Orientation of uniaxially stretched poly(ethylene naphthalene 2,6‐dicarboxylate) films by polarized infrared spectroscopy

Poly(ethylene naphthalene‐2,6‐dicarboxylate) has been uniaxially stretched at different draw ratios and at two different temperatures below and above its glass transition (T_g ～ 120 °C) respectively, at 100 and 160 °C. Crystallinity has been evaluated from calorimetric analyses and compared to the values deduced by FTIR spectroscopic data. As expected, the obtained results are quite similar and show that films stretched at lower temperature (100 °C) are more crystalline than those stretched at 160 °C. Optical anisotropy associated with orientation has been evaluated by birefringence and show that films stretched at 100 °C are more birefringent than those stretched at 160 °C as a result of a higher chain relaxation above T_g. Polarized FTIR was also performed to evaluate the individual orientation of amorphous and crystalline phases by calculating dichroic ratios R and orientation functions 〈P₂(cos θ)〉 and also show that amorphous and crystalline phases are more oriented in the case of films stretched below T_g. Nevertheless, the orientation of the amorphous phase is always weaker than that of the crystalline phase. Films stretched at 100 °C show a rapid increase in orientation (and crystallinity) with draw ratio and 〈P₂(cos θ)〉 reaches a limit value when draw ratio becomes higher than 3.5. Films drawn at 160 °C are less oriented and their orientation is increasing progressively with draw ratio without showing a plateau. A careful measurement of the IR absorbance was necessary to evaluate the structural angles of the transition moments to the molecular chain axis. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1950–1958, 2007     

涂石蜡大米傅立叶变换红外吸收光谱识别分析

针对11种未涂石蜡大米和18个涂不同量石蜡的大米样品,以石油醚提取的油脂为试样,采用傅立叶变换红外光谱仪,扫描样品的傅立叶变换红外吸收光谱,并对光谱进行预处理,提取红外特征信息,将2855与1746、1462与1163 cm-1处特征峰的面积比值为坐标,采用Origín 6.0软件作识别分类图.结果表明:特征峰的面积比值与所涂石蜡量成线性变化,大米油脂的特征峰面积比值在一定的区域分布,涂以0.05%以上石蜡的大米,其油脂特征峰面积比值与未涂石蜡米油脂的值有一定区别.     

Molecular orientation of aromatic polycarbonates containing fluorene side chains by polarized infrared spectroscopy and birefringence analysis

The molecular orientation of an aromatic polycarbonate containing fluorene side chains was investigated by polarized infrared spectroscopy and birefringence analyses. The copolymers were synthesized from 2,2‐bis(4‐hydroxyphenyl)propane (BPA), 9,9‐bis(4‐hydroxy‐3‐methylpheny)fluorene (BMPF), and phosgene by interfacial polycondensation. The 1449‐cm^?1 band of the uniaxially oriented films, stretched at the glass‐transition temperature (T_g) plus 5 °C, was assigned to various combinations of CC stretching and CH in‐plane bending vibrations in the fluorene ring, and the transition moment angle was estimated to be 90°. The intrinsic birefringence of aromatic polycarbonate films with BMPF molar ratios ranging from 0.5 to 1 was obtained with the 1449‐cm^?1 band. The copolymer was estimated to show zero intrinsic birefringence at the BMPF molar ratio of 0.75, and the BMPF homopolymer showed negative intrinsic birefringence. A linear relationship between the volume fraction of BMPF units and the intrinsic birefringence indicated that the two monomer units of BPA and BMPF in each copolymer were not independent, and an intrinsic birefringence could be defined even in the copolymer. The sign of the photoelastic coefficient in the homopolymer with BMPF units was positive. The different signs of the photoelastic coefficient and the intrinsic birefringence suggest that the fluorene side‐chain orientation induced by stress in the glass state is quite different from the orientation of the uniaxially oriented films stretched at T_g + 5 °C. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1554–1562, 2003     

An in situ Fourier transform infrared spectroscopy method for collecting real-time data for the liquid-phase reaction of CO2 and mono-ethanolamine in alcoholic solvent systems

A novel Fourier transform infrared (FTIR) spectroscopy method of analysis was developed to study the industrially important reaction of CO₂ with the primary amine, mono-ethanolamine (MEA), in n-propanol as representative alcoholic solvent. A semi-batch reactor with a piston like ‘floating’ head was specifically designed in order to study the reaction in the liquid phase, thereby eliminating the mass transfer limitations of a gas-liquid system. An attenuated total reflectance (ATR) probe was used to monitor the change in reagent and product concentrations in-situ. Successful spectral peak identification and calibrations were performed in order to collect real time, reaction kinetic data. Data analysis confirmed that the zwitterion reaction mechanism most accurately describes the reaction in non-aqueous systems.     

