竹材表面润湿性研究

从竹材表面润湿性的原理推导入手,采用测定竹材表面接触角的方法,对竹材表面的自由能、路易丝-范得华力和酸碱力关系进行研究,并分析不同部位和不同处理方法对竹材表面湿润性的影响.结果表明:表面粗糙度,抽提物的含量和分布是影响竹材表面润湿性的主要原因;竹材的表面自由能是以路易丝-范得华力为主体;竹材表面的自由能差异主要由竹材表面的酸碱力引起;竹材表面具有稳定的路易丝-范得华力,其数值大小不受竹材表面的化学成分的影响.     

东方蝼蛄膜翅表面形态与润湿性

利用扫描电镜分析了东方蝼蛄膜翅的表面形态.在OCA20型接触角测量仪上测量了水与东方蝼蛄膜翅展开表面各部位的接触角,分析了东方蝼蛄膜翅表面几何微结构与润湿性的关系.研究表明,东方蝼蛄膜翅展开后各部位的几何微结构各不相同,水与东方蝼蛄膜翅展开表面各部位的接触角平均值为94.4°～118.6°,表现出疏水性能.东方蝼蛄膜翅表面几何微结构与疏水性能的综合作用是其折叠后表面不沾土壤和水的重要机理.     

金属材料的功能表面与水的润湿性

本文对研制的减粘功能表面与水的润湿性进行了探讨。结果表明,表面复合材料和表面涂层材料与水的接触角较常用的金属材料显著提高;各种材料的接触角与粗糙度的关系并不完全符合cosθ_γ=γcosθ的规律,当粗糙度提高到一定程度,将使表观接触角增大,其机制与粗糙表面润湿模型和表达式相吻合。     

Study on Surface Wettability of Bamboo by Measurement of Contact Angle

The main objective of this research is to evaluate the wettability of the processed bamboo surfaces. The important surface energy and acid-base properties for processed bamboo have been estimated by using contact angle techniques. According to the results, the change of ages has a positive relation with the contact angles of water on processed bamboo. The contact angles were increased after the bamboo surface treated in high temperature condition and preservation. The different treat methods have a strong influence on acid-base energy component insurface of bamboo. Compared with pinewood, the surface of bamboo seems to be stronger in the acid-base energycontribution.     

Wettability and roughness characteristics of modified wood boards using a hot-press

The aim of this study was to investigate the effect of the thermal modification process by hot-press on the wettability and surface roughness characteristics of the eucalyptus wood boards. The roughness measurements, average roughness (R_a), and maximum roughness (R_max) were taken both parallel and perpendicular to the grain using a fine stylus tracing technique. Contact angle measurements were obtained using a goniometer system connected to a digital camera and computer system. The results showed that surface roughness values of the modified wood boards using a hot-press significantly decreased with increasing press pressure and with decreasing temperature. The contact angle measurements indicated that the thermal modification had a significant influence on the surface wettability of the wood boards. Statistical analyses showed significant differences in the surface roughness and contact angle values of the wood boards following thermal modification. The results acquired in this work provide important information for future research and utilization of the thermally modified wood boards.     

Influence of the CF4 plasma treatments on the wettability of polypropylene fabrics

A plasma treatment using saturated CF₄ gas was employed to improve the resistance of polypropylene fabrics to water wetting. The fabrics were significantly fluorinated even within a short treatment time of 30 seconds. The result of contact angle measurement indicated that such highly hydrophobic surface was considerably durable even after 150 days of aging.     

茶皂素的表面活性及其相关的功能性质

本文根据近10年来的研究结果,对茶皂素的表面活性及临界胶束浓度(CMC)进行了比较分析,确定茶皂素的 CMC 为0.5%左右,并且在水质硬度0—28.7°d 的范围内几乎不受影响。同时,对茶皂素的去污力、起泡力、湿润性、分散性以及乳化作用等功能性质,进行了全面的研究分析,首次提出了茶皂素对疏水性材料接触角θ在0°<θ     

东方蝼蛄体表形态与润湿性

利用扫描电镜分析了东方蝼蛄(Cryllotalpa orientalis Burmeister)前胸背板、腹部、翅膀和足部的体表形态,测定了东方蝼蛄体表刚毛的覆盖密度和尺寸.在OCA20型接触角测量仪上测量了水与东方蝼蛄体表各部位的接触角,分析了东方蝼蛄体表几何微结构与润湿性的关系.研究表明,东方蝼蛄前胸背板、覆翅、腹部、足、膜翅的刚毛覆盖密度分别为40.32%、31.82%、23.89%、19.11%、14.17%,水与东方蝼蛄体表各部位的接触角平均值为110.8°～141.5°,表现出很高的疏水性能.东方蝼蛄体表刚毛形成的几何结构表面与刚毛的高疏水性能的综合作用是其体表不沾土壤和水的重要机理.     

Changes in surface properties of tropical wood species exposed to the Indonesian climate in relation to mold colonies

Changes in mold populations and genera on the exposed surfaces of tropical hardwoods — albizia (Paraserianthes falcata), kapur (Dryobalanop lanceolata), mahoni (Switenia macrophylla), nangka (Artocarpus heterophyllus), puspa (Schima wallchii) — were investigated. The wood specimens were exposed to the Indonesian climate for 32 weeks. Properties including mass loss, wettability, mold growth (colony-forming units), and mold genera were evaluated. The change in properties after exposure was significantly affected by the wood species, but there was no clear relation between mass loss and the initial chemical components or between wettability and wood density. The number of mold populations was different by exposure period and wood species, but there was no significant effect of climate conditions, such as rainfall and ultraviolet radiation. Of the genera identified,Aureobasidium, Cladosporium, andPenicillium were dominant molds on the exposed wood surfaces.     

Improvement of fiberboard made from acetylated fibers by ozonation I: effect of ozonation on mechanical properties

Acetylated fibers with a 24.8% weight gain by acetylation were ozonated with 0%–2.0% ozone on fibers. Fiberboards were then made from these treated fibers. The internal bond and bending strength of the acetylated fiberboards increased drastically with increasing ozone charge up to 0.5%–1.0%, whereas the thickness swelling of the fiberboards decreased. Ozone selectively cleaves the aromatic rings of hydrophobic lignin and introduces a hydrophilic carboxyl group into lignin. Thus, the wettability and thermoplasticity of acetylated fibers increased, and this structural modification improved the interfiber contact. Internal bond and bending strength increased as a result. In addition, steep density profiles were formed by the ozonation, resulting in high bending strength. The high compaction ratio accelerated the effect of ozonation. The optimum ozone charges for improving mechanical properties were 0.5%–1.0%.Part of this report was presented at the 49th Annual Meeting of the Japan Wood Research Society, Tokyo, April 1999