化学改性淀粉胶黏剂研究进展

淀粉具有来源广泛、廉价、可再生、可降解等优点,因此在胶黏剂领域的应用越来越受到重视,但纯淀粉作为胶黏剂有着很多不足之处,例如耐水性和力学性能差,需要通过物理的或化学的方法对其进行改性,才能满足不同应用领域的性能需求,其中化学改性是制备淀粉类胶黏剂的重要手段。从氧化、酯化、醚化、交联、接枝等几个方面介绍了近年来国内外化学改性淀粉类胶黏剂的研究进展,并指出了化学改性淀粉胶黏剂未来发展的方向。     

大豆7S与11S球蛋白尿素变性后的粘接性质研究

随着人们对环境保护意识的增加和地球有限资源的缺乏,大豆蛋白在胶粘剂工业中的应用也越来越显示出强大的吸引力,鉴于前人的研究成果,文章研究了大豆7S和11S球蛋白经过尿素变性后在松木、樱桃木和胡桃木上的粘接强度和湿润能力。结果表明在不同的木块上不同胶粘剂有不同的粘接强度和湿润性能。7S大豆蛋白尿素变性后在硬木上有较好的湿润性。1M尿素变性赋予11S蛋白的粘接强度最高,3M尿素变性后,7S蛋白在硬木上的粘接强度大于11S蛋白。蛋白质的二级结构测量表明β-折叠对于3 M尿素变性后的大豆蛋白在硬木上的粘接强度起着重要作用,而无规则卷曲是降低1 M尿素变性7S大豆蛋白粘接强度的主要因素。     

大豆蛋白胶粉胶合板热压工艺的研究

粉状胶粘剂具有贮存时间长、运输方便、含水量低的优点,为了防止热压过程中的＂鼓泡＂现象,促进大豆蛋白胶粉的应用,研究了用改性大豆蛋白胶粉制造胶合板的热压工艺,通过单因素实验和正交实验,得到最优组合为：胶粉施胶量120 g/m2,胶水施胶量230 g/m2,热压时间110 s/mm,热压压力132 MPa,此时胶合强度为0.98 MPa,达到国家标准Ⅱ类胶合板的要求。     

改性大豆蛋白胶粘剂的研究进展

天然高分子大豆蛋白有着一些卓越的功能特性，可以用作胶粘剂。而改性大豆蛋白胶粘剂功能特性更优越。近几十年，作为环境友好绿色化工产品，改性大豆蛋白胶粘剂的研究与应用开发均取得了很大的进展，综述了大豆蛋白改性技术、改性大豆蛋白胶粘剂的特性及其应用。     

有机填料改性的无毒耐水脲醛树脂胶

主要研究了有机填料对脲醛树脂胶的剪切强度、耐发强度的影响。从而获得一种高剪切强度、高耐水性、游离甲醛含量低于１％的胶料。     

淀粉胶黏剂的应用及改性研究进展

淀粉是常见的天然高分子材料,具有来源广泛、价格低廉、可再生、可降解等优点,作为胶黏剂在各领域的应用逐渐受到重视,但是淀粉胶黏剂在使用过程中存在很多不足,例如耐水性差、流动性不好、易霉变、储存稳定性差等,需要对其进行物理或化学改性,才能满足各行业使用要求。简要介绍了淀粉胶黏剂在各行业的应用情况,针对主要缺陷,详细阐述了近年来国内外研究者对淀粉胶黏剂的改性研究进展,并提出了改性淀粉胶黏剂未来的发展方向。     

