碳织物／PEEK静电粉末预浸工艺树脂含量检测控制系统

介绍了一种由β射线检测仪、微机等组成的碳织物／ＰＥＥＫ（聚醚醚酮）静电粉末预浸过程树脂含量动态监控系统。该系统能够跟踪预浸过程，准确、灵敏地反映树脂含量的变化，并能根据要求及时调整工艺参数，保证预浸料树脂均匀分布，有利于工艺过程的连续化、自动化。本文介绍了这种监控系统的组成及工作原理，绘出了一些预浸料的工作曲线，考察了这种控制系统的性能，验证了其可行性。     

炭/酚醛预浸布树脂含量的β-射线连续监测

利用自行建立的β-射线监测系统对炭/酚醛预浸布的树脂含量进行了连续监测研究。根据实验数据拟合出了树脂含量与β-射线监测系统输出信号间的定量关系式,同时分析了β-射线源的稳定性、炭纤维布的波动性对监测精度的影响。连续监测结果表明,该β-射线监测系统具有较高的测量精度,可以用于预浸布树脂含量的连续、在线监测。     

预浸料的质量控制

预浸料的原料质量尤其是树脂质量是保证预浸料性能的基础,在预浸料制备过程中,及时、有效、无损的在线监测是预浸料发挥性能的保证。简要介绍了几种常用的在线监测手段,包括β射线监测、超声波监测、红外光谱监测及近红外光谱监测等。此外,预浸料成品的质量控制是复合材料性能的关键,其中凝胶时间、树脂流动性、挥发分含量、树脂含量、单位面积纤维质量等是预浸料重要的质量指标。     

复合材料预浸带树脂含量在线监测技术现状

综述了目前国内外有关复合材料预浸带树脂含量的在线监测技术现状，着重对超声、射线、光学及重量监测技术的研究进展和应用前景进行了分析。     

影响蜂窝夹层结构滚筒剥离强度主要因素的研究EI

对预浸料与蜂窝直接接触共固化成形的蜂窝夹层结构的滚筒剥离强度进行了研究，主要讨论了树脂基体、预浸料树脂含量及织物构成对滚筒剥离强度的影响。     

零吸胶炭纤维增强高温固化环氧复合材料预浸料研制

针对大尺寸、大厚度复合材料构件对“零吸胶”预浸料的需求,对低树脂含量炭纤维增强高温固化环氧复合材料预浸料进行了研制,并对预浸料的外观和物理性能、复合材料基本力学性能及成型工艺性能进行了研究.通过对预浸料制造工艺参数的优化,研制出了低树脂含量炭纤维增强高温固化环氧复合材料预浸料,其外观和物理性能满足要求;采用低树脂含量预...     

碳纳米管加入方式对碳纤维/环氧树脂复合材料层间性能的影响

针对碳纤维/环氧树脂预浸料,对比了直接在树脂中加入碳纳米管(CNTs)后制备预浸料以及将CNTs喷涂在预浸料表面2种CNTs加入方式对CNTs-碳纤维/环氧树脂复合材料层合板I型与II型层间断裂韧性及层间剪切强度的影响。通过对树脂黏度、固化反应以及玻璃化转变温度的考察,分析了CNTs含量对树脂性能的影响,考察了添加方法对CNTs长度与形态的影响。分析了2种CNTs加入方式对CNTs-碳纤维/环氧树脂层合板断裂韧性及层间剪切强度的改善效果与作用规律。结果表明:CNTs的加入使树脂的黏度提高,固化反应程度下降;2种分散方法对CNTs的长度与形态无明显影响;直接在树脂中加入CNTs对CNTs-碳纤维/环氧树脂复合材料I型与II型层间断裂韧性的提高效果低于在碳纤维/环氧树脂预浸料表面喷涂CNTs的方式,后者的CNTs利用率较高;由于CNTs团聚及对树脂固化反应的影响,CNTs含量过高会使得其对CNTs-碳纤维/环氧树脂层合板的增韧效果下降。     

连续预浸带的制备工艺研究

本文介绍了用预浸带铺制机湿法制备单向碳纤维预浸带的工艺方法,讨论了影响预浸带树脂含量、外观及挥发分含量的有关因素,优化了工艺条件,确定了制备单向预浸带的最佳工艺参数.制备的预浸带最大宽度为300毫米,连续长度可达200米.可以批量稳定地进行生产.      

