Chemical Modification of Soy Protein for Wood Adhesives

Mussel protein is a strong and water‐resistant adhesive, but is expensive and not readily available. Soy protein is inexpensive, abundant, and annually renewable, but suffers from low adhesive strengths and low water resistance of the bonded products. This study reveals that introducing a key functional group from the marine adhesive protein to soy protein converts the soy protein to a strong and water‐resistant wood adhesive.     

Formaldehyde‐Free Wood Adhesives from Decayed Wood

Summary: Extensive studies using mussel adhesive protein as a formaldehyde‐free, strong, and water‐resistant adhesive model revealed that a combination of a polymer with catechol moieties and a polymer with amino groups could serve as a strong and water‐resistant wood adhesive. This study demonstrated that the treatment of abundant and readily available brown‐rot‐fungus‐decayed wood with NaBH₄ followed by mixing with polyethylenimine resulted in a formaldehyde‐free, strong, and water‐resistant wood adhesive.

Lignin is demethylated by brown‐rot fungi and then reduced using NaBH₄.     

木质素活化及在木材胶粘剂中的应用进展

木质素是相对分子量较高的天然聚合物,由于具有苯酚结构利于制备木材胶粘剂,但是木质素本身反应活性低,一般都将其活化后再利用.而且,除了以往利用最多的造纸工业产生的木质素外,研究发现木材经过褐腐菌降解后残留主要成分是结构部分发生变化的木质素,这种可再生生物质资源以其自身的结构特点在合成胶粘剂上也有很大的优势,本文结合木质素胶粘剂应用中的问题,重点概述了活化木质素的各种方法及褐腐木质素在木材胶粘剂中的应用.     

Microheterogeneous Polyetherhydroxylurethane Elastomers with Controlled Phase Structure for Structural Adhesives

Russian Journal of Applied Chemistry - Polyetherhydroxylurethane elastomers were prepared from mixtures of epoxy urethane oligomers and diglycidyl urethane, synthesized using isophorone...     

Modification of Soy Protein for Wood Adhesives using Mussel Protein as a Model: The Influence of a Mercapto Group

Summary: Mussel protein can serve as a strong and water‐resistant adhesive, but is expensive and not readily available. Soy protein is inexpensive, abundant, and readily available, but is a poor adhesive. Mussel protein contains a high amount of mercapto‐containing cysteine. This study revealed that increasing the free mercapto group content in soy protein could greatly increase the strength and water‐resistance of wood composites bonded with the modified soy protein.

Preparation of the modified SPIs.     

Recent Advances on the Development of Protein-Based Adhesives for Wood Composite Materials—A Review

The industrial market depends intensely on wood-based composites for buildings, furniture, and construction, involving significant developments in wood glues since 80% of wood-based products use adhesives. Although biobased glues have been used for many years, notably proteins, they were replaced by synthetic ones at the beginning of the 20th century, mainly due to their better moisture resistance. Currently, most wood adhesives are based on petroleum-derived products, especially formaldehyde resins commonly used in the particleboard industry due to their high adhesive performance. However, formaldehyde has been subjected to strong regulation, and projections aim for further restrictions within wood-based panels from the European market, due to its harmful emissions. From this perspective, concerns about environmental footprint and the toxicity of these formulations have prompted researchers to re-investigate the utilization of biobased materials to formulate safer alternatives. In this regard, proteins have sparked a new and growing interest in the potential development of industrial adhesives for wood due to their advantages, such as lower toxicity, renewable sourcing, and reduced environmental footprint. This work presents the recent developments in the use of proteins to formulate new wood adhesives. Herein, it includes the historical development of wood adhesives, adhesion mechanism, and the current hotspots and recent progress of potential proteinaceous feedstock resources for adhesive preparation.     

胶粘剂化学

本文简介了无机胶粘剂、环氧树脂胶粘剂、酚醛树脂胶粘剂、丙烯酸系胶粘剂、不饱和聚酯胶粘剂、聚氨酯胶粘剂、耐高温胶粘剂等的组成和化学原理,说明了胶粘剂在国民经济中的重要作用和粘合连接的优越性。     

The Structure of Suginal from the Wood of Juniperus Formosana Hayata

The detailed investigation of the acetone extract from the wood of Juniperus formosana Hayata gave a new diterpene aldehyde which was elucidate as suginal on the basis of chemical and spectroscopic evidence.     

Adhesives for Low-Energy Surfaces

Summary: The wetting and adhesive properties of model pressure-sensitive adhesives synthesised by miniemulsion polymerization were investigated. Wetting experiments of aqueous solutions of three different emulsifiers showed that Silwet L-77 (nonionic ethoxylated trisiloxane) was the best wetting agent. Probing adhesive properties, two different structure modifications of the polymer were investigated: a change in the polymer microstructure by the addition of a chain transfer agent and the introduction of a hydrophobic monomer into the polymer backbone. An addition of chain transfer agent was sufficient to obtain a polymer with a significantly different microstructure and, consequently, enhanced adhesion energy but reduced shear resistance. On the other hand, stearyl acrylate (SA) was employed as the hydrophobic monomer and the synthesis was carried out in miniemulsion polymerization which enables the incorporation of hydrophobic compounds without any diffusion limitations. There were almost no differences in the polymer microstructure, whereas, some differences were observed in adhesion properties.     

How to Increase Water Resistance of Adhesive Wood Compounds Formed by Adhesives Based on Polyvinyl-Acetate Dispersion

The influence of glyoxal on the water resistance of pine–pine and beech–beech wood compounds formed by adhesives on the basis of polyvinyl acetate dispersion is studied. A noticeable increase in water resistance is observed for pine–pine compounds if the adhesive composite contains not only glyoxal, but also aluminum chloride and “chymol” additives. However, in the case of beech–beech compounds, the effect of this composition becomes less pronounced.     

