Investigation of optical and thermally stimulated properties of SiO2 nanoparticles-filled polycarbonate (original) (raw)
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Journal of Thermal Analysis and Calorimetry, 2012
The thermally stimulated charge relaxation properties of polycarbonate (PC) filled with SiO 2 nanofiller were studied by means of thermally stimulated discharge current (TSDC). The nanocomposite samples were further characterized by UV-vis spectroscopy, scanning electron microscopy, energy dispersive X-ray spectra, and differential scanning calorimetry (DSC) techniques to investigate the dispersion of nanofillers in polymer matrix and glass transition temperature. All pristine and nanocomposites samples of thickness about 25 lm were prepared using solution mixing method. The suitable weight percentage of SiO 2 nanofillers has been chosen to prevent the nonuniform dispersion. TSDC measurement of PC (Pristine) and PC? (7% SiO 2) shows the single peak, while TSDC characteristic of other nanocomposites are showing two peaks. The higher temperature TSDC peak of pristine and nanocomposites samples is originated due to the charge relaxation from shallower and deeper trapping sites, however, low temperature peak is caused by dipolar relaxation of charge carriers. Since the position of higher temperature TSDC peak is generally an analysis of glass transition temperature of polymer/polymer nanocomposites. The authors have observed that the temperature of this peak is almost same as the T g measured by DSC with 0 to ±5% variation. This article presents the deeper understanding of charge relaxation mechanism caused by SiO 2 nanofillers in polycarbonate.
2011 14th International Symposium on Electrets, 2011
Polycarbonate nanocomposite containing silicon oxide nanoparticles average size of 5 nm at different weight ratio has been prepared by solution mixing method. The dispersion of nanoparticles in polymer matrix was studied by transmission electron microscopy (TEM). The optical and thermally stimulated behavior of nanocomposites were analyzed by energy dispersive X-ray spectra (EDX), X-ray diffraction pattern (XRD), UV-vis spectroscopy, differential scanning calorimetry (DSC), and thermally stimulated discharge current (TSDC). TEM images show the dispersion and size of the nanoparticles, however, EDX indicate the presence of SiO 2 on the surface of the nanocomposite film. An XRD result reveals that the crystallinity increases with increase in concentration of SiO 2 nanoparticles in polymer matrix. The direct and indirect optical energy band gaps decreased and number of carbon atom increased with concentration of SiO 2 nanoparticles. We have observed that the increase of SiO 2 nanoparticles in PC significantly reduces the refractive index. DSC and TSDC show that glass transition temperature increases according to SiO 2 weight ratio. The TSDC of nanocomposites samples could be understand in terms of non-Debye theory of charge relaxation and co-tunneling mechanism of charge transport. V
Journal of Materials Science: Materials in Electronics, 2020
In this work, a detailed insight to the microstructure, morphology, surface topography, electrical and optical properties in visible and terahertz range was presented for polyethylene oxide (PEO)/silicon dioxide SiO 2 nanocomposites. PEO-filled with various contents of SiO 2 nanoparticles were synthesized via the solution cast technique. The polycrystalline nature of PEO/SiO 2 films was affirmed by the selected area electron diffraction pattern (SAED) recorded by HRTEM measurement and it was found to nearly conformable with X-ray diffraction data. The energy-dispersive X-ray analysis (EDAX) proved the existence of SiO 2 with wt% ranged from 0 to 5% as starting fillers. The high-resolution scanning electron microscope planar images indicated uniform distribution of SiO 2 nanoparticles within the PEO films. The atomic force microscope 3D images depicted the surface changed from rough to smooth upon the filling with SiO 2. The composite samples exhibit absorption spectra that extended from UV-Vis to near infrared regions. Based on Tauc's formula, it was found that the absorption edge shifted from 4.90 to 3.20 eV as the filler fraction increased from 0 to 5 wt%. The analysis of reflective index in the UV-Vis-NIR regions displayed decrement with increasing filler content. Moreover, the refractive index in Vis-NIR regions is good extension to that in THz region expressing the optical quality of studied films. The optical dispersion parameters were analyzed in the view of Wemple-Didomenico single oscillator and Sellmeier model. The values of nonlinear optical parameters (nonlinear susceptibility χ (3) and nonlinear refractive index (n 2) were influenced by the filler fractions. Upon the rise of filler content, the conductivity values show slightly decrement.
