Adhesive properties of soy proteins modified by urea and guanidine hydrochloride

An investigation was conducted on the adhesive and water-resistance properties of soy protein isolates that were modified by varying solutions of urea (1, 3, 5, and 8 M) or guanidine hydrochloride (GH) (0.5, 1, and 3 M) and applied on walnut, cherry, and pine plywoods. Soy proteins modified by 1 and 3 M urea showed greater shear strengths than did unmodified protein. The 3 M urea modification gave soy protein the highest shear strength. Soy proteins modified with 0.5 and 1 M GH gave greater shear strengths than did the unmodified protein. The 1 M GH-modified soy protein gave the highest shear strength. Compared to the unmodified protein, the modified proteins also exhibited higher shear strengths after incubating with two cycles of alternating relative humidity, zero delamination, and higher remaining shear strengths after three cycles water soaking and drying. These results indicate that soy proteins modified with urea and GH enhance water resistance as well as adhesive strength. Secondary structures of globule proteins may enhance adhesion strength, and the exposure of hydrophobic amino acids may enhance water resistance. Proteins modified by 3 M urea or 1 M GH may have higher content of secondary structure and more exposed hydrophobic amino acids, compared with other modifications or unmodified proteins.  

Adhesive properties of soy proteins modified by sodium dodecyl sulfate and sodium dodecylbenzene sulfonate

A study was conducted on adhesive and water-resistance properties of soy protein isolates modified by sodium dodecyl sulfate (SDS) (0.5, 1, and 3%) and sodium dodecylbenzene sulfonate (SDBS) (0.5, 1, and 3%) and applied on walnut, cherry, and pine plywoods. Soy proteins modified by 0.5 and 1% SDS showed greater shear strengths than did unmodified protein. One percent SDS modification had the highest shear strength within each wood type tested. Soy proteins modified with 0.5 and 1% SDBS also showed greater shear strengths than did the unmodified protein. The 1% SDBS-modified soy protein had the highest shear strength in all wood samples tested. Compared to the unmodified protein, the modified proteins also exhibited higher shear strengths after incubation with two cycles of alternating relative humidity and zero delamination rate and higher remaining shear strengths after three cycles of water soaking and drying. These results indicate that soy proteins modified with SDS and SDBS have enhanced water resistance as well as adhesive strength. Possible mechanisms for the effects of SDS and SDBS also are discussed.  

Adhesion properties of soy protein with fiber cardboard

Adhesion properties of soy protein isolate (SPI) on fiber cardboard and effects of press conditions, pre-pressing drying time, and protein concentrations on gluing strength were investigated. Shear strength increased as press time, press pressure, and/or press temperature increased. The effect of temperature on shear strength became more significant at high press pressure. The shear strength of the SPI adhesive on fiber cardboard decreased by 12–25% after water soaking. Shear strength increased as pre-pressing drying time increased and reached its maximal value at about 10 min. An SPI/water ratio of 12∶100 (w/w) gave the highest gluing strength. The specimens showed complete cohesive failure (fiber cardboard failure) except for soaked specimens pressed at low press temperature, low pressure, and short press time. Specimens pressed at 25°C and 2 MPa for 5 min with pre-pressing drying time of 10 min and an SPI/water ratio of 12∶100 (w/w) had T-peel strength and tensile bonding strength of 1.15 N/mm and 0.62 MPa, respectively, without water soaking, and 1.11 N/mm and 0.24 MPa, respectively, with water soaking.  

氧化铝陶瓷内衬不锈钢复合钢管的组织与性能

用自蔓延铝热－重力分离法制备了氧化铝陶瓷内初不锈钢复合钢管。测定了复合钢管的机械性能，并用金相显微镜、扫描电子显微镜、Ｘ射线衍射分析仪分析了复合钢管的组织结构，试验结果表明：外层钢管与层衬陶瓷间因形成ＦｅＯ·Ｃｒ２Ｏ３尖晶石相而产生反应润湿，陶瓷层由隐针状内层、柱状中间层和外层树枝晶组成。由于陶瓷与钢管结合模式的改变，复合钢管的压剪强度由普通碳钢复合管的１５．４ＭＰａ提高到不锈钢复合率的２６．５Ｍ  

一种新兴的绿色胶粘剂-浅谈改性植物蛋白基木材胶粘剂

用植物蛋白制作的木材胶粘剂具有可再生、价廉、原料来源广、环保等优点，本文就植物蛋白改性作木材胶粘剂的研究及发展状况进行了较详尽的阐述。  

我国木材工业用胶粘剂的现状、存在问题及对策

本文介绍了脲醛树脂胶粘剂、酚醛树脂胶粘剂、三聚氰胺甲醛树脂胶粘剂、聚醋酸乙烯乳液胶粘剂、聚氨酯胶粘剂、热熔胶粘剂等木材工业用胶粘剂的现状和研究进展。分析了目前木材工业用胶粘剂存在的问题，初步提出了解决问题的对策。  

碳纤维表面处理的新方法

碳纤维表现处理是为了改善表面形态结构和表面化学环境，提高表面能，强化与基体树脂两相界面之间的粘接，从而达到提高复合材料层间剪切强度（ILSS）的目的。  

酚醛改性聚芳基乙炔基复合材料探索

聚芳基乙炔（PAA）树脂具有残碳率高、吸水率低、固化反应为加聚反应、无低分子物副产物逸出等特点，是专为新一代树脂基热防护复合材料而研制的。但其与碳布的浸润性及粘接性能差，碳布增强复合材料的剪切强度较低。本文采用酚醛树脂对PAA树脂进行改性处理，在不降低残碳率的情况下，明显改善了PAA树脂与碳布的粘接性能。改性后碳／聚芳基乙炔复合材料的剪切强度由5．5MPa提高到11MPa以上。  

以聚乙烯醇接枝玉米淀粉为主剂的API胶粘剂

介绍了一种不含甲醛的聚乙烯醇接枝玉米淀粉胶粘剂的合成方法，探讨了改性机理，对聚乙烯醇与玉米淀粉的配比、次氯酸钠的用量、过硫酸钾的用量等影响胶粘剂性能的因素，以及主剂与交联剂PAPI的配比进行了讨论，该胶粘剂可代替脲醛树脂作为木材、胶合板用胶粘剂。  

碳纤维表面处理

本文主要综述了碳纤维表面性质及表面处理方法，通过表面处理能够达到提高碳纤维复合材料层间剪切强度的目的。