A numerical study into the effects of Bio-synthetic Paraffinic Kerosine blends with Jet-A fuel for civil aircraft engine

Growing concerns regarding fluctuating fuel costs and pollution targets for gas emissions, have led the aviation industry to seek alternative technologies to reduce its dependency on crude oil, and its net emissions. Recently blends of bio-fuel with kerosine, have become an alternative solution as they offer "greener" aircraft and reduce demand on crude oil. Interestingly, this technique is able to be implemented in current aircraft as it does not require any modification to the engine. Therefore, the present study investigates the effect of blends of bio-synthetic paraffinic kerosine with Jet-A in a civil aircraft engine, focusing on its performance and exhaust emissions. Two bio-fuels are considered: Jatropha Bio-synthetic Paraffinic Kerosine (JSPK) and Camelina Bio-synthetic Paraffinic Kerosine (CSPK); there are evaluated as pure fuels, and as 10% and 50% blend with Jet-A. Results obtained show improvement in thrust, fuel flow and SFC as composition of bio-fuel in the blend increases. At design point condition, results on engine emissions show reduction in NO x, and CO, but increases of CO is observed at fixed fuel condition, as the composition of bio-fuel in the mixture increases. Copyright © 2012 by ASME.

Properties of two model soils stabilized with different blends and contents of GGBS, MgO, lime, and PC

This paper addresses the use of ground granulated blast furnace slag (GGBS) and reactive magnesia (MgO) blends for soil stabilization, comparing them with GGBS-lime blends and Portland cement (PC) for enhanced technical performance. A range of tests were conducted to investigate the properties of stabilized soils, including unconfined compressive strength (UCS), permeability, and microstructural analyses by using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The influence of GGBS:MgO ratio, binder content, soil type, and curing period were addressed. The UCS results revealed that GGBS-MgO was more efficient than GGBS-lime as a binder for soil stabilization, with an optimum MgO content in the range of 5-20% of the blends content, varying with binder content and curing age. The 28-day UCS values of the optimum GGBS-MgO mixes were up to almost four times higher than that of corresponding PC mixes. The microstructural analyses showed the hydrotalcite was produced during the GGBS hydration activated by MgO, although the main hydration products of the GGBS-MgO stabilized soils were similar to those of PC. © 2014 American Society of Civil Engineers.

Graphene nanoribbon blends with P3HT for organic electronics.

In organic field-effect transistors (OFETs) the electrical characteristics of polymeric semiconducting materials suffer from the presence of structural/morphological defects and grain boundaries as well as amorphous domains within the film, hindering an efficient transport of charges. To improve the percolation of charges we blend a regioregular poly(3-hexylthiophene) (P3HT) with newly designed N = 18 armchair graphene nanoribbons (GNRs). The latter, prepared by a bottom-up solution synthesis, are expected to form solid aggregates which cannot be easily interfaced with metallic electrodes, limiting charge injection at metal-semiconductor interfaces, and are characterized by a finite size, thus by grain boundaries, which negatively affect the charge transport within the film. Both P3HT and GNRs are soluble/dispersible in organic solvents, enabling the use of a single step co-deposition process. The resulting OFETs show a three-fold increase in the charge carrier mobilities in blend films, when compared to pure P3HT devices. This behavior can be ascribed to GNRs, and aggregates thereof, facilitating the transport of the charges within the conduction channel by connecting the domains of the semiconductor film. The electronic characteristics of the devices such as the Ion/Ioff ratio are not affected by the addition of GNRs at different loads. Studies of the electrical characteristics under illumination for potential use of our blend films as organic phototransistors (OPTs) reveal a tunable photoresponse. Therefore, our strategy offers a new method towards the enhancement of the performance of OFETs, and holds potential for technological applications in (opto)electronics.

A novel method of extraction of blend component structure from SANS measurements of homopolymer bimodal blends

A new method is presented for the extraction of single-chain form factors and interchain interference functions from a range of small-angle neutron scattering (SANS) experiments on bimodal homopolymer blends. The method requires a minimum of three blends, made up of hydrogenated and deuterated components with matched degree of polymerization at two different chain lengths, but with carefully varying deuteration levels. The method is validated through an experimental study on polystyrene homopolymer bimodal blends with M A≈1/2MB. By fitting Debye functions to the structure factors, it is shown that there is good agreement between the molar mass of the components obtained from SANS and from chromatography. The extraction method also enables, for the first time, interchain scattering functions to be produced for scattering between chains of different lengths. © 2014 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

