改性聚偏氟乙烯超滤膜的制备与性能的研究

以接枝马来酸酐的改性聚偏氟乙烯(PVDF-g-MAH)为膜材料,采用浸没沉淀相转化方法制备超滤膜.在绘制PVDF-g-MAH-溶剂-水体系的三元相图基础上,研究并讨论铸膜液中溶剂体系、聚合物浓度以及添加剂浓度配比对膜性能和结构的影响,比较了接枝前后超滤膜的亲水性和抗污染性.研究结果表明:在聚合物-溶剂二元体系发生相分离过程中,4种溶剂体系所需非溶剂(水)的量的顺序为:DMAC>NMP>DMF>DMSO;以DMAC溶剂制备的铸膜液,制得的膜表面相对致密,纯水通量小,截留率高;随着聚合物浓度的提高,膜的通量下降,截留率提高;同时SEM照片也显示了随聚合物浓度的增加,超滤膜表层趋于致密,支撑层指状孔孔径缩小,孔数增多;超滤试验结果表明,在截留率相同的前提下,用PVDF制备的超滤膜纯水通量为104.6 L/(m2·h),而PVDF-g-MAH制得的超滤膜纯水通量为230L/(m2·h),同时对比了连续超滤BSA溶液12 h后的膜通量衰减状况,两种膜的通量的衰减率分别为36%和15.4%,表明以改性材料制备的超滤膜的亲水性和抗污染性能均得到提高.     

基于RTIPS-NIPS法制备含辣素衍生结构防污超滤膜及其性能研究

采用原位聚合法,将含辣素衍生结构功能单体N-(2-羟基-3-甲基-6(甲硫基)苄基)丙烯酰胺(HMMBA)通过物理共混引入聚砜(PSf)铸膜液中,并通过反相热诱导相分离法与非溶剂诱导相分离法(RTIPS-NIPS)联用进行高通量防污超滤膜的制备.系统考察了HMMBA含量对膜的结构形态、亲水性、分离性能和抑菌性能等的影响.结果表明,当HMMBA添加量达到2%(质量分数)时,超滤膜的接触角由PSf膜的85°降低至62°;机械强度由29.46 N增加至31.71 N;以5 mg/L的腐殖酸为料液进行过滤实验时,改性超滤膜的稳定通量为420 L/(m~2·h),与未改性PSf膜[200 L/(m~2·h)]相比提高了110%;抑菌率达到了97%以上,且通量恢复率由67.59%提升至86.34%.因此,采用RTIPS-NIPS联用将HMMBA应用在超滤膜中既可以提高膜的亲水性、机械性能和分离性能,同时还能够有效抑制膜污染的产生.     

两亲性共聚物P(MMA-co-AMPS)对聚偏氟乙烯超滤膜性能的影响

以2-丙烯酰胺基-2-甲基丙磺酸(AMPS)为亲水单体,甲基丙烯酸甲酯(MMA)为疏水单体,偶氮二异丁腈(AIBN)为引发剂,采用自由基共聚合法制得了两亲性共聚物P(AMPS-co-MMA);以两亲性共聚物P(AMPS-co-MMA)与聚偏氟乙烯(PVDF)共混,通过相转变法制备PVDF/P(MMA-co-AMPS)超滤膜。利用傅里叶变换红外光谱、热失重法表征无规共聚物的组成和热稳定性能。并通过扫描电子显微镜,傅里叶变换红外光谱、吸水率测试、表面润湿性测试,探讨了不同单体摩尔比对PVDF/P(MMA-co-AMPS)超滤膜的结构及性能的影响。结果表明,单体AMPS与MMA间发生自由基聚合生成两亲性共聚物P(AMPS-co-MMA)。PVDF/P(MMA-co-AMPS)超滤膜表面多孔,内部有大孔,存在相对致密皮层和多孔的支撑层。当2-丙烯酰胺基-2-甲基丙磺酸和甲基丙烯酸甲酯的摩尔比为2∶1时,PVDF/P(MMA-co-AMPS)超滤膜吸水率和表面润湿性能最好。     

PVDF/PAA-b-PMMA-b-PAA超滤膜的结构调控和性能评价

采用可逆加成-断裂链转移自由基聚合(RAFT)合成了以聚丙烯酸(PAA)为亲水链段和聚甲基丙烯酸甲酯(PMMA)为疏水链段的两亲性三嵌段共聚物PAA-b-PMMA-b-PAA(PAMA),通过傅里叶变换红外光谱(FTIR)和核磁共振氢谱(~1HNMR)对聚合物进行了化学结构表征.然后以聚偏氟乙烯(PVDF)为成膜物质,PAMA为改性剂,利用非溶剂诱导相转化法制备了一系列PVDF/PAMA共混超滤膜.研究了PAMA含量对PVDF/PAMA膜的表面化学结构、微观形貌、亲水性、渗透性能以及抗污性能的影响.结果表明,当共混膜中PAMA含量增大时,PVDF/PAMA膜的表面孔密度、孔径和粗糙度均呈现不断增大的趋势.当共混膜中PAMA质量分数为18.2%时,纯水通量由未改性的PVDF膜的12.9 L/(m~2·h)增大至130.2 L/(m~2·h),BSA截留率为97.2%,通量恢复率高达97.5%.因此,PVDF/PAMA共混超滤膜的渗透性能和抗污性能有明显提高.     