Glutaraldehyde-wheat gluten protein adhesives for wood bonding

ABSTRACT

Wheat gluten protein hydrolysate was used as a biomass feedstock to prepare environmentally friendly protein-based adhesives, with hydrolyzed wheat protein as control. Glutaraldehyde was used to modify it to obtain a glutaraldehyde-wheat protein (GP) adhesive. Polyethylenimine (PEI) was also used as a crosslinking agent. Plywood has been prepared and tested, and its performance was used to measure the wheat gluten protein hydrolysate adhesive bonding performance. Differential scanning calorimetry (DSC) and thermomechanical analysis (TMA) were used to analyze the adhesive thermal properties and the microstructures of the cured adhesives by scanning electron microscopy (SEM). The results show that modification by glutaraldehyde can effectively improve the bonding performance of wheat protein adhesives, the plywood bonded strength having been improved by its addition. The effect of PEI as a crosslinking agent became evident. It can greatly improve the bonding properties of glutaraldehyde-modified wheat protein adhesives. TMA analysis indicates that the glutaraldehyde-modified GP adhesive has a higher storage modulus than the unmodified one. The modulus of the adhesive increased after adding the PEI cross-linking agent.     

Development of High-Strength Soy Protein Adhesives Modified with Sodium Montmorillonite Clay

This study investigated the high strength of a soy protein adhesive system with good flowability at high protein concentration. Sodium montmorillonite (Na MMT), the most widely used silicate clay, was incorporated into viscous, cohesive soy protein adhesives at concentrations ranging from 1 to 11 % (dry basis, w/w). Hydroxyethyl cellulose was used as a suspension agent to stabilize the soy protein and nano clay to be the dispersion system. The interaction between soy protein and Na MMT was characterized by XRD, FTIR, Zeta potential and DSC. Results indicated that soy protein molecules were adsorbed on the surface of the interlayer of Na MMT through hydrogen bonding and electrostatic interaction. The soy protein/Na MMT adhesives had the intercalation structure with Na MMT contents ranging from 1 to 11 %. Adhesion strength, specifically wet adhesion strength, of soy protein adhesives at isoelectric point (pI) was significantly improved by the addition of Na MMT. It is believed that the physical cross‐linking reactions between soy protein and Na MMT mainly contribute to the improved adhesion performance of soy protein adhesives. Wet adhesion strength increased from 2.9 MPa of control soy protein adhesive to 4.3 MPa at 8 % Na MMT. An increase of pH beyond pI value resulted in decreased adhesion strength due to increased surface charges of soy protein and slightly reduced affinity of soy protein on the nano clay surface.     

生物质材料木材胶粘剂的研究进展

大豆蛋白作为一种廉价、易得、资源丰富、环境友好的生物质材料受到了广泛的关注,为了解决豆蛋白胶自身易水解、易受微生物侵蚀的缺陷,化学改性豆蛋白被广泛采用,以贻贝胶为模板对豆蛋白、木素等生物质材料进行化学改性用于制备木材胶粘剂也是研究的热点,本文对这2方面的研究进展做了简要的回顾。     

A Soy Flour-Based Adhesive Reinforced by Low Addition of MUF Resin

The desire to prepare a lower-cost soy-based adhesive has led to an interest in using the abundant and inexpensive soy flour (SF) as a substitute for expensive soy protein isolates (SPI) in wood adhesives. However, the weakness of this adhesive is poor water-resistance and bonding strength due to a low protein content, which limits its application in the wood industry. The objective of this research was to provide a simple and useful approach for improving the adhesion performance of SF-based adhesive by introducing a small addition of melamine-urea-formaldehyde (MUF) resin into the cured system. The optimum addition level of MUF resin, as well as the adhesion performance and conformation change of SF-based adhesive, were investigated. The analytical results indicated that the co-condensed methylene bridges were formed through the reaction of methylol groups of MUF resin with soy units during the hot-press process. The addition of MUF resin, not only significantly decrease the viscosity of SF-based adhesive but also increase its water-resistance and wet shear strength value. The SF-based adhesive containing 20% MUF resin, is a relatively low-cost adhesive, has a reasonable viscosity, and moreover can pass the Chinese Industrial Standard requirement (0.7 MPa) for interior plywood panels.     

