SrAl_2O_4:Eu~(2+),Dy~(3+)发光粉的包覆及其在水性涂料中的应用

采用燃烧法合成Sr Al2O4:Eu2+,Dy3+长余辉发光粉,发光粉经硅烷偶联剂A-174表面包覆改性后,再与改性环氧树脂、丙烯酸酯单体聚合反应制备水性发光环氧-丙烯酸酯复合乳液,研究表面包覆对发光粉发光性能影响,并对复合发光乳液进行性能分析。结果表明:燃烧法制备的单个发光粉粒径为100 nm;表面包覆不仅不影响发光粉的余辉性能,而且还可以提高发光粉的耐水性和改善发光粉在复合乳液中的分散性;制备的水性环氧-丙烯酸酯复合发光乳液涂膜具有优良的综合性能和长达18 h的余辉性能。     

具有光致变色功能的长余辉发光再生纤维素纤维的光学性能

采用物理共混的方法将光致变色染料和长余辉发光粉与纤维进行混合,经湿法纺丝后,制备出具有光致变色功能的纤维素长余辉发光纤维。利用扫描电镜、电脑测配色对比仪、激发发射光谱仪、余辉测试仪等仪器对样品进行表征。结果表明,光致变色微胶囊与再生纤维素纤维具有较好的相容性。经紫外-可见光源激发后,在标准光源下,纤维反射呈现出紫红色,最大K/S值为0.78,在黑暗环境下,纤维的发光呈黄绿色。激发发射光谱表明,在黑暗环境中,纤维的发射峰在510nm左右,发光性能不受光致变色染料影响。余辉测试表明,纤维的初始发光亮度减少14%,衰减速率减小,余辉寿命不变。     

偶联剂在荧光Lyocell纤维中的应用

采用钛酸酯偶联剂对荧光粉进行表面处理,再经物理共混制得荧光粉/Lyocell纺丝液,然后采用干湿法纺丝制备了荧光Lyocell纤维,用红外光谱仪、流变仪、荧光光谱仪及X射线衍射仪等分析了偶联剂处理前后荧光粉的结构、纺丝液的流变性能及纤维的结构与性能。研究表明,偶联剂在荧光粉表面发生了化学键的结合,经偶联剂处理后,荧光Lyocell纺丝液的表观黏度降低,纤维中荧光颗粒分散情况改善,纤维的荧光性能提高,拉伸强度提高约10%,但结晶度从55%降至48%。     

微胶囊法相变调温Lyocell纤维的制备与性能研究

为探索相变调温Lyocell纤维的制备方法及其纤维性能，利用微胶囊法通过原液添加制备了调温Lyocell纤维，通过电子显微镜、激光粒度仪、差示扫描量热仪以及扫描电镜等多种表征方法，表征了微胶囊分散液在N-甲基吗啉-N-氧化物(NMMO)水溶液中的分散情况，并研究了微胶囊添加量对纺丝原液和纤维性能的影响，表征了改性后的纤维形貌，测试了在吸放热条件下，实际的升降温情况。结果表明：微胶囊分散液可以良好的在NMMO水溶液中实现分散，随着微胶囊添加量的增加，纺丝溶液的黏度和可纺性未发生显著的变化；适当提高微胶囊的添加量有利于提高纤维焓值，当微胶囊量提高到35%以上时，纤维焓值不再变化；改性后的纤维横截面可以发现微胶囊的嵌入，纤维表面变得凹凸不平；利用相变调温Lyocell纤维制备的无纺布进行吸放热测试，织物具有明显的双向调温功能。     

以N-甲基吗啉-N-氧化物为溶剂的纤维素氨基甲酸酯纤维与Lyocell纤维的比较

分别以纤维素氨基甲酸酯(CC)及纤维素为原料,采用N-甲基吗啉-N-氧化物(NMMO)为溶剂,通过干湿法纺丝制备了CC纤维及Lyocell纤维,研究比较了不同原料/NMMO·H2O纺丝液的流变性能以及所纺制纤维的结构与性能。结果表明,2种纺丝液均表现出切力变稀的流变行为,且在相同条件下CC纺丝液的表观黏度低于Lyocell纺丝液,因此有利于高浓度CC纺丝液的制备。与Lyocell纤维相比,CC纤维的结晶度和取向度略低,导致CC纤维力学性能有所下降,但其抗原纤化性能明显优于Lyocell纤维。     

耐水型SrAl2O4∶(Eu2+,Dy3+)发光材料制备及性能测试

采用硅烷偶联剂对SrAl₂O₄∶(Eu²⁺,Dy³⁺)发光材料进行耐水性表面包覆,比较不同包覆材料及用量下包覆效果的差异,并通过耐水性实验、余辉性能实验、超景深显微镜、扫描电镜、X射线衍射仪等手段对包覆前后的发光材料进行微观观察及表征,研究改性前后材料性能、表面形貌与成分的差异。结果表明,当以KH560为偶联剂、包覆比为9%(wt,质量分数)时,硅烷偶联剂能均匀地包覆在长余辉发光粉表面,可有效提高材料的耐水性能,同时发光材料的发光性能未受影响。     

