芳纶纤维/浆粕表面能及其复合纸性能

测定了几种间位芳纶短纤维、芳纶纯浆粕及其复合纸的表面接触角,结合倒数平均调和方程计算了芳纶纤维及复合纸的表面能。通过芳纶纸中纤维与浆粕界面张力及粘附功的计算,分析芳纶纤维及浆粕的表面能与其复合纸性能的关系。结果表明:采用水和乙二醇作为接触角测试液体时,芳纶纤维及浆粕的表面能为35～45 mJ·m-2。其中,芳纶短纤维表面能稍高于芳纶浆粕,芳纶短纤维及浆粕的极性分量大于色散分量,表面能越高越利于增强表面可润湿性,粘附功越大。热压导致芳纶复合纸表面能下降,相对于Nomex纸,自制芳纶复合纸的表面能降低得更明显。芳纶短纤维与浆粕的色散分量和极性分量越匹配,表面能之差及界面张力越小,则芳纶复合纸中纤维之间的粘接力越强,抗张指数也越高。      

芳纶Ⅲ纤维拉伸性能的实验研究

测试了芳纶Ⅲ纤维的拉伸性能等,并与F-12和Kevlar-49纤维进行了对比.对由芳纶Ⅲ纤维与环氧树脂基体复合成型的单向纤维增强环形试样,测试了其拉伸强度、弹性模量和层间剪切强度,结果表明:芳纶Ⅲ纤维单向纤维复合材料的拉伸强度和弹性模量与F-12纤维相当,分别比Kevlar-49纤维要高出约25.7%和24.7%;但早期的芳纶Ⅲ纤维与环氧树脂基体的界面结合性较差,层间剪切强度仅为32.0～35.2MPa.     

对位芳酰胺纤维的近况

1.芳酰胺纤维的高性能化随着恩卡(Enka)公司的Twaron和帝人公司的Technora进入市场,对位芳酰胺纤维已从杜邦公司的Kevlar独占市场突入到相互竞争的时代,与此同时,各公司正竞相进行芳酰胺纤维的高性能化的研究。杜邦公司一方面在现在市售的Keyfar、Kevlar-29、Kevlar-49的基础上增加制品的多样化,另一方面则致力于高性能化的研究,并于1987年发表了Kevlar-HT、Kevlar-68、Kevlar-     

剑麻纤维表面特性及其浸润行为

采用Weibull统计分布方法量化了剑麻纤维的横截面积, 并考虑液体在剑麻纤维中空结构中的芯吸质量, 发展了基于Wilhelmy吊片法原理测试剑麻纤维与液体动态接触角的表征方法。在此基础上, 分析了不同表面处理方法对剑麻纤维微观结构、 表面化学组成、 表面能及其色散、 极性特性的影响规律, 并测试了剑麻纤维与E51环氧树脂的浸润性。结果表明: NaOH、 阻燃剂处理使剑麻纤维表面极性官能团增加, 纤维的表面能极性分量增加显著; 硅烷处理增加了剑麻纤维表面的极性基团含量, 但使其极性分量减小, 表面能略有下降; 并且剑麻纤维与E51树脂的浸润性与其极性比匹配特性密切相关。     

单丝拔出实验研究芳纶-环氧树脂界面相

用单丝拔出实验研究了以有机硅表面处理剂处理的Kevlar-49-环氧树脂体系界面相.从力一位移曲线可得到界面破坏强度、界面破坏能、界面摩擦功等界面参数.硅表面处理剂对三者的贡献不同,以2#处理剂处理的综合效果最好.     

芳纶纤维表面分析及其对双马来酰亚胺树脂复合材料界面性能的影响

采用反气相色谱和扫描电子显微镜测试分析了芳纶纤维的表面性能,结果发现K1和K2两种芳纶纤维的表面均比较光滑,总表面能基本相当,但极性表面能和色散表面能分量存在较大差异。层间剪切强度测试表明K2/5405复合材料的界面强度高于K1/5405复合材料,断口形貌分别呈现出不同的基体破坏和界面破坏模式。利用Good-Girifalco相互作用参数分析纤维和树脂的表面能与复合材料界面性能的关系,结果发现复合材料中两相间的相互作用参数增大,匹配性提高,界面性能亦有所提高。     

初露头角的碳化硅纤维

在增强材料家族中,继Kevlar-49纤维之后,近年来又出现了新型碳化硅(SiC)纤维,为宇航业制造先进复合材料提供了新的增强体。 这种新型SiC纤维是日本东北大学金属材料研究所矢岛教授于1975年春发明的;同年9     

织物纤维增强橡胶复合板抗射流侵彻的防护效能

基于DOP实验方法开展了玻璃纤维、 碳纤维、 Kevlar-49及PBO等四种织物增强橡胶复合靶板抗射流侵彻性能实验研究。在68°倾角下, 获取了射流侵彻四种不同结构的复合板在鉴证靶上的剩余穿深。分析了面板变形形态及四种纤维的破坏模式, 计算得到了空间防护系数及差分防护系数。结果表明: 面板的变形是干扰射流的一个重要因素, 面板孔壁与射流作用区域越长, 对射流干扰越明显。四种纤维铺层的破坏模式有着较大的差异, Kevlar-49及PBO织物增强橡胶复合板的防护能力远大于玻璃纤维和碳纤维橡胶复合板。     

炭纤维表面物理特性的表征及其对浸润性能的影响

采用反气相色谱法对除浆前后T300B炭纤维的比表面积、溶解度参数和表面能进行了表征测试,分析了炭纤维表面物理特性对纤维和树脂浸润性能的影响。以一系列不同浓度的正庚烷为吸附质,根据BET吸附理论模型,计算得到除浆前后T300B纤维的比表面积分别为0.43m2/g和0.39m2/g。以正癸烷、正壬烷、正辛烷和正庚烷为非极性溶剂探针,甲苯、二氯甲烷、乙醇、1,4-二氧六环和丙酮为极性溶剂探针,采用DiPaola和Guillet方法得到不同探针分子与纤维表面的Flory-Huggins相互作用参数,计算除浆前后T300B的溶解度参数(δ)分别为11.98MPa1/2和10.01MPa1/2。T300B纤维的上浆剂可以增大纤维表面能的极性分量,使上浆纤维的溶解度参数与E51环氧树脂的δ(11.78MPa1/2)更为接近,提高了T300B纤维与树脂的浸润性能。     

固化阶段环氧树脂表面能及其极性变化的表征

采用座滴、吊片等间接表面能测试方法,表征分析了固化阶段2种典型环氧树脂体系的表面能变化规律,并对座滴法测得的总表面能极性、色散分量进行了深入研究。结果表明：2种方法测得的环氧618-咪唑体系和环氧5224体系的总表面能随固化时间延长均呈下降趋势,座滴法测得的树脂表面能高于吊片法;座滴法结果表明2种环氧树脂体系表面能极性分量均随时间延长而降低;红外分析表明,环氧618-咪唑体系表面能的极性分量的降低是由于羟基及环氧官能团的减少。     

Kevlar－49芳纶纤维表面接枝改性

采用空气等离子体处理Ｋｅｖｌａｒ－４９并在活化处理后的纤维表面接枝聚丙烯酸（ＰＡＡ）、聚丙烯酸乙酯（ＰＥＡ）及丙烯酸和丙烯酸乙酯的共聚物（ＰＡＡ／ＥＡ）。单丝拔出实验研究表明，空气等离子体改性的Ｋｅｖｌａｒ－４９／环氧树脂体系的界面结合强度和界面破坏能均有明显提高，其中接枝了Ｐ（ＡＡ／ＥＡ）的Ｋｅｖｌａｒ－４９／环氧树脂体系的界面破坏能（５５Ｊ／ｍ２）比未改性体系的界面破坏能（２７．８Ｊ／ｍ２）提高了一倍。     

Plasma Modified Polyaramid Fiber Surface and Fiber/Epoxy Interface

Kevlar-49 fiber was surface-modified through cold air plasma treatment and plasma grafting ofacrylic acid (AA).Fiber surface properties were studied with ESCA,while interface properties with asingle fiber pull-out (SFPO) test.The stated surface modifications evidently improved the interfacialadhesion and increased the interfacial fracture energy of the aramid/epoxy composite system.     

