渐变型折射率钇铝硅酸盐玻璃光纤的制备

使用钇铝石榴石(YAG)单晶芯棒和光学级石英管构成预制棒,基于管中熔体共拉法制备了钇铝硅酸盐(YAS)玻璃光纤,研究了拉丝过程中由于元素迁移形成的光纤纤芯附近的元素分布和折射率分布。结果表明,使用管中熔体共拉法制备的光纤为折射率渐变型光纤,芯包层折射率差Δn从预制棒的0.380变为光纤中的0.057。所获得的YAS光纤理论最大数值孔径为0.41,具有较高的耦合效率。这种光纤有潜力应用于自聚焦效应相关的领域。     

氟化物玻璃光纤预制棒制备工艺研究

研究了氟锆酸盐玻璃光纤预制棒制备工艺对块状玻璃散射损耗和光纤损耗的影响。制得了最低损耗为７５ｄｂ／ｋｍ，用氟塑料管作包皮的氟锆酸盐玻璃光纤，并进行了传输能量试验。     

氧化物红外光纤芯、皮玻璃的研究

本文通过对5种芯料、6种皮料玻璃的性能研究,选定了几种比较适用的红外光纤芯皮玻璃成分,并用双坩埚法初步拉制出红外光纤,从理论上简要分析了光在其中传输损耗的原因.文中认为使用硅酸盐红外玻璃成分,具有成纤方便、成本低廉、便于推广等优点,因此待今后进一步扩大、改进拉丝工艺后可望投入生产.     

碲卤系红外玻璃光纤的制备及性质

研究了碲卤系中远红外玻璃光纤的制备及性质,提出了制备碲卤系玻璃预制棒的一个改进的方法,用该方法制备出了高透光率的中远红外玻璃,拉制出了在１０．６μｍ附近光损耗约为１０ｄＢ／ｍｒ Ｔｅ３Ｓｅ４Ｉ３玻璃光纤,并测试了这种玻璃纤维的最小抗弯曲率半径。     

耐热性有机高分子的性能研究及其在塑料光纤中的应用

本文以N－环乙基马来酰亚胺（CHMI）和甲基丙烯酸甲酯（MMA）共聚得耐热性透明材料，讨论了共聚产物的透明性和玻璃化温度与CHMI含量的关系。以上述材料为基础，应用界面凝胶法制备光纤预制棒，在探讨了CHMI和PCHMI的折射率的基础上，分析并测试了光纤预制棒的折射率分布，最后拉制成塑料光纤（GI－POF）并测试了光纤的光透射窗口。     

PMMA芯／氟树脂包层塑料光纤的研制

本文介绍以PMMA为纤芯,比纤芯折射率低的氟树脂为包层,用聚合～纺丝连续装置,通过单体的精制、聚合、芯层和包层的共挤出纺丝,制成塑料光导纤维的情况。所制光纤的直径为0.25～1.00mm,在可见光区具有良好的导光性能,光传导损失为200～400dB/km(650um),最佳情况下为192dB/km(590um)。对影响光纤质量的因素,如芯材的聚合工艺、共挤出纺丝工艺等进行了讨论。结果表明,芯材的聚合过程越平稳,所得光纤的光传导性能越好;纺丝温度、挤出压力和卷绕速度等工艺条件的合理控制,是纺制直径均一、截面圆整及无内部缺陷塑料光纤的关键。     

Ge-As-Se硫系玻璃红外光纤

研究了光纤芯料Ge-As-Se等系统玻璃物理和光谱性质。用棒管法拉制了直径从300--70Oμm的光纤。测定了在O.85μm,1.25μm及10.6μm波长时的光损耗,用电子探针分析了光纤断面的组份均匀性。采用中子活化法分析了芯料中的氧含量,并拍摄了其断面的显微照片。最后讨论了杂质对光损耗的影响。     

硅基电子气去除甲基氯硅烷的分子动力学模拟

光纤通信技术具有通信容量大、传输损耗低、保密性能好等优点,是一种极有前途的多路通信手段。相关技术中利用硅基电子气SiCl₄经化学气相沉积法制备光纤预制棒,但是SiCl₄中的含金属杂质和含氢杂质因对光子产生很大的振动吸收而增加光纤传输中光的吸收损耗。光纤用SiCl₄对纯度的要求极高,其中含氢杂质甲基氯硅烷的含量需降低到5mg/kg或者更低。通过光氯化法结合精馏工艺提纯SiCl₄是目前为止制备光纤用高纯SiCl₄最合适的方法。本文针对光氯化法去除甲基氯硅烷杂质的工艺过程进行分子层面的反应分子动力学模拟研究,重点比较分析了Cl₂与Cl自由基及反应温度对甲基氯硅烷的去除效果,并探究了不同的模拟体系中形成的主要的中间产物及其主要的转化路径,为光氯化除杂反应提供了基础的化学反应机理及工艺的改进方向。模拟结果表明,在反应体系中引入Cl自由基后对甲基氯硅烷的去除效率能够达到相同模拟条件下Cl₂的2倍;体系的反应温度与甲基氯硅烷的去除效率之间的相互关系并不是单调变化的,存在最佳反应温度（373K）使甲基氯硅烷的去除效率达到最大;甲基氯硅烷分子中的C—H键及C—Si键因具有较大的键能而难断裂,只有当体系内反应温度升高到一定值后（423K）才可观察到C—H键的断裂,只有在体系内引入活泼的Cl自由基后才可观察到C—Si键的断裂。     

