Concentration In Polymer Matrix Research Articles

Investigation of ionic conductivity and relaxation in plasticized PMMA-LiClO4 solid polymer electrolytes

We have studied ion conduction and relaxation in plasticized PMMA-LiClO4 solid polymer electrolyte for different salt concentrations over a wide range of temperature. We have measured the complex conductivity spectra in a wide frequency range of 0.01 Hz–3 GHz and analyzed the experimental results using the random barrier model coupled with the contribution of electrode polarization in low frequency region. The temperature dependence of ionic conductivity and charge carrier relaxation time obtained from the analysis follows Vogel-Tammann-Fulcher behavior. The nearly constant loss response has been observed at low temperatures and/or at high frequency region. The temperature and frequency range of nearly constant loss response depends on the salt concentration in polymer matrix. The electric modulus spectra have been used to study charge carrier relaxation further. The stretched exponent, obtained from Kohlrausch-Williams-Watts (KWW) function, indicates highly non-exponential relaxation in the polymer electrolytes.

Study Of Thermal And Mechanical Properties Of Clay/Polymer Nanocomposite Synthesized Via Modified Solution Blending

ABSTRACTThe incorporation of layered nano-silicates in polymer matrix greatly enhances the properties of the polymer. At present, there are many applications of polymer nanocomposites including coatings and architectural, they are also parts of automotive and construction industry among others. The acrylics employed at the present study were based on butyl acrylate (BA), styrene (STY), and methacrylic acid (MAA), and the nano-clay was Na-montomorillonite (MMT). The MMT clay was added to the polymer, which is the mixing matrix in a physical state solution called blend. Furthermore, their mechanical, thermal and wettability of especially prepared acrylic montmorillonite (MMT) nanocomposites were performed. By increasing the MMT in the polymer matrix concentration the Young’s modulus tends to increase it by an order of magnitude. However, by Differential Scanning Calorimetry (DSC), the thermograms show an increase in the glass transition temperature of nanocomposites for all weight percentages of MMT. Also, the wetting angle was determined, in order to know how much water is retained on the surface of the nanocomposite; the results showed that by increasing the particle of nano clay in the polymer matrix will induce a hydrophobic property to the nanocomposite.

Qualitative and quantitative analysis of calcium-based microfillers using terahertz spectroscopy and imaging

In different industrial applications, several strictly defined parameters of calcium-based microfillers such as average particle size, particle size distribution, morphology, specific surface area, polymorphism and chemical purity, play a key role in the determination of its usefulness and effectiveness. Therefore, an analytical tool is required for rapid and non-destructive characterization of calcium-based microfillers during the synthesis process or before its use in a further manufacturing process. Since spectroscopic techniques are preferred over microscopy and thermogravimetry, particularly due to its non-destructive nature and short analysis time, we applied terahertz (THz) spectroscopy to analyse calcite microfillers concentration in polymer matrix, its granulation and chemical treatment. Based on the analysis of peak absorbance amplitude, peak frequency position, and the appearance of additional spectral features, quantitative and qualitative analysis was successfully achieved. In addition, THz imaging was also applied for both quantitative and qualitative analysis of calcium-based microfillers. By using spatial distribution map, the inhomogeneity in concentration of calcium carbonate in polymer matrix was characterized. Moreover, by THz spectroscopy and imaging different calcium compounds were detected in binary mixtures. Finally, we demonstrated that the applied spectroscopic technique offers valuable results and can be, in combination with other spectroscopic and microscopic techniques, converted to a powerful rapid analytical tool.

폴리(비닐 아세테이트)/디메틸설폭사이드 계에서 동적 광산란법에 의한 탐침입자의 배제층 연구

고분자와 용매의 굴절률이 서로 일치되어 자체 산란광의 세기가 극소화된 시스템인 폴리(비닐 아세테이트) (PVAc)/디메틸설폭사이드(DMSO) 계에 폴리스티렌 라텍스 탐침입자(표시 직경 200 nm)를 소량 첨가한 뒤 동적 광산란법으로 용액의 PVAc 농도에 대한 입자의 확산 거동을 정밀하게 조사하였다. 구형 입자의 환산확산계수의 농도의존성은 환산농도 <TEX>$C[{\eta}]$</TEX>의 신장지수함수로 분석할 수 있었고, 묽은 농도에서는 배제층의 두께가 일정하게 유지되었으나 초기 준희박 농도인 <TEX>$1{\leq}C[{\eta}]{\leq}2.5$</TEX> 범위에서는 배제층의 사슬농도 의존지수가 -0.8로써 이론적 계산치 -0.85와 일치하였다. 그러나 보다 높은 농도에서는 배제층의 두께가 이론적 예측보다 급속히 감소하는 현상 또한 관찰되었으며, 그 원인은 인접한 탐침 입자들 사이에 존재하는 Oosawa 인력 때문인 것으로 설명할 수 있었다. In the system of poly(vinyl alcohol) (PVA)/dimethyl sulfoxide, the refractive index of polymer was very well matched to that of solvent and thus its scattered intensity could be minimized. After adding small amount of polystyrene latex particle (nominal diameter 200 nm), diffusion behavior of only probe particle was investigated against the concentration of polymer matrix by means of dynamic light scattering. The polymer concentration dependence of its reduced diffusion coefficient was able to be analysed with the stretched exponential function of the reduced concentration <TEX>$C[{\eta}]$</TEX>. In very dilute concentration regime, the depletion layer kept constant but at the early semi-dilute regime of <TEX>$1{\leq}C[{\eta}]{\leq}2.5$</TEX>, the concentration-dependent exponent of depletion layer <TEX>${\delta}$</TEX> was appeared to be -0.8 which was very close to theoretical one of -0.85. However it was also observed at the higher concentration that its layer thickness decreased more abruptly than theoretical expectation and this phenomenon was ascribed to Oosawa type attractive interaction between adjacent latex particles.

