不同时期商陆果实的红外光谱鉴别

在9月份和10月份,利用衰减全反射(ATR)对商陆果实分别进行活体检测,凭借红外光谱具有的指纹特征性,构建新鲜商陆果实样本的红外指纹图谱。结合二维红外光谱分析商陆果实成熟过程中成分变化。结果表明:不同时期商路果实红外光谱中,酯类特征吸收峰(1 732cm-1)和多糖类成分吸收峰(900~1 100cm-1)之间的相对吸收峰强度和峰面积有所差异;二维红外光谱中差异更加明显。红外光谱为果实成熟过程中活体监测提供了一种新的方法。     

3种菊花花瓣的傅里叶变换红外光谱鉴别

利用傅里叶变换红外光谱技术测试万寿菊、野菊花、七月菊的花瓣,对比它们各自红外光谱的特征,确定叶黄素酯的吸收峰,并分析3种菊花中该吸收峰的相对吸收强度,从而定性研究叶黄素的含量,为菊花的品质提供参考.研究表明,傅里叶变换红外光谱技术能快速定性反映菊花花瓣中酯类物质的含量信息,而且具有用量少、操作方便,不破坏研究对象的分子...     

不同花期八宝景天花的红外光谱鉴别

利用衰减全反射(ATR)结合二维红外光谱技术对不同花期(9月份和10月份)八宝景天花分别进行活体检测,凭借红外光谱具有的指纹特征性,构建新鲜八宝景天花样本的红外指纹图谱。结果表明:不同时期八宝景天红外光谱中,酯类特征吸收峰(1 732cm-1)和多糖类成分吸收峰(900~1 100cm-1)之间的相对吸收峰强度和峰面积有所差异;二维红外光谱中差异更加明显。红外光谱为不同时期鲜花活体鉴别提供了一种新的方法。     

新鲜金盏菊的红外光谱三级鉴别

在9月份和10月份,利用衰减全反射(ATR)对金盏菊分别进行6次活体检测,凭借红外光谱具有的指纹特征性,构建新鲜金盏菊样本的红外指纹图谱,作为三级鉴别提取的特征数据。结果表明:不同时期金盏菊红外光谱中,酯类特征吸收峰(1 732cm-1)和多糖类成分吸收峰(900~1 100cm-1)之间的相对吸收峰强度和峰面积有所差异;二维红外光谱中差异更加明显。红外光谱为不同时期鲜花活体鉴别提供了一种新的方法。     

万寿菊花渣中残余叶黄素酯的红外光谱分析

利用傅里叶变换红外光谱技术测定了万寿菊花瓣和提取叶黄素酯后万寿菊花渣的光谱,比较两者的光谱发现花渣中羰基、甲基和亚甲基的相对吸收强度明显减弱。由于叶黄素酯从万寿菊花瓣中被提取,导致花渣中酯类物质含量减少,从而在光谱中反映出这3个吸收峰减弱。羰基的吸收峰主要来源于酯类物质,利用该吸收峰的强弱可以定性反映出花渣中叶黄素酯残余量的多少。研究表明:傅里叶变换红外光谱技术能准确和快速提供万寿菊花瓣和花渣中酯类物质的含量信息,可以作为一种检测花渣中叶黄素酯残余量的手段。     

艾草与一枝黄花的红外光谱三级鉴别

利用衰减全反射(ATR)、二阶导数红外光谱(SDIR)结合二维相关红外光谱(2DIR)的三级鉴别法对菊科植物艾草与一枝黄花的新鲜叶片分别进行活体检测。结果表明:艾草和一枝黄花红外光谱中,酯类特征吸收峰(1 732cm-1)和多糖类成分吸收峰(900~1 100cm-1)之间的相对吸收峰强度有所差异;二维红外光谱中差异更加明显。红外光谱为不同种类新鲜叶片活体鉴别提供了一种新的方法。     

聚丙烯酸甲酯二乙烯苯交联度的红外光谱研究

采用红外光谱法对聚丙烯酸甲酯-二乙烯苯的交联度进行了表征.结果表明:(1)随交联度增加,红外光谱图中两单体特征峰位置不变,DVB特征峰强度逐渐增加.(2)交联度与特征峰吸收强度比ADVB/AMΛ间存在如下函数关系:y=12.694lnx 44.382,r2=0.9985.     

