Performances of Chitosan Grafted onto Surface of Polyacrylonitrile Functionalized through Amination Reactions

Abstract

Generally, the acrylic fibers have a low chemical reactivity. Two types of treatments were used in order to increase the chemical reactivity: a pretreatment for functionalization and a treatment for polymer grafting. Each stage permitted the generation of new functional groups whose reactivity was much higher than that of the groups existing in the untreated PAN. The pretreatments were carried out with dihydroxyethyl amine (DHEA) and hydroxylamine (HA) in the presence or absence of NaOH. The functionalized samples were treated with chitosan (CS) in order to produce the grafting. The modifications resulting from the treatments were highlighted by Fourier transform infrared (FTIR) and scanning electron microscopy (SEM) analyses, the density of the new functional groups, grafting degree, energy dispersive X-ray (EDAX), yellowness index, color measurements/CIE LAB graphs. The performances referred to hygroscopicity, possibility of dyeing with acid dyestuffs (nonspecific to acrylic fibers), and excellent color fastness properties. A comparative study was performed between the results obtained through functionalization and grafting.

Highlighting a Cotton Grafting Process Using the Spectral Subtraction Method and Statistical Analysis

“…Spectral subtraction method notifies any change between two (or more) FT-IR spectra. This method is very useful when the analyzed spectra are very similar and the classic FT-IR analysis fails to clearly highlight the difference between those 2 spectra, because the overlays are illegible [12,13]. Spectral subtraction method was used only after all spectra were prepared in a certain way, respecting the following steps: atmosphere correction (CO 2 , water), smoothing (with Savitzky-Golay algorithm to attenuate the background noise; the order of the polynomial fit function applied for smoothing was chosen according to the size of noises, namely 9 or higher), baseline correction (concave Rubberband algorithm), normalization, final smoothing and saving in % transmittance of each spectrum.…”

“…Spectral subtraction method was used only after all spectra were prepared in a certain way, respecting the following steps: atmosphere correction (CO 2 , water), smoothing (with Savitzky-Golay algorithm to attenuate the background noise; the order of the polynomial fit function applied for smoothing was chosen according to the size of noises, namely 9 or higher), baseline correction (concave Rubberband algorithm), normalization, final smoothing and saving in % transmittance of each spectrum. In addition to baseline correction and standard normal variate correction, was used the detrending algorithm, which permitted to correct the drifted baseline and to remove the offset and the tilting from spectra [12]. For an easy understanding of spectral subtraction method, all spectra have absorbance on Y axis.…”

“…For an easy understanding of spectral subtraction method, all spectra have absorbance on Y axis. The spectral subtraction method uses the mathematical equation 1 [12,13]: (5) where:…”

“…To perform the subtraction operation, the entire spectrum (within the range 4000-600 cm -1 wavenumbers, with a number of points equal to 1764, XTYPE =1, YTYPE=128 and data spacing of 1.92881) was taken into account [12].The result of the spectral subtraction method is a new spectrum (the difference spectrum) with bands above and below the zero line (i.e. positive and negative values).…”

“…Negative values (i.e. bands located below the zero line) on the difference spectrum indicates that the reference sample had higher values of the absorbance intensity than the analyzed sample [12,13].…”