bluuebunny/crossref_metadata_2025_split huggingface dataset:
Infrared Spectroscopy in Analysis of Polymers and Rubbers
Authors: Chalmers John M. 
Published: September 2006

Abstract

The infrared spectrum of a polymer or rubber is a profile of its absorption characteristics plotted against infrared wavenumber (or frequency). It is generated when infrared radiation interacts with the molecular moieties that constitute the polymer or rubber material. It is a distinctive property (a “fingerprint”) of the polymer or rubber sample in the form, manner and environment in which it is being examined. It is based on the absorption of infrared radiation at frequencies that match those of the normal modes of vibration within the macromolecule. These absorption features are characteristic of the molecular configuration, sequencing and conformation, and state of order. Absorptions by internal vibrations predominate in the mid‐infrared region (ca. 4000–400 cm
−1
); they involve a few selected atoms in a molecular (functional) grouping, which is a sub‐set of those constituting the macromolecule. External vibrations, such as lattice vibrations, which involve segments of macromolecules in crystalline regions, tend to occur at low wavenumbers (<400 cm
−1
). The intensity of an absorption band is, to a first approximation, proportional to the number density of vibrating species giving rise to that band. The intensity of an absorption band is related to the dipole moment change associated with the molecular vibration; if it is large then the band intensity will be high. Infrared spectroscopy is highly specific. For some quantitative analyses, it can be very precise and sensitive (<0.1%). It is complemented with Raman spectroscopy, for which the selection rules are different and relate band intensity to the change of polarizability occurring during a molecular vibration. Infrared spectroscopy can be used to identify and analyse the molecular structure, composition, order and morphology, both qualitatively and quantitatively, of polymers, copolymers and rubbers and their products. However, for heavily filled and plasticized formulations the spectral interferences may be too high to allow direct or adequate interpretation of a spectrum, and separation of the components will be necessary for unambiguous identifications.
Mechanical Properties of Polymers and Rubbers
Authors: Gao Zhanjun (Justin) 
Published: September 2006

Abstract
One major focus of this article is on models and testing techniques that can be applied readily to the research and development of polymers and rubbers. The article is divided into five sections, with the introduction being the first section. Sections 2 and 3 deal with stress–strain relationships and time‐ and temperature‐dependent behavior. The linear Hooke's law is described first, followed by the molecular mechanism of rubber elasticity, the Mooney–Rivlin model, and the Ogden model. Three viscoelastic models are presented, together with the Boltzmann superposition principle. Various types of apparatus for viscoelastic property measurements are described. The Williams–Landel–Ferry (WLF) equation for time–temperature superposition is illustrated with experimental data.
Section 4 covers the ultimate properties. Topics include: cold drawing in crystalline polymers; temperature and pressure effects on yield stress; brittle–ductile transition; crazing; fracture; tearing of rubbers: extension of Griffith theory; viscoelastic rupture of elastomers; fatigue; and the effects of molecular weight and crystallinity. The ultimate properties are more complex and less well understood. Emphasis is placed on the most important aspects and techniques for understanding and representing yielding and fracture.
Section 5 is devoted to polymer blends and composites. Rubber‐toughened polymers are used to discuss the enhancement of the deformation mechanisms in polymers. A general, mechanistic model is then presented to determine the moduli, break strengths, and break strains for polymer films containing liquid and solid microfillers.
Near‐Infrared Spectroscopy of Polymers and Rubbers
Authors: Workman Jerry J. 
Published: September 2006

AbstractMolecular spectroscopy as provided using the near‐infrared (NIR) measurement technique is valuable for polymer identification, characterization, and quantitation. NIR spectroscopy can be completed for in situ process applications where no sample preparation is required, and where rugged optical systems are a necessity. The NIR region is a complimentary band of the electromagnetic spectrum to the mid‐infrared (MIR) region (4000–500 cm−1), encompassing 13 333–4000 cm−1or 750–2500 nm (nanometers, 10−9 m).NIR and infrared (IR) spectroscopy are routinely used to qualify monomers prior to polymerization reactions. NIR is used to measure the kinetics of polymer onset and can be used to detect end‐point completion and initiator compound levels in polymerization reactions. NIR spectroscopy can also be used to sort polymers and to control the quality of incoming raw monomers and finished polymeric materials. Molecular spectroscopy using the NIR and IR measurement techniques is often used for competitive analysis and to determine thermal or photoinduced oxidation or degradation reactions in polymers. This article delineates the background, theory, band assignments, and applications of NIR spectroscopy for the measurement of polymers and rubbers.
Nuclear Magnetic Resonance, Imaging of Polymers
Authors: Hafner Siegfried 
Published: September 2006

