Rapid and direct lodine value and saponification number determination of fats and oils by attenuated total reflectance/fourier transform infrared spectroscopy

A simple, rapid and reproducible method of determining the iodine value (IV) and saponification number (SN) for fats and oils was developed with an attenuated total reflectance/Fourier transform infrared spectrometer and commercially available triglycerides as calibration standards. Partial least squares was used to determine the spectral regions correlating with the known chemical IV and SN values, and the calibration set was augmented with additional standards generated by spectral co-adding techniques. The calibration model obtained was used to analyze commercially available fats and oils with a wide range of IV and SN values, and the results were compared to the values obtained by American Oil Chemists’ Society methods. With the spectrometer calibrated and programmed, IV and SN results could be obtained within 2–3 min per sample, a major improvement over conventional wet chemical methods.     

Zinc Coated Steel/Epoxy Adhesive Systems: Investigation of the Interfacial Zone by FTIR Spectroscopy

The present study takes advantage of the ability of Fourier Transform Infrared Spectroscopy (FTIR) for the analysis of ultrathin organic films on metals. FTIR in the reflection mode (IRRAS) is used in order to study the interaction of ultrathin films of dicyandiamide (hardener of most one-pack epoxy resins) with various substrates, model ones such as gold or zinc and industrial ones such as steel and zinc-coated steels.

Pure zinc surfaces and, to a lesser extent, zinc-coated steels are shown to react with dicyandiamide after heating at 180°C, as evidenced by the frequency shift of the absorption band (at about 2200 cm^-1) characteristic for nitrile groups. As real systems consist of thick layers of a fully formulated adhesive cured onto a metallic substrate, the direct investigation of such a buried interphase is no longer possible by FTIR and by most of the known spectroscopies. Some mechanically tested specimens are then analysed, after failure, by FTIR microspectrometry. The spectra obtained, corresponding to the fracture initiation zone which is about 100 μm in diameter, advocate for the presence of an ultrathin layer of modified polymer still covering the substrate.     

Quantitation of volatile compounds in heated triolein by static headspace capillary gas chromatography/infrared spectroscopy-mass spectrometry

Static headspace and capillary gas chromatography/infrared spectroscopy-mass spectrometry were used to collect, separate, identify and quantitate the oxidative and thermal decomposition products in heated triolein. Approximately 4 L of triolein was heated in a deep-fat fryer at 190°C for 12 h each day for a total of 60 h, until it contained>-20% polymeric material. The concentration of heptane and octane increased after 12 h heating, then decreased upon further heating, while the concentration of volatile aldehydes decreased gradually during heating. After 12 h of heating, the concentrations of the major volatiles changed as follows: heptane (16.36 to 30.17 ppm), octane (24.48 to 40.77 ppm), heptanal (21.68 ppm to 9.11 ppm), octanal (35.53 to 36.64 ppm), nonanal (68.95 to 43.16 ppm), (E)-2-decenal (135.00 to 89.00 ppm) and (E)-2-undecenal (88.50 to 61.00 ppm). After 60 h of heating, when the oil contained over 20% polymeric material, the concentrations of heptane, octane, heptanal, octanol, nonanal, (E)-2-decenal and (E)-2-undecenal were 5.16, 4.39, 5.45, 7.02, 18.07, 12.50 and 6.00 ppm, respectively.     

Ion‐exchange resins. II. Acrylamide crosslinked copolymers as precursors for some ion exchangers

Crosslinked copolymers of acrylamide (AA) and ethylacrylate and some ion exchangers derived from them containing either primary amine groups, obtained by the Hofmann degradation of the amide groups, or carboxylic groups, obtained by the alkaline hydrolysis of the ester groups, were studied. Divinylbenzene and N,N′‐methylenebisacrylamide were used as crosslinkers. The starting copolymers and the corresponding ion exchangers were characterized by IR spectroscopy, swelling behavior, and thermogravimetric analysis. The ion‐exchanger properties were correlated with the crosslinker nature and the chemical reactions performed on the AA copolymers. The average molecular weight between two crosslinks, determined from the swelling data in water, was compared with that calculated on the basis of the copolymerization stoichiometry only for the carboxylic cation exchangers. In this way, the preservation of the crosslink density after the hydrolysis was revealed. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2701–2707, 2003     

采用Raman光谱研究硅烷接枝LLDPE的结晶结构

采用傅里叶变换红外光谱(FTIR)和Raman光谱表征了硅烷接枝线型低密度聚乙烯(LLDPE)的结晶结构。用FTIR和Raman光谱上硅烷特征峰与LLDPE亚甲基峰的强度比,可相对比较硅烷接枝LLDPE的接枝率,随着硅烷用量的增加,由FTIR计算的吸光比从0.96增至2.62,由Raman光谱计算的强度比从11.53增至14．00,两者的变化趋势相同。Raman光谱分析还表明,随着硅烷用量的增加,硅烷接枝聚乙烯的结晶相质量分数由57．58％降至46．99％,非晶相质量分数由11．58％升至16．52％,中间相质量分数从30．84％升至36．48％。     

采用加压-真空两段热缩聚法制备中间相沥青炭纤维的原料

以深度裂解石油渣油为原料，采用两段热缩聚法可制得软化点为268℃，可编性良好的中间相沥青。本文详细考察了温度，时间对中间相沥青软化点，可编性，中间相沥青形态及碳化收率的影响，并初步探讨了两段热缩聚反应的机理。研究结果表明反应温度，时间对中间相沥青的结构和性能影响较大，选择适宜石油渣油，采用加压－真空两段热缩聚法，调整反应条件，可制得可纺性良好的中间相沥青。     

有机磷化物制备羟基磷灰石工艺条件的探讨

探索用有机磷化物制备羟基磷灰石的工艺条件：采用硝酸钙、氨水、磷酸三丁酯为原料进行正交对比研究，优化得到了制备较佳羟基磷灰石的工艺条件。优化的工艺条件为：原料中Ca／P（molar ratio）1．67；Ca（NO3）2、4H2O／NH3H2O（g／g）为0.99；烧结温度为850℃：恒温时间为5h，并对合成的样品进行了化学和红外光谱的分析。     

聚烯烃接枝马来酸酐接枝率的测定—聚乙烯接枝

以非均相化学接枝法和红外光谱法相结合的方法绘制了定量校正曲线,可用于红外光谱法测定聚乙烯接枝马来酸酐的接枝率。该方法简便快速,准确可靠,重复性好。     

Infrared study of salt free and salt treated cellulose pyrolysis under nitrogen atmosphere

The pyrolysis under nitrogen of salt free and salt treated cellulose was studied by infrared spectroscopy. The results confirm the unzipping mechanism suggested by DTA and TGA studies, and show this mechanism to apply to the untreated and salt treated samples. The results also show the unzipping to stop at the stage of char formation. The onset of this stage was found to occur after the volatilization of only 45–50% of the initial sample of the borax treated cellulose, compared with 65–70% of the KCl treated cellulose and 80–85% of the untreated cellulose.