Thesis (Ph. D.)--Ohio State University, 2003. / Title from first page of PDF file. Document formatted into pages; contains xxv, 475 p.; also includes graphics Includes bibliographical references (p. 469-475). Available online via OhioLINK's ETD Center

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Vibrational spectra techniques such as IR, Raman and SFG all carry molecular orientation information. Extracting the orientation information from the vibrational spectra often involves creating model spectra with known orientation details to match the experimental spectra. The running time for the exhaustive approach is O(n!). With the help of linear programming, the running time is pseudo O(n). The linear programming approach is with out a doubt far more superior than exhaustive approach in terms of running time. We verify the accuracy of the answer of the linear programming approach by creating mock experimental data with known molecular orientation distribution information of alanine, isoleucine, methionine, lysine, valine and threonine. Linear programming returns the correct orientation distribution information when the mock experimental spectrum consisted of different amino acids. As soon as the mock experimental spectrum consisted of same amino acids, different conformer with different orientation distribution, linear programming fails to give the correct answer albeit the species population is roughly correct. / Graduate

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Vibrational and thermal behavior of several important systems were studied. The first study was a measurement of the infrared vibrational spectra of glucose and two important glucose dimers (cellobiose and maltose) as a function of temperature. The purpose of his study was to measure shifts in vibrational band positions to gain insight into carbohydrate reactivity. The second study was on hydrothermally treated coffee waste biomass. Here, collaborators at University of Campinas (UNICAMP, Brazil) treated coffee waste biomass in a flow-through subcritical water hydrolysis reactor. The purpose of the M.S. study on coffee waste was to understand the chemical changes that occurred to the residual solids during hydrolysis treatment. Vibrational spectroscopy and thermal analysis techniques were used. The third and final study was to understand the chemical composition of the solid product resulting from co-solvent enhanced lignin fractionation (CELF) of several biomass feeds. Collaborators at University of California Riverside (UCR) recently developed the CELF process. The purpose of the M.S. study on the CELF solid product was to understand its composition to help guide the CELF reactor design and determine applications for the CELF solids. Taken together, the 3 studies are integrated into a cohesive whole that demonstrates the use of spectroscopic and thermal techniques for characterizing biomass and understanding its composition at the molecular level.