水性苯丙乳液长余辉蓄能发光涂料的制备与性能

为了提高新型碱土铝酸盐掺杂稀土元素发光材料的耐水性能,并保持其良好发光性能,以硅酸钠为硅源,采用液相沉积法在SrAl2O4:Eu2+,Dy3+长余辉荧光粉表面包覆SiO2膜。通过红外光谱(IR)、扫描电镜(SEM)、酸度计考察了包覆效果,优选了包覆反应条件。以包膜发光粉为颜料,水性苯丙乳液为成膜物质,添加适量的助剂,配制了一种水性蓄能发光涂料。用激发和发射光谱、发光亮度及余辉衰减研究了涂料及其涂膜的发光特性,优选了发光粉用量,并对发光涂料及其涂膜的其他性能进行了测试。结果表明:当SiO2包覆量为9%(质量分数),反应温度为80℃时,SiO2能均匀地包覆在SrAl2O4:Eu2+,Dy3+长余辉荧光粉表面,使其耐水性提高,而又不影响其发光性能;日光和一般的荧光灯都可以有效激发该发光涂料,当发光粉含量为20%(质量分数)时,水性蓄能发光涂料及其涂膜的综合性能优良,余辉时间可达12 h以上。     

荧光Lyocell纤维的制备和性能

通过共混方法将经预处理的荧光粉均匀分散在NMMO溶液中,采用Lyocell工艺通过干湿法纺丝成功制备了荧光Lyocell纤维,探讨了荧光粉用量对纺丝液流变性能及纤维的结构与性能的影响。结果表明,随着荧光粉用量的增加,Ly-ocell纺丝液的表观黏度先下降后上升,当荧光粉用量达到m(荧光粉)/m(纤维素)=3/100时,纺丝液的黏度呈最低值。此外,随着荧光粉用量的增加,纤维的荧光性能随之提高,但纤维内荧光颗粒的团聚现象逐渐加剧,导致纤维的力学强度和结晶度逐渐降低。     

铝酸盐系长余辉发光粉的表面包覆研究

采用正硅酸乙酯对铝酸盐系长余辉发光粉进行表面包覆。经耐水性、耐酸性和发光性以及扫描电镜的测试表明:发光粉的包覆效果良好,其耐水性和耐酸性得到明显提高。包覆后,发光粉的发光性未发生明显改变。     

以N-甲基吗啉-N-氧化物为溶剂的纤维素氨基甲酸酯纤维的制备及性能

以纤维素氨基甲酸酯(CC)为原料,采用Lyocell工艺,以N-甲基吗啉-N-氧化物(NMMO)为溶剂,通过干湿法纺丝成功制备了CC纤维,并采用X射线衍射、力学性能测试、热重分析、扫描电子显微镜等方法对所得CC纤维的结构与性能进行了研究。结果表明,CC能够很好地溶解于NMMO溶剂中,所纺制的CC纤维具有纤维素Ⅱ晶型结构;随着喷头拉伸比的提高,纤维力学性能提高;纤维表面光滑、结构致密,具有较好的热稳定性和抗原纤化性能。     

Effect of operating parameters and chemical treatment on the tribological performance of natural fiber composites: A review

The demand for high-performance engineering products made from natural resources is increasing because of the low-cost, low-density, biodegradability, renewable nature and lighter than synthetic fibers. With these characteristics, the tribological performance of natural fiber composite has become an important element to be considered in most industrial and manufacturing functions. This paper presents an overview of the factors that influence the tribological performance of natural fiber composites, which include applied load, sliding distance, sliding velocity and fiber orientation. Influences of chemical treatment is also reviewed and illustrated through scanning electron microscope (SEM) observations. This review will focus on kenaf fibers (KFs) and oil palm fibers (OPFs) which have been widely exploited over the past few years among the available natural resources. The results show that the operating parameter, fiber orientation and chemical treatment has significant effects on the tribological performance of natural composite. A clear understanding of the factors that affect the tribological performance is very essential in performance improvement on natural fibers reinforced polymer composite for potential applications.     

催化处理Lyocell纤维在热解过程中的结构与性能变化

分别采用扫描电镜(SEM)、广角X-ray衍射(WAXD)和小角X-ray散射(SAXS)研究分析了经含硫酸和尿素催化剂催化处理的Lyocell纤维在热解过程中结构、性能的变化。发现在低温热解前阶段(<200℃)随着处理温度的升高其密度增大,高于200℃后密度有所下降。纤维强度则表现出先下降后升高的变化规律,并在150℃~200℃温度区存在一个“零强度点”。在此过程中纤维聚合度也发生了类似强度的变化。同时,纤维结晶结构由纤维素II型向炭纤维的二维乱层石墨结构转化。     

