CE/EP/CF复合材料的湿热性能研究

采用溶液预浸渍法分别制备了两种碳纤维(CF)增强环氧树脂(EP)改性氰酸酯树脂(CE)(CE/EP/CF)复合材料,研究了该复合材料的吸湿行为及湿热环境对其力学性能和微观结构的影响。结果表明,CE/EP基体具有比EP更小的吸湿能力;湿热环境对CE/EP/CF复合材料的纵向拉伸强度影响不大,但对其层间剪切强度的影响较为显著。     

潜溶剂对聚氟乙烯熔融挤出成型的影响

选取N,N-二甲基甲酰胺、N,N-二甲基乙酰胺和γ-丁内酯作为潜溶剂,分别加入聚氟乙烯(PVF)树脂中改善其加工性能。研究了不同潜溶剂及其用量对PVF树脂的热力学性能、流变性能与制品力学性能的影响,分析了潜溶剂与PVF树脂的相互作用,评价了潜溶剂在PVF树脂熔融挤出成型中的作用,获得了适宜的改性配方和成型工艺。     

长玻璃纤维增强聚丙烯复合材料力学性能研究

以长玻璃纤维为增强材料,不同聚丙烯(PP)树脂为基体,通过特制的浸渍设备制备长玻璃纤维增强聚丙烯复合材料(LGF-PP)。考察了PP树脂的熔体质量流动速率、聚合类型(共聚和均聚)及长玻璃纤维的含量对增强聚丙烯复合材料的力学性能的影响及其机理。结果表明,基体树脂的流动性越好,增强复合材料力学性能越优;复合材料的力学强度等力学性能随着长玻璃纤维含量的增加而增大;同时,PP的聚合类型(共聚和均聚)对复合材料影响程度各不相同。     

不锈钢纤维填充ABS复合材料的研究及应用

以(丙烯腈/丁二烯/苯乙烯)共聚物(ABS)树脂为主要原料,利用不锈钢纤维(SSF)进行改性,为解决SSF在树脂基体中的分散性问题,采用母料法制样。对ABS/SSF复合材料的力学性能和电学性能进行表征,并利用扫描电子显微镜、差示扫描量热仪等对其微观结构进行研究,探讨了微观结构对复合材料性能的影响。该法制备的ABS/SSF复合材料抗静电性能优异,性价比高,已用于井下探测仪器外壳。     

温度和湿热对玻纤复合材料力学性能的影响

采用真空辅助树脂传递模塑工艺(VARTM)制备了玻纤增强复合材料,测试表征了复合材料在不同温度及湿热环境下的力学性能的变化规律,简单分析了玻纤增强复合材料在不同条件下力学性能变化的原因,结果表明,在-50~150℃范围内,随着温度的升高,玻纤增强复合材料的力学性能呈下降趋势,其下降主要是由树脂的性能变化引起的;长时间的湿热环境也可引起力学性能的降低,这主要是由树脂与纤维的界面受到破坏引起的。温度和湿热对玻纤复合材料力学性能的影响研究为玻纤增强复合材料在工程上的应用提供了技术支撑。     

长玻璃纤维增强热塑性复合材料研究

分别制备了长玻璃纤维(LGF)、短玻璃纤维(SGF)增强聚苯硫醚(PPS)、聚酰胺(PA)6复合材料,研究了基体树脂粘度、口模类型、GF类型及喂料速度对复合材料力学性能、热性能的影响,利用扫描电子显微镜观察了注塑试样断面形貌及LGF在树脂基体中的分布状态.结果表明,基体树脂的粘度越大,对复合材料的力学性能影响越大;在相同GF含量下,LGF增强PPS、PA6复合材料的热变形温度普遍高于SGF增强PPS、PA6复合材料;LGF增强复合材料抵御裂纹开裂的能力提高.     

苎麻增强UP树脂复合材料的研究

以邻苯型不饱和聚酯(UP)树脂为基体、以苎麻布为增强材料,在室温条件下模压成型制备苎麻布／UP树脂复合材料,利用同时热分析仪STA研究了该复合材料的耐热性能,并将其力学性能与纯UP树脂浇铸体的相应性能进行了对比研究。结果表明：苎麻／UP树脂复合材料的耐热性能较纯UP树脂浇铸体有所提高;其拉伸强度及拉伸模量、弯曲强度及弯曲模量、冲击强度等各项力学性能指标均明显优于纯UP树脂浇铸体。     