Photothermal investigation of poly (3-hexylthiophene): ZnSe nanocomposites

Optical and thermal properties of poly (3-hexylthiophene): ZnSe blend thin films with different mass ratio of ZnSe nanoparticles (NPs) are investigated by the photothermal deflection technique. The optical absorption spectra and the sub-band gap energy are evaluated by comparing the experimental and the theoretical PDS signals amplitude. The thermal parameters are estimated by fitting the PTD data. The ZnSe NPs dependency with these parameters has been shown. In fact, it was found a redshift of the sub-band gap energy behavior and a decrease in both thermal conductivities as and thermal diffusivities with the increase in NPs concentration in polymer matrix at low and medium mass ratio. The opto-thermal parameter variations are attributed to the effect of the mass ratio between polymer and ZnSe NPs.

5-Fluorouracil delivery from metal-ion mediated molecularly imprinted cryogel discs

The objective of this study is to prepare imprinted cryogel discs for delivery of 5-fluorouracil. The coordinate bond interactions are utilized to accomplish a coordination complex between metal-chelate monomer N-methacryloyl-l-histidine and 5-FU with the assistance of Cu2+ ion. The complex is copolymerized with hydroxyethyl methacrylate to produce poly(hydroxyethyl methacrylate-N-methacryloyl-(l)-histidine methyl ester) cryogel discs. The cryogel discs are characterized thoroughly by performing swelling tests, scanning electron microscopy, differential scanning calorimetry and X-ray diffraction studies. In vitro delivery studies are performed to investigate the effects of cross-linker ratio, medium pH and drug concentration. 5-FU imprinted cryogel discs have highly macroporous structures. Drug molecules are homogeneously dispersed in the 5-FU imprinted cryogel matrix. The cumulative release of 5-FU decreased by increasing the cross-linker density in the polymer matrix. Delivery rate of 5-FU varied with different pH values in a coordination complex since metal ion acts as a Lewis acid, and the ligand, i.e. 5-FU acts as a Lewis base. The cumulative release of 5-FU increased with increasing drug concentration in polymer matrix. The nature of the 5-FU transport mechanism is non-Fickian.

Blending of TiO2 nanoparticles with cellulose acetate polymer: to study the effect on morphology and gas permeation of blended membranes

ABSTRACTCellulose acetate–titania (CA–TiO2) nanoparticles blended membranes were fabricated using diffusion‐induced phase separation process to observe the effect of inorganic nanofillers on the surface topography and gas permeation properties of CA membrane. Self‐synthesized TiO2 nanoparticles using sol gel reflux condensation were employed as nanofillers, which is the anatase phase of TiO2 with crystallite size of 5–10 nm. The synthesized membranes were characterized using scanning electron microscopy and atomic force microscopy techniques to study the nanoscale distribution of TiO2 nanoparticles, surface roughness, and pores generation in blended membranes, with increasing nanoparticles' concentration in polymer matrix. The permeability of CO2 was found to be increased for CA–TiO2 blended membranes. The CO2/CH4 selectivity up to 23.3 was documented. © 2014 Curtin University of Technology and John Wiley &amp; Sons, Ltd.

Characterization of new biodegradable edible film made from basil seed (Ocimum basilicum L.) gum

It is well known that the market for edible films is experiencing remarkable growth and expected to continue. This study investigated the using of basil seed gum (BSG) as a new film-forming material under the influence of addition of glycerol (GLY) as plasticizer. Edible films based on BSG and three different concentrations of GLY (25%, 35%, and 50% w/w BSG) were developed, and their water vapor permeability (WVP), as well as physical, thermal and mechanical properties were measured. The addition of glycerol significantly increased water vapor permeability and solubility of the film (p<0.05). As expected, the increase in GLY concentration from 25% to 50% (w/w) increased the extensibility, but decreased tensile strength. This suggests weaker mechanical strength and higher mobility of polymer chains by plasticizing effect of GLY. The color measurement values showed that increasing the glycerol concentration in polymer matrix caused the b and L values increased while ΔE value decreased. The electron scanning micrograph showed plasticized films as smooth, and uniform which lacked pores or cracks compared with those were not plasticized. This study revealed that the BSG had a good potential to be used in producing edible films for various food applications.