基于SG法制备SiO2光纤预制棒干胶的研究

SiO2光纤预制棒是制备通信光纤的母体材料,为制备性能优良且价格低廉的SiO2光纤预制棒芯棒,本文以正硅酸乙酯和水为主要原料,乙醇为溶剂,HCl和NH3·H2O为催化剂,甲酰胺为添加剂,采用溶胶-凝胶工艺,且在不同温度(50,60,70,75,80,90℃)下经热处理制得SiO2干胶.讨论了不同摩尔比的水/正硅酸乙酯、...     

旋转浇铸法小芯径掺杂氟化物玻璃光纤预制棒的研制

本文通过对浇铸芯料玻璃时的粘度及皮料管内壁温度的控制，用连续浇铸芯、皮料的旋转法制取了芯皮比小于1:2．5的小芯径氟化物玻璃预制棒，给出了所用的掺钕氟化物芯皮玻璃的组成、物理性能及用此预制棒拉制成光纤的一些性能。该光纤的荧光光谱表明，此工艺还可为光纤有源器件的研制提供氟化物玻璃基质材料。     

一种制备梯度型聚合物光纤预制棒的新方法及其折射率分布的调控

针对现有制备方法对梯度型聚合物光纤（GI—POF）折射率分布（RID，直接影响带宽）的调控能力有限的特点，提出了一种制备GI-POF预制棒的新方法，可以实现对RID的自如调控。通过理论计算阐述了这种方法制备预制棒时RID的调控方法。结果表明，制备预制棒时所用物料的层数越多，预制棒的RID越接近理想分布，最终实际所得预制棒的RID与理论计算十分一致。     

复合材料柔性导向三维织造防变形方法

针对三维结构复合材料预制体成型工艺,提出一种复合材料柔性导向三维分段织造和防变形方法,通过有限元分析得到一定预紧力条件下导向棒变形情况,确定每段织造区域的织造纤维层数,对导向棒做防变形处理,从最下段逐段织造逐段压实预制体。通过预制体织造对比试验发现,分段式织造和防变形处理能够有效地防止预制体织造过程中导向棒阵列的变形、控制预制体外形尺寸;分段压实预制体压实力减小,并能获得层密度较高的预制体。     

农用薄膜的功能化研究进展

随着现代农业科技成果的不断涌现,农用薄膜的种类、功能化改性、成型加工方式等均得到了快速发展。结合多层共挤出薄膜的结构、材料以及加工成型的特点,介绍了多层共挤出薄膜的功能化研究成果,并对多层共挤出成型机的机头流道结构、新型微纳层叠分配器以及辅机的自动测厚、自动调节等智能化改造生产线进行了论述,通过添加不同的功能性助剂以及调节光源的强度,阐述了新型长效防雾滴剂的功能性改性以及光精准调控转光薄膜,分析了流滴剂、转光剂等相关助剂以及单基双能转光剂的规模化应用前景,论述了多种生物降解地膜的研究开发进展以及在不同环境下的降解效果。展望了未来我国农膜相关技术领域的研究方向和发展前景。     

Co‐Extrusion of Multilayer Glass Fiber‐Optic Preforms: Prediction of Layer Dimensions in the Extrudate

A three‐dimensional, incompressible and noncavitating model of a glass‐stack coextrusion process, under isothermal and non‐isothermal conditions is numerically simulated by means of computational fluid dynamics. A dynamic mesh approach is taken in a domain‐subdomain type setup to simulate the transient steps in the steady‐velocity phase of the experimental co‐extrusion. The multiphase setup consists of a glass‐stack which is composed of different glass compositions. Experimentally measured glass properties, such as the temperature coefficient of the viscosity of the supercooled glass melts are used to define the flow behavior of the glasses in the starting stack when extruded. The modeled extrudate is numerically verified for transient and spatial errors, leading to the choice of a suitable mesh. Excellent agreement is found between modeling and experiment when plotting the core/cladding dimensions of a step‐index extruded fiber‐optic preform along the length of the preform. This approach can identify the stable part of the preform, in terms of constant core/cladding layer geometry, obviating costly and time‐consuming experimental iteration. Also, the modeling allows prediction of the starting glass‐stack dimensions for a specified fiber design.     