Two‐dimensional Fourier transform infrared spectroscopy study of biosynthesized poly(hydroxybutyrate‐co‐hydroxyhexanoate) and poly(hydroxybutyrate‐ co‐hydroxyvalerate)

Generalized two‐dimensional (2D) Fourier transform infrared correlation spectroscopy was used to investigate the effect of the comonomer compositions on the crystallization behavior of two types of biosynthesized random copolymers, poly(hydroxybutyrate‐co‐hydroxyhexanoate) and poly(hydroxybutyrate‐co‐hydroxyvalerate). The carbonyl absorption band around 1730 cm^?1 was sensitive to the degree of crystallinity. 2D correlation analysis demonstrated that the 3‐hydroxyhexanoate units preferred to remain in the amorphous phase of the semicrystalline poly(hydroxybutyrate‐co‐hydroxyhexanoate) copolymer, resulting in decreases in the degree of crystallinity and the rate of the crystallization process. The poly(hydroxybutyrate‐co‐hydroxyvalerate) copolymer maintained a high degree of crystallinity when the 3‐hydroxyvalerate fraction was increased from 0 to 25 mol % because of isodimorphism. The crystalline and amorphous absorption bands for the carbonyl bond for this copolymer, therefore, changed simultaneously. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 649–656, 2002; DOI 10.1002/polb.10126     

FTIR spectroscopic characterization of structural changes in polyamide‐6 fibers during annealing and drawing

First, we report the development of Fourier transform infrared (FTIR) spectroscopic methods to determine the α/γ‐crystalline phase ratio of polyamide‐6 fibers and, in combination with density measurements, the total crystallinity. Using density determinations of the crystallinity of pure α and pure γ samples, we found the absorption coefficient ratio for the 930 (α) and 973 cm⁻¹ (γ) bands to be 4.4, from which we could obtain the α/γ ratio for any polyamide‐6 sample. The application of this FTIR method to the quantitative analysis of phase changes during thermal treatment and the drawing of polyamide‐6 was then made. We confirmed that crystallization during thermal treatments involved increases in both phases and did not involve crystal‐to‐crystal transformation, whereas drawing involved both crystallization of the amorphous phase in the α form and γ→α transformation. Finally, we revisited the band assignments for the amorphous phase of polyamide‐6 and found that the band at 1170 cm⁻¹ was not an amorphous band but, because its absorbance was independent of crystallinity, could be used as an internal reference band. The band at 1124 cm⁻¹ was reliably attributed to the amorphous phase. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 536–547, 2001     

Screening effects in blends of a hyperbranched,dendrimer‐like polyester with poly(4‐vinyl phenol)

We previously reported self‐association and interassociation equilibrium constant values describing hydrogen bonding in solutions of a hyperbranched polyester. These allow us to estimate the extent of intramolecular screening and the fraction of same‐chain contacts in this system as a function of generation number. In this article, we use a similar method to evaluate the degree of intramolecular screening in polymer blends. The calculated values reported here are consistent with those previously reported in our solution study, confirming the validity of the calculation procedures we used to evaluate the accessibility of functional groups in these highly branched systems. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1651–1658, 2001     

FTIR spectroscopy of monomolecular layers and multilayers of organic molecules on solid substrates

A method for measuring grazing incidence reflection spectra of monomolecular organic layers is presented which involves the use of a stepmotor-driven translation stage to alternately measure the covered and uncovered part of a metal substrate and averaging of the spectra from several such cycles. The method is applied to Langmuir-Blodgett films of poly(octadecylmethacrylate).     