The tensile and fatigue behaviour of Kevlar-49 (PRD-49) fibre

The tensile, creep and tension-tension fatigue properties of Kevlar-49 fibre (formerly known as PRD-49) have been determined. The fracture morphology of the fibre has been examined and is shown to be complex due to considerable splitting. The fibre quickly stabilizes under a steady load but failure due to creep can occur when it is loaded very near to its simple tensile breaking load. Kevlar-49 has been found to fail by fatigue, and its fatigue lifetime is dependent on the amplitude of the applied oscillatory load as well as the maximum load to which the fibre is cycled.     

接触角测定法研究碳纤维表面酸碱性

用接触角测定法研究了未处理的和经液相氧化处理的碳纤维表面的酸碱性。结果表明,未处理碳纤维表面呈两性,但以碱性为主;经氧化处理后,碳纤维表面的酸性变化不大,而碱性变得更强。得到碳纤维表面自由能的非极性分量为45mJ/m~2。     

等离子改性条件对PEGDA/HEMA凝胶亲水性及表面能的影响

采用氩等离子对聚乙二醇双丙烯酸酯(PEGDA)/甲基丙烯酸-2-羟基乙酯(HEMA)共聚物凝胶进行表面改性,对膜材料进行了光电子能谱(XPS)分析,并讨论了等离子处理时间及功率对凝胶亲水性及表面能的影响。研究结果表明,经等离子处理后凝胶表面引入了含氧极性基团,氧的含量从未处理的23%增加到26%,使材料亲水性得到改善;由于引入极性基团,材料的表面能随等离子处理时间和功率的增加而增加,从未处理前的45.9 mJ/m2增加到72.5 mJ/m2,极性力分量γPs随等离子体处理功率和时间的变化规律与表面能γs基本一致。     

Synthesis and Characterization of High Performance Polymeric Hybrid Siliconized Epoxy Composites for Aerospace Applications

Two different types of hybridized siliconized epoxy matrix systems have been developed using two commercially available (CIBA-GEIGY) epoxy resins with hydroxyl terminated polydimethyl siloxane. The percentage siloxane content in the epoxy systems have been optimized based on the physico-chemical, electrical, mechanical and thermal properties. The matrix resins are cured using aliphatic amine (HY951), aromatic amine (HT972) and polyamidoamine (HY840) from CIBA-GEIGY and γ-aminopropyltriethoxysilane (A-186, Union Carbide). The optimized siliconized epoxy materials are filled with additives like fillers (SiO₂, BaSO₄ and TiO₂), plasticizer (dioctylphthalate), flame retardant (tris (2-chloropropyl) phosphate) and reinforced with E-glass fiber and Kevlar-49 and their effect on electrical and mechanical properties are studied. Introduction of siloxane units (silicone) in to the epoxy systems enhances dielectric properties with little loss of mechanical properties. Additives alter the electrical and mechanical characteristics based on their nature and concentration. Reinforcements enhanced the electrical and mechanical behavior to an appreciable extent. Data resulted from the studies reveal that the siliconized epoxy matrix systems reinforced with E-glass fiber and Kevlar-49 can be used in the filament wound liquid pressure vessels in the field of aerospace and other high performance engineering applications.     

Fracture of Aramid Fiber/Epoxy Resin Micro Composites

Kevlar-49 fiber was modified through cold air plasma treatment and plasma grafting with acrylic monomers. Fracture of aramid fiber/epoxy resin micro composites has been studied by means of single fiber pull-out test. Tow types of pull-out curves are correlated with the different failure modes. A polyacrylic acid-co-ethyl acrylate graft layer can improve the adhesion and protect the fiber from damage caused by interfacial stresses.     

Long term elongation of Kevlar-49 single fiber at low temperature

We have measured the rate of elongation of a loaded Kevlar-49 fiber as a function of time at 4.2 K. The result puts a worst case upper limit of 0.028% in the elongation rate ΔL/L for a 0.5 mm diameter fiber kept under a constant tension of 2.7 kg for 8 months. A value that is probably closer to reality is actually 0.004%. This result proves that Kevlar-49 can be safely used in cryogenic applications in which high mechanical stability under stress is required.