大豆蛋白胶黏剂制备过程中的黏度变化及其黏合性研究

运用Brabender黏度仪研究改性大豆分离蛋白(SPI)胶黏剂制备过程中的黏度变化,并对它们的黏合性进行了研究.结果发现:改性SPI胶黏剂制备过程中的黏度变化趋势大致相同;制备过程中,改性SPI胶黏剂的起始黏度随NaOH浓度的增加而增加,由90BU增加到550 BU,而尿素、三聚磷酸钠、Na3PO4对其影响较小;0.7%(WNaOH/WSPI)NaOH改性SPI胶黏剂的黏合性较好,其T剥离强度为140.8 g/cm,比未改性SPI胶黏剂增加了61.8%.     

谷氨酰胺转胺酶对大豆分离蛋白改性机理的研究

利用微生物谷氨酰胺转胺酶(MTG)对大豆分离蛋白(SPI)进行改性，结果表明：SPI浓度、MTG浓度、反应温度、反应时间和pH值对SPI改性具有显著影响。改性SPI的凝胶性为11．6kcp，比对照提高了1833％。十二烷基硫酸钠-聚丙稀酰胺凝胶电泳结果表明，经MTG改性，SPI可在分子间生成共价键，形成相对分子量较大的聚合物，从而增加了SPI的凝胶性。     

涂料用大豆分离蛋白溶液的碱改性研究

较为系统地研究了涂料用大豆分离蛋白(SPI)溶液的碱改性工艺条件,着重考察了SPI质量分数、氢氧化钠用量、改性温度、改性时间对SPI溶液改性的影响,并用紫外、红外光谱对改性SPI进行表征。结果表明,合理的改性工艺条件为:SPI质量分数8.16%,0.05 g/mL氢氧化钠用量9mL(水和氢氧化钠溶液总体积180 mL),改性温度60℃,改性时间30 min。     

尿素改性大豆分离蛋白与粘胶共混性能的研究

通过尿素改性改变大豆分离蛋白(SPI)分子的空间结构,使其能更好地与粘胶共混。以共混膜中蛋白保留量为指标,考察了尿素浓度、SPI浓度、亚硫酸钠浓度、pH、温度的影响;并采用正交实验优化蛋白质改性条件。优化的改性条件为:尿素浓度6 mol/L,SPI浓度8%,亚硫酸钠浓度1.0%,pH 9,温度25℃,此时共混膜中蛋白保留量为13.87%。     

SDS改性大豆分离蛋白胶粘剂的性能研究

采用碱溶酸沉法从低温脱脂大豆粉中提取大豆分离蛋白(SPI),应用十二烷基硫酸钠(SDS)对SPI进行化学改性,研究不同浓度的SDS溶液对改性SPI胶粘剂的热性能、流变性能以及粘接性能的影响.结果表明,随着SDS浓度的增加,改性SPI胶粘剂的变性温度及变性焓均有下降,表观黏度随着SDS浓度的增加而增大.SDS改性显著提高了SPI胶粘剂在木片胶合中的粘接性能、耐候性能和耐水性能,当改性试剂SDS浓度为1.0%时,其性能最佳.     

氮气对改性大豆分离蛋白功能性的影响

利用氮气对大豆分离蛋白(SPI)进行改性，研究结果表明充氮气、反应温度、反应时间、充氮量四因素对SPI改性均有影响。通过正交试验确定了经氮气改性的SPI凝胶性、保水性、乳化性和乳化稳定性的4组最佳处理组合。试验表明改性后SPI的凝胶性、保水性、乳化性和乳化稳定性分别比对照样提高了100％、210％、7％和91％。     

谷氨酰胺转胺酶对大豆分离蛋白改性机理的研究

利用微生物谷氨酰胺转胺酶 (MTG)对大豆分离蛋白 (SPI)进行改性 ,结果表明 :SPI浓度、MTG浓度、反应温度、反应时间和pH值对SPI改性具有显著影响。改性SPI的凝胶性为11 6kcp ,比对照提高了 1833%。十二烷基硫酸钠 -聚丙稀酰胺凝胶电泳结果表明 ,经MTG改性 ,SPI可在分子间生成共价键 ,形成相对分子量较大的聚合物 ,从而增加了SPI的凝胶性。     

