore sizes 3×104, 3×103, 103, 500, 200, 100, 60 and 60 A and which were eluted with N, N‐dimethylformamide at 50°C. These authors prepared precursors such as monomethylolurea and N, N‐dimethylolurea in aqueous base at 4°C which prevented their autocondensation. These materials were positively identified by proton nuclear magnetic resonance spectroscopy, but they were not resolved from one another nor from urea itself on the G.P.C. columns on account of the fact that the strong solvation by the eluent dimethyl‐formamide was not affected by the substitution of one or two methylol groups into the urea molecule. Using an acid solution at room temperature, it was found that the reaction between formaldehyde and urea or disubstituted urea produced substances such as methylene diurea and methylene di (N, N‐dimethylurea) which, respectively, eluted before and after urea itself. When urea or thiourea was reacted with formaldehyde at a molar ratio of 1:1.8 in a 30% aqueous solution of pH 8 at 95°C, it was shown by nuclear magnetic resonance spectroscopy that the individual urea residues were linked by ether bridges only and that methylenic linkages were totally absent. The degree of cross‐linking of the products was expressed in terms of the ratio of the number of protons included in these bridges to the total number of protons in the various methylene groups as determined by nuclear magnetic resonance spectroscopy. Five samples were taken from such a reaction between urea and formaldehyde. Their G.P.C. curves were obtained and they were shown to display a wider molecular size distribution as the calculated degree of cross‐linking increased. The initial sample was found to be comprised of a mixture of mono‐ and dimethylolurea, but the samples taken later on during the reaction were more highly polymerised and could not be assigned individual molecular structures. A similar conclusion was reached using a mixture of thiourea and formaldehyde in the preparation of a resin.

THE object of this article is to deal with the present day use of urea‐formaldehyde resin glues in the aircraft industry. This type of glue is used in two spheres of the industry. (1) In the manufacture of plywood of aircraft quality, and (2) in the manufacture of wooden aircraft structures.

Water soluble epoxy resins were prepared from male‐opimaric acid, linseed fatty acids and epoxy resin. The methylated urea formaldehyde resin and melamine formaldehyde resin were also prepared for curing purposes. The pigmented coating compositions were prepared from water soluble epoxy resins, red oxide and iron and zinc phosphate. These coating compositions showed good water resistance, acid resistance, alkali resistance and lubricating oil resistance.