聚碳硅烷纤维氧化交联机理的研究

对聚碳硅烷(PCS)原丝在不同氧化交联温度区间生成的逸出产物进行红外、核磁和GC-MAS分析,并结合交联丝的红外分析,推测氧化交联的机理。结果表明,PCS的氧化交联主要是其Si—H氧化生成Si—OH,后者进而彼此缩合生成Si—O—Si交联结构;氧化交联温度高于150℃时,其部分Si—CH3也开始氧化生成Si—OH并进而交联;同时,在氧化交联过程还发生PCS侧链的热裂解,所形成小分子也通过Si—OH彼此结合,形成较大分子,且其分子量随交联温度的提高而提高。因此,要及时排除氧化交联过程废气,以免逸出产物黏附在纤维表面而导致粘结。     

Semiconducting Nanowire‐Based Optoelectronic Fibers

The recent ability to integrate semiconductor‐based optoelectronic functionalities within thin fibers is opening intriguing opportunities for flexible electronics and advanced textiles. The scalable integration of high‐quality semiconducting devices within functional fibers however remains a challenge. It is difficult with current strategies to combine high light absorption, good microstructure and efficient electrical contact. The growth of semiconducting nanowires is a great tool to control crystal orientation and ensure a combination of light absorption and charge extraction for efficient photodetection. Thus far, however, leveraging the attributes of nanowires has remained seemingly incompatible with fiber materials, geometry, and processing approaches. Here, the integration of semiconducting nanowire‐based devices at the tip and along the length of polymer fibers is demonstrated for the first time. The scalable thermal drawing process is combined with a simple sonochemical treatment to grow nanowires out of electrically addressed amorphous selenium domains. First principles density‐functional theory calculations show that this approach enables to tailor the surface energy of crystal facets and favors nanowire growth along a preferred orientation, resulting in fiber‐integrated devices of unprecedented performance. This novel platform is exploited to demonstrate an all‐fiber‐integrated fluorescence imaging system, highlighting novel opportunities in sensing, advanced optical probes, and smart textiles.     

DSC Study on the Polyacrylonitrile Precursors for Carbon Fibers

Different polyacrylonitrile (PAN) precursor fibers that displayed various thermal properties were studied by using differential scanning calorimetry (DSC). Results showed that some commercial PAN precursor fibers displayed double separated peaks and these fibers were of high quality because of their process stability during their conversion to carbon fibers of high performance. Some fabrication processes, such as spinning, drawing, could not apparently change the DSC features of a PAN precursor fiber. It was concluded that the thermal properties of a PAN precursor fiber was mainly determined from its comonomer content type and compositions.     

先驱体转化法制备SiC纤维的研究进展

先驱体法制备的SiC纤维是高性能陶瓷基复合材料(CMC)的关键增强材料. 在过去三十年里, 已发展了三代SiC纤维. 本文综述了三代SiC纤维制备工艺、组成结构和性能的发展变化情况, 分析了SiC纤维的耐高温、抗氧化、模量和高温抗蠕变性能与其组成和结构的相互关系, 总结了提高纤维性能的主要方法.     

OM4 bend insensitive multi-mode fibers’ usefulness for MCM integration

For future generations of electronic systems, a severe bottleneck is expected on the interconnection level and the use of optical interconnection is considered as one of the most promising solutions in this matter. Recent progress in fiber development resulted in new generation of optical fibers that are bend insensitive. This makes them ideal for Multi Chip Module (MCM) application. This paper focuses on OM4 bend insensitive multi-mode fibers’ usefulness for MCM integration, particularly the investigation of MM fiber loss is presented, which is influenced by bend diameter and the fiber's mechanical performance under influence of high temperature (400 °C–1000 °C adequate to MCM production process).     

Lyocell纤维在低温热处理阶段的TG-DSC-MS研究

采用TG-DSC-MS联用技术对Lyocell纤维在低温热处理阶段(温度低于600℃,空气介质)的热分解行为进行了分析。TG和DTG分析发现,加入催化荆后Lyocell纤维的最大失重温度提前,失重总量减少,炭化得率提高。DSC研究发现,催化处理后的Lyocell纤维的放热峰明显变小,所对应的温度也明显降低,说明催化荆改变了反应途径并降低了反应放热。利用质谱(MS)技术重点分析了H2O、C2H5OH和CO2等挥发性物质的离子流强度随温度变化的规律过程。     

A Diffusion Model for Sword in Sheath Failure Mode in Vapour Grown Carbon Fibers

A peculiar failure mode named sword in sheath was reported in previous studies on Vapour Grown Carbon Fibers (VGCFs). It consists in a gliding between the VGCFs catalytic hard core and pyrolitic soft coating. This is a very interesting failure mode, looking to the additional work of fracture that it supposes.After knowing that the main difference between the hard core and the soften cortical carbon is the hydrogen content, some attempts of increase the hydrogen content in the cortical phase are made at the present work via annealing in a pure hydrogen atmosphere.A mathematical model is set up to describe the different phenomena that take place during the annealing. The hydrogen comes to the cortical carbon from the atmosphere and from the inner core. As a consequence of the very significant gradient of hydrogen concentration in the surrounding of the interface core—cortical phase, a shear mechanism is possible under tensile stress. For this reason sword in sheath takes place, mainly in not very thick fibers.