Comparison of Canola and Soy Flour with Added Isocyanate as Wood Adhesives

Canola is widely grown in the northern latitudes for its vegetable oil, generating large quantities of residual, low value canola flour used as animal feed. The common wood adhesive poly(diphenylmethylene diisocyanate) (pMDI) should react with the wide variety of functional groups in proteins. Therefore, it would seem that canola flour with added pMDI could be an effective adhesive. Two main questions are addressed in this study: How do the wood adhesive properties of canola flour compare to the better-studied soy flour? How well do proteins, which contain an abundance of functional groups, cure with the very reactive pMDI? These questions were addressed using the small-scale adhesive strength test ASTM D-7998, with various adhesive formulations and bonding conditions for canola flour plus pMDI compared to soy adhesives. The more challenging wet cohesive bond strength was emphasized because the dry strengths were usually very good. Generally, soy adhesives were better than canola ones, as was the polyamidoamine-epichlorohydrin cross-linker compared to pMDI, but these generalizations can be altered by the conditions selected. Three-ply plywood tests supported the small-scale test results.     

Effect of temperature during vital gluten adhesive preparation and application on shear-bond strength

If protein-based adhesives are to become a competitive bio-based alternative to synthetic adhesives, the preparation and application methods have to be considerable improved to reduce process time and thereby improve the economy of the adhesive system. The purpose of this study was to investigate the impact of the temperature during preparation and application on the shear-bond strength of an adhesive based on vital gluten for use in wood applications. Vital gluten was used in its natural form and mixed with water of different temperatures (preparation temperature 0 °C or 20 °C), and applied on beech veneer at different temperature (application temperature –10, 20, 60 and 100 °C). Tensile shear-bond strength samples were prepared and tested according to EN 205. The results showed that an increase in veneer temperature during application of the adhesive led to a decrease in the shear-bond strength, but that the preparation temperature of the adhesive had no influence on the strength.     

Cottonseed protein-based wood adhesive reinforced with nanocellulose

Although protein-based adhesives are eco-friendly, sustainable, and biodegradable, continued improvement in their adhesive performance is desirable. In this work, the effect of adding nanocellulose particles to cottonseed protein-based wood adhesives was studied. Cellulose nanofibers (CNF) were found to be most beneficial at about a 2% additive level, giving 22% improvement in dry adhesive strength over the cottonseed protein control. Cellulose nanocrystals (CNC) were optimal at about 10% additive level, giving 16% strength improvement relative to cottonseed protein alone. The hot water resistance of cottonseed protein isolate was also improved with CNF addition, but not with CNC addition. For comparison, soy protein isolate was also studied and showed about the same relative dry strength improvements with nanocellulose addition, but improvement of hot water resistance was less apparent. Infrared and thermogravimetric analysis suggested that the protein and the nanocellulose were interacting with each other. Thus, CNF may be a useful additive to cottonseed protein formulations used as wood adhesives.     

Soy-based adhesives for wood-bonding – a review

Over recent years, the interest in bio-adhesives, including soy-based adhesives, has increased rapidly. Among natural renewable resources suitable for industrial use, soy is a reasonable choice due to its high production volume and the small use of soy meal-based products for human food consumption. Soy flour can be an ideal raw material for the manufacturing of wood adhesives due to its low cost, high protein content and easy processing. There are also more concentrated forms of soy proteins, i.e. concentrates and isolates, which are also suitable raw materials for adhesive production except that their prices are higher. Extensive research has been carried out on improving the cohesive properties, especially water resistance, of soy-based adhesives. However, there is insufficient experimental data available for understanding the influences of modification methods on the structure of soy proteins and therefore for understanding the influences of structural changes on the adhesion. In this paper, some experimental techniques are proposed to be used for analysing soy-based adhesives to enable better understanding of those factors and improve future development. This review of soy-based adhesives is made with the focus on soy proteins’ chemical composition, soy protein product types (raw materials for adhesive production), modification methods for improving the adhesive properties of soy-based adhesives, and commercial soy-based adhesives.     

