近红外光谱技术在酚醛预浸布中的应用

为了对预浸布进行快速检测,采用近红外漫反射的方法对高硅氧/酚醛预浸布,碳/酚醛预浸布中的树脂含量、可溶树脂含量和挥发份含量进行在线监测,三项指标同时显示.通过偏最小二乘方法分别建立标准模型,用模型的评价指标评价,分析未知样品.用近红外方法在1 min之内同时分析出结果,没有破坏性.用近红外的测定结果和标准方法的测定结果相比,两者不存在显著性差异.近红外光谱的方法可以应用在酚醛预浸料生产线上.     

Mechanical characterization of carbon fiber reinforced phenolic resol and epoxy condensate plastic

A matrix resin for carbon fiber reinforced composite was developed that consisted of resol type phenolic and difunctional epoxy resin (PR-EP) condensate or adduct. Carbon fiber reinforced composite with fiber volume fraction of 0.6 was prepared with PR-EP matrix containing 0, 50, 100, 150, and 175 parts of epoxy resin per hundred parts of phenolic resin (php), especially a synthesized resol type. One-shot and prepreg techniques have been adopted and the study of loss of volatiles has indicated the superiority in terms of favorable processability of prepreg technique over the other. FTIR spectroscopic analysis confirmed the PR-EP adduct formation at the prepreg preparation stage. The improvement in properties such as tensile strength and elongation at break was observed in resin matrices with epoxy and phenolic resin; however, the flexural strength and modulus remained more or less unaltered. The prepreg technique of composite preparation has resulted in substantial improvement in mechanical properties and the same was attributed to the formation of PR-EP adduct and low volatiles during cure. Composites of carbon fiber reinforced PR-EP matrix developed here are likely to meet the requirement of aerospace structures in view of the realization of a wide spectrum of properties.     

两种预浸工艺对玻璃布预浸料性能的影响

着重研究了用溶液法和热熔胶膜法工艺所制备的5231/823玻璃布预浸料的物理性能、工艺性能、力学性能和滚筒剥离性能,旨在探讨不同预浸工艺对预浸料及其复合材料性能的影响,试验结果表明:这2种工艺所制的5231/823预浸料的工艺性能和剥离性能相当,但在预浸料树脂含量控制精度方面,热熔法工艺高于溶液法工艺;在预浸料挥发分方面,热熔法工艺的较低,一般低于0.8%。在复合材料常规力学性能方面,一般前者高于后者。     

四烯丙基二苯甲烷二胺／双马来酰亚胺共聚树脂玻璃布层压板的研制

本文以Ｎ，Ｎ，Ｎ’，Ｎ’－四烯丙基二苯甲烷二胺和二苯甲烷双与来酰亚胺为主要原料合成了一类新型的耐高温双马来酰亚胺共聚树脂，并以此树脂为基体制得了玻璃布预浸料及层压板，考察了共聚树脂及玻璃布预浸料的贮存稳定性和层压板的性能，实验结果表明，共聚树脂及预浸料贮存期长，工艺性良好，层压板制备工艺幅度宽，电性能和高温力学性能优异，可作为耐高温绝缘材料和结构材料使用。     

新型耐高温阻燃层压板的研制

以苯酚、甲醛为原料,在催化剂的作用下合成酚醛树脂,然后用硼酸改性得到硼酚醛(FB)树脂.采用FB树脂作为基材树脂制作玻璃布层压板,FB树脂的耐热性比普通酚醛树脂高.FB树脂层压板具有好的耐热、阻燃、机械和电气性能,其阻燃性能达到了UL-94垂直燃烧法V-0级.     

Cure behavior of some resin–glass cloth systems

Changes in the dynamic modulus E′_dyn of some phenolic glass cloth systems were studied as a function of cure temperatures and formaldehyde factors. The modulus changes were followed by continuously monitoring in situ the fundamental frequency of vibration of resin-impregnated glass cloth systems bonded to metallic cantilever reeds. The apparent activation energy of crosslinking was a direct function of the formaldehyde content in the resin synthesis, ranging from 9 kcal/mole for a 1.2 formaldehyde factor phenolic, to 20 kcal/mole for a 1.8 factor. Two cure parameters at 50% and 100% apparent mechanical conversion were established.     