Polymer Composites, 2020
In the present work, polyvinyl alcohol (PVA) films were prepared for polymer optoelectronic applications, in which the SiO 2 nanoparticles were incorporated through a sonication technique followed by a solution casting method. The structure of PVA/SiO 2 films was evaluated using the experimental results attained by X-ray diffraction (XRD), Fourier transform infrared (FTIR), and scanning electron microscope (SEM) examinations. A thermal stability study of the nanocomposite films was performed. UV-vis spectra were used to investigate the optical properties of PVA/SiO 2 nanocomposite films. The XRD results confirmed the semicrystalline nature of the PVA. The SEM results ascertained the homogeneity of the SiO 2 nanoparticles in the polymer matrix. From the study, a simultaneous increase of SiO 2 nanoparticle content decreased the direct optical band gap and Urbach energy; however, the refractive index and extinction coefficient were increased. The acquired nanocomposite films could be utilized in polymer optoelectronic applications.
Composites Science and Technology, 2012
Polycarbonate/silica nanocomposites with different silica quantities were prepared by a melt compounding method. The effect of silica amount, in the range 1-5 wt.%, on the morphology, mechanical properties and thermal degradation kinetics of polycarbonate (PC) was investigated. Clusters of silica nanoparticles were well dispersed in the polycarbonate whose structure remained amorphous. NMR results showed intermolecular interactions involving the carbonyl groups of different polymeric chains which did not affect the intramolecular rotational motions. The presence of the lowest silica content showed a decrease in the storage and loss moduli below the glass transition temperature, probably due to a plasticization effect. However, an increase in the amount of silica increased the moduli. The presence of silica in PC slightly increased the thermal stability, except for the highest silica content which showed a decrease. The activation energies of thermal degradation for the nanocomposites depended on the amount of silica and on the degree of conversion.
Thin Solid Films, 2005
Composites made by incorporation of silicon oxide (SiO 2) or titanium (TiO 2) nanoparticles into poly(p-phenylene vinylene) (PPV) have been fabricated and their electrical and optical properties have been investigated. The UV-vis absorption and Raman spectra showed that SiO 2 nanoparticles reduced the conjugation lengths of PPV chains, while TiO 2 nanoparticles did not. In the case of SiO 2 nanoparticles, the reduction of conjugation length was more noticeable on increasing the oxide concentration or on decreasing the particle size. Fourier transform infrared (FT-IR) spectra showed that both types of nanoparticles also reduced the formation of carbonyl groups in PPV main chains. Current-voltage characteristics measured in the indium tin oxide (ITO)-composite-MgAg diodes exhibit different electrical behavior to the composites depending on the particle size and the nature of the used oxide. The composite-electrode contact morphology, the polymer-dielectric particle contact, and the change in the polymer chain length are the possible explanations for these changes in behavior of the diodes.
