FRICTION AND WEAR PROPERTIES OF ALUMINUM BORATE WHISKERS MODIFIED BISMALEIMIDE RESIN

[中文文摘]　研究了不同偶联剂及硼酸铝晶须添加量对硼酸铝晶须/双马来酰亚胺复合材料的摩擦磨损性能的影响。结果发现,硼酸铝晶须能有效地提高复合材料的耐磨性,晶须的加入使材料的磨损率明显降低;偶联剂对材料摩擦磨损性能的影响不明显;体系中添加硼酸铝晶须后随摩擦时间的延长复合材料的摩擦系数呈增大趋势。当晶须含量较小时摩擦机制主要是轻微的粘着磨损和疲劳磨损,当晶须含量大于8%时,疲劳磨损占主导地位,同时伴有粘着磨损和磨粒磨损。[英文文摘]The friction and wear behaviors of aluminum borate whiskers modified bismaleimide resin were investigated at different coupling agents and whisker contents. The results show that wear resistance can be improved by adding aluminum borate whiskers. Coupling agents have no marked influence on the friction and wear resistance, and the friction coefficient of the composite reveals increasing tendency with the prolonging frictional time. At a relatively lower whisker content, the wear of the composites is characteristic of adhesion and fatigue. When the whisker content is higher than 8%, it is dominated by fatigue, and accompanied by adhesion

Bioabsorbable chitosan rod reinforced by chitosan fiber

[中文文摘]在采用原位沉析法制备壳聚糖棒材的同时,加入壳聚糖纤维作为增强材料,制成了壳聚糖纤维增强的壳聚糖棒材复合材料。研究了壳聚糖纤维的长度及添加量对壳聚糖棒材力学性能的影响,通过扫描电镜观察分析了材料的断面形貌。结果表明,壳聚糖纤维能显著提高壳聚糖棒材的力学性能,壳聚糖棒材的弯曲强度随壳聚糖纤维添加量的增加先增加而后下降,随着壳聚糖纤维长度的增加而增加。当壳聚糖纤维(17 mm)质量分数为5%时,壳聚糖棒材的弯曲强度达到134 MPa,与未增强的壳聚糖棒材相比,弯曲强度提高了55.7%。这种纯天然的复合材料在可吸收内固定材料方面将具有广阔的用途。[英文文摘]The chitosan rods were prepared by insitu precipitation , and then chitosan fibers were filled into the mat rix to reinforce the chitosan composite rod. The mechanical properties of this composite rod were investigated ,and the morphology of the f racture surfaces was observed by means of SEM. The result sindicate that chitosan fiber can improve the mechanical properties of the chitosan composite rod obviously. It is shown that the flexural st rength of the composite is improved firstly and then decreases with increasing the mass f raction of chitosan fiber. Compared with the chitosan rod without chitosam fiber , the flexural strength of the composite increases with increasing the length of chitosan fiber. The flexural st rength of the composite increases by 55.7% when 5% mass fraction of chitosan fiber with the length 17 mm was filled. This kind of chitosan fiber/ chitosan composite will be widely used in the field of internal fixation in surgery.国家自然科学基金(20774077); 福建省自然科学基金(E0710025); 厦门大学科技创新项目（XDKJCX20053010

Bismaleimide Matrix Composites with High Wear Resistance Modified by Potassium Titanate Whiskers

Conference Name:International Conference on Advances in Materials and Manufacturing Processes. Conference Address: Shenzhen, PEOPLES R CHINA. Time:NOV 06-08, 2010.Tribological behaviors and wear mechanism of bismaleimide resin and its composites modified by potassium titanate whiskers were investigated. The composites with outstanding tribological properties were prepared through several coupling agents and whisker contents under different friction loads. The incorporation of whiskers treated with slime into the matrix effectively improved wear properties and friction stability of the matrix, especially at severe friction condition as 30 kg. The wear volume of the neat resin at 15 kg and 30 kg friction load are 1.14 and 6.87 mm(3), respectively. However, the wear volume of the composites containing 3 wt% potassium titanate whiskers at 15 kg and 30 kg friction load are 0.75 and 1.14 mm(3), respectively. Furthermore, the addition of whiskers increased the ability to resist plastic deformation and crack of the matrix in a higher friction load

硫酸钙晶须改性双马来酰亚胺树脂摩擦磨损性能的研究

The friction and wear behaviors of calcium sulphate whiskers modified bismaleimide resin under different friction load, coupling agent, and whisker content were investigated. The results show that the resin matrix exhibits adhesion wear under lower friction load, but it shows serious plastic distortion and crack under high friction load. The properties of composites with calcium sulphate whisker are improved obviously. The wear rates of the composites are decreased markedly by adding calcium sulphate whiskers. When friction load increases from 200 N to 300 N, the wear of the resin matrix is changed from an adhesion wear to a fatigue one. At lower whisker contents, the wear of the composites shows adhesion features. While at higher whisker contents, it is dominated by particle wear