Crystallization studies of poly(trimethylene terephthalate) using thermal analysis and far‐infrared spectroscopy

Crystallization of poly(trimethylene terephthalate) (PTT) by annealing was examined using density measurement, differential scanning calorimetry, and far‐infrared spectroscopy (FIR). Crystallinity, measured by density, increased slowly up to the T_a of 185 °C and increases rapidly once T_a exceeds 185 °C. It was found that thermally induced crystallization is mainly temperature‐dependent above T_a = 185 °C and temperature‐ and time‐dependent below T_a = 60 °C. Two melting transitions, T and T, were observed for those samples annealed above 120 °C. No significant change in T was observed as a function of T_a while T showed strong dependency on T_a. Digital subtraction of the amorphous contribution from the semicrystalline FIR spectra provided characteristic spectra of amorphous and crystalline PTT. The bands at 373, 282, and 92 cm^?1 were assigned to the crystalline phase, while the bands at 525, 406, and 351 cm^?1 were attributed to the amorphous phase. It was shown that FIR spectroscopy can be used as a means to estimate the degree of crystallinity of PTT. The band ratio of 373 and 501 cm^?1 was plotted against crystallinity measured by density and reasonably good correlation was obtained. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1675–1682, 2007     

Correlating light and thermal stability of silver carboxylate complexes by infrared and 13C NMR spectroscopy

Bond nature of carboxylic groups can play an important role in Ag(I)-carboxylate compounds because light and thermal stability are important requirements for future applications such as antibacterial additives. A linear correlation between bond character and light stability of silver carboxylate complexes has been predicted by a direct relationship of infrared and ¹³C NMR spectroscopic data. This correlation is in agreement with the thermogravimetric analysis and provides a new approach to explore the interaction and the physical properties of metal-carboxylate bonds.     

Quality control of Metamitron in agrochemicals using Fourier transform infrared spectroscopy in the middle and near range

Two vibrational spectrometry-based methodologies were developed for Metamitron determination in pesticide formulations. Fourier transform-middle infrared (FT-MIR) procedure was based on the extraction of Metamitron by CHCl₃ and latter determination by peak area measurement between 1556 and 1533 cm⁻¹, corrected with a two points baseline established from 1572 to 1514 cm⁻¹. Fourier transform-near infrared (FT-NIR) determination was made after the extraction of Metamitron in acetonitrile and measuring the peak area between 6434 and 6394 cm⁻¹ corrected using a two points baseline defined between 6555 and 6228 cm⁻¹. Repeatability, as relative standard deviation, of 5 independent measurements at mg g⁻¹ concentration level, of 0.16% and 0.07% for MIR and NIR and a limit of detection of 0.03 and 0.004 mg g⁻¹ were obtained for MIR and NIR, respectively.NIR determination provides a sample frequency of 120 h⁻¹, higher than that found by MIR and liquid chromatographic methods (60 and 15 h⁻¹, respectively). On the other hand, the NIR method reduces the solvent consumption and waste generation, to only 1 ml acetonitrile per sample as compared with 3.4 ml chloroform required for the MIR determination and 60 ml acetonitrile used in the chromatographic reference procedure. So, vibrational procedures can be considered serious alternatives to long and time consuming chromatographic methods usually recommended for quality control of commercially available pesticide formulations.     

The influence of pre‐treatments of aluminium alloys on bonding of PET coatings

Application of organic coatings on aluminium alloys is commonplace for corrosion protection. The adhesion of coatings is of great importance to the final protection properties. It is therefore necessary to understand on a molecular level the mechanisms with which a coating is able to bond. In this paper, we explore the possibilities of combining model molecules for a poly(ethylene terephthalate) (PET) type coating, di‐methyl terephthalate (DMT), with differently pre‐treated samples of AA1050 and AA5182 alloys. Bonding is studied by means of Fourier‐transform infrared (FTIR) spectroscopy. Because the type of bonding gives a direction for adhesion of a coated system, we also test (macroscopically) the adhesion of PET coatings with a novel technique: asymmetrical double cantilever beam (ADCB). In this method, a thin knife is used as a wedge on the interface of the alloy and the polymer. The displacement of the crack front as measured from the knife's contact point with the coating is used as an input parameter to obtain the adhesion energy for various systems. We show that there is a relationship between the character of bonding of DMT molecules and adhesion energies of PET on both alloys after pre‐treatments in alkali and acid and boiling in water. Copyright © 2010 John Wiley & Sons, Ltd.     