工业改性对大豆蛋白结构及大豆蛋白-肌原纤维蛋白复合凝胶的影响

采用工业热改性、工业碱改性、工业糖基化改性、工业氧化改性4种方法对大豆分离蛋白(soybean proteinisolate,SPI)进行改性处理,研究其对SPI结构的影响,进而探讨改性蛋白与肌原纤维蛋白(myofibrillar protein,MP)制成的复合凝胶的质构特性及凝胶特性。结果表明:4种工业改性对SPI亚基组成并未造成显著影响,但是均减少了SPI的α-螺旋和无规卷曲结构相对含量,并增加了β-折叠与β-转角结构相对含量;工业热改性、工业碱改性、工业糖基化改性处理显著增加了SPI的二硫键含量并降低了SPI的游离巯基含量,而工业氧化改性显著降低了SPI的二硫键含量(P0.05),且4种工业改性处理均改变了SPI的二硫键构型;4种工业改性蛋白的酪氨酸残基均趋向于"暴露式",工业热改性、工业碱改性、工业糖基化改性处理使色氨酸残基趋向于"暴露"态,而工业氧化改性导致氧化蛋白聚集使色氨酸残基被包埋。SPI-MP复合凝胶的质构特性结果表明,工业热改性、工业碱改性、工业糖基化改性3种改性SPI与MP形成的复合凝胶硬度、弹性等质构特性均显著优于对照SPI(P0.05),而工业氧化改性SPI形成的混合凝胶除黏结性外各项质构特性均差于对照SPI。观察SPI-MP复合凝胶扫描电镜图可知,工业热改性、工业碱改性、工业糖基化改性SPI形成的复合凝胶更加致密均匀,工业氧化改性SPI与MP形成的复合凝胶粗糙多孔。     

转谷氨酰胺酶改性大豆分离蛋白条件研究

利用微生物转谷氨酰胺酶(MTGase)对大豆分离蛋白(SPI)进行改性,探讨pH、反应温度、反应时间、底物浓度、酶/蛋白质比对SPI改性影响,采用正交试验优化改性条件。结果显示,酶/蛋白质比和底物浓度对SPI改性影响较小;pH、温度和时间对该改性作用影响较大,该3种因素对SPI改性影响大小依次为pH、温度和时间;MTGase改性SPI的最佳条件为pH 5.5、温度55℃、时间30 min、底物浓度2.0%、酶/蛋白质比10 U/g。     

酶改性大豆分离蛋白的制备及产品功能性的研究

为了改善碱溶酸沉法大豆分离蛋白产品(简称SPI)的功能性,采用有限酶解的方法,从6种蛋白酶中选出中性蛋白酶(Neutrase)作为改性用酶.通过单因素实验,分析了底物浓度,E/S,反应时间对水解度和氮收率的影响,并通过正交实验确定制备酶改性大豆分离蛋白(简称ESPI)的最佳工艺参数为:底物浓度为3%,E/S为1 200U/g,时间为60 min.得到的ESPI的蛋白含量与SPI相近,但NSI由SPI的90%提高到97%.而且在功能性方面,ESPI也得到了很好的改善,尤其是乳化性和起泡性.     

大豆蛋白作为胶粘剂应用的研究进展

大豆蛋白作为胶粘剂应用的改性方法有盐、硫化物、碱、胰蛋白酶、尿素、盐酸胍、SDS、SDBS、酰化和磷酸化法。简述了改性大豆蛋白作为胶粘剂的研究现状以及改性后的大豆蛋白应用在木板上的胶粘特性的变化情况。大豆蛋白经改性后其胶粘特性有所变化,变化情况受改性剂浓度的影响,改性后蛋白质的部分二级结构展开,胶粘强度提高,同时改性可以暴露出包埋在蛋白质内部的疏水基团,提高大豆蛋白胶粘剂的耐水性。     

Investigation of modified water glass as adhesive for wood and particleboard: mechanical,thermal and flame retardant properties

Water glass (WG) is an inorganic binder with excellent fire resistance in porous materials but has limited application to wood bonding. In this work, modified WG adhesive was developed and the effect of modification on the properties of adhesive and particleboard bonded with it was investigated. The bonding strength of WG adhesives increased by the modification with boric acid and aminofunctional silane. Stable siloxane linkage can lead to enhanced bonding. Particleboards with modified WG were manufactured with a target density of 750 kg m^?3. The silane was selected as the best modifier; it was the only one to meet the requirements of EN 312 (Type 2). The reaction of amino groups onto the surface of wood was confirmed by Fourier-transform infrared spectrum. All particleboards produced with WG adhesives showed resistance to fire comparable to those with urea formaldehyde in the combustion test for 30 min. As a result of this investigation, WG modified with silane could be a desirable alternative to current synthetic adhesives for wood composites and fire resistance application.     

乳化剂十二烷基硫酸钠(SDS)对淀粉基木材胶特性的影响

研究了乳化剂十二烷基硫酸钠(SDS)对淀粉胶胶接强度和低温储藏稳定性的影响。对比没有加入SDS的淀粉胶,加入SDS后胶的粘结强度均有所提高,最佳添加量为淀粉用量的1%,此时干强度提高了60.1%,湿强度提高了211.5%。此外,SDS可以有效地提高反应的接枝参数,接枝率提高了93.7%,接枝百分率提高了83.8%。耐低温稳定性实验证明,加入乳化剂可以增加淀粉胶通过冷藏-解冻循环的次数。动态时间扫描实验和TEM的结果证明,加入SDS有利于削弱淀粉分子之间的氢键作用力,促进淀粉与单体之间发生接枝反应,从而改善了淀粉胶乳液的粘结性能及稳定性。     

苯乙烯改性丙烯酸酯类乳液粘合剂的制备及热性能分析

探讨了预乳化种子乳液聚合法制备苯乙烯改性丙烯酸酯类乳液粘合剂(SA).研究了苯乙烯单体含量对胶膜吸水性和胶接抗剥离性能的影响,利用差示扫描量热仪(DSC)和热重分析仪(TG)测试了SA的热性能.结果表明:丙烯酸酯类共聚物分子链中引入苯乙烯后,提高了共聚物分子链的耐水性和耐热性,玻璃化转变温度升高;将其涂膜于棉织物表面,棉织物的热分解温度提高至370℃以上,具有较好的热稳定性.     

增塑和变性大豆蛋白塑料抗水性

将甲酰胺、甲酰胺―甘油复合增塑剂、脲和SDS以不同比例与大豆蛋白混合,经模压成型制成大豆蛋白塑料,并采用材料实验机和鼓风干燥箱研究该塑料耐水性和吸水率。结果表明,采用甲酰胺增塑、甲酰胺―甘油复合增塑或脲变性处理,大豆蛋白塑料2 h和24 h吸水率降低、R值增大,表明塑料抗水性得以改善;而采用SDS变性处理,塑料2 h和24 h吸水率提高,R值减小,塑料抗水性降低。     

我国木材工业用胶黏剂研究与应用现状及发展趋势

介绍了我国木材工业用胶黏剂在生产原料、工艺与技术、工业化设备等方面的研究与技术革新,重点综述了环保型脲醛树脂、酚醛树脂、异氰酸酯类胶黏剂、大豆蛋白胶黏剂、淀粉胶黏剂以及高性能、多功能胶黏剂的研究进展与应用现状,并对我国木材工业用胶黏剂的发展趋势进行了展望。     

