马来酸酐/丙烯酸丁酯双单体接枝聚丙烯

采用熔融法进行马来酸酐(MAH)和丙烯酸丁酯(BA)双单体接枝聚丙烯(PP)的研究。结果表明,在一定工艺条件下,仅添加一单体马来酸酐时,接枝率G在其加入量为4%(质量分数)时达到最大(0.65 mmol/g PP);马来酸酐添加量保持不变,接枝率随第二单体丙烯酸丁酯添加量增加而出现一极值(1.34 mmol/g PP),比一单体接枝聚丙烯的接枝率高出一倍,并高于文献值(0.36 mmol/g PP)。经红外光谱、热失重分析和差示扫描量热分析表明,马来酸酐、丙烯酸丁酯均与聚丙烯发生接枝反应,并且以短支链的形式连接在PP的主链上。     

改性聚丙烯和聚丙烯包装膜的研究

用双螺杆挤出机研究了马来酸酐(MAH)对聚丙烯(PP)的自由基熔融接枝.采用正交试验优化了熔融接枝条件, 考察了引发剂过氧化二异丙苯DCP、单体MAH用量对马来酸酐接枝率的影响,并对其影响因素作了分析.研究表明改性以后的PP制成的PP膜性能更进一步提高.确定了较佳的原料(质量)配比为PP:MAH:DCP =100:3:0.4.     

反应性挤出粉料PE接枝MA的研究

在高速混合机中,均匀混合HDPE粉料、马来酸酐(MA)和过氧化二异丙苯(DCP),然后在单螺杆挤出机中,于180℃下熔融挤出反应,得到PE接枝MA(PE-MA)样品。反复用二甲苯溶解,经丙酮沉淀后,测得的红外光谱表明,如上处理2～3次可完全除去未反应的MA。经二次挤出,产物的接枝率(G_x)和熔融指数(MI)变化很小,说明一次挤出后PE-MA中无残留过氧化物。研究了G_x随DCP或MA用量的变化,得知采用MI高的HDPE有利于接枝反应。     

大分子相容剂改性纳米CaCO3 / PP复合材料的非等温结晶行为

熔融混炼制备了4 种大分子相容剂改性的纳米CaCO₃ / PP 复合材料, 用DSC 和WXRD 研究了复合材料中PP 的结晶与熔融行为。结果表明, 纳米CaCO₃对PP 结晶存在异相成核作用, 并诱导PP 形成β晶。相容剂丙烯酸接枝聚丙烯( PP-g-AA) 和马来酸酐接枝聚丙烯( PP-g-MA) 也存在异相成核作用, 提高PP 结晶温度。PP-g-AA、PP-g-MA 和马来酸酐接枝乙烯2辛烯共聚物(POE-g-MA) 与纳米CaCO₃存在异相成核协同作用, 进一步提高PP 的结晶和熔融温度, PP-g-MA 和POE-g-MA 还促使纳米CaCO₃诱导PP 生成β晶。但马来酸酐接枝乙烯2醋酸乙烯酯共聚物( EVA-g-MA) 则阻碍纳米CaCO₃对PP 的异相成核作用。实验结果表明纳米CaCO₃ / PP 复合材料中PP 结晶的异相成核作用与纳米CaCO₃ / PP 界面的相互作用有关, 而纳米CaCO₃ / PP 界面的相互作用与相容剂的结构有关。      

反应挤出法制备马来酸酐接枝聚乳酸

采用反应挤出方法制备了聚乳酸(PLA)与马来酸酐(MAH)的接枝共聚物,研究了工艺条件和配方对产物接枝率和熔体流动速率的影响。结果表明,聚乳酸的接枝反应主要依赖于大分子侧链自由基进行,过高的螺杆转速或过高的挤出反应温度会引发聚乳酸的降解反应,不利于产物接枝率的提高;在适宜的反应条件下(马来酸酐含量2%,DCP含量0.35%,温度180℃,螺杆转速100 r/min),可以方便制得马来酸酐接枝聚乳酸产物(接枝率≥0.45%);SEM观察显示,马来酸酐接枝聚乳酸有效改善了PLA/淀粉共混材料的相容性。     

