双重酯化糯米淀粉标签胶的制备与性能研究

目的 为了进一步提高酯化糯米淀粉标签胶的黏结性能,以达到国家标准。方法 在丁二酸酐酯化糯米淀粉的基础上,利用马来酸酐对其进行二次酯化改性。通过单因素及响应面试验确定出最优条件,并测定其结构特性、黏合强度、剥离强度和耐水时间。结果 马来酸酐二次酯化改性糯米淀粉的最优工艺条件:二次酯化时间为77 min、酯化温度为45.3 ℃、酯化pH为9.0,在此条件下制得的糯米淀粉标签胶的黏合强度为250.672 N/m,剥离强度为216.935 N/m,比未经酯化的标签胶黏合强度提高了55.64%,剥离强度提高了122%;比单一酯化的标签胶黏合强度提高了48.77%,剥离强度提高了76.73%,并且双重酯化后的标签胶耐水性提高。傅里叶红外光谱分析可知,酯化后的淀粉分子在1 730 cm^?1存在酯基特征峰,扫描电镜分析表明二次酯化后淀粉颗粒崩解,表面粗糙,出现凹陷与裂缝。热力学性质表明酯化淀粉具有更低的糊化温度。结论 经过丁二酸酐与马来酸酐双重酯化后,糯米淀粉标签胶的黏结性能与耐水性能大大增强。     

二步交联法改善淀粉胶黏剂的耐水性

以甲苯二异氰酸酯(TDI)和环氧氯丙烷为交联剂,对氧化淀粉进行两步交联改性,提高了淀粉胶黏剂的耐水性。实验结果表明,先用0.8%TDI对氧化淀粉交联改性,再在弱碱性条件下用1.0%的环氧氯丙烷对其进行二次交联,可以使淀粉胶黏剂耐水时间从0.4 h提高到20 h。在两步交联改性之间,用1.0%过硫酸铵(APS)对淀粉分子进行适度的氧化降解,可以降低体系粘度。     

变性淀粉的添加对米淀粉抗老化影响的研究

目的:改善米淀粉制品的抗老化性能.方法:以圆糯米为原料制取湿淀粉,加入不同的改性淀粉,测定老化率和持水率.结果:高粘度变性淀粉和山梨糖醇的交互作用对老化率的影响具有高度的显著性;中粘度变性淀粉,高粘度变性淀粉,高粘度变性淀粉和中粘度变性淀粉的交互作用对糯米淀粉制品持水性的影响具有高度的显著性.结论:添加高粘度的淀粉可提...     

糯米的湿热处理及其结构表征

目的为了解决新糯米制粉峰值粘度过低的问题。方法对糯米进行湿热处理,研究糯米含水量、湿热处理时间和温度对糯米粉粘度等糊化特性的影响,并进行响应面优化。结果得到了湿热处理的最佳工艺条件,温度为70℃,含水量(质量分数)为20%,时间为1.6 h,在此工艺条件下糯米粉的峰值粘度为3.146Pa·s,与原糯米粉相比增加了37.3%,且谷值粘度、最终粘度和崩解值均增加。差示扫描量热仪分析表明,湿热处理后糊化温度有所升高,热焓值无显著性变化。X-衍射图谱表明,结晶度变化不大,且糯米淀粉晶型仍呈A型。通过扫描电镜观察,湿热处理后糯米淀粉粒的表面出现部分孔洞、凹陷和粘结等现象,整体形貌未发生显著变化。结论该工艺能够大幅度提升糯米粉的峰值粘度。     

氧化淀粉胶黏剂的交联改性及其性能研究

用玉米淀粉与过硫酸铵反应制备了氧化淀粉胶黏剂,再与二羟甲基双氰胺(DMDCD)进行交联反应,制备了一种交联改性氧化淀粉胶黏剂。采用红外光谱对样品进行了表征,并讨论了交联改性对氧化淀粉胶黏剂耐水性和贮存稳定性的影响。实验结果表明:DMDCD改性提高了淀粉胶黏剂的耐水性与贮存稳定性;当过硫酸铵质量分数为淀粉质量的1.5%,DMDCD质量分数为淀粉质量的3%时,交联改性氧化淀粉胶黏剂的贮存稳定性在45 d以上,其耐水时间、黏度分别为102 h和1680 mPa.s;红外分析证实了DMDCD与氧化淀粉发生了交联反应。     