植物油料蛋白木材胶黏剂改性的研究进展

植物油料蛋白胶黏剂具有来源广泛、无毒、可再生及制备简单等优点,但胶接强度低、耐水性能差、易霉变等问题限制了其发展和应用。综述了近年来几种主要植物油料蛋白胶黏剂如大豆蛋白胶黏剂、花生蛋白胶黏剂、棉籽蛋白胶黏剂等在木材行业的研究和应用现状,重点阐述了提高植物油料蛋白胶黏剂耐水性能的改性方法,包括物理改性、变性剂改性、接枝改性、交联改性、仿生改性、酶改性、纳米材料改性、复合改性等,指出了植物油料蛋白胶黏剂存在的问题,并对未来发展方向和应用前景进行了展望。     

六羟树脂改性对人造板生产用淀粉胶粘剂性能影响的研究

研究了六羟树脂改性对淀粉胶粘剂性能的影响。结果表明,六羟树脂与淀粉在催化剂存在的条件下发生了醚化反应,最佳改性条件为:六羟树脂添加量7mL/100g淀粉胶,催化剂(柠檬酸)添加量0.3g/100g淀粉胶,反应温度65℃,反应时间1h。将最佳改性条件下制备的淀粉胶粘剂用于刨花板的压制,结果表明,六羟树脂改性在保证淀粉胶流动性的情况下,提高了所制刨花板的内结合强度和耐水性。     

Hydroxymethyl furfural-modified urea–formaldehyde resin: synthesis and properties

Considering the importance of urea–formaldehyde (UF) resins in the wood industry, this work reports on a new bio-based modification of UF resins. The use of 5-hydroxymethyl furfural (HMF) is motivated by the current concerns about the effects of formaldehyde on human health. UF and urea–HMF–formaldehyde (UHF) resins were synthesized by an alkaline-acid method and characterized by FTIR, thermogravimetric analysis, and differential scanning calorimetry. The UHF, as a newly modified polymeric resin, was thermally characterized, and it was found that its thermo-stability and char yield was improved. In order to investigate the performance of the UHF, the preparation of particleboards with the UHF as adhesive, as well as its film formation ability have been studied. The UHF films formed on wood panels were uniform without any crack. Film formation ability of the UHF resin was improved due to the presence of more hydroxyl groups as well as furan rings of the HMF moieties resulting in more activated groups to be bonded by wood. Furthermore, formaldehyde release of the particleboards bonded by UHF was significantly lower than that of which bonded by the UF resin. Lab particleboards using the UHF resins showed higher modulus of rupture, modulus of elasticity, and internal bond compared to boards with UF resins, as well as lower water absorption and thickness swelling. Based on these results UHF resin can be considered as a possible candidate as adhesive for wood and wood based panels.     

Failure mechanisms in wood joints bonded with urea-formaldehyde adhesives

Wood joints bonded with urea-formaldehyde (UF) are weakened by cyclic swelling and shrinking. To study the failure mechanisms in UF-bonded joints, specimens were bonded with unmodified, modified (amine), or phenol formaldehyde adhesive and subjected to accelerated aging. Modification of the adhesive properties increased the cleavage fracture toughness and shear strength of bonded joints and improved the resistance of joints to cyclic swell-shrink treatment and accelerated moist-heat aging. Joints bonded with some modified urea-formaldehyde adhesives were as resistant to these treatments as joints bonded with phenol formaldehyde. Physical and mechanical origins of the improved adhesive performance were determined by microscopic analysis. Cure-shrinkage stresses precracked unmodified adhesive layers and damaged the wood interphase. The damaged interphase was especially susceptible to the effects of cyclic swelling and shrinking stresses. Certain modifiers reduced or eliminated cure-shrinkage cracking and damage to the wood. Moist-heat aging caused molecular scission in the bulk unmodified adhesive layer as revealed by the onset of shear cracking in the adhesive layer and erosion of exposed surfaces. Certain modifiers reduced or eliminated molecular scission and erosion responsible for adhesive weakening in moist-heat aging. We conclude that incorporating flexible amines in the adhesive structure improves the durability and stability of UF-bonded joints.