Changes in wettability of wood surface using electron beam irradiation

ABSTRACT

This study deals with the influence of electron beam irradiation (EBI) on the wettability of Norway spruce surface samples. To evaluate this possible effect in detail, the changes in chemistry and wood structure were analysed using the methods of IR spectroscopy and Scanning Electron Microscopy (SEM). The surface wettability was determined by the contact angle measurement method. The results of infrared spectra show decreased relative numbers of available hydrophilic groups (e.g. hydroxyl and carbonyl groups) in the wood surfaces due to the electron beam irradiation. This behaviour is consistent with the values from the surface wettability measurements. Structural differences of the wood surfaces after electron beam irradiation were not detectable. Based on these findings pre-treatment of wood surfaces for industrial usages can be a potential field of application of this technology.     

Mixed acylation of Scots pine sawdust and impact on hydrophobicity

Abstract

Acetic–fatty esters of Scots pine sawdust (SPS) were obtained by reaction of SPS with mixtures containing acetic–fatty anhydrides and no solvent or catalyst. Such mixtures were synthesized by reaction between a carboxylic acid and acetic anhydride. The global reaction of acetic anhydride and a fatty acid yields at equilibrium a mixture of five compounds: acetic–fatty anhydride, acetic anhydride, fatty acid, acetic acid and fatty anhydride. The influence of temperature, molar ratio, reaction time and length of the fatty chain on the esterification and on the ratio of grafted acetyl/fatty acyl was investigated. Static contact angles (CAs) with water were measured over 5 min. CA values were dependent on the fatty acyl content and independent of the acetyl content. The minimum ester content of the oleoyl group required to obtain permanent water repellency was 25 mmol kg^?1. Water vapour adsorption measurements indicated that in contrast to water repellency, hydrophobicity to water vapour was correlated with the total mass acyl content.     

THE DEVELOPMENT OF ALUMINIUM MATRIX MICRO -GLASSBALL COMPOSITE AND THE ANALYSIS ON ITS FORMING MECHANISMS

The problem that the micro-glassball is not wettable in molten aluminium alloys can be solved by a special technology that is different from rheocasting and squeezecasting methods. The metten metal can fill the cavity of the glass ball through the broken place on its wall, and an original micro -structure will be formed. This material has good comprehensive mechanical proper ties and this method can be used to other kinds of ceramic powders. The mechanisms of the formation of this materials have been discussed as well.     

利用OWRK法预测桃叶表面润湿性能的研究

对桃叶表面润湿性能的预测方法进行了研究。应用OWRK法对不同生长期桃叶的近轴面、远轴面的表面自由能及其分量进行了测定。无论近轴叶面还是远轴叶面,随着桃叶生长期的增长,均表现出表面自由能减小,润湿性能变差,极性分量所占比例下降,色散分量所占比例上升等特性。这些变化与前人对于桃叶表皮蜡的蜡质含量、组份含量变化的研究成果相一致。说明用OWRK法测定桃叶表面自由能及其分量所得结果可靠,可以较好地描述桃叶表面的润湿性能和能量特征。     

Physical carbon‐sequestration mechanisms under special consideration of soil wettability

The protective impact of aggregation on microbial degradation through separation has been described frequently, especially for biotically formed aggregates. However, to date little information exists on the effects of organic‐matter (OM) quantity and OM quality on physical protection, i.e., reduced degradability by microorganisms caused by physical factors. In the present paper, we hypothesize that soil wettability, which is significantly influenced by OM, may act as a key factor for OM stabilization as it controls the microbial accessibility for water, nutrients, and oxygen in three‐phase systems like soil. Based on this hypothesis, the first objective is to evaluate new findings on the organization of organo‐mineral complexes at the nanoscale as one of the processes creating water‐repellent coatings on mineral surfaces. The second objective is to quantify the degree of alteration of coated surfaces with regard to water repellence. We introduce a recently developed trial that combines FTIR spectra with contact‐angle data as the link between chemical composition of OM and the physical wetting behavior of soil particles. In addition to characterizing the wetting properties of OM coatings, we discuss the implications of water‐repellent surfaces for different physical protection mechanisms of OM. For typical minerals, the OM loading on mineral surfaces is patchy, whereas OM forms nanoscaled micro‐aggregates together with metal oxides and hydroxides and with layered clay minerals. Such small aggregates may efficiently stabilize OM against microbial decomposition. However, despite the patchy structure of OM coating, we observed a relation between the chemical composition of OM and wettability. A higher hydrophobicity of the OM appears to stabilize the organic C in soil, either caused by a specific reduced biodegradability of OM or indirectly caused by increased aggregate stability. In partly saturated nonaggregated soil, the specific distribution of the pore water appears to further affect the mineralization of OM as a function of wettability. We conclude that the wettability of OM, quantified by the contact angle, links the chemical structure of OM with a bundle of physical soil properties and that reduced wettability results in the stabilization of OM in soils.     