酯化改性淀粉的表征

以玉米淀粉为原料,乙酸酐为酯化剂,乙酸为活化剂,浓硫酸为催化剂,对玉米淀粉进行酯化改性。酯化淀粉取代度范围为0-0.5。采用傅里叶红外(FT-IR)、扫描电镜(SEM)、差示扫描量热(DSC)手段对酯化淀粉进行了结构、表观形貌以及热塑性的进行了表征。红外分析显示乙酰基的成功引入,淀粉分子之间的羟基缔合基团打开。SEM显示了引入乙酰基之后淀粉的表面结构的变化:酯化淀粉的结构随着取代度的增加变得更加疏松。DSC显示了酯化淀粉熔融温度的降低,成膜变得可能。     

三聚氰胺甲醛树脂(MF)改性淀粉胶粘剂的研究与应用

以淀粉为主要原料,制备三聚氰胺甲醛树脂(MF),改性淀粉胶粘剂。用红外光谱表征改性的每个阶段,验证其改性机理。X-ray衍射说明了MF对淀粉的结晶度影响不大,MF主要是交联改性的淀粉的无定型区;扫描电镜显示MF对淀粉颗粒形成塑化,改变了淀粉颗粒的表面形貌,通过交联形成网状结构。结果表明,MF改性提高了淀粉胶粘剂的耐水性与稳定性,常温下保存7 d后,其耐水时间、粘度分别为96 h和500 mPa.s。     

淀粉改性的研究进展

淀粉作为可再生的绿色生物材料具有巨大的潜在利用价值,但原淀粉本身的不足限制了其推广应用。为了提高淀粉的性能,需要对其进行改性处理。近年来,关于淀粉改性的研究报道引起了广泛关注,淀粉被赋予越来越多的功能特性。淀粉改性后,粘接力、冻融稳定性能、吸水以及热稳定性明显提高,广泛应用于胶粘剂、食品、污水处理以及生物医药等工业生产领域。概述了目前淀粉改性研究中的多种手段,主要包括化学改性(氧化、交联、接枝共聚、酯化、醚化和复合改性)、物理改性(热液处理、微波处理、电离放射线处理、超声波处理、球磨处理和挤压处理)、酶改性三大类,并综述了其研究进展及应用,最后对改性淀粉的研究现状以及改性方向进行了分析与展望。     

硬脂酸改性纳米ZnO的研究

采用酯化反应法,以水为溶剂,采用硬脂酸对纳米ZnO的表面进行改性,对改性效果进行测试表征。其最佳工艺条件为:硬脂酸质量分数为6%,反应温度为90℃,反应时间为90 min。结果表明,改性后的ZnO粒子呈纳米级的分散,亲油化度值达到72.31%,吸水率达到3.04%;经表面改性的纳米ZnO表现了很好的亲油疏水性;改性后的纳米ZnO表面引入了硬脂酸的官能团,使其表面羟基的数目明显减少,其改性机理为纳米ZnO表面羟基与硬脂酸分子中的羧基发生了类似醇和酸的酯化反应。     

磺酸盐改性无烟煤对丁苯橡胶复合材料微观结构和力学性能的影响

无烟煤经磺酸盐球磨改性后,与丁苯橡胶(SBR)进行熔融共混,制得改性无烟煤/SBR复合材料,然后对改性无烟煤和无烟煤/SBR复合材料的表面性质、微观结构和力学性能进行了表征测试。结果表明,磺酸盐与无烟煤发生了酯化反应,改性无烟煤片层结构被剥离,多以细小鳞片状呈现,颗粒变小,分散均匀,改性无烟煤的微观结构和表面性质发生了明显变化;无烟煤颗粒在橡胶复合材料中均匀分散后,其填充橡胶复合材料的力学性能和交联密度显著增加,在填充70份时,拉伸强度达到10.7MPa,交联密度增大为116mol/m3,改性无烟煤补强效果明显。     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

Certification Becomes Important for the I Quality; and Safety Supervision of the Chinese Liquor Sector

The end of 2007, over 200 unit products of more than 80 Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits, beer, wine, yellow wine, fruit syrup wine and others, and cover over 80% of the national top-branded liquor products.……     

Deposition and Coating Properties on CVD Tungsten

Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster.     

Analysis of marine hydrobiont lipid extracts as possible cryoprotective agents

We studied a combined effect of the cryoprotectants both of lipid and carbohydrate origin at the presence of DMSO or without it on cell viability and the RNA synthesis in the embryonic mollusc and echinoderm cell cultures obtained at different developmental stages. Cryoprotective properties of exogenous lipids correlated with their thermotropic behavior. Lipid extracts from marine hydrobiontes, which thermal transitions are characterized by relatively small part of calorimetric thermogram area lying at temperatures above 0 °C (6–18%), were found to possess a considerable cryoprotective activity. The results are discussed in relation to the prediction of the cryoprotective activity of lipid extracts for marine animal cells. In addition, it was found that marine invertebrate cells can be cryopreserved without DMSO at the presence of trehalose and lipid extracts of some marine hydrobiontes.     