AbstractNuclear magnetic resonance (NMR) imaging is a non‐invasive technique which is based on the phenomenon of NMR. The resonance frequencies of the nuclear spins can be made spatially dependent by introducing a magnetic field gradient into the NMR experiment. The acquired NMR signal is thus spatially encoded and a spin‐density image of the sample can be reconstructed.While originally developed for medical applications, NMR imaging is now increasingly applied for materials investigations. The main advantages of the technique are its nondestructivity, which allows processes to be investigated in situ, and the possibility of introducing NMR spectroscopic information and relaxation contrast into the NMR images. Limitations, on the other hand, are the relatively low sensitivity and the broad NMR lines of polymers, both of which limit the spatial resolution. Whereas the latter can be dealt with by suitable methods, the sensitivity ultimately restricts the achievable spatial resolution of conventional NMR imaging techniques to about 10µm3. NMR imaging therefore must not be considered as a competitor of other microscopic techniques such as electron microscopy but as a characterization technique that provides supplementary information. Examples illustrating all these aspects are given in this article.
Surface Energetics of Polymers and Rubbers, Characterization of
Authors: Eley Richard R. , Petrash Stanislaw 
Published: September 2006

Abstract
Adhesion of polymeric materials to various substrates, from metals to glass to other polymers, is a subject that continues to grow in importance, with today's technologies. The biocompatibility of polymer‐based implantable devices and prostheses is largely determined by the tendency of the material surfaces to be ‘wetted’ or adhered to by proteins. Surface and interfacial energy relationships determine in large part whether the adhesive and adherend achieve the intimacy of molecular contact that is a requisite for good adhesion. An aspect of the behavior of polymer blends and of block copolymers is that, depending on the relative surface energy of the components, and on the phase morphology and chain mobility, lower energy components may segregate to the surface to the detriment of interfacial adhesion, or perhaps promoting heterophase nucleation. There are numerous both technological and scientific motivations for the characterization of polymer surface energy.
The objective in surface energy measurement is to characterize the free energy of a solid or a liquid surface (or, in general, an interface). The surface free energy per unit area (or surface tension) of polymers is a fundamental property. It may be measured in the solid, liquid, or solution state, but perhaps most often the intention is to refer the measured value to the solid state. Hence, one approach involves measuring the surface tension of polymer melts and low molecular weight liquid polymers by conventional methods and using one of several equations to extrapolate to values for the polymer in the solid state.
Methods for determining the surface energy of solid polymers usually involve measuring the contact angle of a sessile liquid drop, and this methodology will be discussed in some detail. A relatively new technique for direct polymer surface energy measurement based on Johnson, Kendall, Roberts (JKR) (contact mechanics) theory will be discussed.
X‐Ray Scattering in Analysis of Polymers
Authors: Li Christopher Y. , Wang Bojie , Cheng Stephen Z.D. 
Published: September 2006

Abstract
It has been proved that X‐rays play a very important role in the characterization of polymers. A wealth of information concerning polymer structures and morphologies are accessible by using X‐ray techniques. X‐ray studies in the polymer area are based on the same principle as that in studies of other materials. The present review attempts to give a short summary of the roles that X‐rays play in modern polymer science.
The first three sections provide a brief introduction about the origin of X‐rays, the principle of the interaction of X‐rays and matter, and X‐ray diffraction. Section 4 briefly describes X‐ray instrumentation. In section 5, crystal unit cell and structural determination methods are discussed. The focus is on the use of uniaxially oriented polymers, as this is the most commonly used method for determination of polymer crystal structures. Crystallinity is another issue, which is specifically important to semicrystalline polymers. A short summary of the concept of crystallinity and its determination based on X‐ray diffraction is discussed. Polymer liquid crystals are a new field which has been growing rapidly since the late 1970s. X‐rays have again played an important role in liquid crystal phase determination. By combination of X‐ray techniques with other structure and thermal property measurements, almost every polymer liquid crystal phase can be identified. Section 6 discusses the small angle X‐ray scattering (SAXS) technique. The cause of X‐ray scattering in the small‐angle region in most polymers is due to the heterogeneous electron density distribution over distances that are large in comparison with the wavelength of the X‐ray (5–100 nm). SAXS is a powerful tool in semicrystalline morphology and block copolymer phase‐morphology studies. In the thin film field, X‐ray diffraction at small angles is also useful in determining the film thickness and interface structure.
Chromatography in Process Analysis
Authors: Clemons Jerry M. 
Published: September 2006