Temperature‐dependent polymorphic crystalline structure and melting behavior of poly(butylene adipate) investigated by time‐resolved FTIR spectroscopy

The polymorphic crystalline structure and melting behavior of biodegradable poly(butylene adipate) (PBA) samples melt‐crystallized at different crystallization temperatures were studied by differential scanning calorimetry (DSC) and fourier transform infrared (FTIR) spectroscopy. The crystalline structure and melting behavior of PBA were found to be greatly dependent on the crystallization temperature. By comparison of the FTIR spectra and the corresponding second derivatives between the α‐ and β‐crystal of PBA, the spectral differences were identified for the IR bands appeared at 1485, 1271, 1183, and 930 cm^?1 and the possible reasons were presented. Especially, the 930 cm^?1 band was found to be a characteristic band for the β‐crystal. Combining the DSC data with the analysis of normalized intensity changes of several main IR bands during the melting process, the melting behaviors of the α‐ and β‐crystal were clarified in detail. It is demonstrated by the in situ IR measurement that the β‐crystalline phase would transform into the α‐crystalline phase during the melting process, and the solid–solid phase transition from the β‐ to α‐crystal was well elucidated by comparing the intensity changes of the 1170 and 930 cm^?1 bands. The dependence of the β‐ to α‐crystal phase transition on the heating rate was revealed by monitoring the intensity ratio of the 909 and 930 cm^?1 band. It was suggested that at the heating rate of 0.5 or 1 °C/min, the percent amount of the transformed α‐crystal from the β‐crystal was much higher than that at the higher heating rate. The β‐crystal transforms into the α‐crystal incompletely at the higher heating rate because of the less time available for the phase transition. In addition, the β‐ to α‐crystal phase transition was further confirmed by the IR band shifts during the melting process. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1997–2007, 2009     

Temperature dependence of molecular conformation in uniaxially deformed isotactic polypropylene investigated by combination of polarized FTIR spectroscopy and 2D correlation analysis

Evolution of molecular conformation in uniaxially deformed isotactic polypropylene (iPP) as a function of temperature is investigated by time‐resolved polarized Fourier‐transform infrared spectroscopy. It is observed that oriented crystals (microfibrils) induced by deformation possess better thermal stability compared with isotropic spherulites. 2D correlation analysis reveals that the relaxation process of ordered helices in deformed iPP could be divided into two regions referring to the melting of different crystalline structures. No obvious sequential change of ordering conformations observed in low temperature region is attributed to melting of defective or destructed crystals. However, notable sequential changes of helices occur in the high temperature region; interestingly, long helices are more thermally stable than short helices. The central region of microfibrils is suggested to consist of a large amount of long helical bundles, and the short ordering segments are primarily located in the outer lateral surfaces. A physical picture of the conformational distribution in deformation‐induced microfibrils is thus gained. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 673–684     

Classification of Rat FTIR Colon Cancer Data Using Waveletsand BPNN

本文提出了一种新的基于水平衰减全反射-傅里叶变换红外光谱（HATR-FTIR）的小波特征提取与反向传播人工神经网络模式分类方法以提高FTIR对早期大鼠结肠癌的诊断准确率．对60只DMH诱导的SD大鼠,44只诱导鼠的第二代鼠,36只正常SD大鼠的结肠正常组织、异常增生、早癌及进展期癌组织所获得的的HATR-FTIR,利用连续小波多尺度分析法提取12个特征量,采用反向传播人工神经网络进行分类,识别准确率分别为100%、94%、97.5%及100%．实验结果表明此方法对早期结肠癌具有较高的诊断率．     

Molecular deformation mechanisms of isotactic polypropylene in α‐ and β‐crystal forms by FTIR spectroscopy

The orientation behavior of isotactic polypropylene (iPP) in α‐ and β‐crystal form was investigated by rheo‐optical Fourier transformed infrared (FTIR) spectroscopy. This method enabled quantification of the degree of orientation as a feature of structural changes during uniaxial elongation in not only the crystalline phase but also the amorphous one. Molecular orientation mechanisms can be successfully derived from experimental results. Generally, three mechanisms were detected for iPP: (1) interlamellar separation in the amorphous phase, (2) interlamellar slip and lamellar twisting at small elongations, and (3) intralamellar slip at high elongations. The third mechanism was favored by α‐PP, whereas β‐PP favored the second mechanism, which, in fact, was responsible for the different mechanical properties of both materials at the macroscopic level. On the other hand, crystallization conditions may have significantly affected the amorphous orientation. Nevertheless, for both iPP types the chains in the amorphous phase always oriented less than did those in the crystalline phase. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 4478–4488, 2004     