植物叶片润湿性特征的初步研究

植物叶片的润湿性表现了叶片对水的亲和能力,叶片上润湿的一层水膜对植物的光合作用、叶片截流降水有重要的影响.测定了陕西省境内34种植物叶片对水的接触角,初步探讨了叶片润湿性的一些特征.所研究植物叶片正面的接触角为O°～140°,平均85.4°.接触角大于95°不润湿的植物占到测定总数的31.4%;小于85°润湿植物中占到51%以上;而介于润湿与不润湿之间的物种占17.1%.叶片的正面和背面的润湿性具有一定水平的差异.叶面角质与腊质的比例对润湿性有重要的影响.叶片上附属物的多少也会对润湿性产生影响,附属物愈多,润湿性愈差;人为去除附属物可以极大地增加叶片的润湿性能.植物叶片上的气孔和叶脉通过影响叶片的粗糙程度来影响叶片的湿润性.     

竹造纸污泥纤维的特性分析

选取竹造纸污泥纤维为研究对象,对其化学成分、纤维形态、红外特征和润湿性能进行了研究分析。结果表明:污泥纤维形态完好,红外特征峰明显,具有良好的润湿性,具有很好的可再利用性。     

微波处理对杨木表面动态润湿性能的影响

以速生杨木为试材,采用不同的微波处理工艺进行处理,并分别以水和甘油为试剂,分析微波处理前后试材表面动态润湿性能的变化情况。结果表明：微波处理对于木材的表面动态润湿性能有一定影响,经适当微波处理后试材的润湿性要好于未经处理的试材的润湿性,且效果与微波处理强度和处理时间有关。在相同的微波处理工艺下,随着处理强度和处理时间的增加,试材的润湿性能总体上均呈先上升后下降的趋势。     

多孔介质的润湿性对聚驱稠油微宏观效率的影响

岩石表面的润湿性影响聚合物微观和宏观驱油效率。采用可视化微观模型和微观照相技术研究了强水湿和油湿多孔介质下聚合物微观驱油效率和驱替机理。分析了束缚水与稠油分别在两种润湿介质下的微观形态和分布对聚合物的吸附、滞留,连续性和非连续性流动,驱替前缘以及洗油效率的影响。微观模型实验结果表明,在水湿环境,地层水趋向分布于岩石骨架表面并在孔壁附近形成较厚的水膜,聚合物趋于附着在孔壁处,在这些区域聚合物的洗油效率较高;在油湿环境,束缚水主要以非连续相分布在孔隙介质中,聚合物溶液发生咬断效应,原油吸附在孔喉处,聚合物只能部分扫除原油,乳液的形成能辅助聚合物溶液驱替油相。聚合物在水湿介质的微观驱油效率明显高于油湿介质。岩心流动实验结果与微观模型分析一致,相同浓度的聚合物溶液在强水湿岩心前缘突破所需的时间长于油湿岩心,突破前缘更规整,水湿岩心和油湿岩心的水驱采出程度分别为21.5%OOIP和15%OOIP。聚合物在油湿岩心的“门槛”黏度较大。聚合物黏度为500 mPa·s时,水驱后水湿岩心和油湿岩心的原油采收率增幅分别为23%OOIP和17%OOIP。     

植物叶面自由能特征和水滴形态对截留降水的影响

采用浸水法和喷水法测定21种植物叶片的最大持水量,初步探讨叶面润湿性、表面自由能及其极性和色散分量对叶片最大持水量的影响,并分析2种方法测定叶片持水量不同的可能原因。浸水法和喷水法测定的叶片最大持水量物种间有显著差异(P<0.001),叶片的最大持水量变化范围分别为29.4～180.0g/m2,94.1～278.3g/m2。浸水法测定的叶片最大持水量与表面自由能、色散分量分别呈正相关(P=0.002,P=0.000),与极性分量呈乘幂关系(P=0.006),与叶接触角呈指数关系(P=0.004)。喷水法测定的叶片最大持水量与表面自由能、极性分量、色散分量、叶接触角的相关关系均不显著(P>0.05)。这可能是由于喷水过程中,在叶片表面自由能的作用首先在叶面上形成了小液滴,随着喷水过程的进行,液滴在水的表面张力和重力的作用下逐渐聚集形成大的液滴。