复合引发剂对乙烯基酯树脂固化及性能的影响

采用示差扫描量热法(DSC)及力学性能测试研究了添加引发剂过氧化苯甲酸叔丁酯(TBPB)及双(4-叔丁基环己基)过氧化二碳酸酯(P16)对乙烯基酯树脂的固化反应及其拉挤复合材料性能的影响。结果表明,当乙烯基树脂,复合引发剂TBPB与P16质量比为100∶1∶0.3时,其拉挤复合材料的各项力学性能较好。     

碳纳米管改性氰酸酯树脂/碳纤维复合材料研究

采用多壁碳纳米管(MWNTs)为改性剂,对环氧树脂/双酚A型氰酸酯树脂体系进行增韧改性。以该改性体系制备了碳纳米管改性氰酸酯树脂/碳纤维复合材料。研究了MWNTs加入量对复合材料力学性能的影响,利用动态力学分析仪和扫描电子显微镜分别对该复合材料的耐热性及微观形貌进行了分析。结果表明,MWNTs的加入能明显地改善复合材料的耐热性和力学性能,当MWNTs的含量为1份和1.5份时,复合材料的层间剪切强度和弯曲强度分别提高约31%和23%。     

原位聚合制备热塑性环氧树脂及其复合材料性能的研究

实验制备了一种新型的热塑性环氧树脂基复合材料,该热塑性聚合物基复合材料是由环氧树脂、双马来酰亚胺树脂、一元胺的混合物浸渍增强材料并原位聚合制得的。通过将聚合好的树脂浸入有机溶剂中,发现树脂溶解于溶剂中,表明该树脂基体没有交联。利用示差扫描量热法(DSC)、红外光谱法(FTIR)研究了树脂体系的聚合制度,利用DSC和同步热分析仪研究了该体系的耐热性。采用电子万能材料实验机研究了复合材料的力学性能。结果表明,最佳的聚合制度为70℃/1 h+120℃/2 h+150℃/5 h+170℃/2 h。双马来酰亚胺树脂的加入能有效改善体系的玻璃化转变温度(Tg)。当其含量达到10%时,Tg达到90℃,与不添加双马来酰亚胺的树脂体系相比,玻璃化转变温度提高了36%。     

SEDIMENTATION OF BINARY MIXTURES OF PARTICLES OF UNEQUAL DENSITIES AND OF DIFFERENT SIZES

A model is developed for the sedimentation from a suspension of two particle species of unequal densities and of different sizes. The composition and the thickness of various layers in the sediments are predicted using graphical and analytical methods. The model predictions were in excellent agreement with experimental results, when the particle size ratio was ≥ 108. When size ratio of the particles was 2.60 and 4.31 the agreement occurred in about 50 percent of the cases.     

骑式摩托车油箱喷涂工艺的改进

面对日益激烈的市场竞争,摩托车油箱外观质量越来越成为影响销售的因素之一。文章介绍了改进工艺后的油箱涂装,该涂装体系提高了油箱外观的丰满度,降低了油箱涂装的生产成本。     

COMPARISON OF METHODS OF ANALYSIS OF GYPSUM1

The different analytical methods proposed for the evaluation of gypsum have been subjected to an experimental test. A combination method, consisting of a fusion with KHCO₃ and determination of CaO by KMnO₄ titration, the SO₃ by Andrews method of titration of BaCrO₄ has been found to give very reliable results with the least consumption of time.     

HEASUREHENT OF INSTANTANEOUS RATES OF LOSS OF VOIATILE COMPOUNDS DURING DRYING OF DROPS

A novel technique serves to monitor instantaneous rates of loss of a volatile solute from a suspended drop during drying. A highly sensitive electron capture detector is used to monitor concentrations of SF6 released into a flowing gas stream from a suspended, drying drop. Simultaneously, the appearance and morphological development of the drop are monitored with a video camera. This provides the wherewithal of relating instantaneous rates of loss of the volatile solute to particular events during the development of particle morphology.

Initial experiments have been carried out with drops of aqueous solutions of glucose, sucrose, maltodextrin and coffee extract. The results clearly display the onset of the volatiles-retentive selective diffusion phenomenon. There is also substantial loss of the volatile component later in the drying process, when the drops undergo repeated ex ansion, bursting and cratering due to the formation of internaf bubbles. These experiments appear to be the first quantitative demonstration of major losses accompanying changes in drop morphology.     