复合材料用几种新型树脂研究进展

本文介绍了作为先进复合材料的几种新型树脂基体的进展,预浸料的制备方法,纤维增强复合材料的性能。本文所涉及的预浸方法具有如下优点:适于不同体系的树脂,预浸料树脂含量均匀,生产效率高等。     

用近红外光谱技术检测酚醛树脂基高硅氧预浸料质量指标

通过对酚醛树脂基高硅氧预浸料的近红外光谱进行分析,采用化学计量学方法建立了预浸料树脂含量、挥发份含量和预固化度的定量分析模型,研究了光谱预处理方式及光谱区域的选择对定量分析精度的影响。结果表明,用所建立的模型对未知样品预测,树脂含量、挥发份含量和预固化度平均绝对误差分别为0.46%,0.24%和0.42%,可以满足质量检测要求,对生产过程的质量控制具有指导意义。     

热残余应力对内埋光纤光栅传感器性能的影响

将布拉格光纤光栅(FBG)埋植于复合材料T型加筋板结构非干涉区—三角填充区作为应变传感器对复合材料加筋板在固化过程及冲击后压缩过程中的应变变化进行监测。对比了光纤刻栅区采用UV光固化树脂涂层保护和未保护的两种FBG传感器的波谱信号变化; 分析了复合材料在固化成型过程中产生的非轴对称热残余应力对FBG传感性能的影响。结果表明, 刻栅区采用聚合物涂层保护的FBG传感器的半峰宽(FWHM)在固化过程中未发生变化, 并且聚合物涂层可以有效地消除非轴对称热残余应力对光纤光栅反射波谱的影响。在冲击后压缩过程中, 采用聚合物涂层保护的FBG传感器测得的应变与贴于试样表面的应变片测得的应变数据一致性较好。本文对埋植于复合材料加筋板三角填充区的FBG传感器在复合材料固化过程及冲击后压缩过程中应变监测的有效性及可靠性进行了有益的探索。     

Preparation and In-Vitro Evaluation of A Controlled Release Drug Delivery System of Theophylline Using An Aqueous Acrylic Resin Dispersion.

Abstract

Eudragit® E30D was utilized in conjunction with talc and xanthan gum to coat theophylline granules via a Wurster-type air suspension column. Since the resin is extremely tacky and cannot be used alone as a coating formulation, different amounts of talc and xanthan gum were incorporated into the Eudragit® E30D suspension to allow for coating of theophylline granules. The release profile of theophylline from the coated granules was found to be dependent on the ratio of the additives to the resin used in the coating suspension as well as on the coating level applied to the final product. A sample of theophylline granules coated with a film-coating suspension containing 1.5:1.0: :Talc: Eudragit® E30D resin (calculated on dry basis) exhibited a zero order release profile. However, the in-vitro release rates of this formulation decreased on storage. As the ratio of talc and Eudragit® E30D was changed to 1:1, the coated theophylline granules showed a release profile that remained unchanged even after exposure at room temperature, 30° C and 40° C for three months. A stable theophylline formulation was achieved by curing the coated product at 40°C for 24 hours.     

The effect of pyrocarbon coating permeability on uranium redistribution in high temperature gas-cooled reactor fuels

The current reference recycle fuel particle for steam-cycle high temperature gas-cooled nuclear reactors is a UO₂-UC₂ kernel with a multilayered coating (Triso) deposited in a fluidized bed. The coating comprises a low density pyrolytic carbon buffer, a high density inner pyrolytic carbon coating, SiC and a high density outer pyrolytic carbon coating. The kernel is fabricated from a weak acid ion exchange resin.Microradiographic examination of coated weak acid, ion exchange resin particles demonstrated that a considerable quantity of uranium can be transferred from the kernel into the buffer coating during fabrication. Since one function of the buffer coating is to absord fission product recoil, this behavior is a potential source of failure of the high density inner pyrolytic carbon coating. Fuel redistribution in Triso particles can result from permeation of the inner pyrolytic carbon by HCl during SiC deposition. Since the SiC deposition employs decomposition of methyltrichlorosilane (CH₃SiCl₃), HCl is readily available during this process. The permeability of the inner pyrolytic carbon coating to HCl gas has a marked effect on the extent of this fuel dispersion for certain fuel kernel conditions. Permeability of pyrolytic carbon to chlorine was determined by 1500°C chlorine-leaching studies to be a strong function of the coating density, the hydrocarbon gas dilution in the coating furnace and the coating temperature but to be relatively unaffected by application of a “seal” coat, by the coating thickness or by subsequent annealing of the pyrolytic carbon coatings at 1800°C. With this information it is possible to modify the inner pyrolytic carbon coating to prevent uranium redistribution due to coating permeability.     

