发动机油变温中红外光谱研究

采用中红外(MIR)光谱研究了发动机油(机油)的分子结构,实验发现:机油分子的红外吸收模式主要包括vasCH3-机油、vsCH 3-机油、vasCH2-机油、vsCH2-机油、vC=O-机油、δCH2-机油、δsCH3-机油和γCH2-机油.进一步开展了机油分子的变温中红外(TD-MIR)光谱研究,实验发现:随着测定温...     

单硬脂酸甘油酯中红外光谱研究

采用中红外(MIR)光谱研究了单硬脂酸甘油酯分子的结构。实验发现:单硬脂酸甘油酯分子的红外吸收模式主要包括:ν_(asCH3-单硬脂酸甘油酯)、νs_(CH3-单硬脂酸甘油酯)、ν_(asCH2-单硬脂酸甘油酯)、ν_(sCH2-单硬脂酸甘油酯)、ν_(C=O-单硬脂酸甘油酯)、δ_(CH2-单硬脂酸甘油酯)、δ_(sCH3-单硬脂酸甘油酯)和γ_(CH2-单硬脂酸甘油酯)。进一步开展了单硬脂酸甘油酯分子的变温中红外(TD-MIR)光谱研究。实验发现:随着测定温度的升高(303～393 K),单硬脂酸甘油酯分子主要官能团对应的红外吸收频率及强度均有明显的改变,并进一步进行了相关机理的研究。     

凯芙拉酰胺基团结构及热变性三级中红外光谱

聚对苯二甲酰对苯二胺(凯芙拉)是美国杜邦公司研制的一种芳纶纤维材料。采用中红外(MIR)光谱开展了凯芙拉分子结构研究。结果表明,凯芙拉分子的红外吸收模式主要包括：ν_NH、ν_amide-Ⅰ、ν_amide-Ⅱ、ν_amide-Ⅲ、ν_amide-Ⅴ、ν_amide-Ⅵ、ν_CC、β_C—H和γ_C—H。进一步开展了凯芙拉分子的变温中红外(TD-MIR)光谱研究。在303～573 K的温度范围内,随着测定温度的升高,凯芙拉分子酰胺基团(ν_NH、ν_amide-Ⅴ和ν_amide-Ⅵ)对应的红外吸收频率及强度均有明显的改变。采用二维中红外(2D-MIR)光谱,进一步开展了凯芙拉分子热变性的研究。在三个温度区间,凯芙拉分子酰胺基团(ν_NH、ν_amide-Ⅴ和ν_amide-Ⅵ)对热的敏感程...     

亚硫酸钠三级中红外光谱研究

采用中红外(MIR)光谱开展了亚硫酸钠分子结构研究。研究发现:亚硫酸钠红外吸收模式主要包括:亚硫酸钠分子SO₃不对称伸缩振动模式(v_asSO3-Na2SO3)和亚硫酸钠分子SO₃面内弯曲缩振动模式(β_SO3-Na2SO3)。采用变温中红外(TD-MIR)光谱进一步开展了温度变化对于亚硫酸钠分子结构的影响。研究发现:在293～393 K,随着测定温度的升高,亚硫酸钠v_asSO3-Na2SO3和β_SO3-Na2SO3对应的红外吸收频率和强度均发生明显的改变。以亚硫酸钠v_asSO3-Na2SO3和β_SO     

聚乙烯红外及变温红外光谱研究

采用红外(IR)光谱进行了聚乙烯的结构研究,结果表明,聚乙烯主要存在νa(s CH2–聚乙烯)、νs(CH2–聚乙烯)、δ(CH2–聚乙烯)和ρ(CH2–聚乙烯)等红外吸收模式。采用变温红外(TD-IR)光谱进一步进行了聚乙烯的热稳定性研究,结果表明,在303~423 K,聚乙烯的热稳定性明显下降。     

美国杜邦公司推出凯芙拉纤维创新奖

位于美国特拉华州威尔明的杜邦公司,于2011年5月19日宣布,推出凯芙拉纤维创新奖,在使用凯芙拉纤维防护及合作方面,预先计划好庆祝仪式。据说,该奖金面向对使用凯芙拉纤维持续改进防护技术,在许多情况下,保护人的生命,促进创新与合作,寻找新方法。     