热固性树脂半固化片树脂流动度研究

采用聚丁二烯、丙酮、陶瓷粉填料和其他助剂,制得胶液,用偶联剂处理过的玻璃布在胶液中浸渍后,在70℃干燥脱溶剂,在140℃继续烘烤10 min,得到半固化状态的预浸片.将浸渍片按固定的尺寸裁切后即得到所需的热固性树脂半固化片.对半固化片关键指标之一的树脂流动度的影响因素及调控方法进行了较为详细的讨论.结果表明,在良好界面...     

Room-temperature aging of Narmco 5208 carbon-epoxy prepreg. Part II: Physical,mechanical, and nondestructive characterization

Samples of Narmco Rigidite 5208/WC3000 carbon-epoxy composite prepreg were exposed to ambient temperature (22°C) and 50 percent relative humidity for different periods up to 66 days. The aging has a significant effect on prepreg physical properties such as tack, volatiles content, and gel time. A set of 4-ply laminates made from aged prepreg was subjected to tensile testing, ultrasonic inspection, and optothermal inspection. No relationship could be discerned between laminate properties and prepreg aging time. However, variations in panel homogeneity were observed, and these correlated with thermal diffusivity and tensile modulus measurements, but not with ultimate tensile strength or elongation. A set of 6-ply laminates was used to measure compressive properties, interlaminar shear strength, and physical properties. These panels also showed variations in porosity, again unrelated to aging, but in addition, the fiber/resin ratio was observed to decrease with aging time. Both factors were found to affect mechanical properties. The implications concerning the importance of monitoring the aging by physicochemical methods are discussed.     

In-process vibrational spectroscopy and ultrasound measurements in polymer melt extrusion

Spectroscopic techniques have the potential to provide powerful, molecular-specific, non-invasive measurements on polymers during melt processing operations. An exploration is reported of the application and assessment of sensitivity of in-process vibrational spectroscopy—on-line mid-infrared (MIR), on-line near-infrared (NIR), in-line NIR and in-line Raman—for monitoring of single screw extrusion of high-density polyethylene and polypropylene blends. These vibrational spectroscopic techniques are compared with novel in-line ultrasound velocity measurements, which were acquired simultaneously, to assess the sensitivity of each method to changes in blend composition and to explore the suitability for their use in real time process monitoring and control.     

低成本高性能酚醛树脂基烧蚀材料的性能研究

本文对硼酚醛树脂、高残碳酚醛树脂、S-157酚醛树脂的固体含量、粘度、凝胶时间进行了表征和对比,此基础上对比研究了连续玄武岩纤维平纹布增强三种酚醛树脂复合材料的密度、硬度、导热系数,同时对三种复合材料的烧蚀性能和力学性能进行了测试和对比。研究结果表明：硼酚醛树脂复合材料的力学性能最好,S-157酚醛树脂复合材料其次,高残碳酚醛树脂复合材料的力学性能最差;在烧蚀性能方面,硼酚醛树脂复合材料和高残碳酚醛树脂复合材料相当,S-157酚醛树脂复合材料最差。     

Process analytical technology applied for end-point detection of pharmaceutical blending by combining two calibration-free methods: Simultaneously monitoring specific near-infrared peak intensity and moving block standard deviation

Here, we describe a combination approach using Two Calibration-Free Methods with reflectance near-infrared (TCFM-NIR), which involves detecting end-points for active pharmaceutical ingredients (APIs) blending by simultaneously monitoring specific NIR peak intensity of APIs and calculating moving block standard deviation (MBSD). After determining the specific NIR peak range of nicaldipine hydrochloride, conditions for TCFM-NIR were established by monitoring the differential intensity of the second peak (1136 nm) while MBSD was calculated from the NIR peak intensity between 1100 and 1150 nm. In comparison with the validated reference method of UV-VIS spectroscopy, which is particularly destructive, TCFM-NIR was found to be useful in detecting end-points for blending of nicaldipine hydrochloride. TCFM-NIR monitors two important factors for estimation of blend uniformity: API concentration, using specific NIR peak intensity for APIs, and blend homogeneity, using MBSD. Also, the conditions of TCFM-NIR were confirmed to be adequate by using Partial Least Square (PLS). Further, simultaneously monitoring these two blend uniformity factors is more useful in preventing estimation errors for nondestructive monitoring of blend homogeneity than monitoring only one factor, as with NIR spectroscopy.     