Comparison of LMS Algorithm and RLS Algorithm Using

摘要:为了减小水声通信系统中存在的由于多径传播效应引起的符号间干扰,可在系统中使用线性均衡器。首先介绍了LMS 算法和RLS 算法基本原理,利用Matlab 仿真软件,给出了两种算法在水声信道通信系统中的自适应均衡的仿真系统,并对这两种算法对于均衡器的影响进行了比较,最后对比较的结果进行了分析。Abstract : To induce inter symbol interference which is due to multipath transmit effect in the water acoustic communication sys2 tem ,linear equalization can be adopted in the system. This article introduces the basic principle of LMS algorithm and RLS algorithm , and makes use of Matlab simulation software to provide the adaptive equalization system in the water acoustic system based on these two algorithms ,compares the performance of these two algorithms ,and analyzes the result of comparison at last .基金项目:国家自然科学基金(60572106

基于FBG传感技术的复合材料加筋板低速冲击损伤监测

针对碳纤维增强树脂基复合材料低速冲击损伤的实时监测,本文设计将布拉格光纤光栅(FBG)传感器埋植在复合材料加筋板结构的三角填充区,在线监测复合材料T型加筋板冲击损伤过程。分别将FBG传感器埋植于复合材料层合板内部和复合材料T型加筋板的三角填充区,对比FBG传感器的埋入对复合材料层合板与复合材料T型加筋板对力学性能的影响,结果表明内埋FBG传感器的复合材料层合板试样的拉伸强度比未埋植传感器的层合板试样降低了约5%,但在FBG传感器的破坏应变范围内,FBG传感器可以准确、实时地监测复合材料的应变信号。将FBG传感器埋入复合材料T型加筋板的三角填充区,内埋FBG传感器的加筋板样件压缩破坏载荷与未埋植的样件基本一致。通过对比加筋板蒙皮上冲击位置、冲击能量对FBG传感器测得的冲击过程持续时间和最大应变值的影响,表明冲击过程持续时间随着冲击能量增加而延长,最大应变值随着冲击距离的增加呈下降趋势,而最大应变值随着冲击能量的增加呈上升趋势。利用FBG传感器测得的应变信号可初步实现对复合材料T型加筋板蒙皮冲击损伤位置及冲击能量的实时监测。国家重点研发计划(2016YFD0700603);;航空科学基金(2016ZF68011);;江苏省重点研发计划(BE2015007);;福建省科技创新平台建设计划(2014H2006

Studies on Synthesis of Two Novel Bowl-like Molecules and Their Fibrous Crystals

[中文文摘]以香兰素为原料,采用三聚法合成了2种外围脂肪族基团碳数分别为3和5的环三亚藜芦基(cyclotriveratrylene,CTV)系衍生物碗形分子——CTV-3和CTV-5,其中,用先关环后衍生化的合成路线克服了因CTV-5的外围基团太长、分子对称性不好而无法用传统方法合成的难题。产物的化学结构经1H NMR、13CNMR、质谱以及元素分析确认。在偏光显微镜下观察到纤维状晶叠加在碗形分子的向列液晶织构上。纤维状晶是从液晶态冷却时形成并装饰在原液晶织构上的一种结晶形态。通过SEM测定,观察到纤维状晶实际上是由厚度约为100～200nm、宽度为2～5μm的无限长的单层片晶组成的多层片晶,而片晶则是由直径约为100nm的微纤组成的。微纤可以推断是碗形分子柱的束状聚集体。[英文文摘]　Two novel bowl-like cyclotriveratrylene (CTV) ,i. e. CTV23 and CTV25 termed according to the different peripheral groups with carbon number 3 and 5 espectively,were synthesized. CTV23 was prepared by a the typical trimerization via a multistep sequence from vanillin ,however it remains restricted to the preparation of the CTV25 with larger peripheral group and less molecular symmetry via this conventional method. In this paper ,an alternative synthesis route with first closing ring and then derivatization was designed to prepare CTV25. The chemical structures of the products were characterized by means of 1H NMR ,13C NMR ,mass spectrometry and element analysis. For the final products CTV23 and CTV25 ,many fibrous crystals were observed under polarized optical microscopy ,which crystallized during the cooling from nematic phase ,and decorated the so-called liquid crystal grainy texture. By means of scanning electron microscope ,it can be observed the fibrous crystals were actually very long multi-layer lamellae ,which consist of single layer lamellae with the thickness of about 100 to 200nm ,width of 2 to 5μm and infinite length. The single layer lamellae were further composed of fibrils which diameter was about 100nm. It could be deduced that these fibrils were the aggregates of bowlic molecular columns国家自然科学基金项目(20774077); 福建省自然科学基金项目(E0510003); 厦门市科技计划项目(3502Z20055013)资助