Combined processing of polypropylene film by coextrusion and zone-annealing

In order to improve the mechanical properties of polypropylene film, a new processing combining extrusion and zone-annealing has been applied. It was found that there are suitable conditions for each step in the combined processing. When the coextrusion draw ratio was low, the total draw ratio and modulus could be increased by the zone-annealing subsequently done. The highest modulus was obtained when the film was coextruded at extrusion draw ratio 4 and then zone-annealed at 120°C under 7 kg/mm². The value was 12 GPa in Young's modulus or 17 GPa in dynamic modulus. The peak temperature of α_c dynamic dispersion for the combinedly processed film was 109°C, which is higher by 10°C than that for the as-coextruded film. Four drawing methods were compared in dynamic viscoelasticity. These methods are the coextrusion, zone-drawing/zone-annealing, two-step coextrusion, and the combined processing by coextrusion and zone-annealing. The highest dynamic modulus for each method was arranged in the above order. The combined processing indicated the most effective improvement in mechanical properties, because it is believed that lamellae in the original film were broken by cooperating interaction of shear stress, compression, and tension on coextrusion and then the superstructure with a high crystallinity and a high molecular orientation was formed on zone-annealing.     

聚合物共挤出技术及其应用

综述了聚合物共挤出技术近年来的发展及应用,包括多色共挤出技术及问题、微米层/纳米层共挤出技术及优势、共挤绝缘橡胶管感应器,以及多层共挤中空容器共挤出技术及应用.介绍了气体辅助共挤出成型技术及其优势.     

后共挤（PCE）成型工艺的研究

后共挤技术是共挤出技术的最新发展,成形工艺是其重要组成部分。本课题围绕研制开发软硬PCV共挤窗型材,对后共挤成型工艺进行了研究。研究结果表明,共挤料熔体温度和基材的热处理温度对复合制品的粘接强度有着最重要的影响,通过调节这两个参数,可制品的复合强度进行调控。本文介绍了在此方面的研究工作,对影响成型过程的主要工艺因素进行了分析。     

复合材料液体模塑成型中纤维预成型体制备技术进展

总结了20世纪90年代以来关于复合材料液体模塑成型(LCM)技术中纤维预成型体制备技术的相关文献报道,指出LCM用纤维预成型体应满足的工艺性要求,且对当前国内外纤维预成型体的成型方法及其制备技术中应用的几种增粘剂进行了分析和概述,并对纤维预成型体制备技术的发展方向进行了展望。     

Predicting heat and mass transfer to a growing, rotating preform during soot deposition in the outside vapor deposition process

During the manufacture of optical fibers using the outside vapor deposition (OVD) process, porous soot preforms are made by depositing soot onto a rotating cylindrical target from a soot-laden flame traversing along the target axis. The dominant mechanism of soot deposition in the OVD process is thermophoresis, which is the tendency of particles to migrate down the local gas temperature gradient. Accurate methods to estimate the heat and mass transfer rates from the flame to the growing preform are critical, as these rates dictate important preform characteristics. The heat and mass transfer during the OVD process are coupled due to particle thermophoresis and growth of the preform. We here present methods to predict the growth rate of a rotating preform along with the evolution of temperature profile at different radial locations within the preform for specified process parameters of flame temperature, burner traverse speed and number of burners. Sensitivity of preform temperature profile and deposition rate to each of the process parameters is presented, along with the critical discussion of our principal results.     

Incorporation of lead phthalocyanine into periodic nanolayered assemblies for advanced optical systems

Periodically structured polymeric materials can lead to the next generation of electro‐optic and nonlinear optical devices for applications in information technology. Layer‐multiplying melt coextrusion is an attractive method for fabricating periodic structures with thousands of alternating polymer microlayers or nanolayers. Many advanced applications for periodic polymeric structures would be enabled by locating a photoactive dye in one or both layers. However, it is anticipated that due to the thinness of the individual layers and the relatively low molecular weight of many dyes, a substantial fraction of the dye will diffuse from the doped layers into the undoped layers during melt coextrusion. In the present study, we demonstrate two methods for confining the activity of a photoactive dye, lead phthalocyanine, to the doped layers. Polycarbonate containing lead phthalocyanine was coextruded with undoped polyester as an assembly of 128 alternating 86 nm‐thick layers. Using the absorption spectra, we demonstrated that a high concentration of the monomer form persisted in the polycarbonate layers, whereas the lead form was converted to the less active lead‐free form in the polyester layers. Thus, the active monomer form of PbPc(β‐CP)₄ was maintained selectively in the polycarbonate layers. In the second approach, the coextrusion process was altered so that the alternating polycarbonate and polyester layers were separated by a thin layer of a barrier polymer. The barrier layer prevented diffusion of the dye during melt coextrusion and the dye remained selectively in the polycarbonate layers. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009