杜邦扩产凯芙拉纤维

美国杜邦公司近日称，公司将投资5亿美元在位于南卡罗来纳州的库柏河厂再建一条可用于工业及军事用途的高性能凯芙拉纤维生产线。该项目将使全球凯芙拉纤维产能增加25％以上。该项目今年1月份将开工。预计2010年建成投产。     

凯芙拉纤维/尼龙6热塑性复合材料的研制

研究了凯芙拉纤维与尼龙 6单体通过阴离子原位聚合制备热塑性复合材料的方法。以氢氧化钠为引发剂 ,甲苯二异氰酸酯 (TDI)为活化剂 ,确定体系的聚合温度为 160℃ ,引发剂、活化剂用量为6.42 m ol/L ,聚合时间 60 min,在此条件下聚合速度较快 ,单体转化率 1h后达 95 %以上。研究发现 ,凯芙拉纤维经酰化处理后 ,基本上不会对己内酰胺阴离子聚合体系产生阻聚作用     

医用胶带基材结构变温中红外光谱研究

采用中红外(MIR)光谱,开展了医用胶带基材(主要为乙烯–醋酸乙烯酯共聚物,简称基材)的结构表征。实验发现,基材的红外吸收模式主要包括ν_as(CH₃–基材结构)、ν_as(CH₂–基材结构)、νs(CH₃–基材结构)、νs(CH₂–基材结构)、ν(C=O–基材结构)、δ(CH₂–基材结构)、δ_as(CH₃–基材结构)、δ_s(CH₃–基材结构)和ρ(CH₂–基材结构)。采用变温中红外(TD–MIR)光谱进一步开展了基材的热变性研究,发现随测定温度的升高,基材中主要官能团对应的红外吸收频率及吸收强度均有明显改变。     

Kevlar纤维的表面改性研究

采用甲苯-2,4-二异氰酸酯(TDI)和环氧树脂(EP)混合制得的表面改性剂对Kevlar纤维进行表面接枝处理,利用扫描电子显微镜观察Kevlar纤维改性前后的表面形貌及改性Kevlar纤维与弹性体间剥离界面的破坏形貌,用衰减全反射傅里叶变换红外光谱仪分析Kevlar纤维改性前后表面化学基团的变化,研究了改性效果和机理。结果表明,TDI和EP发生了化学反应,改性剂可在Kevlar纤维表面引入活性基团,从而显著改善了Kevlar纤维与聚合物基体之间的界面粘合状态。     

丁腈橡胶/芳纶短切纤维复合材料的制备及性能研究

采用高锰酸钾硫酸溶液对芳纶短切纤维表面进行改性处理,然后再与丁腈橡胶复合制备了丁腈橡胶/芳纶短切纤维复合材料。探讨了芳纶短切纤维表面不同处理时间对复合材料机械性能的影响。结果显示,当芳纶短切纤维表面处理时间为20 min时,复合材料的拉伸强度达到最大值;复合材料的扯断伸长率随纤维表面处理时间的增加呈上升趋势,但处理时间超过20 min后,扯断伸长率的变化趋于平缓;复合材料的撕裂强度和硬度随处理时间的增加变化不明显。     

PP及芳纶/PP结晶性能的分析研究

本文通过DSC对PP及芳纶／PP复合体系结晶性能的分析研究，得到了PP长丝热压成膜结晶性能的变化，芳纶对PP结晶性能的影响以及不同冷却方式对芳纶／PP结晶性的影响等规律。     

Compressional behaviour of Kevlar fibres

The compressional deformation of poly(p-phenylene terephthalamide) (PPT) fibres of the Kevlar type has been followed by scanning and transmission electron microscope methods in order to explain changes in mechanical properties. A structural mechanism describing the mode of deformation is proposed which is based on the initial formation of kink-bands. The propagation of the latter appears to be unaffected by the presence of the axially pleated-sheet structure exhibited by Kevlar fibres. The proposed mechanism is consistent with an observed loss in tensile strength after compression. It is considered that the relatively poor compressional behaviour of aramid-type fibres arises from the weak lateral cohesion between their essentially rigid molecular chains, in agreement with the findings of Greenwood and Rose.     

