摘要:

AbstractTwo‐dimensional infrared (2D IR) correlation spectroscopy has found diverse applications in characterizing polymers. The versatility of this powerful technique is demonstrated in the study of a polymeric laminate film by using depth‐profiling photoacoustic spectroscopy, mid‐ and near‐IR dynamic rheo‐optical measurements, and spectroscopic imaging microscopy. Spatial and temporal variations of near‐IR spectra are effectively analyzed by the 2D correlation technique. Step‐scanning FT‐IR spectrometers provide a unique opportunity to obtain desired spectral information often difficult to access by the conventional rapid‐

ISSN:1022-1360    

DOI:10.1002/masy.19971190103

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractThe dielectric properties of poly(ethylene oxide) (PEO) are studied by dielectric relaxation spectroscopy measurements in wide ranges of frequency (5–2×109Hz) and temperature (193 − 300 K). PEO/water systems are also studied in a wide range of water content h (0 − 0.85 grams of water per grams of dry PEO). The measurements allow to distinguish between the dipolar secondary mechanism γ and effects related to free charge motion. The data are analyzed within the formalisms of permittivity, ϵ*, and electric modulus, M*. The water has been found to plasticize the dipolar process and to affect strongly the conduction process. A critical water content hc, hc= 0.13, has been found for the mechanism of charge t

ISSN:1022-1360    

DOI:10.1002/masy.19971190104

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractA rapid‐scan version of 2D‐IR spectroscopy is introduced and applied to study the phases of an acrylonitrile‐butadienestyrene polymer system. Then, as the main part of this paper and in particular to stimulate further application in this field, some recent advances in the application of computational chemistry to the evaluation of vibrational spectra are presented. Some specific applications are disc

ISSN:1022-1360    

DOI:10.1002/masy.19971190105

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractThis review paper discusses the potential of generalized two‐dimensional (2D) near‐infrared (NIR) correlation spectroscopy in studies of pre‐melting behavior and hydrogen bonds of nylon 12. A 2D NIR study on dissociation and hydrogen bonds ofN‐methylacetamide (NMA) is also reviewed here as a model compound study of nylon 12. Fourier transform (FT)‐NIR spectra in the region of 9000–5000 cm−1of nylon 12 were measured over a temperature range of 30–150°C where gradual weakening of inter‐ or intramolecular associative interactions and decrease of local order leading to the eventual fusion of nylon 12 crystals are observed. The 2D correlation analysis provided the following conclusions for the pre‐melting behavior of nylon 12. (i) There are at least eight bands in the 6800–6100 cm−1region assignable to free‐ and hydrogen‐bonded NH groups of nylon 12 in various environments. The asynchronous 2D correlation spectrum in the above region indicates that the amide groups with free carbonyl oxygen appear first and then the unassociated free amide and amide groups with free NH follow as the temperature is increased. (ii) The asynchronous spectrum in the 6000–5500 cm−1region, where the first overtones of the CH2stretching modes are expected to appear, indicates that substantial amount of disordered or dissociated components start appearing before the disappearance of more ordered components. It seems that they appear as the pre‐melting precursors (or even possibly as the indirect cause) to the precipitous decrease of the ordered components associated with melting of nylon 12 occu

ISSN:1022-1360    

DOI:10.1002/masy.19971190106

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractThis investigation was done with a PC of 850 MB/33 MHz, Windows 3.1 and the SPECTACLE program of LabControl/Cologne. The libraries contained standardizedFTIRspectra of 3061 defined polymers, 530 industrial polymers and resins, 1969 additives (pigments, stabilizers, plasticizers etc.) 1190 surfactants and 1614 monomers, pyrolyzates and educts. For searches, the data density was reduced to 4/cm.Similarity search with standardized full spectra yields quantitative dissimilarity figures; it allows an experimental definition ofidentity.The derivative functions 3 and 4 of Lowry and Huppler increase the gap between identical and similar spectra. With the LH2 algorithm spectra are defined as identical if their dissimilarity values are within 103. Since all organic matter has some spectral similarity the LH2 dissimilarity for organics will not go far beyond 105. ‐ The quality ofIRpreparation has a strong impact on search results. If a library contains spectra with false‐light, Christiansen effect, high noise or other artefacts, peak search yields better results than similarity search with full spectra.Multicomponent systems can be searched successfully for their constituents with an algorithm combining peak and similarity searches. This algorithm is superior to all other algorithms if a library contains spectra with artefa