Physical, barrier and antioxidant properties of a novel plasticized edible film from quince seed mucilage

In this study, we investigated the potential of quince seed mucilage (QSM) as a new source for preparation of edible films and determined the physical, mechanical, barrier, antioxidant, microstructural and thermal properties. QSM films were prepared by incorporation of three levels of glycerol (25–50%, w/w). As glycerol concentration increased, water vapor permeability (WVP), oxygen permeability (O2P), elongation at break (EB), water solubility and moisture content of QSM films increased while, tensile strength (TS), density and surface hydrophobicity decreased significantly. The measurement of color values showed that by the increasing of the glycerol concentration in polymer matrix, the b and L values increased while ΔE value decreased. Microscopic views indicated smooth and uniform surface morphology without obvious cracks, breaks, or openings on the surfaces after the incorporation of glycerol as a plasticizer. The results of the present study suggest that QSM as a new antioxidant edible film with interesting specifications can potentially be used for packaging of a wide range of food products.

Effect of glycerol concentration on edible film production from cress seed carbohydrate gum

In this study an edible film plasticized with glycerol was successfully prepared from cress seed gum (CSG). The physical, optical, water vapor permeability (WVP) and mechanical properties of CSG films incorporated with three levels of glycerol (25%, 35%, and 50% w/w) as plasticizer were determined. Dynamic mechanical thermal analysis was used to determine the glass transition temperature. WVP of the films was found to increase as the glycerol content increased from 25% to 50% w/w in the formulation, resulted in improvement of films flexibility and significantly lower tensile strength and higher elongation at break. The color measurement values showed that increasing the glycerol concentration in polymer matrix caused the b and L values increased while ΔE value decreased. The electron scanning micrograph indicated smooth and uniform surface morphology without signs of phase separation between the film components. The results of the present study demonstrated that CSG can promisingly be used in producing edible films with improved quality characteristics.

Nanocrystalline Nd-Fe-B Alloys for Polymer-Bonded Magnets Production

This study presents how different nanostructures of starting Nd-Fe-B particles have influence on magnetic properties of polymer-bonded Nd-Fe-B materials. Two types of nanocrystalline Nd-Fe-B alloys were used for polymer composite production by compression molding technique. The particles with low neodymium content (Nd-low) have nanocomposite structure with small exchange coupling effect between hard and soft magnetic phase. In other hand, practically monophase hard magnetic structure of Nd-Fe-B particles with stoichiometric neodymium content (Nd-stoich) shows improved magnetic properties. With increasing concentration of polymer matrix, the coercivity (Hcb), remanence (Br), and maximum energy product ((BH)max) decrease more prominenty for composites with stoichiometric Nd-Fe-B content.

“Swiss-cheese” polyelectrolyte gels as media with extremely inhomogeneous distribution of charged species

"Swiss-cheese" polyelectrolyte gels (i.e., gels containing a regular set of closed spherical pores) are considered as a suitable system for modeling of a medium with extremely inhomogeneous distribution of charged species. It is shown that the inhomogeneous distribution of ions in Swiss-cheese polyelectrolyte gels can be reached simply by immersion of the gels in an aqueous solution of charged species (e.g., low-molecular 1-1 salt or multivalent ions and macroions charged likely to the gel chains). If a polymer gel is kept in such a solution for a long time, the concentration of ions within relatively big voids becomes equal to that in external solution. On the other hand, due to the Donnan effect the ion's concentration in polymer matrix is always lower than that in external solution. As a result the multivalent ions distribute between water voids and polymer matrix. The extent of this distribution is characterized by partition coefficient kD (determined as ratio kD = n(s)(void)/n(s)(mat) of the concentrations n(s)(void) and n(s)(mat) of ions in water voids and in polymer matrix, correspondingly). It is shown that the partition coefficient kD can be larger than 10 for low-molecular salt, reaches 10(3) for bivalent ions, and is higher than 10(6) for tetravalent ions. In the case of polymer macroions the partition coefficient kD tends to infinity. Our calculations show that the lower limit of characteristic scales of heterogeneity (determined by water voids size starting from which the condition of total electroneutrality is fulfilled and effect of partition is the most pronounced) can be equal to tens of nanometers.

A basic investigation of anhydrous proton conducting gel electrolytes

The aim of this paper is to summarize recent trends in the studies on nonaqueous proton conducting gel electrolytes. The physical–chemical properties of these systems are described and their relation to the type and concentration of polymer matrix, proton donor as well as the solvent used is discussed. This analysis is performed on the basis of electrochemical (impedance spectroscopy, cyclic voltammetry), spectroscopic (NMR, PFG NMR, FT-IR), and thermogravimetric (DSC) experiments. The proton conduction mechanism is postulated and its dependence on the sample composition is discussed. The possibility of application of proton conducting gels in electrochromic devices is presented.