Adhesives for rubber bonding

Properties of adhesives for high-strength bonding for the shoe industry, the butt joining of conveyer belts, rubberizing of large-size machinery, and building construction are reported as compared with domestic and foreign analogs.     

Adhesives for aviation equipment

The properties of high-strength and high-elastic film adhesives, high-strength cold- and hot-setting adhesive pastes, adhesives intended for bonding of metals, different nonmetallic and composite materials are overviewed. The properties of self-adhesive materials of different grades used for temporary repair of airframe surfaces are also described.     

On the Development of Phenol-Formaldehyde Resins Using a New Type of Lignin Extracted from Pine Wood with a Levulinic-Acid Based Solvent

Resole resins have many applications, especially for foam production. However, the use of phenol, a key ingredient in resoles, has serious environmental and economic disadvantages. In this work, lignin extracted from pine wood using a “green” solvent, levulinic acid, was used to partially replace the non-sustainable phenol. The physicochemical properties of this novel resin were compared with resins composed of different types of commercial lignins. All resins were optimized to keep their free formaldehyde content below 1 wt%, by carefully adjusting the pH of the mixture. Substitution of phenol with lignin generally increases the viscosity of the resins, which is further increased with the lignin mass fraction. The addition of lignin decreases the kinetics of gelification of the resin. The type and amount of lignin also affect the thermal stability of the resins. It was possible to obtain resins with higher thermal stability than the standard phenol-formaldehyde resins without lignin. This work provides new insights regarding the development of lignin-based resoles as a very promising sustainable alternative to petrol-based resins.     

Reverse-Phase Liquid Chromatography of Phenol-Formaldehyde All-Ortho Oligomers

Abstract

High Performance Liquid Chromatography was proven to be a powerful method for the separation and quantitation of ortho-linked Phenol-Formaldehyde oligomers. A homologous series of oligo [(2-hydroxyl-1, 3-phenylene) methylenes] (dinuclear to octanuclear compounds) was analyzed. The samples were separated by reverse-phase chromatography and monitored at 280 nm. Optimum conditions were obtained on a μ-Bondapack C₁₈ column employing isocratic ambient elution with a metanol/water 80:20 (v/v) mixture. Four reference mixtures of oligomers of known composition were used to assure the reliability of the method. Subsequent analysis of two samples of all-ortho novolac resins was performed in order to substantiate further the validity of the technique.     

Strong Protein Adhesives through Lanthanide-enhanced Structure Folding and Stack Density

Generating strong adhesion by engineered proteins has the potential for high technical applications. Current studies of adhesive proteins are primarily limited to marine organisms, e.g., mussel adhesive proteins. Here, we present a modular engineering strategy to generate a type of exotic protein adhesives with super strong adhesion behaviors. In the protein complexes, the lanmodulin (LanM) underwent α-helical conformational transition induced by lanthanides, thereby enhancing the stacking density and molecular interactions of adhesive protein. The resulting adhesives exhibited outstanding lap-shear strength of ≈31.7 MPa, surpassing many supramolecular and polymer adhesives. The extreme temperature (−196 to 200 °C) resistance capacity and underwater adhesion performance can significantly broaden their practical application scenarios. Ex vivo and in vivo experiments further demonstrated the persistent adhesion performance for surgical sealing and healing applications.     

Chemoselective Reduction of Some Condensates derived from Chromone-3-carbaldehyde using Sm and Zn

Condensates 4–6 undergo reductive dimerization with Sm in THF containing aqueous NH₄Cl to produce 7–9, whereas with Zn under similar reaction condition 3–5 produce 10–12.     

酚醛树脂热裂解产物的导电特性

近年来,无论是从理论方面还是从实验方面,人们对导电高分子材料的研究都不断深入,最近报道掺杂的聚乙炔电导率已高达10~5S·cm~(-1),但聚乙炔在空气中不稳定,应用受到限制。 一维石墨由于具有缩合芳香环结构,在空气中表现出很高的稳定性,日本K.Tanaka等人对一维石墨成员从理论上进行了详细讨论,认为具有多并苯骨架结构的一维石墨成员     

Thermal Behaviour of Phenol-Formaldehyde (PF) Compounds

The self-condensation reactions of 2- and 4-mono-methylol phenols (2-MMP and 4-MMP), in the presence of varying concentrations of NaOH, have been studied by differential scanning calorimetry (DSC). The reaction exotherms were analysed to derive the activation energy, E_a, and the heat of reaction, H_T, for the condensation reactions. In the case of 2-MMP an increase in NaOH:2-MMP molar ratio caused an increased in E_a and a decrease in H_T up to a molar ratio of 0.6:1. However, for 4-MMP, an increase in NaOH concentration caused an increase in E_a up to a molar ratio of 0.3:1 beyond which there appeared to be no further effect. The presence of NaOH had no effect on H_T for this compound. The results suggest that in the range of NaOH concentration used the effect of NaOH was substantially greater on 2-MMP compared to 4-MMP. This revised version was published online in August 2006 with corrections to the Cover Date.     

Analysis of Tobacco Smoke Condensates

The applicability of standard methods to determining tar and nicotine in tobacco smoke condensates by the mechanical smoking of cigarettes was assessed for the differentiation of samples satisfying currently accepted hygienic standards. The tar-to-nicotine concentration ratio was proposed as an assessment criterion for characterizing samples in order to reveal off-grade products.__________Translated from Zhurnal Analiticheskoi Khimii, Vol. 60, No. 8, 2005, pp. 881–885.Original Russian Text Copyright © 2005 by Uryupin, Fomina.Presented at the International Forum “Analytics and Analysts,” Voronezh, 2003.