Properties Of Polyvinyl Alcohol Films Research Articles

Influence of Polyol Plasticizers on the Properties of Polyvinyl Alcohol Films Fabricated by Melt Processing

In this work, high-alcoholysis polyvinyl alcohol (PVA) films were fabricated by melt processing and the plasticizing effect of compound polyol plasticizers on PVA were investigated with X-ray diffraction (XRD), differential scanning calorimetry (DSC), rheological measurements, mechanical tests etc. Hydrogen bonding interactions occurred between PVA and plasticizer. With the increase of plasticizer, the flowability of PVA was improved and reached the maximum value at the plasticizer of 20%. Glass transition temperature (T g) and melting point (T m) decreased with the increase of plasticizer content. For the heterogeneous nucleation effect of plasticizer, new polymorph of PVA formed. The viscosity was sensitive to the shear rates. The incorporation of plasticizers into PVA resulted in the increase of elongation at break and impact strength, as well as the decrease of tensile strength.

Role of CoBr2 on the structural, optical and magnetic properties of polyvinyl alcohol films

AbstractPolyvinyl alcohol (PVA) films filled with different concentrations of CoBr2 were prepared using the casting method. These films were characterized by FTIR, UV–visible, XRD, and ESR techniques. FTIR spectra were used to clarify the structural variations due to the filling level from CoBr2. The observed bands at 3484, 1733, and 1640 cm−1 were assigned to OH, CO, and CC stretching vibrations, respectively. UV–visible spectra shows the absorption band at 280 nm which is assigned to π → π* transition. This indicates the presence of unsaturated bonds in tail to head of PVA. Optical energy gap decreased with increasing the concentration of CoBr2. X‐ray diffraction scans show some decrease in the degree of crystallinity in the filled films which reveals an increase in amorphous phase of PVA due to the interaction between Co+2 and polymeric matrix causing a molecular rearrangement within the amorphous phase of PVA. The observed complex ESR spectrum due to hyperfine interactions confirms the role of free radicals. Spectroscopic and magnetic properties of PVA/CoBr2 composite films were investigated and compared with those of PVA alone. The results show that the change of the structure due to the interaction of filler with the polymer. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Effect of molecular weight on dielectric properties of polyvinyl alcohol films

AbstractImpedance analysis is the best technique to reveal the microstructural details of the polymeric material. The dielectric polarization not only depends on physical and chemical properties, but also on the degree of polymerization (DP) of the polymeric material. In the present study, to understand the polarizing mechanism, two different molecular weights of polyvinyl alcohol (PVA) films were used for impedance analysis. Dielectric polarization of PVA film measured at normal temperature and pressure (NTP) condition by using LCR‐4282A Impedance analyzer, within the frequency range 20 Hz to 1 MHz. The importance of investigation is to know the simultaneous application of DC bias potential from 0 to 40 V with AC signal for measurement of over all electrical parameters. The result shows higher magnitude of dielectric constant for low‐molecular weight (LMW) of PVA film in comparison to higher molecular weight (HMW), which is based on Maxwell‐Wagner (M–W) theory. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1014–1016, 2006

Supermolecular Structure and Properties of Polyvinyl Alcohol Films Containing a Complex of Biologically Active Substances

The properties of polyvinyl alcohol films containing biologically active polymer additives and modifying reagents are a function of the supermolecular structure, determined by the composition of the spinning compositions. The variable character of the water vapor permeability of the films caused by the stresses that arise in the structure of the biologically active polyvinyl alcohol film in structural transitions that lead to variable water vapor permeability conditions, was established.

The Effect of Plasticizers on the Properties of Polyvinyl Alcohol Films

The effect of water-soluble plasticizers viz propylene glycol (PG), glycerol and polyethylene glycol 600 (PEG) on the morphology and water resistance of polyvinyl alcohol (PVA) films was investigated. Polyvinyl alcohol films were cast from aqueous solutions, and their morphology studied using differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). Water resistance was characterized by the extent of film dissolution and the water uptake capacity of remnant films after immersion of the films in distilled water for 3 days at 37° C. DSC thermograms showed that crystallite formation in the PVA films was affected to different extent by addition of the three plasticizers. The plasticizers not only reduced the degree of crystallinity in the films, but also lowered the crystalline melting temperatures probably by introducing defects into the crystal lattice. This factor, coupled with leaching of the water-soluble plasticizers from the films when immersed in distilled water, lowered the water resistance of the plasticized PVA films. The influence of plasticizers on the properties of PVA films was further related to the degree of compatibility between the plasticizers and PVA.

The effect of active dyes on the change in the mechanical properties of polyvinyl alcohol films induced by UV radiation

The effect of active dyes on the change in the mechanical properties of polyvinyl alcohol films induced by UV radiation