AbstractProcess chromatography is an analytical technique which provides for the on‐line separation and measurement of the components of a mixture in a chemical process. The chromatographic analyzers utilized for on‐line analysis must operate in a continuous and automatic manner, taking a fixed quantity of sample, separating the chemical components using adsorption or partitioning columns, and measuring the concentration of each with a detector. The chromatograph provides both quantitative results, by measuring the area of the peak generated as the components pass through the detector and qualitative results based on the retention time, which is measured from injection to detection.The most commonly used process chromatographic analyzer is the process gas chromatograph because of its many applications in the hydrocarbon processing industry. A variety of valve, column, and detector configurations are available for these analyses from parts per million to percent levels. All samples must be gas phase or liquids which can be vaporized prior to analysis. The analyzers are controlled using a cyclic timing device which switches valves and columns as the components pass through the system to provide the necessary separation. This time cycle is a limitation of the technique for applications requiring continuous or very fast analysis times. Even with these limitations, the advantages of cost, flexibility, sensitivity, and reliability have made process gas chromatography (PGC) the most widely used analytical technique for on‐line process control.
Mass Spectrometry in Process Analysis
Authors: Olivares José A. 
Published: September 2006

AbstractThe mass spectrometer can provide a versatile, highly specific and sensitive tool for the analysis and control of industrial processes. More common techniques for industrial process control are gas chromatography and infrared spectroscopy. Ion mobility spectrometry and chemical sensors are slowly being introduced. Although mass spectrometry is relatively more complex and expensive to implement than these other techniques, the sensitivity and specificity offered is often unmatched. This article gives a general review of the roots of mass spectrometry as it applies to on‐line process control. A short discussion of instrumentation commonly used in the practice of this technique has been added and limited only to the more popular and currently commercially available instruments. These include sector, quadrupole and time‐of‐flight mass spectrometers. The capabilities and specifications of the different classes of mass spectrometers are discussed and compared. Specific sampling methodology for the operation of these instruments in on‐line processes is given. Also included is a discussion of common practices in the reduction of interferences and deconvolution of mass spectra from mixtures. In‐depth examples of industrial process and control applications have been selected and are discussed in the areas of biotechnology, technical incineration, petrochemical, and semiconductor production.
Sampling and Sample Preparation in Process Analysis
Authors: Creasy Kenneth E. , Francisco Troy W. 
Published: September 2006

Abstract
The purpose of this article is to introduce the reader to the important design characteristics of sampling and sample preparation systems for process analytical measurements, as well as to discuss several of the most commonly used configurations for gas‐ and liquid‐phase process streams. Design criteria essential to the success of any process analyzer installation are discussed at length, and the pitfalls associated with neglecting these items are highlighted. This article provides an overview of what must be considered when building the interface between the analytical instrument and the process stream. It is not intended to be a comprehensive dissertation on the subject or a tutorial. The reader is referred to literature references and textbooks for detailed explanations and relevant design formulae. In addition, we also provide several sections regarding calibration procedures, maintenance concerns, and safety considerations.
Titration Techniques for Process Analysis
Authors: Fossum Tore K. , Wolcott Duane K. 
Published: September 2006

Abstract
Titration remains a method of choice for quantitation and assay because the techniques are simple and the repeatability and accuracy can be better than with other analytical methods. Titration has moved from the laboratory bench to the process in order to obtain more timely information for the control of the process. This has become possible with the development of sampling techniques for getting clean samples from a pipe or tank, sensors suitable for remote measurements, highly precise automated titrant delivery pumps, and microprocessor‐based controllers adapting the time‐honored methodologies of the bench chemist.
Topics discussed in this paper include theory, sampling techniques, titration control, detection and applications using pH, argentometric, redox, and photometric sensors.
Ultraviolet/Visible Spectroscopy in Process Analyses
Authors: Saltzman Robert S. 
Published: September 2006

Abstract
Process analyzers based on selective ultraviolet (UV) and/or visible (VIS) absorption provide highly reliable on‐line composition monitoring and closed‐loop control throughout the process industries. Design criteria for ultraviolet/visible (UV/VIS) analyzers are different to those for laboratory instruments since the process instrument must meet the area electrical classification and often withstand harsh plant environments such as vibration, wide temperature swings, corrosive atmospheres and “dirty” samples.
The designs of various types of UV/VIS process analyzers are reviewed, and applications of these analyzers in major process industries are described.
Fourier Transform Infrared Spectroscopy in the Pulp and Paper Industry
Authors: Leclerc Denys F. 
Published: September 2006

