Finishing chemicals infrared spectroscopy

The application of chemometrics in near-infrared spectroscopy is finding widespread use in many different industries for monitoring the identity and quality of raw materials and finished products in the food and agricultural industry [46], polymer, pharmaceutical, and organic chemical manufacturing industries [18, 47],... 

Determination of finish add-ons or blend ratios for textiles containing cotton are of prime Interest in textile finishing laboratories. Many approaches have been taken to acquire this information including Kjeldahl nitrogen analysis, other wet chemical determinations, x-ray fluorescence or diffraction (O, and Infrared spectroscopy (2-6). 

The development of repellent finishing is benefiting from recent progress in surface analyses by electron spectroscopy for chemical analyses, scanning electron microscopy, and the attenuated total reflection technique of infrared spectroscopy. 

Molecular spectroscopic techniques have been widely used in pharmaceutical analysis for both qualitative (identification of chemical species) and quantitative purposes (determination of concentration of species in pharmaceutical preparations). In many cases, they constitute effective alternatives to chromatographic techniques as they provide results of comparable quality in a more simple and expeditious manner. The differential sensitivity and selectivity of spectroscopic techniques have so far dictated their specihc uses. While UV-vis spectroscopy has typically been used for quantitative analysis by virtue of its high sensitivity, infrared (IR) spectrometry has been employed mainly for the identihcation of chemical compounds on account of its high selectivity. The development and consolidation of spectroscopic techniques have been strongly influenced by additional factors such as the ease of sample preparation and the reproducibility of measurements, which have often dictated their use in quality control analyses of both raw materials and finished products. 

Dias et al., used, what they called, a hyphenated rapid real-time dynamic mechanical analysis (RT DMA) and time resolved near-infi ared spectroscopy to simultaneously monitor photopolymerization of acrylate coating compositions. This allowed them to determine the rate of conversion and the mechanical properties of the finished films. It is claimed that up to 374 near infrared spectra and to 50 dynamic analysis points can be accumulated within a second. They observed that modulus buildup does not linearly follow chemical conversion of acrylate bonds. The gel point is detected after passing a certain critical acrylate conversion. Their experimental data revealed a critical dependence of the mechanical property development during the later stage of acrylate conversion. 

Near-infrared (NIR) spectroscopy has been found to be a useful technique to characterize raw materials and finished textile products, and NIR methods and techniques continue to find increasingly diverse and wide-ranging quantitative and qualitative applications in the textile industry. Quantitative analyses determine the amount (or quantity) of the property/species of interest in a substance or material. Qualitative analyses can be used to either identify a specific species or subsfance present in a material (i.e., coating on a fiber), the type of material itself (i.e., cotton, nylon, or polyester), or the quality of the material. NIR quantitative and qualitative methods allow the user to rapidly, accurately, and precisely monitor key chemical, physical, and morphological properties of textile fibers, yarns, fabrics, and chemical textile auxiliaries. Chemical properties are specific chemical species or groups present in the material (i.e., CH, OH, NH) that result in NIR spectral absorbencies at distinctive... 

Infrared (IR) spectroscopy is a reliable, fast, and cost-effective analytic technique. It is one of the classic methods to determine the structure of small molecules or fimctional groups. IR is ideally suited for quahtative analysis of polymers and finished products as well as for quantification of components in polymer mixtures. Thermal analysis techniques include physical-chemical methods to study materials and processes under conditions of programmed changes in the surrounding temperature. Thermal volatihzation analysis (TVA) is a technique that analyzes the products formed when, for example, a polymer is heated. It analyzes the polymer itself as well as the volatile compounds released during this heating. In this chapter, we present the application of TVA to biodegradable polymers, especially polylactic acid (PLA), starch, and their mixtures. 

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