Effects of phosphorus-containing additives on soy and cottonseed protein as wood adhesives

Soy and cottonseed proteins appear promising as sustainable and environment-friendly wood adhesives. Because of their higher cost relative to formaldehyde-based adhesives, improvement in the adhesive performance of proteins is needed. In this work, we evaluated the adhesive properties of soy and cottonseed protein formulations that included phosphorus-containing acids and esters. For cottonseed protein isolate, most of these additives improved dry adhesive strength, with methylphosphonic acid, phosphorous acid, and phosphoric acid increasing the dry strength by 47, 44, and 42%, respectively, at their optimal concentrations. For soy protein isolate, these additives did not show significant benefits. The phosphorus-containing additives also improved the hot water resistance of the cottonseed protein formulations but showed either no effect or a negative effect for the of soy protein formulations. Thus, the combination of cottonseed protein with phosphorus additives appears to be attractive as wood adhesives.     

Preparation and Characterization of Demethylated Lignin-Polyethylenimine Adhesives

Petrochemical-based adhesives such as urea-formaldehyde and phenol-formaldehyde resins are predominant wood adhesives. In this study, a new wood adhesive from lignin was developed and characterized. The new adhesive consisted of demethylated kraft lignin (DKL), a byproduct in the production of dimethyl sulfoxide from kraft lignin, and a polyethylenimine (PEI). Lap-shear specimens bonded with this new DKL-PEI adhesive system had very high shear strength and were very water-resistant. The effects of the preparation time, the curing conditions, the total solids content of the adhesive, the DKL/PEI weight ratio and the molecular weight of PEI on the shear strength and water-resistance of the resulting lap-shear specimens were studied in detail. Investigation on the curing chemistry of this new adhesive revealed that phenolic hydroxyl groups were oxidized to form quinones that further reacted with PEI. It was proposed that the curing mechanisms of this DKL-PEI adhesive were similar to the quinone-tanning processes in nature.     

Preparation and Characterization of Demethylated Lignin-Polyethylenimine Adhesives

Petrochemical-based adhesives such as urea-formaldehyde and phenol-formaldehyde resins are predominant wood adhesives. In this study, a new wood adhesive from lignin was developed and characterized. The new adhesive consisted of demethylated kraft lignin (DKL), a byproduct in the production of dimethyl sulfoxide from kraft lignin, and a polyethylenimine (PEI). Lap-shear specimens bonded with this new DKL-PEI adhesive system had very high shear strength and were very water-resistant. The effects of the preparation time, the curing conditions, the total solids content of the adhesive, the DKL/PEI weight ratio and the molecular weight of PEI on the shear strength and water-resistance of the resulting lap-shear specimens were studied in detail. Investigation on the curing chemistry of this new adhesive revealed that phenolic hydroxyl groups were oxidized to form quinones that further reacted with PEI. It was proposed that the curing mechanisms of this DKL-PEI adhesive were similar to the quinone-tanning processes in nature.     

大豆基胶粘剂的性能表征

介绍了大豆蛋白质的结构、组成和大豆基胶粘剂的改性原理;着重介绍了大豆基胶粘剂的力学性能、耐水性能、热学性能、防腐性能、结构特征及表面形貌的实验研究与表征方法;提出了大豆基胶粘剂性能表征中存在的问题及发展方向。     

大豆基木材胶黏剂的研究进展

随着近年来环境保护与资源节约受到重视,开发环保高效的新一代木材胶黏剂已经成为研究热点.大豆蛋白作为最具应用前景的天然胶黏剂之一,被进行了充分的改性研究.综述了近年来围绕大豆蛋白作为木材胶黏剂应用而进行的改性研究.并对研究中存在的问题和将来的发展方向进行了归纳和展望.     

Bonding strength of oak with different adhesives after humid-water-heat tests

Composite materials manufactured from wood with different adhesives are being used increasingly in the construction of furniture frames and buildings. In this study, it is aimed to describe the effects of adhesives (PVAc, VTKA and UF) on white oak cut tangentially and radially impregnated with Protim WR 230, CCA, and Celcure AC 500 and exposed to humid-water-heat resistance and heating and cooling tests. Impregnation chemicals have decreased the bonding strength, and control samples gave higher bonding strength value. According to the control samples, it can be said that humid-resistance test, water-resistance test, heat-resistance test have decreased the bonding strength. As a result of the tests, white oak cut tangentially and impregnated with Protim WR 230 and bonded with VTKA adhesive can be used as a material in damp condition where the strength is required.