P(MA-AA)纳米纤维膜的制备及其吸附铅离子的研究

采用溶液聚合法制备丙烯酸甲酯-丙烯酸的共聚物。用水及丙酮分别萃取纯化,以N,N-二甲基甲酰胺(DMF)为溶剂,配成质量分数为22%、26%、30%溶液,通过静电纺丝技术制备P(MA-AA)纳米纤维膜。借助扫描电镜(SEM)观察纳米纤维的表面形态,利用红外光谱对纳米纤维膜进行表征,并研究了P(MA-AA)纳米纤维膜对pb2+吸附性能。结果表明,当P(MA-AA)质量分数在30%时,可纺性较好,其平均直径分布在200~400nm之间;纳米纤维膜吸附pb2+是化学吸附过程,其平衡吸附量为269.35mg/g,而且有着良好的吸附再生性能。     

两亲聚合物的合成及其在聚偏氟乙烯膜改性中的应用

利用异佛尔酮-二异氰酸酯(IPDI)、聚乙二醇(PEG)、甲基丙烯酸-β-羟乙酯(HEMA)和乙二醇(EG)合成了一种新型的聚氨酯丙烯酸酯大分子单体,并进一步与甲基丙烯酸甲酯(MMA)聚合,制备了一种既含有相对疏水链段、又含有相对亲水链段的两亲聚合物.最终产物添加到聚偏氟乙烯(PVDF)原材料中通过L-S相转化法制得聚合物分离膜.通过FT-IR表征了大分子单体的结构,GPC测定了两亲聚合物的分子量;通过纯水渗透通量、对牛血清蛋白(BSA)的截留率、接触角测定和耐污染性实验表征了超滤膜的性能.实验表明,两亲聚合物占聚合物质量分数的5%时,膜的纯水渗透通量由23.4 L/(m2.h)提高到78 L/(m2.h),而截留性能基本保持不变.在两亲聚合物质量分数从0~15%变化范围内,接触角由79°降至62°.膜通量衰减实验表明改性后膜的耐污染性得到提高.     

PLGA/PCL复合材料的制备及其性能研究

在聚乳酸-羟基乙酸(PLGA)中加入聚ε-己内酯(PCL)、柠檬酸三丁酯(TBC),通过溶液共混制备了PLGA/PCL共混聚合物,通过静电纺膜及涂膜法制备了不同比表面积的降解膜,并对共混材料力学性能和膜的降解性能进行了研究。结果表明:柠檬酸三丁酯作为增容剂对整个共混聚合物的韧性和强度有明显的影响;当聚乳酸-羟基乙酸和聚ε-己内酯的质量比为80/20、增容剂柠檬酸三丁酯的用量为6%时,所得共混聚合物的断裂伸长率达到130%、冲击强度达到9.55kJ·m-2。相同条件下加入聚ε-己内酯(PCL)的膜的降解性能优于单一的聚乳酸-羟基乙酸(PLGA)膜,静电纺丝膜降解性能优于流延法膜。     

聚酰胺复合纳滤膜的制备与表征

以聚砜超滤膜为基膜,通过间苯二胺(PDA)与均苯三甲酰氯(TMC)界面聚合制备聚酰胺复合纳滤膜.系统地考察了界面聚合条件对所得复合膜性能的影响及膜对不同类型的无机盐的分离性能.详细表征了基膜与复合膜的表面形貌和接触角.结果表明:最佳聚合条件为:PDA质量分数1.5%,TMC质量分数0.1%,水相浸泡时间3min,反应时间20s,热处理温度80℃,热处理时间3min.在0.6MPa下,对2 000mg/L的MgSO4的截留率和通量分别为95.6%和7L/(m2·h).复合膜对四种不同类型无机盐的截留率的次序依次为Na2SO4MgSO4NaClMgCl2.此外,表面形貌和接触角研究表明通过界面聚合在基膜表面形成了一层聚酰胺功能层.     