ISSN:1022-1360    

DOI:10.1002/masy.19971190107

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractAn original laser‐interferometric Creep Rate Spectroscopy (CRS) method has been developed and used as the low‐frequency and high‐resolution technique for studying of microplasticity and relaxations in different materials including brittle ones. New possibilities of CRS for polymers are demonst

ISSN:1022-1360    

DOI:10.1002/masy.19971190108

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractSpecific interactions in binary blends of ethylene/vinyl acetate copolymer (EVA) with various low molecular weight terpene‐phenol tackifying resins (TPR) were systematically investigated, as a function of the composition of the blend and of the electron‐acceptor ability of the resin, by using attenuated total reflection‐Fourier transform infrared (ATR‐FTIR) spectroscopy. Molecular acid‐base were evidenced between TPR hydroxyl groups and EVA carbonyl groups. Quantitative information on the fraction of acid‐base bonded entities, the enthalpy and the equilibrium constant of pair formation were obtained. A crystalline transition of the EVA copolymer is observed and is discussed in terms of enthalpy and entropy considerations based on FTIR and calorimetric differential scanning calorimetry (DSC) investigations. Fundamental results are then summarized in order to predict the interfacial reactivity of such polymer blends towards acid or basic

ISSN:1022-1360    

DOI:10.1002/masy.19971190109

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractThin coatings technology demands that characterization tools are readily available to distinguish between the composition and physical state of the coated layers versus the substrate. In principle, infrared photoacoustic spectroscopy (PAS) possesses all the appropriate features to become a mainstream technique for these types of characterizations. These features include the ability to characterize coatings of a variety of thickness (monolayers to tens of microns) and the fact that the technique requires virtually no sample preparation. One category of such samples involves systems having few micron thin layered structures coated on relatively thick polyester substrates. The phase delay of the photoacoustic signal can be used in conjunction with the knowledge of the thermal properties of the coated fluids in the calculation of the relative as well as the absolute depths of these multi‐layered coatings. The phase delay is calculated at wavelengths that are characteristic of the various components of the different layers in the system. The technique is applied to the characterization of a coated system having a submicron layer as the top layer. Step‐scan FT‐IR photoacoustic data are presented that prove the ability of the technique to successfully isolate the infrared signature of the top layer from the infrared spectrum of the bulk material, proving the sub‐micron resolution capability of the method. In addition, results will be shown that underline the fact that the most serious problem in PAS is saturation at high absorpt

ISSN:1022-1360    

DOI:10.1002/masy.19971190110

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractAmong the synthetic polymers of commercial potential, poly‐butadiene is an important rubbery material and it encompasses the bulk elastomers in use. To the best of our knowledge, a complete normal coordinate analysis with full phonon dispersion curves for cis 1,4 polybutadiene (CPBD) have not been reported so far. In the present communication, we report a complete normal coordinate analysis with full dispersion curves, density‐of‐states and calculation of heat capacity. The normal coordinate analysis has been carried out using the Urey‐Bradley force field and the Wilson's GF matrix method as modified by Higgs. A comparison has been made with trans 1,4 polybutadiene (TPBD). The prominent features of the dispersion curves like crossing over and regions of zero‐slope away from the zone centre are discussed. To check the validity of the force field used and the assignments, normal mode calculations are also performed for unsaturated C‐deuterated and fully deut

ISSN:1022-1360    

DOI:10.1002/masy.19971190111

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractFluorescence spectroscopy using an intramolecular excimer‐forming probe has been used to investigate chain mobility in various polybutadienes. The spectroscopic technique is completed by a rheological study carried out in order to identify the molecular parameters governing polymer dynamics. The temperature dependence of the correlation time of the probe motion can be fitted to a WLF equation which shows that the probe mobility reflects the glass transition phenomenon of the host matri

ISSN:1022-1360    

DOI:10.1002/masy.19971190112

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY