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。     

大豆基胶粘剂的研究进展

介绍了大豆蛋白的结构与组成,综述了近年来国内外大豆基胶粘剂的发展概况和改性进展,提出了研发中存在的问题以及发展大豆基胶粘剂的意义。     

大豆蛋白胶粘剂的化学改性研究进展

由于石油危机和环境污染,传统的甲醛胶粘剂受到了严峻挑战,用天然可再生物质制取环保、绿色胶粘剂已成为趋势。文章就大豆蛋白胶粘剂性能、化学改性方法及其在环保型胶粘剂的应用前景进行全面描述。     

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。     

Shear strength and water resistance of modified soy protein adhesives

Soy protein polymers recently have been considered as alternatives to petroleum polymers to ease environmental pollution. The use of soy proteins as adhesives for plywood has been limited because of their low water resistance. The objective of this research was to test the water resistance of adhesives containing modified soy proteins in walnut, maple, poplar, and pine plywood applications. Gluing strength and water resistance of wood were tested by using two ASTM standard methods. Glues with modified soy proteins had stronger bond strength than those containing unmodified soy proteins. Plywood made with glue containing urea-modified proteins had higher water resistance than those bonded with glues containing alkali-modified and heat-treated proteins. After three 48-h cycles of water-soaking, followed by 48 h of air-drying, no delamination was observed for either walnut or pine specimens glued with the urea-modified soy protein adhesives. Gluing strength for wood species with smooth and oriented surface structure was lower than for those with rough, randomly oriented, surface structures. Wood species with greater expansion of dimensions during water-soaking had a higher delamination rate than those showing less expansion.     

Characterization of defatted soy flour and elastomer composites

Defatted soy flour (DSF) is an abundant renewable commodity and is more economically favorable then soy protein isolate or soy protein concentrate. DSF contains soy protein, soy carbohydrate, and soy whey. The aqueous dispersion of DSF was blended with styrene‐butadiene latex to form elastomer composites. The inclusion of soy carbohydrate increased the tensile stress in the small strain region, but reduced the elongation at break. The shear elastic modulus of the composites showed an increase in the small strain region, consistent with its stress‐strain behavior. The inclusion of soy carbohydrate and soy whey also improved the recovery behavior in the nonlinear region. At small strain, the shear elastic modulus of 30% filled composites at 140°C was about 500 times higher than that of the unfilled elastomer, indicating a significant reinforcement effect generated by DSF. Compared with soy protein isolate (SPI), the stress softening effect and recovery behavior under dynamic strain indicate the addition of soy carbohydrate and soy whey may have increased the filler‐rubber interaction. In general, the DSF composites gave better mechanical properties compared with the protein composites. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 353–361, 2005     

PVAc乳胶/改性大豆分离蛋白共混胶黏剂的制备及性能

针对大豆蛋白胶黏剂耐水性差的缺点,用尿素初步改性大豆分离蛋白（SPI）,然后与白乳胶（PVAc）共混合成了共混改性大豆分离蛋白胶黏剂。采用正交实验方法考察了大豆蛋白胶与白乳胶质量比、共混时间、交联剂质量分数、交联时间对大豆蛋白胶黏剂剪切粘接强度的影响,确定了优化配比及制备工艺条件,并在此基础上采用正交试验优化了热压参数。结果表明：大豆蛋白胶与白乳胶质量比10∶1,共混时间1h,交联剂质量分数1.0%,交联时间1.5h,热压温度120℃,热压压强1.2MPa,热压时间2min/mm,涂胶量250g/m2时,测得胶黏剂的干态剪切粘接强度为2.01MPa,按照Ⅰ类胶合板标准测得湿态剪切粘接强度为1.04MPa,并对优化配方进行了结构与性能分析。     

改性大豆蛋白胶粘剂的研究进展

综述了碱降解改性大豆蛋白胶粘剂的研究进展以及接枝共聚反应在交联改性反应中的重要性,认为在复合碱降解改性大豆蛋白基础上进行接枝共聚改性作为一种与交联反应方法平行的改进方法或补充方法是可行的。     

大豆蛋白胶麻杆刨花板制备工艺的研究

为了开发环境友好型刨花板,探讨利用大豆蛋白胶黏剂压制麻杆刨花板的制备工艺,分析热压温度、热压时间、施胶量和密度对麻杆刨花板性能的影响。结果表明,大豆蛋白胶可以用于麻杆刨花板的制造,其最佳工艺参数为:热压温度180℃,热压时间25 min,施胶量18%,密度0.80 g/cm3。在此条件下,压制的板材的性能超过GB/T 4897.4—2003的要求。     

Development and characterization of plasticized starch‐based biocomposites with soy pulp as reinforcement filler

Soy pulp, a byproduct of soymilk industry, was used in varying amount as reinforcement filler with thermoplastic starch, to develop and characterize starch–soy (SS) composites. The composite filled with 10 wt % soy pulp showed 112% and 98% increment in tensile and flexural strength, respectively. Fourier transform infrared spectrum of composite revealed occurrence of chemical bonding between hydroxyl group of soy pulp and that of starch matrix. The optimized composite containing 10 wt % soy pulp, with maximum mechanical strength was found thermally stable up to 312°C. Water absorption of these composites was enhanced with the increase in filler loading due to increase in hydrophilicity as evident from lowering of contact angle value. These composites are expected to be ecofriendly as soy pulp and starch are biodegradable in nature. The SS pulp composites so developed and characterized find potential application as disposable and packaging items. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Soy-oil-based waterborne polyurethane improved wet strength of soy protein adhesives on wood

Soy-oil-based waterborne polyurethane (WPU) is used to improve wet strength in shear test of wood bonded with an adhesive of soy protein isolate (SPI) by dispersing WPU into SPI slurry. WPU׳s effects on the physiochemical properties of WPU-SPI adhesives are characterized through Fourier transform infrared spectrum, transmission electron microscopy, thermal analysis, contact angle, and mechanical strength. Wet strength of the WPU-SPI adhesives increases by 65% compared to SPI control. Moreover, the microstructure of WPU has effects on the interactions between WPU and SPI. In this study, smaller and more uniform distributed WPU0002 is easier to interact and form stronger crosslinking network with protein than WPU0500. The stronger interaction between WPU0002 and protein results in increased viscosity and bond strength. The WPU-SPI blended adhesives show significantly improved wet strength, demonstrating their potential as wood adhesives.     

Functional properties of hydrothermally cooked soy protein products

The effects of hydrothermal cooking on the functional properties of defatted soy flour, aqueous alcohol washed soy protein concentrate, and soy protein isolate were determined in samples that were treated at 154°C by infusing steam under pressure for 11, 19, 30, and 42 s, and then spray dried. Hydrothermal cooking increased the nitrogen solubility index (NSI) of the concentrate from 15 to 56% and altered the solubility profile from a flat profile to one more typical of native soy protein. Hydrothermal cooking also improved foaming and emulsifying properties of the concentrate. For isolate, hydrothermal cooking also improved NSI and foaming and emulsifying properties, although the improvements were less dramatic than with concentrate. NSI and emulsifying properties of the flour were improved by some processing conditions, but foaming properties were not improved by hydrothermal cooking. Dramatically increased protein solubility of concentrate and modestly improved protein solubilities of flour and isolate by hydrothermal cooking, which will also inactivate trypsin inhibitors and microorganisms, have considerable practical significance to protein ingredient manufacturers and those who use these ingredients in foods and industrial products.     

大豆蛋白胶研究进展

大豆蛋白胶作为一种生物基胶黏剂和环境友好型材料逐渐成为研究热点,对近年来的主要研究情况进行归纳和总结,探讨了大豆蛋白胶黏剂的研究方向和发展趋势,针对其发展方向和存在问题进行展望。     

Jet cooking dramatically improves the wet strength of soy adhesives

The impact of jet cooking on shear strength of soy-and-water adhesives was investigated to understand the higher shear strength of commercial soy protein isolates compared to soy flours. Soy flour-based wood adhesives are appealing because of their bio-based content, low formaldehyde emission, and low cost, but their commercial application is limited by low wet cohesive strength. Previous researchers proposed that the process of jet cooking (steam injection with high turbulence followed by rapid cooling) was responsible for the high (~3 MPa) wet shear strength of adhesives made with commercially produced soy protein isolate, using the ASTM D 7998 test. In this work, we show that jet cooking did dramatically increase the wet strength of laboratory-produced, native-state soy protein isolate from 0.6 to 3 MPa, a strength similar to many commercial isolates. Jet cooking was far less effective at developing wet strength of soy flours, but greatly increased the viscosity of virtually all our soy materials. We hypothesize that the benefits of jet cooking are primarily a result of nonequilibrium protein aggregation states because subsequent wet autoclaving of jet cooked soy proteins dramatically decreased wet strength. The dramatic differences in adhesive properties between commercial soy protein isolates and soy flours suggests that the common practice of using results obtained with commercial isolates to predict the performance of soy flour adhesives is inappropriate.     

Polyurethane networks from formiated soy polyols: Synthesis and mechanical characterization

Polyurethanes can be prepared using polyols obtained from vegetable oils in natura, such as castor oil, or from functionalized vegetable oils, such as hydroxylated soybean oil. These polyurethanes have different valuable properties, determined by their chemical composition and cross-linking density. In this study, soy epoxy polyols with different OH contents were prepared through a one-step reaction using the method of in situ performic acid generation. Polyols with OH functionalities from 1.9 to 3.2 were reacted in bulk with different diisocyanates at a NCO/OH molar ratio of 0.8 and 60°C for 24 h. Mechanical properties of the polyurethanes were determined by dynamic mechanical thermal analysis, hardness (Shore A), and swelling measurements. Polymer networks with glass-transition temperatures (T _g ) from −13 to 48°C were obtained. We observed that the higher the OH functionality of the polyols, the higher the T _g and cross-linking density of the polyurethane network. The influence of diisocyanate structure (rigid or flexible chain), curing temperature, and curing reaction time on mechanical properties was also investigated.     

Adhesion strength of sodium dodecyl sulfate-modified soy protein to fiberboard

Thermal and rheological properties of sodium dodecyl sulfate (SDS)-modified soy protein isolate (SPI) adhesives were studied using differential scanning calorimetry (DSC) and rheometry. The ordered structure of native SPI was denatured as SDS concentration increased, and thermal stability of native SPI decreased at high SDS concentration. The enthalpy of SPI denaturation decreased significantly with increasing SDS concentration. Apparent viscosity of the SPI adhesives increased as SDS concentration increased. The SPI adhesives modified by high concentrations of SDS exhibited characteristics of a Newtonian-type flow. The SDS-modified SPI adhesives were applied to fiberboard, and effects of SDS concentration, press conditions, and assembly time on bond strength were investigated. Shear strength of the SPI adhesives increased with SDS concentration, reaching its maximum value at 3 wt% of SDS, and then decreased significantly. The shear strength increased as press time and/or press temperature increased. High press temperature (100 °C) and long press time (5 min) are needed to achieve relatively good adhesion properties. The shear strength also increased as assembly time increased. The shear strength of the SDS-modified SPI adhesives decreased after soaking in water for 24 h.     

Effect of value-enhanced texturized soy protein on the sensory and cooking properties of beef patties

Texturized soy protein (TSP) originating from varieties of value-enhanced soybeans and commodity soybeans, which were processed by extrusion-expelling, were incorporated into ground-beef patties. The soybean varieties included high-cysteine, low-linolenic, lipoxygenase-null, high-sucrose, low-saturated-fat, and high-oleic. The lower the bulk density was, the better the water-holding capacity of TSP. Neither property was affected by the protein dispersibility index or residual oil of the low-fat soy flours from which the TSP was prepared. All extruded-expelled processed flours from value-enhanced soybeans made acceptable TSP. The high-sucrose soybeans produced TSP with higher expansion and improved water-holding capacity. There were no differences in cooking properties or proximate compositions of patties for all treatments. Inside and outside colors were darker for the TSP-extended patties than for the all-beef control, and there was little difference among soybean varieties. The patties containing TSP had significantly more soy flavor and were harder than the all-beef control patties. Some TSP treatments produced more tender and less cohesive cooked patties than did the all-beef control.     

Structure and mechanical properties of cellulose derivatives/soy protein isolate blends

Biodegradable and biocompatible composites based on soy protein isolate (SPI) and various cellulose derivatives have been prepared, and the dependence of structures and mechanical properties on the content and species of cellulose derivatives for the composites were investigated by X‐ray diffraction, differential scanning calorimetry, scanning electron microscope, and tensile test. The selected cellulose derivatives, such as methyl cellulose (MC), hydroxyethyl cellulose (HEC), and hydroxypropyl cellulose, were miscible with SPI when the content of cellulose derivatives was low, and then the isolated crystalline domains, shown as the structures of network and great aggregate, formed with an increase of cellulose derivative content. The miscible blends could produce the higher strength, and even result in the simultaneous enhancement of strength and elongation for the HEC/SPI and MC/SPI blends. Meanwhile, the moderate content of great MC domains also reinforced the materials. However, the damage of original ordered structure in SPI gave the decreased modulus. Since all the components, i.e., cellulose derivatives and soy protein, are biocompatible, the resultant composites are not only used as environment‐friendly material, but the biomedical application can be expected, especially for the tissue engineering scaffold. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Preparation and evaluation of particleboard bonded with a soy flour-based adhesive with a new curing agent

Urea-formaldehyde (UF) resin is one of the most commonly used wood adhesives for making particleboards. However, UF emits carcinogenic formaldehyde and is derived from nonrenewable petrochemicals. In this study, a new formaldehyde-free wood adhesive that is based on soy flour and a renewable material-based curing agent (CA) were prepared and evaluated for the preparation of M-2 grade particleboards. The new CA was derived from ammonia and epichlorohydrin that can be derived from renewable glycerol. The composition of the adhesive was soy flour/sodium hydroxide/CA at a dry weight ratio of 9/0.3/1.0. The modulus of rupture, modulus of elasticity, and internal bond strength met the minimum industrial requirements of M-2 particleboards using the following variables: hot-press temperature of 190?°C, hot-press time of 240?s, the adhesive usage of the face particles of 12?wt.%, the adhesive usage of the core particles of 10?wt.%, and the target particleboard density of 0.80?g/cm³.     

Thermal and mechanical properties of plastics molded from urea-modified soy protein isolates

Soy protein has been considered as a potential alternative of some petroleum polymers in the manufacture of plastics. The purpose of this investigation was to characterize the thermal and mechanical properties of plastics made from urea-modified soy protein. Soy protein isolate was separated from the defatted soy flour, modified with various urea concentrations, and compression-molded into plastics. Differential scanning calorimetry showed that the temperatures of denaturation and the enthalpies of denaturation of the modified soy protein decreased as urea concentrations increased above 1 M. At the same urea concentration, molded plastics made from the modified soy proteins showed a similar temperature of denaturation as the modified soy protein, but a lower enthalpy of denaturation. Tensile strength and Young's modulus of the molded plastics from the modified soy proteins increased as urea concentration increased and reached their maximum values at 8 M urea modification. Both storage modulus and glass transition temperature of the plastics from the modified soy proteins increased as urea concentration increased. The plastics made from the 2 M urea-modified soy proteins showed improvements in elongation, tough fracture behavior, and water resistance. The urea may function as a denaturant, a plasticizer, and a filler.