玫瑰花花瓣微观结构与水滴黏附性质的关系

利用环境扫描电镜(ESEM)分别观察了新鲜、枯萎的玫瑰花花瓣正、反两面的微观形貌,并通过测量样品的表观接触角表征了其浸润性,采用高敏感性微电力学天平测试了样品表面的粘附力,分析了玫瑰花花瓣微观结构与水滴粘附性质的关系.实验结果表明,微米结构主要影响玫瑰花花瓣的超疏水性,而纳米结构则是导致玫瑰花花瓣具有高粘附力的关键原因.     

Isolation and characterization of kurstakin and surfactin isoforms produced by Enterobacter cloacae C3 strain

In this work, the extraction, structural analysis, and identification as well as antimicrobial, anti‐adhesive, and antibiofilm activities of lipopeptides produced by Enterobacter cloacae C3 strain were studied. A combination of chromatographic and spectroscopic techniques offers opportunities for a better characterization of the biosurfactant structure. Thin layer chromatography (TLC) and HPLC for amino acid composition determination are used. Efficient spectroscopic techniques have been utilized for investigations on the biochemical structure of biosurfactants, such as Fourier transform infrared (FT‐IR) spectroscopy and mass spectrometry analysis. This is the first work describing the production of different isoforms belonging to kurstakin and surfactin families by E cloacae strain. Three kurstakin homologues differing by the fatty acid chain length from C₁₀ to C₁₂ were detected. The spectrum of lipopeptides belonging to surfactin family contains various isoforms differing by the fatty acid chain length as well as the amino acids at positions four and seven. Lipopeptide C3 extract exhibited important antibacterial activity against Gram‐positive and Gram‐negative bacteria, antifungal activity, and interesting anti‐adhesive and disruptive properties against biofilm formation by human pathogenic bacterial strains: Salmonella typhimurium, Klebsiella pneumoniae, Staphylococcus aureus, Bacillus cereus, and Candida albicans.     

聚氨酯/苯丙杂化乳液的合成、表征和特性及其在复膜胶中的应用

由聚氨酯(PU)预聚物、丙烯酸丁酯和苯乙烯单体的乳液聚合制备了聚氨酯-苯乙烯-丙烯酸酯(PUSA)杂化乳液,1H NMR显示所得的PU预聚物由烯烃基团封端。 TEM表明,其粒径约为150 nm,且为颜色深浅不同的两部分所组成。 随着PU含量的降低,杂化乳液的热稳定性增加。 DSC分析表明,所得杂化乳液有单一的Tg值,且处于聚氨酯和聚苯丙(PSA)乳液Tg值的中间。 当将得到的杂化乳液用于纸塑和塑塑复合时,其剥离强度分别为14.1 N/2.5 cm和12.2 N/2.5 cm。     

环氧树脂导电胶用铜粉抗氧化性

根据铜本身具有的性质,选用γ-氨丙基甲基二乙氧基硅烷（KH-902）对铜粉进行改性,并采用FT-IR、超景深显微镜、TG、SEM及EDS技术对改性铜粉及铜粉导电胶进行表征。 结果表明,添加硅烷偶联剂KH-902可以有效改善铜粉的易氧化的问题,当添加量为3%时,不仅可以明显改善铜粉导电胶在高温固化下抗氧化性能,而且铜粉在环氧树脂胶体体系中能够均匀分散,且铜粉与铜粉之间的搭接紧密,具有良好的导电性能,体积电阻率仅1.31×10-2 Ω·cm。     

冻雨环境下润湿性表面覆冰黏附力测试方法

覆冰黏附力是仿生超疏水材料防结冰工程应用的关键技术指标之一. 根据覆冰样片降温过程中产生应变受冰层黏附力作用的原理, 提出利用电阻应变片传感器于模拟冻雨结冰环境下在线检测覆冰黏附力的方案. 应变片应变信号经数据采集、信号转换和软件处理, 实现了应变传感电压实时监测与在线显示, 结合受力分析对比计算出不同润湿性表面覆冰黏附力. 该方法可实时表征低温结冰环境下不同润湿性表面的结/融冰行为及覆冰黏附力变化趋势.     