Low-Temperature Properties of Silver

Pure silver is used extensively in the preparation of high-temperature superconductor wires, tapes, films, and other configurations in which the silver not only shields the superconducting material from the surrounding materials, but also provides a degree of flexibility and strain relief, as well as stabilization and low-resistance electrical contact. Silver is relatively expensive, but at this stage of superconductor development, its unique combination of properties seems to offer the only reasonable means of achieving usable lengths of conductor. In this role, the low-temperature physical (electrical, thermal, magnetic, optical) and mechanical properties of the silver all become important. Here we present a collection of properties data extracted from the cryogenic literature and, to the extent possible, selected for reliability.     

Early ironwork in Biscay: Survey,excavation, experimentation and materials characterization. An integral study of the mountainside ironworks (ferrerías de monte or “haizeolak”)

ABSTRACT

The production of iron in Biscay (Basque Country, Spain) has been a hallmark of this territory of the North of the Iberian Peninsula throughout its history. The Archaeology team of the Basque Country Mining Museum has spent 13 years, so far, studying the origins of this activity through the evidences left at the old pre-hydraulic iron production workshops known as mountainside ironworks (ferrerías de monte) or haizeolak. It has catalogued 170 archaeometallurgical sites of this type in Biscay, and the archeological excavation of some of them has led to the knowledge of the different stages of the production process that took place in these workshops. The team has also experimentally reproduced the work carried out in a mountainside ironworks from the High Middle Ages, and it has currently started the characterization process of this type of activity through the study of the collected materials.     

Mechanism Study on the Wear of CrAlTiN Coated High-Speed Steel Twist Drills Under Dry Cutting Conditions

As demands about environment protection are growing up, dry cutting technology is getting more and more concerns from all over the world. Main works performed here are study on dry cutting performances and wear mechanisms of M2high-speed steel (HSS) twist drills with CrAlTiN multicomponent coatings, which was deposited using magnetron sputter ion plating system, in drilling 45 and 30CrMnSiA steel, and their comparisons to those in drilling the same steel but using monolayer CrN and commercial TiN coated drills. Drilling performances of drills are evaluated mainly through the measurements of width on outer corner flank land and the cutting forces. Results show that performances of CrAlTiN coated drills are better than those of monolayer CrN and TiN coated drills. In drilling 45 and 30CrMnSiA steel, the average tool life of the CrAlTiN coated drills are 17.2 and 11.8 times higher than those of the uncoated drills. Observing wear of the drill with scanning electronic microscope, results show that there is no crack or spallation of the CrAlTiN coatings in wear zones. Main mechanism of the wear here is adhesion.     

Study on Bond Ability of Arc-Spraying Coatings with Different Surface Pretreatment on Cast-Iron

Arc spraying coatings are widely used in various applications, but uncommon in cast iron substrate. Different surface pretreatment technology is tested on substrates of gray cast iron. Surface roughness and residual stress were measured by TR200 and X-ray diffraction analyzer. Influence of different surface pretreatment methods ( dry blasting and fusebond) on roughness and residual stress was analyzed. The arc-sprayed coatings of wire 3Cr13 (φ2mm) on gray cast iron substrate is studied. The microstructure and interface of bonding layer were observed by SEM. The bond strength was taken by tensile test. Results show that bond strength with grit blasting is higher than fuse-bond; it is feasible to make wire 3Cr13 coating with arc spraying on cast iron substrate roughened by grit blasting.     

Structural Characteristics of TiO2 Ceramic Coating by Micro-Plasma Oxidation

TiO2 ceramic coatings with thickness of 20 μm were formed on the surface of pure titanium by micro-plasma oxidation. Their micro-structures were investigated by by using X-ray diffraction and their surface images were detected by using scan electronic microscope. There were three kinds of TiO2 coatings, pure anatase type TiO2 phase, mixed phases consisted of rutile type TiO2 phase and anatase type TiO2 phase, pure rutile type TiO2 phase. The coating surface with the pure anatase type TiO2 phase is rough, while the coating surface with the pure rutile type TiO2phase is smooth. The upper coating surface with the mixed type TiO2 phases is anatase type TiO2 structure and the subsurface of the TiO2 coating is rutile type TiO2structure.     

Evaluation of fatigue life of steel using steel grain size

The insightful discussion of the relationship between the construction of metallographic and fatigue life and proposition of mathematical relationships describing this relationship was conducted in the paper. This paper presents a method for estimating the fatigue life, based on the construction of the microstructural material taking into account the grain size and the participation of ferrite and pearlite phase.