AbstractFourier transform infrared spectroscopy (FTIRS) is the combined use of infrared (IR) light, for illuminating a light‐absorbing sample, with an interferometer, for producing an interference pattern from which an absorption spectrum characteristic of the sample is recovered through Fourier transformation. The majority of current IR pulp and paper applications involve the routine characterization of samples that contain variable amounts of water, a very strong IR absorber. Consequently, qualitative IR analysis of pulp and paper samples is best performed with a Fourier transform infrared (FTIR) spectrometer because of the larger optical throughput offered by an interferometer over a dispersive spectrometer. Also, an interferometer simultaneously records all IR frequencies present in the spectrum. These two advantages enable one to acquire high‐quality spectra in a few minutes or less. Additionally, since an interferometer accurately determines IR frequencies with the output of a visible‐light laser, quantitative determinations which use multivariate calibration methods such as partial least squares (PLS) are much less prone to instrument drift, and hence more accurate. Liquid and solid samples can be analyzed either neat or suitably diluted in a nonabsorbing matrix, through a variety of sampling techniques such as transmission, diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), attenuated total reflectance (ATR), IR microscopy, and photo‐acoustic spectrometry (PAS). Detection limits for quantitative methods vary from 0.01 to 1 percent, depending on the sampling method and the complexity of a sample matrix. However, FTIR spectrometry cannot resolve more than a few components at a time in liquid and solid samples because of the presence of strongly overlapping bands. Therefore, FTIR spectroscopy must often be used in combination with separation techniques such as gas chromatography (GC) or solid‐phase extraction (SPE), especially when a complete analysis of the sample is required.
Mechanical Pulps, Ultraviolet/Visible Spectroscopy of Chromophores in
Authors: Schmidt John A. 
Published: September 2006

Abstract

Mechanical pulps are those where the starting wood is rendered into a suspension of fibers by the application of mechanical energy. Most of the lignin component is retained in the fibers by this process. The yellowish coloration of wood fiber is a consequence of the presence of chromophores in the lignin that absorb both visible and ultraviolet (UV) light. In most cases, the fibers must be bleached before they are acceptable for their final use. Lignin‐containing fibers are also susceptible to yellowing when exposed to UV light. To study the chemistry of these processes in pulp fibers, a technique capable of detecting chromophores in materials that both absorb and scatter radiation is needed. Diffuse reflectance ultraviolet/visible (UV/VIS) spectroscopy is such a technique. For nonscattering materials, the Beer–Lambert law provides a simple linear relationship between absorbance and the concentration of absorbers. This has been used for the analysis of soluble lignins and pulping liquors. For scattering materials, there is no similar simple linear relationship between reflectance and concentration of absorbers. A single reflectance measurement from an opaque sample can be related to the ratio of absorption to scattering by the Kubelka–Munk remission function, F(R
∞
) = k/s = (1 − R
∞
)
2
/2 R
∞
, where R
∞
is the reflectance of an opaque sample, k is the specific absorption coefficient and s is the specific scattering coefficient. The specific absorption coefficient k is linearly related to absorber concentration. If the scattering coefficient remains constant, the remission function is proportional to chromophore concentration. However, for many samples of interest, such as pulps prepared by different mechanical processes, scattering is not constant. Here, it would be uncertain whether a difference in remission function should be attributed to a change in absorption or a change in scattering. Also, in samples where the chromophores are not homogeneously distributed throughout the sample thickness, such as sheets yellowed by light, the linearity of the remission function no longer holds. In such cases, k can be calculated explicitly by taking additional reflectance measurements from thin transmitting samples that are suspended over backgrounds of known reflectance. While spectra of k versus λ (wavelength) are usually broad and featureless, difference spectra can reveal a surprising amount of detail about the changes in chromophore content.
Pyrolysis in the Pulp and Paper Industry
Authors: Sitholé B. Bruce 
Published: September 2006

Abstract
Analytical pyrolysis is a powerful technique that is seldom used in the pulp and paper industry. This article illustrates the utility of the technique to study the chemistry of wood and pulps, mechanistic aspects of pulping, troubleshooting process upsets in pulp and papermaking, and evaluating the quality of finished products. The technique has advantages over other analytical techniques in that little sample preparation is required and enough data can be obtained from very small amounts such as dirt spots on paper. In many cases good data can be obtained by analyzing the pyrolysis products by gas chromatography (GC) with flame ionization detection (FID). Detection with mass spectrometry (MS) offers the advantage of absolute qualitative and quantitative determination of the chemistry of the analytes. In many instances the chromatography can be improved by on‐line derivatization of the pyrolysis products with an alkylating agent.
This article takes the reader through a survey of the different types of analytical pyrolysis systems, through data analysis and processing, and examples of applications of analytical pyrolysis in the pulp and paper industry. Ample illustrations are used to highlight the usefulness of the technique.