The use of near infrared (NIR) spectroscopy to study specific interactions in polymer blends

Abstract

The purpose of this brief communication is to demonstrate how near infrared (NIR) spectroscopy can be used to study specific interactions in miscible polymer blends. We will first demonstrate, using model systems and blends of polycaprolactone (PCL) and phenoxy [ poly (hydroxypropylether of bisphenol-A) 1, that information obtained from the OH stretch overtone absorption in the NIR is consistent with the information obtained from the OH stretch fundamental in the mid-IR region. We will then illustrate the advantages of NIR analysis of specific interaction with spectra obtained, over a range of temperatures, from thick ( 2 mm) films of blends of Nylon-6 and the zinc salt of sulfonated polystyrene ( ZnSPS) .

Near Infrared Spectroscopy

“…63 In a study of specific interactions in miscible blends, Ghebremeskel et al 14 show that information obtained from the OH stretch overtone absorption in the NIR is consistent with that obtained from the OH stretch fundamental in the mid-IR region. Their analysis of a model system: isopropanol in a mixed solvent (heptane : ethyl acetate) reveals NIR spectral shifts due to interaction between the hydroxyl of the isopropanol and the ester functionality of ethyl acetate.…”

“…Similarly, the NIR spectra of blends of polycaprolactone (PCL) and phenoxy [poly(hydroxypropylether of bisphenol-A] show that the peak maximum of the OH stretch overtone decreased in wavelength from 1431 to 1425 nm as the fraction of PCL increased. 14 In connection with OH absorptions, let us mention one of the major applications of NIR spectroscopy which is the determination of moisture in food analysis. 3,64,65 Water displays specific bands at 1940 nm (combination), and 1440 nm (first overtone of the OH stretch) which have been very useful in the study of the state of water in various samples.…”

“…NIR spectroscopy has proved to be a powerful tool for research in agriculture, food, pharmaceutical, chemical, polymer and petroleum industries. [2][3][4][5][6][7][8][9] NIR investigations include various applications ranging from the quality control of a pharmaceutical product, 10 the measurement of hemoglobin in unlysed blood, 11 the estimation of octane number in gasoline samples, 12 the characterisation of polymer properties such as configuration, conformation, crystallinity, orientation, miscibility 13,14 or the description of the kinetics and mechanisms of cure reaction in different epoxy-amine systems. [15][16][17][18][19][20][21][22][23][24] By its ability to analyse rapidly and non-destructively a wide range of chemical and physical properties of various samples, the NIR technique appears well suited for process control testing, particularly for on-line and at-line applications.…”

Near infrared studies of styrene-sodium methacrylate ionomers

“…Ionomer studies in the near infrared (NIR) [15][16][17][18] have not received as much attention as the midand far-infrared spectral regions. Extending from 1000 to 2500 nm, NIR is the domain of overtones and combinations involving high frequency fundamental transitions.…”

“…Examples of structure-property relationship studies are the work of C. E. Miller et al 23,24 for inter-and intramolecular interactions in PET, phase separation in poly(ether urethane urea) polymers, and microstructure of styrene butadiene copolymers and Zhu et al 25 for intrinsic viscosity correlations. Specific NIR studies of ionomers include the work of Ghebremeskel and coworkers, 15 which details blend interaction studies in Nylon-6/sulfonated polystyrene zinc ionomer, qualitatively examining band assignments for the specific interactions. Additionally Zen et al 16 studied Nafion in situ using NIR absorbing dyes to probe the sorption phenomena of water and alkali salt solutions.…”