Influence of glycerol content on the electrical properties of potato starch films

Abstract

Effects of glycerol (G) and temperature (T) on the electrical properties of potato starch (PS) films were investigated by impedance spectroscopy measurements in the radio frequency range (20 Hz–3 MHz). The membranes were prepared by a solution casting method with weight fraction glycerol/potato starch (G/PS) = 0.1, 0.3, and 0.5 and characterized by DSC, FTIR, and moisture content measurements. The dc‐conductivity (σ0) of all compositions increases with the glycerol concentration and temperature, reaching the value of 5.2 × 10−5/Scm at 423 K, for G/PS = 0.5. The real part of the conductivity shows power–law frequency dependence (fn, n ≈ 0.98) at frequencies higher than a crossover frequency (fp). The imaginary part of the electric modulus plots shows non‐Debye asymmetrical peaks at about the frequency fp and it is characterized by a “stretched” exponential parameter β ≈ 0.8. The temperature dependence of σ0, fp (both showing an Arrhenius‐type behavior) and DSC data shows a phase boundary at about 353 K for all compositions. Results are discussed in terms of correlation effects in ion motion that takes place in a separate second phase in the G/PS films with composition G/H2O.

Effect of apricot kernel seed extract on biophysical properties of chitosan film for packaging applications

“…The dielectric characteristics of a material can offer useful information regarding the mobility of polymers' chemical chains that contain dipolar regions or dipolar side groups 27 . The movement of ions in a separate second phase, which is primarily made up of water and glycerol, is what primarily causes the conductivity to increase as the glycerol content is increased in potato starch films 28 . The domains of bound and free water in the film were attributed, respectively, to a constant value and a linear region in the dielectric permittivity of CS films, which showed a considerable dependence on the moisture content 29 .…”

Mathematical Models for Prediction of Water Evaporation and Thermal Degradation Kinetics of Potato Starch Nanoparticles Obtained by Nanoprecipitation

“…Fourier Transform Infrared (FTIR) spectra of PS and SNPs were obtained using a FTIR spectrometer (Shimadzu Prestige 21, Japan). Samples were prepared as previously reported by Valencia et al The analyses were recorded in transmission mode from 4000 to 500 cm −1 , with a spectral resolution of 4 cm −1 at room temperature. Spectra were averaged over 60 scans.…”

“…First, PS granules were dispersed in a solution previously prepared of sodium hydroxide (1.5% w/w) in deionized water. Then, PS dispersions were heated at 363 ± 1 K for 30 min under constant agitation (1050 rpm), to promote starch gelatinization . In sequence, three drops of absolute ethanol were added to the gelatinized PS solution to a proportion 1:1 (% v/v).…”

Studying physical state of films based on casava starch and/or chitosan by dielectric and thermal properties and effects of pitanga leaf hydroethanolic extract

“…3B. It can be observed that CS spectrum exhibited a diffraction pattern of A-type crystalline, typical of starch originated from plant roots (Valencia et al, 2014(Valencia et al, , 2016, with a crystallinity of 17%. CS presented crystalline peaks at 2θ = 15°and 23°, and an unresolved doublet at 2θ = 17°and 18°, over a big and broad peak corresponding to the amorphous portion of this material.…”

“…The dielectric properties (e.g., ε′ and ε'') were especially sensitive to moisture in gelatin films (Bergo et al, 2013) and CS films (Bergo et al, 2012), a phenomenon that can be explained based on the way water penetrates the film matrix (Bergo et al, 2012). Valencia et al (2014) observed that the conductivity, another dielectric property, increased with the concentration of glycerol in potato starch films, mainly due to the movement of ions that occurs in a separate second phase composed mainly of water and glycerol. Bergo et al (2012) observed that ε' of CS films was strongly dependent on the moisture content, showing a constant value and a linear region, which were attributed to the domain of bound and free water in the film, respectively.…”