官能化LLDPE及其合金材料(LLDPE/HIPS)的制备及结构性能研究

本文采用核磁共振碳谱、电喷雾质谱研究LLDPE-g-AA接枝产物的链结构。电喷雾质谱显示所有的丙烯酸单体都发生自聚形成低聚物，核磁共振碳谱进一步证明了丙烯酸在聚乙烯链上形成支链，并且由于反应挤出过程中的高温作用，丙烯酸支链脱水形成酸酐。丙烯酸支链在聚乙烯的结晶过程中影响链段的规整性排列，并有可能充当成核剂，使得聚乙烯晶体随着接枝率的升高变得小而不规整。接枝产物的流变行为表明丙烯酸支链起到内增塑剂作用，降低接枝产物的表观粘度，有利于产物的后加工处理。由于接枝率低的缘故，我们采用角鲨烷模拟乙丙共聚物与马来酸酐进行接枝反应。在170℃，单体浓度为2%W/V，引发剂浓度为0.2%W/V下，体系中存在马来酸酐自聚和接枝一对竞争反应。但由于存在链转移，马来酸酐大部分以单个分子形式接在角鲨烷上。对于LLDPE/HIPS共混体系，我们采用不同于以外加增容剂的办法，直接在共混过程中加入路易斯酸，利用聚乙烯本身带有或降解过程中生成的少量双键与苯发生Friedel-Crafts烷基化反应。为了找到最佳反应条件，我们研究了不同AlCl_3含量、反应时间、反应温度对增容效果的影响。增容共混物的力学性能，特别是冲击强度和微观形态照片表明加入AlCl_3后，在PE/HIPS两相界面处生成接枝共聚物PE-g-HIPS，降低界面张力，改善共混性。由于增容剂只在两相界面处生成，因此加入AlCl_3对共混物中聚乙烯组分的热学性能和结晶性并没有太大影响。

线性低密度聚乙烯和聚苯乙烯共混物的原位增容

采用反应挤出的方法，通过使用Friedel-Crofts反应，以AICl3为催化剂对原位增容线性低密度聚乙烯（LLDPE）和聚苯乙烯（PS）共混体系的反应机理、接枝物结构、材料的结构一性能关系、共混物的相分布形态以及多重结晶行为进行了深入研究。使用激光拉曼光谱研究了以AICl3作为LLDPE/PS共混体系的Friedel-Crafts反应的催化剂生成的接枝物的结构，通过对一系列模型化合物结构的分析，确定了发生接枝反应的点应为聚苯乙烯苯环上次甲基的对位。对于增容后共混物的力学性能进行了分析，并找出有效提高力学性能的工艺。根据测定，增容后的LLDPE/PS（80／20）共混物的Izod冲击性能从80J／m提高到了400）／m以上。断裂伸长率从350％提高到了800％以上。相对应的共混物的相分布形态也得到了极大的改善。这种力学性能上的提高，使得LLDPE／PS共混物真正具有了使用价值及商业前景。这也是研究LLDPE/PS共混物主要目的之一。随着含量AICl3的增加，共混物中PS分散相粒子的尺寸逐渐减小，直至共混物的相分布形态由原来的分散相一连续相结构变为双连续结构。这种形态上的改变，正是力学性能提高的基础。添加过量的AlCl3会对共混物产生一定的降解作用。通过GPC和MER等手段的分析，发现这种降解作用对于共混物中的 PS组分更加明显，而且这种降解只发生在接枝反应之后，与接枝反应是一对竞争的反应。研究了增容后的LLDP／PS（20／80）共混物的熔融结晶行为，发现了这个共混物具有复杂的多重结晶行为。通过对共混物界面层的SEM和TEM观察分析发现：在共混物的LLDPE和PS两相的中间，具有一层由LLDPE-g-PS接枝共聚物形成的界面层。这个界面层中的LLDPE链段与LLDPE均聚物在熔体中紧密的缠结着。当共混体系从较高的熔融温度逐渐下降的时候，接枝共聚物会因为链段之间的相互作用而在熔体下就形成相分离。在接枝共聚物的有序化过程中，与之紧密缠结的LLDPE均聚物分子也会随着有序化的过程而进入相分离所形成的微域结构中。研究了共棍物的这种多重结晶行为。根据共聚物的特性，首次采用了对共混物进行熔点温度之上的高温退火来研究有序一无序转变对共混物多重结晶行为的影响。由于在两相界面层的LLDPE-g-PS接枝共聚物有序化所形成的大量的微域结构限制了处于其中的LLDPE分子的结晶，导致这部分LLDPE分子结晶所需的过冷程度增加，最终只能采用均相成核的方式结晶所致。研究发现，在不同的熔融温度、退火温度以及退火时间都会对共混物的这种受限结晶行为产生很大的影响。在低于接枝共聚物的有序一无序转化温度下退火时，受限于接枝物形成的微域结构中的LLDPE均聚物分子会在这个过程中从微域结构中脱离，重新进入更大的LLDPE分散相粒子中。如果退火的温度高于接枝共聚物的有序一无序转化温度，那么这些LLDPE均聚物分子仍然会在降温的时候被“吞入”有序化所形成的微域结构中而无法脱离这种受限环境。