气压变化对光纤陀螺仪零偏稳定性的影响及改进

研究了气压变化对光纤陀螺仪零偏稳定性的影响,提出了降低光纤陀螺仪气压灵敏度的设计方法。理论分析并实际测量了气压变化对光纤陀螺仪零偏稳定性的影响,试验研究了光纤环浸胶固化和密封这两种降低光纤陀螺仪气压灵敏度设计方法的有效性。结果表明,变气压条件下光纤陀螺仪的零偏稳定性劣化1~2个量级,对光纤环浸胶固化后,光纤陀螺仪的气压灵敏度减小1倍,可以在一定程度上减小空气的扰动,改善气压变化对光纤陀螺仪的影响。而对光纤陀螺仪进行密封设计是一种更有效的措施。对光纤陀螺仪进行密封设计后,光纤陀螺仪的气压灵敏度为零,光纤陀螺仪零偏稳定性基本不受变气压环境的影响,解决了光纤陀螺仪受气压变化影响精度的问题。     

新型汽车结构胶剪切实验研究

利用数字图像相关方法(DICM),分别测定了准静态单向剪切拉伸试验条件下,新型汽车结构胶粘接试件和传统点焊连接试件粘接部分的剪切力学性能。实验采用了非接触测量物体应变的方法,运用CCD及其计算机图像处理系统,实时获取变形前后试件表面图像。利用数字相关软件对变形前后的图像进行分析,从而获得试件该时刻的应变。最后确定了试件拉伸过程中的力-位移曲线及应力-应变关系曲线。测试结果及分析表明:采用新型结构胶粘接试件的力学性能与点焊结构相比有明显的优势。这为该结构胶进一步改进提供了一定的实验依据。测试中的数字图像相关法是非接触测量物体应变的方法,在实际应用中有很大的意义。     

高速烟支质量检测装置中陶瓷涂层/浸树脂石墨摩擦副材料的选择研究

本文根据烟草机械高速烟支质量检测装置中陶瓷涂层的实际工作情况,对比分析了Al2O3-40%TiO2、Al2O3-20%TiO2、WC-12%Co和Cr2O34种涂层材料与浸树脂石墨作为摩擦配副材料时的磨损性能,并根据耐磨性好的原则对涂层材料进行选择,以达到减少零件失效、降低维修费用的目的.结果表明:在相同条件下,涂层材料磨损率由大到小分别为Al2O3-40%TiO2、Al2O3-20%TiO2、WC-12%Co和Cr2O3,其中Cr2O3涂层的耐磨性最好.陶瓷涂层材料的主要磨损机理为黏着磨损、脆性剥落和磨粒磨损.     

基于贻贝启发的水下仿生胶黏剂

海洋中的贻贝依靠丝足(Byssus)与足盘(Plaque)可以在潮湿及水下环境中快速而牢固地黏附于各种固体表面。贻贝强健的足部具有沟渠状的生理结构,通过类似于“注塑生产”的生理过程,它们可以生成丝足与足盘。贻贝将液态的蛋白质挤压到沟渠里,只需几秒钟时间,这些蛋白质就能形成一条条发丝一样纤细的丝足。每条丝足的末端都有一个黏性足盘,足盘可以牢牢地黏附在岩石及固体表面。丝足及足盘由多种黏附蛋白(Mfps)组成,且几乎每种黏附蛋白都含有L-3,4-二羟基苯丙氨酸(DOPA)成分。在过去的数十年间,科研人员基本揭示了贻贝黏附蛋白的结构及其黏附机理。DOPA的儿茶酚基团,通过氧化交联、金属螯合、氢键、静电作用、疏水作用、π-π作用、阳离子-π作用等各种共价和非共价相互作用,实现强大的界面黏接。基于贻贝黏附蛋白的结构及其黏附机理,通过使用DOPA及其类似物修饰的聚合物体系,人们得到了多种具有优秀机械性能和功能化的新型仿生多巴类水下胶黏剂。本综述首先介绍了贻贝黏附蛋白的组成特点及其黏附机理;随后分别介绍了凝聚层类胶黏剂、水凝胶类胶黏剂、智能型水下胶黏剂的结构特点及黏附机理;最后讨论了目前仿生水下胶黏剂存在的问题及未来发展前景。     

High thermal conductivity EP adhesive based on the GO/EP interface optimized by TDI

Graphene oxide (GO) was used as the filler to modify the epoxy resin (EP) adhesive, and the GO/EP interface was optimized by toluene diisocyanate (TDI) in order to improve the thermal conductivity and T peel strength performance of the adhesive. Through the characterization of the GO product, which was modified by TDI, TDI was grafted onto the surface of GO, and there were NCO groups remaining; thus the chemical bonds were built onto the interface which was non‐wetting between GO and EP. The results of the properties characterization of the adhesive indicated that the bonding properties were significantly enhanced, especially the T peel strength, which was up to 9.62 N/mm, which was contributed by the optimized GO/EP interface. The thermal conductivity of the adhesive increased to 0.624 W m^?1 K^?1, as the interface thermal resistance was reduced after the interface between GO/EP was optimized by TDI. The insulation performance of the adhesive was also improved, since the well‐dispersed GO formed a micro‐capacitance model in EP, and the surface of GO was covered by the EP so that the electronic paths were blocked by the formed chemical bonds.