Attenuated total reflectance/fourier transform infrared studies on the phase‐separation process of aqueous solutions of poly(n‐isopropylacrylamide)

Temperature‐induced phase separation of poly(N‐isopropylacrylamide) in aqueous solutions was studied by attenuated total reflectance (ATR)/Fourier transform infrared spectroscopy. The main objectives of the study were to understand, on a molecular level, the role of hydrogen bonding and hydrophobic effects below and above the phase‐separation temperature and to derive the scenario leading to this process. Understanding the behavior of this particular system could be quite relevant to many biological phenomena, such as protein denaturation. The temperature‐induced phase transition was easily detected by the ATR method. A sharp increase in the peaks of both hydrophobic and hydrophilic groups of the polymer and a decrease in the water‐related signals could be explained in terms of the formation of a polymer‐enriched film near the ATR crystal. Deconvolution of the amide I and amide II peaks and the O? H stretch envelope of water revealed that the phase‐separation scenario could be divided, below the phase‐separation temperature, into two steps. The first step consisted of the breaking of intermolecular hydrogen bonds between the amide groups of the polymer and the solvent and the formation of free amide groups, and the second step consisted of an increase in intramolecular hydrogen bonding, which induced a coil–globule transition. No changes in the hydrophobic signals below the separation temperature could be observed, suggesting that hydrophobic interactions played a dominant role during the aggregation of the collapsed chains but not before. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1665–1677, 2001     

概率神经网络和FTIR光谱用于食道癌的辅助分析

利用正常与相应癌化食道组织的主要FTIR特征峰aυs,CH3、sυ,CH2、σCH2、aυs,po4-、υc-o、sυ,po2-及sυ,磷酸化蛋白作为概率神经网络的输入向量,对网络的主要参数(网络径向基函数分布spread(0~5))、输入向量和网络表现(m ean accurate rate of recogn ition)之间的关系进行了研究。主要结论如下:i)无论输入向量是哪种特征频率的组合,其平均识别正确率都高于71.40%;ii)当输入向量为特征频率sυ,po2、sυ,磷酸化蛋白或υc-0、sυ,po2、sυ,磷酸化蛋白时,网络表现较佳,平均识别正确率较好。当spread介于1.4~2.3时,两者均达到网络具有的最高平均识别正确率(85.71%);iii)大多数情况下,网络的平均识别正确率与spread之间呈现二个高峰的特征,即spread介于0.1~0.3和1.5~5.0之间时,网络均具有较高的平均识别正确率。研究表明,以傅里叶变换红外光谱的主要特征峰为概率神经网络的输入向量,用于食道组织样品的癌化识别分析是完全可能的,其平均识别正确率可达85.71%。     

Molecular orientation of rigid‐rod polyimide films characterized by polarized attenuated total reflection/fourier transform infrared spectroscopy

The variations in the molecular orientation of uniaxially drawn rigid‐rod polyimide films were systematically characterized in all three dimensions with polarized attenuated total reflection/Fourier transform infrared spectroscopy. The second‐order orientation coefficients were directly deduced from the anisotropy in IR absorptions of particular bands. With the draw ratio increasing, the state of the molecular orientation changed from being nearly planar to completely uniaxial via biaxial orientation, and the degree of orientation was much larger than that of a semirigid polyimide having an ether linkage at the same draw ratio, which originated from the rigid‐rod structure. In addition, the imide planes were rotationally oriented to the out‐of‐plane direction of the film geometry. Furthermore, the relationship between the molecular chain orientation and the in‐plane birefringence in the biaxial orientation state was examined. The intrinsic birefringence was estimated from biaxial orientation films to be 0.33 at a wavelength of 1307 nm. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 418–428, 2003     

傅里叶变换表面等离子体共振频率对金膜表面溶液折射率响应

采用新型傅里叶变换表面等离子体共振仪（FT-SPR）,测定了NaCl、KCl和乙醇3种水溶液在不同浓度下的SPR响应值,建立了SPR响应与溶液浓度和折射率之间的定量关系R=1.53×105(n -1.3333),测定了FT-SPR 100型仪器的折射率响应常数m=1.53×105,即液体折射率每变化0.000 1,FT-SPR响应值变化为15 cm-1。 其结果为用FT-SPR直接测定液体样品的折射率提供了可能。