LLDPE接枝新型表面活性剂共聚物的制备及其结构、性能与应用的基础研究

合成三个系列的新型表面活性剂，制备了三个系列的聚乙烯接枝共聚物。第一系列的表面活性剂是将Tween8O、span80，聚氧乙烯肉桂醇醚，PEO（400），PEO（1000），PEO（2000）OCOC1’7H35和PEO（6000）-OCOC17H35引入双键而使其功能化，然后接枝到聚乙烯分子链上，表面活性剂的引入改变了聚乙烯的表面性能，使其亲水性增加。前三者为商品防雾滴剂，实验发现防雾滴剂的聚乙烯接枝共聚物膜的防雾滴性不如物理共混法制备的聚乙烯防雾滴膜的效果好。接枝聚乙烯共聚物LLDPE-g-PEO和LLDPE-g-PEO-sterate，由于结构差别，共聚物表面组成不同。前者随着支链长度的增加，支链柔性降低，共聚物表面氧的富集量趋于减少；而后者由于疏水基硬脂酸中碳链的存在，随着支链的增加，共聚物表面氧的富集量增加。LLDPE-g-PEO（400）和LLDPE-g-PEO（1000）的等温结晶速率都比空白聚乙烯的快。由于PEO与聚乙烯不相容，支链PEo在接枝共聚物中起异相成核剂的作用，使结晶速率加快。LLDPE-g-PEO（2000）-stearate的等温结晶速率与聚乙烯的接近，但比空白聚乙烯的略慢。这是由于支链末端硬脂酸碳链是柔性的疏水链，且与聚乙烯有较好的相容性，在本体聚乙烯非晶区中活动性较强，带动聚氧乙烯支链向相同的方向运动，使支链在聚乙烯中分散且伸展，对聚乙烯分子起惰性稀释剂的作用而导致结晶速率降低；但聚氧乙烯（2000）又具有结晶性，在本体聚乙烯中起异相成核剂的作用，使聚乙烯结晶速率加快，这两种作用消长的结果，使LLDPE-g-PEO（2000）-stearte接枝共聚物的结晶速率接近聚乙烯，但比聚乙烯的结晶速率略慢。LLDPE-g-PEO（6000）-stearate接枝共聚物的结晶速率比聚乙烯的快，这是由于聚氧乙烯（6000）的结晶性较强，活动性较强的硬脂酸基团很难使其伸展，其晶粒在本体聚乙烯中主要起异相成核剂的作用，导致其结晶速率比聚乙烯的快。为了弄清表面活性剂接枝到大分子链上的作用机理，特设计第二、第三系列的表面活性剂。第二系列的新型表面活性剂是I、II、III、IV和V，以及含有不饱和键的表面活性剂A-I、A-II和A-III。这些表面活性剂是以聚乙二醇、乙二醇、1，6-己二醇和1，10-癸二醇为主要的起始原料制得的。实验结果发现这些表面活性剂的表面张力随着疏水链长度的增加而增加。以A-I、A-II和A-II作为接枝单体，将其成功接枝到聚乙烯分子链上，从而改善了聚乙烯的表面性能。 由FTIR确定了其接枝率。由DSc对其等温结晶行为的研究发现：接枝链在本体聚合物中起异相成核剂的作用，加速了结晶过程，但没有改变聚乙烯晶格结构（WXA）。随着接枝链中的疏水链长度的增加，等温结晶速率加快。在低剪切速率时，空白聚乙烯具有牛顿流体的特性，而接枝聚乙烯表现出非牛顿流体行为。接枝聚合物在低剪切速率具有剪切变稠、高剪切速率时剪切变稀的现象。第三系列的新型表面活性剂是含氟和聚氧乙烯的特种表面活性剂：productIII（600-4600）。以FTIR和1HNMR表征其结构。以productIII（600-4600）为接枝单体，成功制得含氟接枝聚乙烯共聚物，亲水性表面活性剂的引入，同样改变了聚乙烯的表面性能。当PEO分子量较低时，含氟接枝聚乙烯共聚物的表面极性随着接枝链的分子量增加，极性增加，在ProductIII（1500）时，达到最大值，分子量继续增加，极性反而降低。这是由于支链结晶增加而影响分子链的迁移。含氟接枝聚乙烯共聚物的等温结晶速率比空白LLDPE的高，而且接枝共聚物的结晶速率随着支链分子量的增加而加快。这是由于含氟聚氧乙烯的接枝链在结晶体系中起成核剂的作用，使结晶过程加速。由于接枝率低，接枝链在接枝共聚物起异相成核剂的作用，虽然加速了结晶速率，但没有破坏聚乙烯晶格。