摘要:

AbstractVarious types of molecular assembly of long‐chain compounds in solid states were investigated by means of infrared absorption, Raman and Brillouin spectroscopic methods. As for the polymorphism in even‐numberedn‐fatty acids, three monoclinic modifications, B, C, and E, all consisting of the orthorhombic polyethylene sublattice, give rise to their characteristic infrared and Raman spectra. A dynamical equilibrium betweencisandtransconformations of the hydrogen‐bonded carboxyl groups in modification C, which is related to the high‐temperature stable character of this phase, is reflected to a dramatic change with temperature in the low‐frequency Raman spectra. A new type of reversible solid state phase transition was found between two A‐type (triclinic) modifications of myristic, palmitic, and stearic acids. The γ→α phase transition of oleic acid was found to be caused by a conformational disordering of polymethylene chains at the lamellar interfacial region.Two basic polytype structures, Mon and Orth II, of stearic acid B were investigated, and it was found that the low‐frequency phonon frequencies (below 50 cm−1) were strongly influenced by the polytype structure. Based on the spectroscopic considerations, Orth II was predicted as the thermodynamically stable phase around room temperature compared with Mon, and the stability is responsible for the vibrational free energy term. Some experimental findings which support this prediction were obtained. The values of the stiffness tensor elements of Mon and Orth II, measured by Brillouin scattering, indicate that the mechanical behavior of bulk crystals is very dependent on the polytype structure.The relationship between the mobility of chain molecules and the width of the spectral bands was investigated in a quantitative manner for the case ofn‐alkane molecules entrapped in the urea inclusion adducts. The changes in the half‐width for the polarization components of various Raman bands on the transition from the orthorhombic to the hexagonal phase are interpreted in terms of the correlation functions of the Raman tensor related to the rotational motion of the alkane molecu

ISSN:0258-0322    

DOI:10.1002/masy.19860050103

出版商:Hüthig&Wepf Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractFourier transform infrared temperature studies of two semi‐crystalline polyamides, nylon 12 and a terpolymer of nylon 6/66/610 are presented. The results obtained are consistent with those recently published from similar studies of an amorphous polyamide and nylon 11 and further bolster our general interpretation of the infrared spectra of polyamide

ISSN:0258-0322    

DOI:10.1002/masy.19860050104

出版商:Hüthig&Wepf Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractThe limit to the information on the microstructure of polymers that may be obtained from their vibrational spectra is often set by overlapping bands, markedly broader than the spectrometer resolution. Following the initial pioneering work of Pohl and Hummel, using a simple curve fitting technique, mathematical methods of spectral quality enhancement have progressed very considerably. These methods are reviewed critically and new results are presented. The desirability of imposing some parameter constraints in curve fitting is demonstrated, and this has led to the development of methods for peak narrowing, as an aid to peak finding. The two important approaches, derivative spectroscopy and Fourier selfdeconvolution (FSD), are discussed in terms of their application to the complex of overlapping bands in thev(C‐Cl) region of the infrared spectrum of poly(vinyl chloride). A development of the FSD method termed Fourier band isolation, is described and preliminary results indicate that it has considerable promise. The maximum entropy method is discussed briefl

ISSN:0258-0322    

DOI:10.1002/masy.19860050105

出版商:Hüthig&Wepf Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractPolymer coatings on steel substrates were analyzed by reflectance/absorbance infrared spectroscopy. Initial studies were performedex‐situon samples which had been cured at a variety of temperatures on two different substrates. Further studies were donein‐situunder both air and nitrogen atmospheres. The two substrates studied were untreated cold‐rolled steel and cold‐rolled steel with a conversion coating of zinc phosphate. Changes in the spectra of the phosphate conversion layer correlated well with anti‐corrosion properties. Mechanisms of degradation and cure could be determined from thein‐situ

ISSN:0258-0322    

DOI:10.1002/masy.19860050106

出版商:Hüthig&Wepf Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractThe intensity of the IR‐absorption bands of PET, which depends on the chain conformation (crystallinity), has been correlated with the specific volume of the samples produced under different conditions. It has been found that the absorption data of the ‐0‐CH2‐CH2‐0‐groups, discussed in the literature, leads to wrong vc‐ and va‐values. From our FTIR measurements of PET we obtained the spec. volume vc=ca. 0,66 cm3/g and va=0, 747 cm3/g. The amount of the trans‐conformation in the amorphous (for a well quenched sample) PET is about 12 ‐ 15%. The absorption band at 990cm−1is not due to t

ISSN:0258-0322    

DOI:10.1002/masy.19860050107

出版商:Hüthig&Wepf Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractQuantitative high‐pressure absorption spectroscopy in the mid infrared, near infrared, and ultraviolet region enables direct and precise investigation of high‐pressure ethylene polymerizations with thermal, chemical, and laser‐photochemical initiation. The special advantages of kinetic studies via quantitative near infrared spectroscopy in an extended wavenumber range are outlined. Extensions of the method on copolymer systems are indicated. The spectroscopic technique is of general applicability in studies on reactions and equilibria in dense fluid states including liquids and compressed

ISSN:0258-0322    

DOI:10.1002/masy.19860050108

出版商:Hüthig&Wepf Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractIR microspectroscopy allows the identification and even quantitative analysis of tiny objects down to nanograms. A typical example is the investigation of specks or fish eyes in plastics. Other applications include the determination of local concentration changes of plasticizer or the oxygen uptake during aging. Such microinvestigations require sophisticated preparation techniques and specially equipped high‐performance spectrometers. Some practical examples and results are presented; they demonstrate the use of micro‐KBr, microtome, microsheet, and micropyrolysis techniq

ISSN:0258-0322    

DOI:10.1002/masy.19860050109

出版商:Hüthig&Wepf Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractInfrared measurements of the dicroic ratio of poly‐(methyl methacrylate) absorption bands provide a valuable method for determining the orientation as well as the relaxation of chains during stretching. Different strain rates and temperatures of stretching were used. Orientation relaxation was determined and a master curve was obtained at a reference temperature TO= 135°C. The master curve shows that orientation relaxation behaves similarly to mechanical relaxati

ISSN:0258-0322    

DOI:10.1002/masy.19860050110

出版商:Hüthig&Wepf Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractA newly developed infrared photoacoustic technique has been used to obtain information about the orientation of the surface functional groups of Kevlar‐49Rfibers. This method involves the use of a highly polarizable gas in the photoacoustic cell and comparison of the spectra with a non‐polarizable coupling gas. A highly polarizable inert gas, xenon, enhances the surface modes oriented parallel to the surface and suppresses the intensity of the perpendicular modes. This method shows differences in the structure of the skin and the core of the fibers. The polymer chains in the skin are oriented parallel to the surface, and in the core they are almost radially orien

ISSN:0258-0322    

DOI:10.1002/masy.19860050111

出版商:Hüthig&Wepf Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractThe advent of computer‐supported IR spectrometers, especially Fourier‐transform IR interferometers, made possible considerable progress in the fine‐structure elucidation of the seemingly well‐known polyethylene and ethene copolymers. This paper gives a review on the results obtained in several laboratories in the following fields: identification of side‐groups and olefinic structures, characterization of ethene homo‐ and copolymers made with different catalysts, by spectral enhancement, difference and derivative spectroscopy, and measurements of the dichroism of oriented samples. In one chapter, recent results with amorphous poly(alkyl ethylene)s obtained with a modified Phillips catalyst a

ISSN:0258-0322    

DOI:10.1002/masy.19860050112

出版商:Hüthig&Wepf Verlag    

年代:1986

数据来源: WILEY