Polymers are macromolecules formed by repetitive units called monomers which are covalently bonded. The fingerprint region is very important to characterize structures such as polymers. It should be noted that the fingerprint region falls within the mid-infrared, which is also called fundamental infrared because organic molecules and most inorganic substances absorb IR in this region. In this region, the molecular vibrations are unique for each compound, therefore, this area is very important accurately to characterize chemical compounds. Within these two categories, vibration signals can appear in the range of 1200 cm -1 to 600 cm -1, which is called the “fingerprint region” of the chemical bond studied or a sample. When these conditions are fulfilled, the molecular bond can experience different types of vibrations, which are grouped into two categories, stretching vibrations (changes in bond length) and bending (changes in the bond angle). The second term is based on the frequency of the IR radiation (emitted by the IR spectrometer lamp), which must correspond to the molecular vibrational frequency of the chemical bond for which its vibration is possible. The first term is based on the polarity of a chemical bond (+δ - δ-) within a covalently linked molecule (e.g., +δH-Cl δ-), if the value of μ is different from zero it is possible to absorb IR radiation. This instrumental technique is based on the dipole moment (μ) and the molecular vibrational frequency. This spectral zone is divided into three regions: near-infrared (12500 cm -1 - 4000 cm -1), mid-infrared (4000 cm -1 - 200 cm -1) and far-infrared (200 cm -1 - 10 cm -1). Palabras clave: vibración, intensidad, sobrelapadas, cristalinidad, cadenas lineales.įourier transform infrared (FTIR) spectroscopy is a nondestructive chemical characterization technique that encompasses the wave number range of 12500 cm -1 to 10 cm -1 of the electromagnetic spectrum ( Fig. En cuanto al ordenamiento estructural, la cantidad de cadenas lineales del copolímero EVA disminuye conforme aumenta la concentración de vinil acetato (VA), lo cual favorece la disminución de los grados de libertad y la formación de puentes de hidrógeno. La cristalinidad para el EVA18, EVA28 y EVA40 fueron 24.39%, 6.95% y 1.03%, respectivamente. En comparación con otras técnicas instrumentales, la cristalinidad y el ordenamiento estructural de los copolímeros de EVA fueron determinados de forma sencilla y económica. En este trabajo se realizó el análisis de la huella dactilar del copolímero etileno-acetato de vinilo (EVA) con diferentes porcentajes de acetato de vinilo (VA) (18%, 28%, 40%). Keywords: vibration, intensity, overlapping, crystallinity, linear chains.Įl análisis de los materiales por espectrometría infrarroja con transformada de Fourier (FTIR) poseen una zona llamada huella dactilar única para cada compuesto, sin embargo, esta zona casi nunca se discute por su complejidad debida al gran número de señales que en ella aparecen. In terms of structural ordering, the number of linear chains of EVA copolymer decreases as the concentration of VA increases, which favors the reduction of degrees of freedom and the formation of hydrogen bonds. The crystallinities for EVA18, EVA28 and EVA40 were 24.39%, 6.95% and 1.03%, respectively. In comparison with other instrumental techniques, the crystallinity and structural arrangement of the EVA copolymers were determined simply and economically. In this work, the fingerprint region analysis of the ethylene-vinyl acetate copolymer (EVA) with different percentages of vinyl acetate (VA) (18%, 28%, 40%) was performed. However, this area is almost never discussed because of its complexity due to the large number of signals that appear in it. The analysis of materials using Fourier transform infrared (FTIR) spectroscopy has a unique area called the fingerprint region for each compound.
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