用两个形状指数表征粉煤灰颗粒形貌的研究

引用两个形状指数表征颗粒形状的概念,即先将颗粒形状近似为椭圆,再将椭圆图像分离:以圆为基准的颗粒宏观形状指数δ;以光滑椭圆为基准的颗粒轮廓凹凸度,即微观形状指数ζ。分析和发展了近似椭圆模型。并运用图像分析仪对粉煤灰、水泥样品进行实验。结果表明,粉煤灰颗粒的两个形状指数δ和ζ都大于水泥颗粒。证明粉煤灰颗粒的球形度、表面光滑度优于水泥,而且,随着粒径增大,δ和ζ呈下降趋势,表明磨制颗粒越粗。(?)粒形状越不规则。文中还运用近似椭圆模型再现了颗粒的模拟图像。     

典型煤碳燃烧特性研究和数值模拟

本文以三种典型煤的碳燃烧为研究对象，分别采用简单一维沉降燃烧方式和等温加热燃烧方式，实验研究了煤在快速加热条件下，其碳的初期和中，后期燃烧过程。以实验为基础，建立了煤的碳燃烧模型，变工况数值模拟了煤的碳燃烧过程，揭示了煤不同条件下的单颗粒碳燃烧特性。     

氢气纯度分析方法准确性的探讨

ONACCURACYOFANALYSISOFOFHYDROGEN1前言我公司目前应用的氢气纯度分析方法有两种,一种是爆炸反应法,另一种是焦性没食子酸吸收法。几年来,人们对两种分析方法的准确性曾有过褒贬不一的评论。这里我们也谈谈自己粗浅的观点。2爆炸法测定氢气纯度一定量的氢气样品与适量的空气之均匀混合物因反应后生成液体水而引起气体体积减少,减少的体积等于参加反应气体体积之和。其中l／3为氧气,2／3为氢气。根据氢气取样量和反应前后混气体体积之差,以及氢气在反应中的体积比例关系,可计算出样品的氢气纯度。计算公式式中：A一混…     

ANALYSIS OF RECENT MEASUREMENTS OF THE VISCOSITY OF GLASSES

Viscosity of Simple Soda-Silicate 500° to 1400°C Comparison of the results given by English with those of Washburn, Shelton and Libman, indicates a discrepancy in the absolute values of log₁₀ viscosity amounting to 0.6, those of Washburn et al., being relatively too high. If correction for this is made, the isothermal curves of log₁₀ viscosity as a function of soda content are smooth up to 50% Na₂O, showing no inflection. The observations as a function of temperature T are all represented within accidental error by an equation of the type where all three constants vary regularly with the composition. Change of Viscosity of Glass (6SiO₂, 2Na₂O) due to Molecular Substitution of CaO, MgO and Al₂O₃ for Na₂O The effect is clearly brought out by plotting (from the results of English) the change of log₁₀η due to the substitution as a function of temperature. The curves each show a sharp bend at a temperature between 840° and 1050°C, which is designated the aggregation temperature T_a. If we divide these curves by the corresponding percentage substituted, we get curves for each oxide which are straight and parallel below the aggregation temperatures, the slopes (increase of change of log₁₀η per 100°C) being −0.056 (CaO), −0.055 (MgO), −0.018 (A1₂O₃) per per cent oxide substituted. For substitution of 1/2 molecule the slopes are −0.325 (CaO), −0.23 (MgO) and −0.18 (Al₂O₃) per 100°. At the aggregation temperature the change of log₁₀η per per cent is a minimum, 0.03 to 0.06 for CaO, 0.12 for MgO, 0.07 for Al₂O₃. Evidence of Aggregation in Glasses, from viscosity Measurements The sharp bends in the plots of change of log₁₀η due to substitution of an oxide for Na₂O, suggest the beginning of molecular aggregation at these temperatures. These aggregation temperatures are close to the devitrification temperatures, but the effect on the viscosity curves cannot be due to actual devitrification since it does not change with time. Taking the aggregation temperatures as equal to devitrification temperatures, additional isotherms are roughly sketched into the equilibrium triangle of the system Na₂O-CaO-SiO₂. Change of Viscosity of Glass (4SiO₂, 2Na₂O) due to of Substitution of B₂O₃ for SiO₂ The change of log₁₀η (from the results of English) is plotted as a function of temperature, and also the change of log₁₀η per per cent B₂O₃. The curves are more complex than for the substitution for Na₂O.     

环氧树脂羟基值测定方法的研究

利用乙酸酐、吡啶和浓硫酸混合的乙酰化试剂测定环氧树脂中羟基值含量的方法具有操作简便、滴定终点明显和分析结果误差小等优点。     

茶多酚提取方法进展

本文综述了国内外现有茶多酚提取方法的现状以及近期的研究进展，并对其优缺点进行了评价。这将有助于中低档茶的综合利用和茶多酚的进一步开发应用。