热拉伸对尼龙6薄膜微观结构与力学性能的影响

本工作研究了尼龙6(PA6)薄膜的热拉伸工艺对其微观结构和力学性能的影响规律.在玻璃化转变温度(Tg)到熔点(Tm)之间的加工温度范围内对PA6薄膜进行了不同程度的单向热拉伸,并对其微观结构与力学性能进行表征测试.结果表明:随着拉伸温度和拉伸比的提高,PA6中的β晶型向α晶型的转变程度增大,促进了PA6中分子链沿拉伸方向的结晶和取向,从而显著提高了PA6的结晶度,并发现其无定形区减少,玻璃化转变温度(Tg)提高.拉伸温度的提高有利于PA6中α(002)晶面的生长,高温下拉伸形成的α晶体更完整;随着拉伸比的提高,形成的α晶体完整程度先升高后降低.热拉伸后的PA6薄膜的拉伸强度和储能模量增加,断裂伸长率降低;与未拉伸的PA6薄膜相比,拉伸温度为160℃、拉伸比为3的PA6薄膜拉伸强度增加371％,断裂伸长率降低235％.     

双向拉伸聚对苯二甲酸乙二醇酯/聚己二酰间苯二胺的形态结构与阻隔及力学性能

以聚对苯二甲酸乙二醇酯(PET)和聚己二酰间苯二胺(MXD6)为原料,通过熔融共混和同步双向拉伸的方法制备了双向拉伸PET/MXD6复合材料。通过扫描电子显微镜、气体渗透试验、差示扫描量热仪及力学性能测试研究了双向拉伸PET/MXD6复合材料的形态结构及其对复合材料气体阻隔性能、力学性能及结晶性能的影响。研究结果表明,通过同步双向拉伸,使MXD6在PET基体中的分散相形态由零维球形变为高长径比的二维片状,这些形态使得双向拉伸复合材料的气体阻隔性能与力学性能大幅提高,其中质量分数20%的PET/MXD6复合薄膜材料在拉伸倍率为3×3时,较纯PET相比提升了2.3倍。与此同时,断裂伸长率与拉伸强度也大幅提高,最大增幅分别达到10.6倍和3.1倍。     

树形分子对尼龙11/尼龙6共混物的增韧增强

在尼龙11／尼龙6共混物中添加4．0代树形分子，提高了共混物的性能；研究了不同树形分子含量对共混物力学性能的影响。结果表明，与尼龙11／尼龙6直接共混物相比，在本实验中添加0．25％树形分子所得共混物的拉伸强度、断裂伸长率有明显提高，缺口冲击强度略有增加。     

拉伸对PA6/PET/AX8900薄膜直线易撕裂性能的影响

以PA6为基体，引入PET相，制备五种不同配比的PA6/PET/AX8900复合材料薄膜和双向拉伸薄膜，采用SEM、DMA、DSC等研究了双向拉伸前后PA6/PET/AX8900复合材料薄膜的微观形貌、热力学和结晶行为，探讨了复合材料薄膜的直线撕裂性能、力学性能、阻隔性能和光学性能，同时研究相容剂EAG(AX8900)对PA6与PET相容性的影响。研究结果表明，添加3%AX8900对PA6/PET复合材料薄膜有明显的增容效果，PET在PA6基体中分散良好；当PET添加量从0%增加到35%时，PA6/PET/AX8900复合材料薄膜熔点降低，与此同时，由于PET中刚性苯环的存在，结晶温度从187.01℃下降到183.47℃。力学性能测试显示，当PET添加量为25%时，PA6/PET/AX8900薄膜拉伸强度相较于纯PA6膜提升25%,断裂伸长率基本不变。当拉伸比为3×1时，PET添加量为25%的PA6/PET/AX8900双向拉伸薄膜的拉伸强度较纯PA6提高了88%。直线易撕裂测试结果表明，当PET添加量从0%增加到25%时，复合材料薄膜的撕裂偏差从100%降低到46%。PET添加量为2...     

双向拉伸工艺对PLA薄膜结晶、力学、阻隔及光学性能的影响

研究不同拉伸工艺对双向拉伸聚乳酸（BOPLA）薄膜的晶体结构及宏观性能的影响。采用挤出流延工艺制备PLA预制膜,在双向拉伸试验机上制备了不同拉伸工艺下的BOPLA薄膜,研究了薄膜的结晶、力学、阻隔及光学性能。结果表明,随着拉伸比的增大,拉伸诱导PLA薄膜结晶,相对结晶度提高至37.84%,较1×1（未拉伸）的BOPLA薄膜提高了近3倍,玻璃化转变温度（Tg）提高至65.32 ℃。沿纵向（MD）、横向（TD）的抗拉强度得到提升,分别达到84.47, 93.44 MPa,而断后伸长率在拉伸比为2×2时达到最大值,分别为39.81%、42.29%。拉伸温度的升高,导致分子链热运动加快,链段向晶核扩散和堆砌速度提高,结晶速率加快,从而相对结晶度提高,提升至48.99%,且热诱导结晶促进了更加完善的晶型（α晶型）的生成。拉伸温度升高有利于提高双向拉伸PLA薄膜的氧气阻隔性能,130 ℃时氧气透过系数下降至8.61×10-16 cm3·cm/（cm2·s·Pa）,相比80 ℃拉伸温度下降了59.7%,但抗拉强度、断后伸长率都呈下降趋势。这是因为快速的链松弛会促使分子链解取向,限制应变诱导结晶,破坏分子链的缠结网络。拉伸速率的增加,增强了非晶链的取向和结晶。当拉伸速率为600%/s时,薄膜沿MD方向的断后伸长率得到大幅提升,能提升至37.62%。     