镀Ni-P和Ni-N合金碳纳米管的磁性能及其复合材料的微波吸收性能

用竖式炉流动法,以二茂铁为催化剂,噻吩为助催化剂,苯为碳源通过催化裂解反应在1100~1200℃制备了直线形碳纳米管,外径为20~50 nm,内径10~30 nm,长度50~1000 μm。用化学镀工艺在碳纳米管表面均匀包覆了Ni-P和Ni-N合金,研究了它们的磁性能及其环氧树脂基复合材料在2~18 GHz的微波吸收性能。与纯碳纳米管相比,镀Ni-P合金碳纳米管复合材料的吸收峰向高频移动,镀Ni-P和Ni-N合金碳纳米管经热处理后,复合材料的吸收峰向低频移动。镀Ni-P合金碳纳米管以及镀Ni-P和Ni-N合金经热处理碳纳米管的矫顽力分别为304.34 Oe、 81.65 Oe、 183.85 Oe。随着矫顽力的增加,在2~18 GHz,复合材料的微波吸收峰向高频移动。在复合材料中,碳纳米管以及镀Ni-P和Ni-N合金的碳纳米管作为偶极子吸收微波。      

Microstructure and oxidation resistance of SiC coated carbon-carbon composites via pressureless reaction sintering

The effects of processing parameters on the microstructure and oxidation resistance of silicon carbide (SiC) coated carbon-carbon (C-C) composites were investigated. C-C composites were made from plain woven carbon cloths and phenolic derived carbon matrices in the laboratory. Pressureless reaction sintering has been used to apply SiC coating to C-C composites using epoxy resin and silicon powder as the precursor. Results showed that the oxidation resistance of C-C composites was enhanced by coating with SiC. The pressureless reaction sintering process exhibits good processability. -SiC was formed after heat treatment at 1800 °C and the -SiC formed after heat treatment at 2200 °C. The SiC coated C-C composites exhibit good oxidation resistance at 1000 °C for 100 h under the test conditions.     

Angular dependence of the TL reading of thin alpha-Al2O3:C dosemeters exposed to different beta spectra

The angular dependence of the thermoluminescent (TL) signal of thin alpha-Al2O3:C dosemeters was investigated for a series of beta-emitting radionuclides commonly employed in nuclear medicine and characterised by different mean energies (99Tc, 177Lu, 90Sr/90Y and 90Y). Irradiations were performed in a controlled geometry, using a properly designed irradiator intended to realistically reproduce the situation of exposure of hospital personnel to beta-emitting pharmaceuticals. Under the conditions of extended source and short source to detector distance, the TL signal of thin alpha-Al2O3:C layers per unit irradiation time was observed to be independent on the angle of incidence within acceptable limits, particularly for those radionuclides with maximum energy >500 keV. This property may be easily explained by using simple physical considerations, such as the limited thickness of the dosemeters. The results confirm that these detectors are suitable for beta-ray extremity dose measurements, when the photon contribution is negligible, as in the case considered.     

有机胶体黏附力作用下的钎焊工艺

利用有机胶体的黏附作用力改善待连接表面的界面张力,可为实现异种材料间的钎焊连接提供有利条件。以环氧树脂为黏性胶体,TiH_2粉为活性元素源,AgCu共晶合金箔为钎料,将TiH2与环氧树脂混合后涂敷在SiO_2f/SiO_2复合材料表面,并在此表面进行钎料润湿实验。结果表明:胶体黏附力对钎料的润湿铺展具有促进作用。将此工艺用于钎焊连接,可实现SiO_2f/SiO_2复合材料、Cf/SiC复合材料以及Al_2O_3陶瓷与Invar合金的冶金致密连接。     

Evaluation of self-dose S values for positron emitters in voxel phantoms

In recent years, concern has been raised about patient-specific doses due to the increased use of PET imaging. It is of scientific and practical interest for the accurate quantification of the doses to patients administered a radiopharmaceutical for PET imaging. In the present study, Monte Carlo simulations have been carried out to evaluate S values--the mean absorbed dose to the target region per unit cumulated activity in the source region--for positron emitters in the brain, heart and the urinary bladder content. The positron emitters considered were four radionuclides that are frequently used for PET imaging: 11C, 13N, 15O and 18F. S values were evaluated for the Medical Internal Radiation Dose 5 type mathematical phantom and the adult voxel phantoms developed at the Japan Atomic Energy Research Institute (JAERI). Consequently, Monte Carlo simulation and voxel phantoms were found to be useful in the evaluation of the beta dose to organs, in particular to hollow organs such as the urinary bladder. It was also demonstrated that the self-dose S values largely depend on the beta-ray energy and the mass of each target region.     

复合材料孔隙率计算的误差分析

本文具体分析了用组分密度和含量来计算复合材料孔隙率时所具有的误差。对纤维增强塑料来说,最大的误差来自用整块树脂的密度代替了复合材料中树脂基体的密度。      

纳米TiO-2保鲜包装纸的制备及其对迷你黄瓜保鲜效果的研究

为研究纳米包装纸和保鲜膜结合对迷你黄瓜的保鲜效果,试制了不同浓度的TiO2涂膜纸,并与保鲜膜结合包装保鲜迷你黄瓜,观察了贮藏过程中迷你黄瓜的感官品质变化,并测定了迷你黄瓜的失重率、硬度、维生素C含量、叶绿素含量。实验结果表明,纳米TiO2保鲜纸结合保鲜膜包装迷你黄瓜可有效延长其货架期,15%(体积分数)的纳米涂膜纸与保鲜膜结合,可使迷你黄瓜的保质期延长到30 d以上。