近红外漫反射分析技术在测定聚丙烯粉料中二甲苯可溶物方面的应用

文章探讨了利用近红外分析技术快速判断聚丙烯粉料中的二甲苯可溶物含量的应用。用近红外漫反射法收集了样品的近红外光谱图。参照化学计量学分析方法测定聚丙烯样品的二甲苯可溶物含量。利用偏最小二乘法线性回归法建立了聚丙烯二甲苯可溶物的近红外光谱预测模型。将近红外法测定结果与化学分析方法测定结果进行了比较,对光谱测量的重复性进行了考察。结果表明,利用近红外光谱法与化学分析法的测定结果无显著差异。     

近红外光谱技术在中草药口服液在线质量监控中的模型建立和模型转移

应用近红外光谱技术在线监测工业产品质量时,会出现环境条件变化或仪器的部件如探头或光纤更换的情况,使原模型不再具有原来的预测效果,但是完全从头开始采集数据重新建立新模型工作量大,造成原来宝贵的模型和数据的浪费。为了解决这一矛盾,本文以一种中草药口服液中多糖含量、可溶性固形物含量及pH 为研究对象,利用近红外光谱技术对其进行实时在线检测,研究了主从机分辨率不同的光谱之间的模型转移。模型转移过程利用已建模完成并成功上线应用的模型为原模型,在不能获取原主仪器和从仪器一一对应的标准标样的条件下,找到虚拟标样建立转移矩阵。以直接标准化法结合主成分分析降维作为模型转移方法,以质量指标化学参考值与预测值间的相对误差为指标筛选最佳模型。模型转移结果显示,多糖模型预测值与化学参考值间的相对误差可控制在10%以内,可溶性固形物相对误差在5%以内,pH 相对误差在3%以内。在线生产使用表明,转移的模型同原模型一样可有效应用于在线、快速对质量指标做出准确的预测。结果表明,本文提出的采用虚拟标样的模型转移方法对于无法获得主从机一一对应的标准标样的情况下的模型转移,是一个可行的有效方法。     

玄武岩纤维/酚醛树脂基复合材料性能研究

对玄武岩纤维增强酚醛树脂基复合材料进行了实验研究。制备了连续玄武岩纤维平纹织物增强酚醛树脂复合材料。研究了胶含量对玄武岩纤维/酚醛树脂复合材料拉伸、压缩和层间剪切强度等力学性能、耐烧蚀性能的影响。利用SEM对复合材料压缩、层间剪切破坏断口和烧蚀试样的微观形貌进行了分析。研究结果表明,玄武岩纤维/酚醛树脂复合材料具有较好的界面性能,树脂含量在36%时CBF/酚醛树脂复合材料的力学性能最佳,线烧蚀性率和质量烧蚀率最低。     

Behavior of volatile depletion for LaRC™‐PETI‐5 amide acid/N‐methylpyrrolidinone solution

The fabrication of composites from polyimide precursors (polyamide acids) that involve condensation reactions requires the removal of volatiles (solvent and reaction by‐products) prior to consolidation in order to achieve a void‐free laminate. Volatile removal is commonly accomplished with a B‐stage processing step. In this study, a PETAA/NMP (p henyle thynyl t erminated a mide a cid in N‐methylpyrrolidinone) solution and prepreg were characterized using therogravimetric analysis (TGA) and microdielectrometry. A master weight loss profile was constructed by superimposing measurements at various heating rates. The TGA results correlated well with the dielectric ionic conductivities. Under the same thermal conditions, volatiles were depleted at slower rates from the wet prepreg than the neat resin solution. Dielectric properties were more sensitive to the residual volatile contents than the TGA measurements in both the neat resin and wet prepreg. Dielectric sensing technology was demonstrated to be a feasible tool for future volatile management in the fabrication of PETI composites. This study demonstrates that the combination of TGA and dielectrometry provides useful information to develop proper processing conditions for composite fabrication from prepregs containing volatiles. © Published 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1906–1916, 2003     