黑豆和牵牛子红外光谱的分析与鉴定

种子类中药材黑豆和牵牛子都含有大量的油脂和蛋白质,因此两种药材的一维红外光谱极其相似,为了区别科属不同的两种药材,采用红外光谱三级鉴定法对黑豆和牵牛子进行分析鉴定。经典红外光谱中,黑豆和牵牛子均有1 745 cm-1表征油脂类的特征吸收峰,以及1 656和1 547 cm-1表征蛋白质酰胺Ⅰ带和酰胺Ⅱ带的特征吸收峰。其中油脂特征吸收峰与蛋白质特征吸收峰的相对高度不同,说明二者的相对含量不同。同时,一维红外光谱对两种中药材主体成分的分析结果,即含有大量的油脂和蛋白质,与文献所报道的一致。在二阶导数红外光谱中,牵牛子中存在1 712 cm-1属于有机酸类的特征吸收峰,然而黑豆中却没有此吸收峰的存在。此外导数光谱中两种药材峰形和峰强度的差别更为明显。二维相关红外光谱中,黑豆和牵牛子自动峰的峰位置和峰强度等均具有显著差异。在1 500~1 700 cm-1波数范围内,黑豆有2个明显自动峰,牵牛子有3个明显的自动峰。在2 800~3 000 cm-1波数范围内,黑豆和牵牛子均有2个强自动峰,但最强自动峰的位置不同。运用红外光谱三级鉴定法,可以更直接快速简便的分辨出主体成分相同的两种种子类中药材,为今后的研究打下基础。     

溪黄草四种基源植物的二维相关红外光谱鉴别研究

采用傅里叶红外光谱法和二维相关红外光谱法对中药溪黄草的4种基源植物进行了鉴别研究。结果表明,溪黄草4种基源植物共有成分为酯类、羧酸类、黄酮类、木质素、芳香类、糖苷类等,但四者各主体成分的相对含量差别较大,其中纤花线纹香茶菜和溪黄草富含酯类、羧酸类物质、木质素、芳香族化合物,而线纹香茶菜和狭基线纹香茶菜中富含黄酮类物质。在二维相关红外光谱上,根据它们自动峰的数目、位置、相对峰强度的差异,可实现对中药溪黄草4种基源植物的鉴别。该方法快速、简便、无损、客观、成本低、重复性好,为中药溪黄草的基源种的鉴别提供了新的有效方法。     

二维红外光谱法对肉豆蔻酸相变过程的研究

脂肪酸由于成本低、相变潜热大、热稳定性好的特点,在有机固-液相变材料中应用较多。对脂肪酸进行热分析一般采用热重法（TG）或差示扫描量热法（DSC）得到材料宏观上的热力学性质,但难以对其微观结构变化进行深入探讨。二维红外光谱（2D-IR）在温度扰动的作用下,样品的光谱信号将随之发生动态变化。通过数学处理能够发现样品在相变过程中微观结构的变化。以肉豆蔻酸为例,采用傅里叶红外光谱仪,在4 000～400 cm-1和30～100 ℃温度范围内对肉豆蔻酸进行一系列红外光谱实验。采用二维移动窗口（MW2D）红外光谱技术,对肉豆蔻酸中的CO和O—H键进行分析,发现MW2D测出的肉豆蔻酸熔点与传统的DSC测出的基本一致,且两种化学键显示的热数据具有良好的一致性和稳定性。对光谱数据进行2D-IR分析,结果表明,由于分辨率的提高,一维光谱中单一的重叠吸收峰对应着二维光谱中的多个吸收峰,根据2D-IR的理论知识,推测可能存在二聚体肉豆蔻酸构型向单聚体肉豆蔻酸构型转变的情况。从峰强度和温度的变化关系中发现,升温时CO键和O—H键存在三个变化过程,达到相变温度之前,CO吸收峰强度基本不变,O—H吸收峰强度逐渐下降,说明O—H键偶极矩的变化比CO键更易受温度影响;相变过程中,两者吸收峰强度都显著减弱且O—H吸收峰强度下降幅度更大;达到相变温度之后,可能因O—H形成的分子间氢键,受热导致由强变弱,O—H上的电子云移向CO,导致CO吸收峰强度增大、O—H吸收峰强度减小。同时,结合密度泛函理论,对二维红外光谱的推论进行理论验证,可知存在二聚体肉豆蔻酸向单聚体肉豆蔻酸的转化过程。     