A polymer is rarely used as a pure material and the baseline physical, chemical and rheological properties such as molecular weight, strength, stiffness and viscosity are often modified by the addition of fillers or by blending with another polymer. However, as many polymers are immiscible, compatibilisation and graft processing polymer blends are very important techniques to increase miscibility of the blends as well as to improve chemical, physical and mechanical properties. Reactive extrusion, or melt-state processing, is one of the most appropriate techniques for improving polymer properties. Compatibilisation and graft polymer processing are often carried out under reactive extrusion conditions. This technique is an efficient approach because it is easy, inexpensive and has a short processing time. Although reactive extrusion has numerous advantages one of the limitations is degradation of the polymer under the high temperatures and mechanical stresses encountered. In the polymer industry, because of increasing customer demand for improved product quality, optimising the polymerisation process by decreasing product costs and controlling the reaction during polymerisation has become more important. It can be said that any method used for monitoring the polymerisation process has to be fast, accurate and reliable. Both in-line and on-line methods may be involved in in-process monitoring. The primary information from in-process monitoring is used for identifying and understanding molecular structure and changes, optimising and improving process modelling and understanding whether the process is under control. This also involves considering whether the products have the required properties. This thesis describes research in a number of aspects of melt processing of polymers, including examination of extruded products, an in situ spectroscopic study of the reaction of MAH and PP, a study of the melt processing of TPU, and a study of the use of nitroxide radicals as probes for degradation reactions. As mentioned previously, a suitable method for improving polymer properties is polymer blending. Starch is a hydrophilic biodegradable polymer which may be blended with other polymers to produce biodegradable products. In spite of its benefits, it is immiscible with most synthetic polymers, such as polyesters. The main technique for improving the miscibility of starch with the other polymer is a grafting reaction. The reactive extrusion technique was applied to the production of starch and polyester blends, the product of which was a biodegradable aliphatic polyester. In this process dicumyl peroxide (DCP) and maleic anhydride (MAH) were used as an initiator and cross-linker, respectively. Extruded samples were investigated by infrared microscopic mapping using the attenuated total reflectance (ATR) technique. Measurement of various band parameters from the spectra allowed IR maps to be constructed with semi-quantitative information about the distribution of blend components. IR maps were generated by measuring the band area ratio of O-H and C=O stretching bands which are related to starch and polyester, respectively. This was the first time this method has been used for understanding the homogeneity of a polymer blend system. This method successfully indicated that the polyester/starch blend was not a homogenised blend. It was concluded that to improve the homogeneity the reaction conditions should be modified. Another important compatibilisation reaction is the reaction between a polyolefin and MAH. This was investigated by combining a near infrared (NIR) spectrometer with a small laboratory scale extruder, a Haake Minilab. The NIR spectra were collected in situ during melt processing by the use of a fibre optic cable. In addition to this the viscosity of the polymer melt was measured continuously during processing through two pressure transducers within the Minilab extruder. The vinyl C-H stretch overtone of the MAH was clearly seen in the NIR spectra near 6100 cm-1 and diminished over time as the MAH reacted with PP. The spectra obtained were analysed by two techniques: principal component analysis (PCA); and peak area ratios. The peak area ratios were calculated using the =C-H first overtone of MAH with respect to the band observed between 6600 and 7400 cm-1. This band corresponds to a combination band of CH2 and CH3 in PP and was unchanged during the reaction. These data facilitated interpretation of the reaction kinetics and experiments at different temperatures allowed determination of the activation energy of the reaction. These results have thrown new light on the PP-MAH reaction mechanism. It was also shown that although the presence of DCP causes production of a high concentration of macro-radicals it does not have any effect on the rate and kinetics of the reaction. As mentioned previously, one of the limitations of reactive extrusion is degradation of the polymer under high temperatures and shear rates. Hindered amine stabilisers (HAS) are often used as inhibitors to control the thermal-oxidative degradation of polymers. They are used in various polymeric materials but were primarily developed for polyolefins, particularly PP. The stabilisation mechanism of HAS involves interaction firstly with the alkyl peroxyl radicals produced during oxidative degradation so that the hindered amine converts to the corresponding nitroxide. The nitroxide is then able to capture a carbon-centred radical and so retard the subsequent degradation chain reaction. 1,1,3,3- tetramethyldibenzo[e,g]isoindoline-2-yloxyl (TMDBIO) was used as a probe for investigation of PP during reactive extrusion conditions. The TMDBIO is a profluorescent compound that has been used previously to identify polymer degradation. In the radical form, there is no fluorescence since the unpaired spin on the nitroxide quenches the fluorescence of the phenanthrene moiety. When the radical is removed (by radical trapping or reduction) fluorescence is observed. As a result, the location and intensity of fluorescence can be used as a probe for identification of degradation and to determine the concentration of carbon-centred radicals produced during thermal or mechanical degradation such as occurs during reaction processing. This novel method shows that, the degradation of PP started at the early stage of processing. Also this method can be used as a useful technique to modify the processing conditions to decrease degradation of the polymer during processing. The second system investigated using in situ monitoring via the NIR fibre optic was the melt processing of a TPU nano-composite. This was the first time that the in situ monitoring of TPU nano-composite had been examined. In this investigation the effect of temperature during processing on the TPU molecular structure and rheological behaviour was again investigated. In addition, dispersion of clay nano-particles through the TPU matrix and rheological changes due to this was investigated. This investigation was successful in that it was found that several factors affected the viscosity of the nano-composite. However, to fully understand the degradation mechanism and viscosity changes further studies must be performed.

