PVA/Gd2O3@Zno Nanocomposite Films as New Uv-Blockers: Structure and Optical Revealations

Herein we have synthesised Gadolinium oxide doped Zinc oxide (Gd 2 O 3 @ZnO) by solution combustion method and incorporated it as a nanofiller into Polyvinyl alcohol (PVA) polymer matrix using solution intercalation technique to get PVA/Gd 2 O 3 @ZnO nanocomposite film. The X-ray diffraction (XRD), Scanning electron microscopy (SEM), Differential scanning calorimetry (DSC) and UV-Vis spectroscopy were used to investigate the structural, morphological, glass transition temperature and optical properties of synthesized nanocomposites respectively. The optical propertiesof PVA/Gd 2 O 3 @ZnO film shows the interaction of –OH groups in PVA and dopant. From DSC, it is clear that Tg of prepared nano composites increases with increasing in dopant concentration. XRD analysis showed that the crystalline characteristics of the nanocomposites increases with increase in dopant concentration. The UV-Visible spectra reveals that there is decrease in indirect band gap of PVA from 4.94 eV to 3.12 eV and direct band gap from 4.90eV to 3.03 eV compared to pristine PVA Gd 2 O 3 @ZnO doped nanocomposite films showed multifold enhancement in optical characteristics such as refractive index of PVA doped nanocomposites compared pristine PVA, optical conductivity, finess coefficient, extinction coefficient on increasing in dopant concentration (0%, 2%, 4%, 6% and 8wt%). The optical characteristics of PVA/Gd 2 O 3 @ZnO nanocomposite films show excellent UV-blocking behaviour suggesting that, they are promising materials for optical devices.

Phase Change Materials (PCMs) Based in Paraffin/Synthetic Saponite Used as Heat Storage Composites

Synthetic saponites were successfully used to prepare phase change materials (PCMs) based on paraffin/synthetic saponite. Paraffin/synthetic saponites PCMs were prepared by a solution intercalation process. The PCMs were characterized by powder X-ray diffraction, FT-IR spectroscopy, thermal analyses and nitrogen adsorption. The thermal properties and the stability of PCMs were measured by DSC analysis and from heating–cooling curves. The results showed that the prepared PCMs have a higher heating rate and a lower cooling speed than paraffin because the heat storage was improved with the synthetic saponite. A one-pot synthesis method for obtaining PCM has been successfully developed in this work. The material thus obtained had better results for heat storage applications.

Polyvinylpyrrolidone/Montmorillonite/Zinc Oxide Bionanosystems Prepared by Spray Drying

In this study, microparticles of bionanomaterials were obtained by polyvinylpyrrolidone, montmoril-lonite, and zinc oxide bionanosystems produced through solution intercalation technique combined with a spray-drying process, aiming for possible application as drug delivery systems. The final microparticles obtained were evaluated in terms of their production yield, which varies between 39.2% and 56.9%. Thermal analysis showed no major changes in Tg of the nanocomposites, compared to the pure PVP polymer. Scanning electron microscopy analysis revealed a pseudo-spherical shape and confirmed the micrometric size of the microparticles. Transmission electron microscopy analysis corroborated the embedding of montmorillonite and ZnO within the polymer phase. Nuclear magnetic resonance and X-rays diffraction were used to study the nanoparticles dispersion, indicating a predominant intercalated morphology. This study suggests that the applied methodology is suitable for the high yields synthesis of nanocomposites PVP based microparticles with uniform size and shape, which can be promising for the production of a new drug delivery system.

Preparation of a Novel Millet Straw Biochar-Bentonite Composite and Its Adsorption Property of Hg2+ in Aqueous Solution