聚苯胺纳米纤维@还原氧化石墨烯纳米卷复合材料的制备及其在超级电容器中的应用

针对聚苯胺作为赝电容超级电容器电极材料时存在循环稳定性差的问题,设计利用还原氧化石墨烯纳米卷包裹聚苯胺纳米纤维.采用高沸点有机溶剂辅助冷冻干燥法制备了聚苯胺纳米纤维@还原氧化石墨烯纳米卷复合材料,利用扫描电子显微镜、透射电子显微镜、能谱分析仪、傅里叶变换红外光谱以及X-射线衍射等对该复合材料的形貌、组成和结构进行表征,并采用循环伏安、恒流充放电、电化学阻抗等方法对其电容性能进行研究.结果表明,利用高沸点有机溶剂辅助冷冻干燥法能够成功将聚苯胺纳米纤维包裹进氧化石墨烯纳米卷中,最终将氧化石墨烯还原后得到聚苯胺纳米纤维@还原氧化石墨烯纳米卷复合材料;该复合材料经过5 000次循环充放电后电容量保持率达到75%;当复合材料中的聚苯胺纳米纤维质量分数为67%时,该复合材料在2.2A/g的电流密度下,质量比电容达到639F/g,表现出优异的电容性能.国家自然科学基金（21774104）航空科学基金（2016ZF68011

聚苯胺纳米纤维@还原氧化石墨烯复合纳米卷及其在超级电容器中的应用

聚苯胺是一种高比电容、高倍率性能的赝电容超级电容器电极材料，但是其存在循环稳定性差的问题。本文设计利用还原氧化石墨烯纳米卷包裹聚苯胺纳米纤维以改善聚苯胺纳米纤维的循环稳定性。采用高沸点有机溶剂辅助冷冻干燥法制备了聚苯胺纳米纤维@还原氧化石墨烯纳米卷复合材料，利用扫描电子显微镜、透射电子显微镜、能谱分析仪、傅里叶变换红外光谱以及X-射线衍射等对该复合材料的形貌、组成和结构进行表征，并采用循环伏安、恒流充放电、电化学阻抗等方法对其电容性能进行了研究。结果表明，利用高沸点有机溶剂辅助冷冻干燥法能够成功将聚苯胺纳米纤维包裹进氧化石墨烯纳米卷中，最终将氧化石墨烯还原后得到聚苯胺纳米纤维@还原氧化石墨烯纳米卷复合材料；该复合材料经过5 000次循环充放电后电容量保持率达到75%。当复合材料中的聚苯胺纳米纤维质量分数为67%时，该复合材料在2.2 A/g的电流密度下，质量比电容达到639 F/g，表现出优异的电容性能

Disclination and molecular director studies on bowlic columnar nematic phase using mosaic-like morphology decoration method

National Natural Science Foundation of China [20774077]; Natural Science Foundation of Fujian, China [E0510003, E0710025]; Project of Science and Technology of Xiamen, China [3502Z20055013]Two bowlic cyclotriveratrylene CTV-1 and CTV-2, with different peripheral groups of -OCH(3) and -OCH(2)CH(3) for CTV-1 and -OCH(3) and -OCH(2)COOCH(3) for CTV-2, respectively, were synthesized by typical trimerization via a multistep sequence from vanillin. Both bowlic CTV molecules were thermotropic liquid crystals, and presented typical grainy textures of the nematic phase and homogeneous texture of the single domain nematic phase. It is of interest to observe the regular and beautiful mosaic-like morphologies after cooling from liquid crystalline phases, which appeared and vanished repeatedly in several circles of cooling and heating. The size of each mosaic was several dozens of micron. In nature, the mosaic-like morphologies are the optical pattern of cracks formed by the shrinking, due to the crystallization of frozen texture of nematic phases. By means of scanning electron microscopy, the mosaic-like morphologies were observed to consist of lamellae, and each mosaic is a rectangular multi-layer lamella, which is composed of packed single-layered lamellae. The fibrils in the diameter of about 1 mu m were observed, which are the structural units of lamellae and would be the bundles of the bowlic molecular columns. The mosaic-like morphologies decorate the bowlic molecular columnar nematic phase, therefore, a novel mosaic-like morphologies decoration method was applied to reveal the director distribution of several kinds of point disclinations, such as s = +1(delta=0A degrees and delta =90 A degrees) and s = +/- 1/2, and NSel domain walls. It was shown that the bowlic molecular columnar nematic phase behaved as normal nematic phases; however, the basic structural units ordered were the bowlic molecular column or the bundles of bowlic molecular column (i.e. fibrils), but not the bowlic molecules themselves. The bowlic molecular columns acted as the rod-like molecules in a normal nematic phase. Therefore, a new term BCN (bowlic columnar nematic phase) is used to describe the anomalous nematic phase in this paper