钢渣制备水滑石阻燃剂及其在EVA复合发泡材料中的应用

以钢渣为原料合成了磷酸根型水滑石(P-LDHs),并用十二烷基硫酸钠(SDS)插层P-LDHs得到改性水滑石(SDS-P-LDHs).分别将P-LDHs,SDS-P-LDHs和膨胀石墨、EVA共混,发泡得到EVA复合发泡材料.利用XRD,XRF,FT-IR,SEM,TEM对P-LDHs和SDS-P-LDHs的形貌结构进行表征.结合极限氧指数(LOI),垂直燃烧(UL-94),SEM,TG,拉伸强度、断裂伸长率等测试,讨论了P-LDHs和SDS-P-LDHs用量对EVA复合发泡材料的阻燃性能和力学性能的影响.结果表明,P-LDHs和SDS-P-LDHs的加入显著提高了EVA复合发泡材料的阻燃性能,可起到良好的成炭作用.相比P-LDHs,SDS-P-LDHs与EVA基体相容性更好,当SDS-P-LDHs添加量为30％(质量分数)时,LOI达到27.5％,UL-94达到V-0级别,拉伸强度和断裂伸长率分别为2.27 MPa和251％,体系综合性能达到最佳.     

异佛尔酮二异氰酸酯反应增容聚己二酸-对苯二甲酸丁二酯/聚乳酸生物降解阻隔膜的结构与性能

以异佛尔酮二异氰酸酯(IPDI)为聚己二酸-对苯二甲酸丁二酯/聚乳酸(PBAT/PLA)共混物的增容剂,通过熔融共混法制备了PBAT/PLA/IPDI共混粒子并吹制得到薄膜。采用红外光谱、扫描电镜、差示扫描量热分析、拉伸试验、热重分析和水蒸气透过率测试等研究了不同含量IPDI对共混薄膜形态结构、结晶性能、力学性能、热性能和阻隔性能的影响。结果表明,IPDI的异氰酸酯基团能与PBAT和PLA发生化学反应,分散相尺寸变小,两相界面变得模糊,有效改善了共混物的相容性。随着IPDI含量的增加,共混物中PBAT的结晶度升高,薄膜的拉伸强度逐渐增大,水蒸气阻隔性能呈现先增大后减小的趋势。当IPDI质量分数为0.5%时,PBAT/PLA/IPDI薄膜的横纵向拉伸强度相较于纯PBAT/PLA薄膜分别提升了74.2%和28.6%,断裂伸长率维持在790%和244%,水蒸气透过率降低了38.2%,表现出良好的力学和水蒸气阻隔等综合性能。     

加载速率对低密度聚乙烯薄膜拉伸性能的影响

研究了在不同加载速率下低密度聚乙烯薄膜横向、纵向拉伸强度和断裂伸长率的变化规律.实验结果表明,其横向拉伸强度和断裂伸长率大于纵向拉伸强度和断裂伸长率;拉伸速率对拉伸强度和断裂伸长率没有显著影响.     

SYNTHESIS AND MECHANICAL PROPERITIES OF REACTABLE NANO-SILICA/PA1010 HYBRID COMPOSITES

以可反应性纳米SiO2(RNS)为填料, 用熔融共混法制备SiO2/尼龙1010纳米复合材料, 表征其力学性能并研究了增强和增韧机理. 结果表明,在熔融共混过程中RNS与尼龙1010发生了强烈的界面相互作用, 提高了材料的拉伸强度、断裂伸长率和弹性模量; 而纳米SiO2的表面有机修饰层使材料的韧性有所提高.纳米SiO2质量分数为1.0 %的复合材料拉伸强度最大, 比纯尼龙1010的高4%;而0.7%纳米SiO2 的复合材料断裂伸长率和弹性模量最大, 分别比纯尼龙的高16.6%和13.4%.     

可反应性纳米SiO2/尼龙1010复合材料的制备和力学性能

以可反应性纳米SiO2(RNS)为填料,用熔融共混法制备SiO2/尼龙1010纳米复合材料,表征其力学性能并研究了增强和增韧机理.结果表明,在熔融共混过程中RNS与尼龙1010发生了强烈的界面相互作用,提高了材料的拉伸强度、断裂伸长率和弹性模量;而纳米SiO2的表面有机修饰层使材料的韧性有所提高.纳米SiO2质量分数为1.0%的复合材料拉伸强度最大,比纯尼龙1010的高4%;而0.7%纳米SiO2的复合材料断裂伸长率和弹性模量最大,分别比纯尼龙的高16.6%和13.4%.     

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.