Journal of Applied Polymer Science, 2012
Effects of silica and silica/titania nanoparticles on glass transition and segmental dynamics of poly(dimethylsiloxane) (PDMS) were studied for composites of a core-shell type using differential scanning calorimetry, thermally stimulated depolarization current, and dielectric relaxation spectroscopy techniques. Strong interactions between the filler and the polymer suppress crystallinity (T c , X c) and affect significantly the evolution of the glass transition in the nanocomposites. The segmental relaxation associated with the glass transition consists of three contributions, arising, in the order of decreasing mobility, from the bulk (unaffected) amorphous polymer fraction (a relaxation), from polymer chains restricted between condensed crystal regions (a c relaxation), and from the semibound polymers in an interfacial layer with strongly reduced mobility due to interactions with surface hydroxyls of silica and silica/ titania nanoparticles (a 0 relaxation). The evolution of surface affected CH 3 groups, as well as the degree of interaction of PDMS molecules with surface hydroxyl groups as a function of treatment temperature, was assessed by Fourier transform infrared spectroscopy, thermogravimetry and differential thermal analysis. The effectiveness of silica/PDMS and silica/titania/PDMS nanocomposites as hydrophobic coatings was investigated by static contact angle measurements. It was shown that the presence of titania nanoparticles and adsorbed PDMS promotes the hydrophobic properties of the PDMS coating after treatment in the 80-650 C range. V
International Journal of Engineering Sciences & Research Technology, 2014
In this article optical and physical property of the composition of polyurethane open cell (PUOC) with two different concentrations of SiO2 nanoparticles (1 and 2wt. %) will be reported. Tetra ortho silicate (TEOS) as an organic agent with different concentrations (0.05, 0.1, 0.15 and 0.2 Vol./Vol.) was added to polyurethane composition. Optical microscopy imaging, watering uptake, FTIR and Raman spectroscopy of the synthesized samples were measured. The cell size of samples by adding SiO2 NPs and TEOS was SiO2 was recognized as a best specimen for absorbing water. By focusing on the recorded Raman spectra, it is revealed that PUOC/1wt. % SiO2 and PUOC/200 phase separation, DPS, and the hydrogen bonding index, R, in samples were evaluated in terms of their FTIR spectroscopy data. Two samples, PUOC/1wt. % SiO2 and PUOC/800 among the synthesized samples. By adding SiO2 NPs and TEOS in increased. This is similar to the behavior of real density in SiO2 NPs into PUOC but by adding TEOS into PUOC, the real density of samples were decreased. The total porosity, open porosity and closed porosity of t samples were calculated. By adding SiO2 NPs and TEOS into PUOC, the open porosity of samples was increased.
Irradiation effects in poly(ethylene oxide)/silica nanocomposite films and gels
Polymer Engineering & Science, 2013
Poly(ethylene oxide)/silica (PEO/SiO 2 ) nanocomposite films were modified, and nanocomposite gels were prepared by c-irradiation up to 100 kGy. Thermal analysis, optical microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy revealed that the outcome mostly depended on the state of the PEO matrix on irradiation and that the state of the sample had a bearing on the effect of nanosilica addition. In unirradiated films, nanosilica induced heterogenous nucleation and increased crystallization temperatures proportional to its content. On irradiation of nanocomposite films, degradation prevailed, resulting in an increased crystallinity of samples irradiated to 50 kGy and a significant deterioration of mechanical properties at higher doses. In films irradiated in air, nanosilica did not provide radiation resistance. It enhanced oxidative degradation by increasing the content of a more radiation sensitive amorphous phase and probably facilitated the crystallization of broken chains resulting in an additional crystallinity increase. In the same dose range, the irradiation of PEO/nano-SiO 2 aqueous solutions produced cross-linked nanocomposite gels of much lower crystallinity and phase transformation temperatures and better mechanical properties. Interactions and radiation-induced effects in nanosilica likely contributed to a further crystallinity reduction in nanocomposite gels. Pronounced changes on the addition of 20 wt% of nano-SiO 2 to both nanocomposite films and gels indicate a possible synergism of girradiation and nanoparticle addition.
Physical Properties of Polyacrylamide/Polyvinylalcohol Silica Nanocomposites
Journal of Research Updates in Polymer Science, 2016
In this paper, samples of Polyacrylamide (PAAm) nanosilica nanocomposites were prepared having different concentration of nanosilica (0.125, 0.25, and 0.5). Polyacrylamide (PAAm) and poly (vinyl alcohol) (PVA) were blended with different ratio (3/1, 1/1, 1/3) using solution-cast technique. The prepared films were characterized by Fourier transform infrared (FTIR), X-ray diffractions (XRD) and scanning electron microscopy (SEM). FTIR spectra showed the presence of hydrogen bonding between-CONH2 groups in PAAm and-OH group in PVA and confirm the hydrophilic nature of the blends. X-ray diffractions shows the presence of a strong broad peak centered at 22º (2) confirms the amorphous nature of silica which is supposed to be the characteristic of SiO2. The results obtained from different experimental techniques were supported by SEM image analysis. The thermal stability of the nanocomposites enhanced by increasing the silica content in the blend. The DC electrical conductivity was studied for all prepared samples. It was found that the conductivity increase by increasing silica content as well as, increased by increasing the wt% of PVA.