Experimental investigation of the adhesive contact of an elastomer

The present work is an experimental study of adhesion between an elastomer and a rigid cylindrical indented The experimental characterization was carried out using a specially developed apparatus. Adhesive force was measured as function of contact geometry, pull-off velocity, normal force, temperature, waiting time, and material properties. Experimental results are compared with existing theoretical models for adhesion of elastic and viscoelastic bodies. Our study shows that the adhesive force between the studied elastomer and a steel cylinder is determined by completely different mechanisms than assumed in the Kendall’s theory. In particular, it does not depend on the surface energy and is almost entirely dominated by the viscosity of the elastomer.     

密度泛函理论研究对位卤代二苯醚的结构、电荷分布及光谱

利用密度泛函理论,对三种对位卤代二苯醚及二苯醚的分子结构、电荷分布及光谱振动进行定量化研究。选取B3LYP/6-31G(d)方法优化对位卤代二苯醚的分子结构,计算所获最优结构的红外及拉曼光谱振动频率,归属对位卤代二苯醚的光谱振动;借助核磁共振和密立根电荷分布计算,并结合二苯醚电荷分布分析引入不同对位卤素取代基对二苯醚各原子电荷分布的影响,从电荷分布角度研究对位卤素取代基对对位卤代二苯醚特征振动频率影响的变化规律和振动机理。结果表明：在对位卤代二苯醚最优结构下,对位卤代二苯醚取代基电负性越小,原子半径越大,C—X键长越大,越易被自然环境降解;对位卤素取代基的引入对二苯醚电荷分布影响较大,取代基电负性越大,醚键对位碳原子的电子云密度下降越多,间位碳原子的电荷分布变化受到卤素取代基与醚键氧原子的综合电子效应的影响,对邻位碳原子电荷分布影响不大;原子间电荷密度差对成键稳定性及特征振动频率影响较大,对位卤素取代基电负性越大,特征振动频率越高。     

8～14μm波长低红外发射率涂料的研究

研究了红外隐身涂料粘合剂的物理和化学性能,以及红外隐身涂料粘合剂、填料、颜料颗粒的红外发射率。通过研究发现,铝粉和氧化铅具有较低的发射率,并得到了以有机硅清漆和EPDM(三元乙丙橡胶)接枝聚合物为基体的低红外发射率涂料,它有助于对红外隐身涂料粘合剂、填料、颜料颗粒的选择。     

Relationship between electric current and matrix modulus in electrorheological elastomers

We have carried out a series of tests on electrorheological elastomers, which consist of semi-conducting solid particles dispersed in a low-conductivity silicone-based elastomer, with the investigations focussing on the dependence of the DC electric current on the elastomer modulus. We find that when other conditions are held constant, the electric current under a particular electric field shows a significant decrease when an elastomer of higher modulus is used. This behaviour is explained qualitatively using a simple model based on the mechanical equilibrium of two competing forces: the electrostatic attraction force between the two adjacent particles in the field direction, and the elastic squeezing force due to the elastomer between the particles which resists their approach.     

Isothermal solidification stage during transient liquid-phase bonding single-crystal superalloys

In this work, the isothermal solidification stage during transient liquid-phase bonding (TLP) single-crystal superalloys has been investigated. Experiments were performed to ascertain the bonding microstructures and the kinetics during the isothermal solidification. The results have shown that the isothermal solidification stage deviates from the standard parabolic TLP models. Lots of the borides with fine, short bar and acicular morphologies formed in the diffusion affected zone (DAZ) in the thick wall and thin wall substrate specimens at the isothermal solidification stage. Electron probe microanalysis results have shown that there exists B composition peak in the DAZ. Examination of the bonding kinetics presented that there are three stages in the isothermal solidification stage: initial stage, transient stage and final stage with different growth velocity of the isothermal solidification zone (ISZ). And the relationship of the width of the ISZ with the square root of the bonding time didn’t satisfy the parabolic relationship. Based on the microstructures and kinetics observed, a film ISZ mechanism is proposed, and a model is constructed to illustrate the isothermal solidification stage during bonding single-crystal superalloys.     