马来酸酐-苯乙烯多单体熔融接枝EVA的研究

用单螺杆挤出机研究了马来酸酐（MAH）－苯乙烯（St)多组分单体熔融接枝EVA的反应,考察了温度、引发剂用量、MAH和St用量对接枝率及凝胶率的影响。结果表明：MAH接枝率随DCP用量、St用量的增加、反应温度的降低有最大值;当EVA／MAH／St/DCP质量比为100：4：4：0.4时,MAH接枝率最大,而凝胶率最小;以St作共单体能够显著提高MAH的接枝率,抑制体系交联;St和MAH的相互作用和共聚反应生成的SMA共聚物在接枝反应中起重要作用。     

增容剂聚丙烯乳液接枝丙烯酸甲酯的研究

以丙烯酸甲酯为单体,通过乳液聚合制得聚丙烯接枝丙烯酸甲酯(PP-g-MA)的新型增容剂,并用红外光谱表征了接枝产物。考察了反应条件对接枝率和熔融指数(MFR)的影响;研究了PP-g-MA对复合材料力学性能的影响。结果表明,在70℃下,引发剂及单体用量分别为PP质量的7%和10%,反应2.5h时,接枝率最高可达到3.52%,MFR可达到35g/10min,PP-g-MA是良好的相容剂,可大大提高复合材料的力学性能。     

超临界CO_2中SBS与马来酸酐的接枝及表面性能

利用超临界CO2作为溶胀剂,进行了苯乙烯-丁二烯-苯乙烯嵌段共聚物(SBS)与马来酸酐(MA)的接枝反应,研究了单体浓度、反应时间等因素对接枝率的影响规律。结果表明,超临界CO2可以作为MA与SBS接枝反应的良好介质,MA的接枝率最高可达12.8%。用红外光谱(FT-IR)、扫描电镜(SEM)以及表面接触角测量仪等仪器对样品进行了表征,FT-IR证明了MA已接枝到SBS分子上,SEM观察到接枝后产物表面形成了微/纳米级的粗糙结构,接触角测试发现接枝后SBS表面水的接触角明显变小,表面由疏水变为亲水。     

马来酸酐接枝氯化聚丙烯的制备和性能研究

以马来酸酐(MAH)为接枝单体、过氧化苯甲酰为引发剂,采用熔融接枝法改性氯化聚丙烯(CPP)。采用红外和核磁对产物进行表征,计算了改性产品的接枝率,系统探讨了引发剂用量、反应温度、接枝率对接枝产物酯溶性和在聚丙烯(PP)基材表面附着力和粘接强度的影响及原因。结果表明:MAH接枝CPP改变了产品极性,提高了产品在乙酸乙酯中的溶解度,在反应条件适宜时也提高了产品在PP基材表面的附着力。当过氧化苯甲酰(BPO)用量为0.05份,100℃时,接枝改性CPP在乙酸乙酯中溶解度最大(9.58g),较未改性CPP提升了4.67倍,在PP基材上的附着力最好(国际0级),粘接强度最大(0.689MPa)。     

聚丙烯相对分子质量对以马来酸酐/苯乙烯为接枝单体的聚丙烯长链支化改性的影响

以马来酸酐/苯乙烯混合物为接枝单体,采用反应挤出制备长链支化聚丙烯,研究了不同相对分子质量聚丙烯在自由基反应中的活性,通过红外光谱表征改性聚丙烯的相对接枝率,表明大分子聚丙烯接枝率高于小分子。通过流变性质表征接枝物支化结构,并且通过对改性聚丙烯凝胶渗透色谱结果进行高斯分解,分析聚合物中不同相对分子质量组分,表征改性前后聚合物接枝与降解反应程度,综合分析不同相对分子质量聚丙烯在接枝反应中的表现。结果表明,分子量分布窄、相对分子质量大的聚丙烯在自由基反应中更占优势,但相对分子质量过大也会导致降解反应加剧。     

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.     

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.     

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.