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The matching of colours on dyed fabric is an important task in the textile industry. The current method is based on the matching the visible reflectance spectrum to standard spectral libraries. In this study, the amount of dye on various wool and wool-blend fabric was measured using vibrational-spectroscopic techniques. FT-IR PAS and FT-Raman spectroscopy was used to analyse the following set of samples: woollen fabrics (supplied by CSIRO- Geelong, Australia), dyed with Lanasol dyes (Red 6G, Blue 3G and Yellow 4G) and wool/polyester fabrics (supplied by Ceiba-Geigy, Switzerland), dyed with Forosyn dyes (grey, yellow, green, brown, orange, red). A minimum of six spectra was recorded for each sample. The spectra recorded were consistent with those reported previously. FT-IR PA spectral data were block normalised with Y-mean centring and examined using Principle Component Analysis (PCA) and Partial Least Squares (PLS). Although PCA separates the woollen fabrics dyed with a combination of two colours, it does not do equally well for samples dyed with three colours. The dyed wool/ polyester blend samples appeared in a totally random fashion on the PCA plot. The PLS analysis of PA spectra of various ratios of dyes on woollen fabrics as well as wool/polyester blend was found to be a viable procedure and should be investigated further, perhaps with a broader set of data. FT-Raman spectra were examined using PCA and PLS. The best pre treatment for FT-Raman spectral data was found to be normalising followed by Y-mean centring. The PCA plots demonstrate that woollen samples are separated according to the dye ratios and that the presence or absence of some of the peaks is influenced by individual dyes. For example, the presence of the peak at 1430cm 1 is inversely related to the presence of blue dye on the fabric. The PLS resulted in SEE and SEP values of around 1 and 2 respectively indicating that the prediction of the dye ratios have not been very successful and suggesting that there was some problem with the measured values of the calibration set. PCA plots of wool/polyester fabrics dyed with a single colour indicate that PC1 separates the samples according to how close the shades are together, while PC2 and PC3 separate samples according to their individual colours. PC4, although explaining only a small percentage of variance, suggests that the samples are not homogeneously dyed. PCA plots of the samples dyed with various combinations of the three main dyes display each cluster of samples in their right position on the colour card. Calculated SEE and SEP values (Yellow: ~0.30, ~0.55, Brown: ~0.30, ~0.79, Red: 0.16, 0.49 and Grey: ~0.2, ~0.40, respectively) indicate that FT-Raman spectroscopy and chemometrics may offer promising methods for measuring the ratio of various dyes on wool/polyester fabrics. FT-Raman spectroscopy and chemometrics were also used to investigate the change in the ratio of dyes on UV-treated dyed woollen samples. Samples were weathered for 7 and 21 days, using accelerated weathering instrument. The substrate subtracted spectral data were normalised to 100% substrate of the first derivative (9 points and 7 degrees) followed by double centring of the matrix in the spectral region of 1500-500cm-1. PCA effectively separated non-irradiated from the irradiated sample but did not separate the irradiated samples further according to the number of days of irradiation. The pre-treatment used for PLS was first derivative of substrate subtracted spectral data normalised to 100% substrate, and then Y-mean centred. PLS failed to predict the ratio of the irradiated dyes very well. This may be because degradation products are not modelled by PLS or because the total amount of dye has reduced without changing the dye ratios.

The electronic and vibrational spectra of Ni+(H2O) were measured using photofragment spectroscopy. In the electronic spectrum, photodissociation is observed at photon energies above 16875 cm-1. The only fragment observed is Ni+. The electronic spectrum consists of well-resolved peaks spaced by ~340 cm-1, due to a vibrational progression in the excited electronic state. These peaks have complex sub-structure, consisting of a triplet, spaced by ~30 cm-1. The sub-structure is due to rotational structure in a perpendicular transition of a prolate top molecule. In addition to this major progression, there is a series of less intense, single peaks spaced by ~340 cm-1. These may be due to a vibrational progression in a second electronic state, this time due to a parallel transition. The O-H stretching vibrations of Ni+(H2O) were measured using vibrationally mediated photodissociation (VMP) in a depletion experiment, only monitoring transitions from K’’=1. This revealed a O-H symmetric stretch at 3629 cm-1 and antisymmetric O-H stretch at 3692 cm-1. Several electronic structure calculations complement the experiments using the BHandHLYP hybrid density functional and the 6-311++G(3dp, f) basis set. At this level of theory, Ni+(H2O) is predicted to have C2v symmetry and 2A1 ground state. The Ni-O bond length is 1.95, the O-H bond lengths are .955 and the H-O-H angle is 108.2˚ The molecule is a near-prolate top, with rotational constants A=13.98 cm-1, B=0.297 cm-1 and C=0.296 cm-1 . Analysis of the electronic and vibrational spectra reveals that binding to Ni+ removes electron density from the oxygen lone pairs, increasing the H-O-H bond angle from its value in bare H2O. The electronic and vibrational spectra corresponds to 4s ¬3d transistion in Ni+. As a result of electronic excitation, the Ni-O bond stretches by .20 Å, and the H-O-H bond angle is reduced.