Measuring the solidification time of silicone rubber using optical inspection technology

A room temperature vulcanization silicone rubber was widely used as the mold making material due to its high elasticity, good heat-resistance and low surface energy. To enhance the efficiency of making the silicone rubber mold, accurately measuring the solidification time is an important issue. This study demonstrated a non-invasive measurement system to measure the solidification time of silicone rubber. The solidification time can be determined rapidly from the thickness of silicone rubber according to the predicted equation. The maximum relative error of the predicted equation is about 8.26%. The temperature rise of the silicone during the solidification process is an important phenomenon to determine the solidification behavior of silicone rubber. The solidification mechanism of silicone rubber mold is demonstrated.     

Characterization of Epoxy Glues with FTIR

Abstract

Adhesives have been used since ancient times, but in the mid-19509, when new polymeric adhesives were introduced, the concept of glues changed dramatically. These new adhesives have become the predominant method for fastening materials together. Adhesive glues can be classified as thermoplastic o r thermosetting. The thermoplastic category includes hot melts, cyanoacrylates, solutions (acetates, acrylics), and dispersions (synthetic rubber, latex). Thermoplastics soften when heated, are soluble in at least a few solvents, and tend to creep (undergo permanent change in dimension) under stress. They are composed of long linear chains lying together, but the three dimensions are not interconnected. On the other hand, thermosetting adhesives do not deform readily. They are insoluble in nearly all solvents, so analysis is difficult. The polymer chain segments are cross linked in all three dimensions, making deformation difficult o r impossible at room temperature. In addition to phenolics, polyurethanes, and silicones, epoxies are classified as thermosetting adhesives. Epoxy glues are used to bond metals, glass, ceramics, plastics, wood, concrete, and many other surfaces. Their strength, versatility, and excellent adhesion to a variety of surfaces in addition to their ease of use have made epoxies an important commercial product as well as invaluable to industry [1].     

Castor Oil-Based Polyurethane/Epoxy Intercross-linked Polymer Network Adhesives for Metal Substrates

Castor oil based polyurethane (CO-PU) was first synthesized from castor oil and 4, 4’-diphenyl-methane-diisocyanate (MDI). Then, a series of CO-PU/epoxy (EP) intercross-linked polymer network (ICPN) adhesives for metal substrates were prepared by a sequential method. The functional groups, tack -free time, mechanical properties, adhesive properties, and thermal stability were studied. Fourier transform infrared spectroscopy analysis indicated that an ICPN structure was formed through the introduction of CO-PU into EP. Results of adhesive measurements showed that the maximal value of lap shear strength was achieved at the CO-PU content of 20%. Thermogravimetric analysis results indicated that thermal stability of the adhesive film decreased with increased CO-PU content.     

1.319μm处45#钢反射率随温度变化的实验研究

 使用积分球系统测量了1.319μm处45#钢反射率随温度的变化规律,通过对实验后钢片表面的能谱分析,揭示了反射率发生变化的原因。测量结果表明,钢片温度从常温升高至325℃时,表面反射率不会发生显著变化;在325℃到395℃之间,反射率从0.64降低到约0.15;在395℃与440℃之间,反射率不再发生明显变化;钢片降温过程中反射率不再发生明显变化,其值与最高温度处的数值基本相同。反射率的变化主要源于钢片表面发生的氧化反应,温度越高,氧化反应越剧烈,表面氧元素的含量就越高,反射率也就越低。     

YAG Laser Face Joining Technology of A6061 Aluminium and SPCC Plates

Laser and pressure roll combination joining tests on SPCC-A6061 plates were carried out by changing the roll pressure. Adhesive strengths on SPCC-A6061 were measured by peel tests. When the pressure increased from 80 MPa to 320 MPa, the adhesive strength increased from 10 N/mm to 30 N/mm. It was obvious that the higher pressure brought some good influence to the joint interface of the metals. From observation results on the joint layer by EDX, we recognized ductile compounds Fe₃Al and metallic bonds when 320 MPa pressure was laid on by twin rolls. Moreover, it resulted in the achievement of high adhesive strength during the joining of SPCC-A6061 plates. PACS 42.62.Cf