树月旨基体对芳纶材料防刺性能的影响

从材料的选择、防刺材料的制备、测试仪器、模压工艺条件以及防刺层结构等方面,研究了树脂对芳纶材料防刺性能的影响,并对所制备的防刺材料,按照公安部GA68-2008《防刺服》标准进行了测试。结果表明,树脂基体能够提高芳纶材料的防刺性能。     

NaH-DMSO对Kevlar纤维表面处理的影响

采用化学镀工艺制备阻燃型导电纤维,为提高金属镀层与纤维基材的结合力,自制金属化试剂对Kevlar纤维进行表面粗化处理。利用分析天平、万能强力机、扫描电子显微镜、X射线衍射仪和X射线光电子能谱仪对粗化前后的Kevlar纤维进行分析和表征。结果表明:经粗化处理后,Kevlar纤维表面呈现凹凸不平的粗糙表面,有大量的微坑和凹槽,能够增大纤维与镀层间的接触面积,纤维断裂强力降低;当处理温度为30℃、粗化时间为10 min时,粗化效果较好,纤维本体强度损失为6.6%;纤维表面极性基团含量增加,表面活性增强,从而改善了Kevlar纤维与金属镀层间的结合力和黏结性。     

芳纶纤维复合材料弯曲性能试验仿真

对叠层结构芳纶纤维织物增强复合材料的弯曲性能试验进行仿真,分析±45°纤维铺层对复合材料弯曲性能的影响.参照GB/T 3356-1999弯曲性能试验,生成了4种不同铺层结构小尺寸试样的几何模型,建立了三点弯曲试验的有限元模型,计算得到了试样的应力场结果,预测了试样的弯曲弹性模量及弯曲强度.结果表明:±45°芳纶纤维铺层将提高叠层结构的弯曲性能,为叠层结构的铺层优化设计提供了技术支持.     

Raman spectroscopy of Kevlar 49 fibre

The Raman spectrum of poly(p-phenylene terephthalate) fibre, Kevlar 49, is reported. Fibre which had been exposed to heat, stress and radiation indicated that within experimental error, no general change takes place in the chemical structure of the material as a whole. However the spectrum of a filament under stress shows that all bands in the spectrum become increasingly polarized with increased stress. The spectral characteristics of the stress fibre lead to a possible explanation of the polymer's response to deformation — opening of the angles in the amide linkage of the polymeric chain and improved alignment of crystallites along the fibre axis.     

Strain birefringence of Kevlar aramid fibers

We have measured the strain birefringence of Kevlar aramid fibers under static loading via a spectrophotometric method. At very low strain rates, the birefringence of Kevlar fibers increases markedly with increasing strain. On initial straining, the birefringence increases even at relatively constant modulus. This is attributed to the orientation of macroscopic species in the fiber which were observed by visible light microscopy. Such behavior is supported by the experimental observation of laser diffraction patterns and optical transmission images of Kevlar fibers under load. In the final stage of straining where the fiber modulus increases rapidly, the birefringence increase is attributable to crystalline orientation. The spectrophotometric method is useful for the simultaneous measurement of stress, strain, and birefringence of highly oriented, highly crystalline fibers such as Kevlar aramid. It is particularly useful to study the morphological inhomogeneity of a fiber which is undetectable by the conventional tensile test.     

Kevlar 49 composite performance: Dependence on thermoset resin microstructure

Molecular structures for cured, thermoset resins have been examined by analyses of resin extracts by gel permeation chromatography. Numerical interpretation of leached oligomeric fractions coupled with kinetic reaction theory yields microscopic estimates of the network's structure, including crosslink average molecular weight. Leached monomeric fractions describe extent of cure. Analyses of test data incorporate irreversible, mechanical deformations for neat resin castings and for filament wound, Kevlar 49 composites. Heat distortion temperatures correlate with crosslink architecture. Short beam shear strength data for naval ordinance laboratory rings and pressure vessel burst performance are examined in terms of the resin's molecular structure. Variations in resin cure observed by positive feedback via chromatography indicate fluctuations in extent of crosslink development. Test specimen performance correlates with these microscopic, molecular distributions. Resin applications include filament wound composites for the aerospace industry, anhydride cured epoxies, and amine cured epoxies. The former resin is an elastic body at ambient test conditions. A third resin, a crosslinked resin of 1,2 polybutadiene/t-butylstyrene, is in final developmental stages and may exhibit a higher degree of viscoelastic behavior.