PVC/ PVA共混膜的制备及性能研究

采用相转化法制备了聚氯乙烯/聚乙烯醇(PVC/PVA)共混膜,讨论了聚乙烯醇与聚氯乙烯的共混相容性,以及聚乙烯醇含量对共混膜透过性能、亲水性能及机械性能的影响.实验结果表明,聚氯乙烯/聚乙烯醇共混体系为部分相容体系;当铸膜液中聚合物质量分数为12%、聚合物中聚乙烯醇质量分数为10%时,共混膜亲水性较好,水通量可由160.3 L/(m~2·h)增大到298.5 L/(m~2·h),对牛血清蛋白的截留率为82.5%,同时膜的弹性和韧性明显增强;聚乙烯醇可以有效地改善聚氯乙烯超滤膜的亲水性和机械性能,是优良的聚氯乙烯膜共混改性材料.     

新型杂萘联苯聚醚砜酮中空纤维超滤膜的研制

以杂萘联苯聚醚砜酮(PPESK)为膜材料,N-甲基-2-吡咯烷酮(NMP)为溶剂,乙二醇甲醚(EGME)、丁酮和1,4-二氧六环为添加剂,采用干-湿相转化法制备了中空纤维膜.考察了聚合物浓度、添加剂种类、添加剂含量和干纺程对中空纤维超滤膜性能的影响.结果表明,当干纺程为15~20 mm时,聚合物浓度为19%~22%,添加剂为乙二醇甲醚时,中空纤维膜对PEG6000的截留率高于95%,纯水通量为100~120 L/(m2.h).     

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.     

Effect of Permeable Crystalline Material on Steel Reinforcement Corrosion of Concrete

Permeable crystalline materialcan permeate into pores and cracks of concrete and catalyze the reaction between Ca(OH) 2and unhydrated cement to generate a great quantity needle non-soluble crystals, which can stop up the pores and cracks of concrete, and increase the impermeability of concrete. This paper reported the results of a study conducted to evaluate steel reinforcement corrosion of concrete specimens uncoated and coated with permeable crystalline material as well as mixed with the permeable crystalline material. The properties evaluated for corrosion test were water impermeability, water absorption, compressive strength and potential. The results of water impermeability, water absorption, compressive strength clearly showed that the permeable crystalline material could prohibit water, any soluble salts and moisture from penetrating the concrete to cause corrosion, leaking, and other problems, and it did increase the compressive strength, which was favorable for protection of corrosion of reinforcing steel. Moreover, it was concluded from the potential-time curve that the steel reinforcement of uncoated specimen was in the state of activation whereas that of other specimens coated and mixed with the permeable crystalline material was in the state of inactivation. Above all, it was indicated that the permeable crystalline materialis very effective to protect the steel reinforcement of concrete from corrosion.     

The Research and Application About "Dry Peeling Off" Technology for Airplane Surface Paint Layer

In this paper, the principle of spurting take off lacquer were introduced; and with orthogonal method the unsaturate polyester was prepared ;it was easy to peel airplane paint layer off with this material and equipment.     

Quality Study of Honeycomb Core Shaping Without Wax Stabilization

Sandwich panels utilizing honeycomb cores result in lightweight, high-strength units that are very rigid. Indeed, they give honeycomb panels the best strength-to-weight ratio of any construction type available. Conventionally, the wax is poured into the cell of the core to strengthen the structure and prevent the core from being crushed during milling. Much time and labor is required to wax, mill, and clean the cores. In this study, the process of pouring wax into the core was skipped. In other words, the cutter directly milled the core. Experiments showed that the compressive strength of the core produced without wax stabilization was only 3% lower than that of cores produced using the traditional method. In addition, the drum peel strengths of cores produced without wax stabilization were 38.4% higher than cores produced using the traditional method, in which residual wax seriously polluted the adhesive. It was also found that eliminating the wax process can reduce costs.     

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.     

In-process thermal treatment of polylactic acid in fused deposition modelling

Polylactic acid (PLA) is one of the most widely used open source fused filament fabrication materials due to its ease of extrusion, biodegradability, and mechanical strength. The mechanical strength of PLA largely depends on the proper growth of its semi-crystalline structure, which can be severely impaired by a low rate of crystallization, particularly in open source printers. This can be further aggravated by the non-uniform thermal distribution of heat that causes improper curing among the extruded beads of the printing material. As a result, PLA printed on open source printers does not achieve the best mechanical properties. This research, for the first time, proposes an additive-free solution implemented through a detailed set of experimentation to improve the curing rate through in-process temperature variations to cure the joints among the beads. Scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy is used to confirm the improvements in the bead joints. This work is conducted in two phases of experiments. In the first phase, a full factorial ANOVA is used to investigate various process parameters and the important variables are used in the second phase to print test specimens in four different sets.     

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.