磺化酚醛树脂改性苯丙共聚物表面施胶剂的合成应用研究

以自制的磺化酚醛树脂作为交联单体对酶转化淀粉接枝苯丙共聚物进行改性,合成了环保型的苯丙共聚物表面施胶剂。采用FT-IR、DSC、SEM等测试仪器对其性能以及施胶度进行了表征。探讨了引发剂的用量与比例、淀粉与单体比例、乳化剂以及功能单体等合成条件对产品性能的影响。其结果表明当引发剂的量6%,H2O2-FeSO4比例为50：1,m（淀粉）/m（单体）为1：2,阳离子乳化剂添加量2%,磺化酚醛树脂功能单体添加量3%时,优化合成的苯丙共聚物表面施胶剂,其施胶性能达到市场领先水平。     

S-157酚醛树脂/CBFTC复合材料的研究

制备了连续玄武岩纤维平纹布(CBFTC)增强S-157酚醛树脂复合材料。研究了树脂含量对S-157酚醛树脂/CBFTC复合材料力学性能和烧蚀性能的影响,并借助扫描电子显微镜对复合材料断面的微观形貌进行了分析,同时将S-157酚醛树脂/CBFTC复合材料与S-157酚醛树脂/高强玻璃纤维平纹布(GFTC)复合材料进行了性能对比。结果表明,树脂含量在30%时S-157酚醛树脂/CBFTC复合材料的力学性能和烧蚀性能最佳;S-157酚醛树脂/CBFTC复合材料比S-157酚醛树脂/GFTC复合材料具有更好的力学性能和烧蚀性能。     

Mechanical Properties of Carbon Epoxy Prepreg Insert Phenolic Resin Injection Moldings

This study focuses on the insert-injection molding process. The thermoset composite inserts in this study were carbon fiber/epoxy(CF/Epoxy) prepreg sheets. The injected molded part was glass fiber contained phenolic resin(GF/PF). The CF/Epoxy was placed in the mold cavity prior to injecting GF/PF onto the inserted injection molded CF/Epoxy specimens. The role of adhesion between the inserted part and injected resin on the mechanical properties was evaluated by 3 point bending and impact tests. In addition, the effect of prepreg orientation on the mechanical properties of the prepreg inserted-injection molding system was investigated. It was found that the prepreg with unidirectional orientation significantly improved flexural and impact strength of the inserted injection molding composites, providing better support and resistance to bending and impact loading. The main failure modes of the specimens were structural and adhesive failure.     

Solvent-dependent adsorption of phenolic resin onto silica substrate

The solution impregnation route is commonly exploited to prepare polymer-based composites. However, the adsorption of polymer components is complicated, which is the result of interactions between reinforcement, solvent and polymer. In this study, the adsorption of phenolic resin onto silica substrate from different solvents was investigated by diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, UV-visible absorption spectroscopy and thermogravimetric analysis (TGA). Isotherms for phenolic resin adsorption from solvents onto silica substrate have been examined as a function of phenolic resin content in different solvents. The viscosity and surface tension were measured for the solution systems before and after adsorption. Hydrogen bonding interaction was considered to be operative in the resin–solvent–silica system. The adsorption of phenolic resin is dependent on its relative affinity for the solvent on one hand and for the silica surface on the other. UV-visible absorption spectroscopy results suggested that phenolic resin forms hydrogen bonds with the solvent, which competes with the hydrogen-bonding adsorption mechanism for phenolic resin occurring on silica surface. This hydrogen bonding in solution along with the competitive adsorption of solvent onto silica surface suppresses the adsorption of phenolic resin and such suppression is unfavorable in a solution impregnation process.     

Some Experiences of Using Different Analytical Methods in Screening for Oil and Protein Content in Rapeseed

In this study some analytical methods, which have been used in oil crop breeding, are compared from the point of view of plant breeding. For oil content determination a gravimetric method, NMR and NIR have been used. Protein content has been determined by the classical Kjeldahl technique, by the Biuret method and by NIR. The results indicate that the NIR spectroscopy is specially useful in screening breeding materials. This method enables the breeder to select for several quality characters simultaneously at a high speed and at a low cost. Since NIR spectroscopy is nondestructive, the same seed lot can be used for analysis and planting. Thus it is possible to select on a large scale for single plants.