The remediation of mercury (Hg) contaminated soil and water requires the continuous development of efficient pollutant removal technologies. To solve this problem, a biochar–bentonite composite (CB) was prepared from local millet straw and bentonite using the solution intercalation-composite heating method, and its physical and chemical properties and micromorphology were then studied. The prepared CB and MB (modified biochar) had a maximum adsorption capacity for Hg2+ of 11.722 and 9.152 mg·g−1, respectively, far exceeding the corresponding adsorption value of biochar and bentonite (6.541 and 2.013 mg·g−1, respectively).The adsorption of Hg2+ on the CB was characterized using a kinetic model and an isothermal adsorption line, which revealed that the pseudo-second-order kinetic model and Langmuir isothermal model well represented the adsorption of Hg2+ on the CB, indicating that the adsorption was mainly chemical adsorption of the monolayer. Thermodynamic experiments confirmed that the adsorption process of Hg2+ by the CB was spontaneous and endothermic. Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and a thermogravimetric analysis (TGA) showed that after Hg2+ was adsorbed by CB, functional groups, such as the –OH group (or C=O, COO–, C=C) on the CB, induced complexation between Hg and –O–, and part of Hg (ii) was reduced Hg (i), resulting in the formation of single or double tooth complexes of Hg–O– (or Hg–O–Hg). Therefore, the prepared composite (CB) showed potential application as an excellent adsorbent for removing heavy metal Hg2+ from polluted water compared with using any one material alone.

A Review on Barrier Properties of Poly(Lactic Acid)/Clay Nanocomposites

Poly(lactic acid) (PLA) is considered to be among the best biopolymer substitutes for the existing petroleum-based polymers in the field of food packaging owing to its renewability, biodegradability, non-toxicity and mechanical properties. However, PLA displays only moderate barrier properties to gases, vapors and organic compounds, which can limit its application as a packaging material. Hence, it becomes essential to understand the mass transport properties of PLA and address the transport challenges. Significant improvements in the barrier properties can be achieved by incorporating two-dimensional clay nanofillers, the planes of which create tortuosity to the diffusing molecules, thereby increasing the effective length of the diffusion path. This article reviews the literature on barrier properties of PLA/clay nanocomposites. The important PLA/clay nanocomposite preparation techniques, such as solution intercalation, melt processing and in situ polymerization, are outlined followed by an extensive account of barrier performance of nanocomposites drawn from the literature. Fundamentals of mass transport phenomena and the factors affecting mass transport are also presented. Furthermore, mathematical models that have been proposed/used to predict the permeability in polymer/clay nanocomposites are reviewed and the extent to which the models are validated in PLA/clay composites is discussed.

Transparent Polyimide/Organoclay Nanocomposite Films Containing Different Diamine Monomers

Poly (amic acid) s (PAAs) were synthesized using 4,4′-(hexafluoroisopropyl-idene) diphthalic anhydride (6FDA) and two types of diamines—bis(3-aminophenyl) sulfone (BAS) and bis(3-amino-4-hydroxyphenyl) sulfone (BAS-OH). Two series of transparent polyimide (PI) hybrid films were synthesized by solution intercalation polymerization and thermal imidization using various concentrations (from 0 to 1 wt%) of organically modified clay Cloisite 30B in PAA solution. The thermo-mechanical properties, morphology, and optical transparency of the hybrid films were observed. The transmission electronic microscopy (TEM) results showed that some of the clays were agglomerated, but most of them showed dispersed nanoscale clay. The effects of -OH groups on the properties of the two PI hybrids synthesized using BAS and BAS-OH monomers were compared. The BAS PI hybrids were superior to the BAS-OH PI hybrids in terms of thermal stability and optical transparency, but the BAS-OH PI hybrids exhibited higher glass transition temperatures (Tg) and mechanical properties. Analysis of the thermal properties and tensile strength showed that the highest critical concentration of organoclay was 0.50 wt%.

Nitroxide-mediated graft copolymerization of styrene from cellulose and its polymer/montmorillonite nanocomposite

Nitroxide-mediated polymerization was successfully employed for well-defined graft copolymerization of styrene (St) monomer from cellulose (Cell) backbone. For this purpose, Cell was acylated by 2-bromoisobutyryl bromide, and then 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) was immobilized onto Cell backbone using a nucleophilic substitution reaction to produce Cell-TEMPO macroinitiator. Afterward, St monomer was grafted onto Cell backbone through “grafting from” technique. The successful synthesis of Cell- g-polystyrene (PSt) copolymer was confirmed using Fourier transform infrared and proton nuclear magnetic resonance spectroscopies and scanning electron microscopy analysis. Finally, Cell- g-PSt/montmorillonite nanocomposite was fabricated through solution intercalation approach. The thermal properties and structural morphology of the resultant nanocomposite were investigated using thermogravimetric analysis and differential scanning calorimetry and transmission electron microscopy, respectively.

PREPARATION OF BIO-NANOCOMPOSITE MEMBRANE FOR METHYLENE BLUE ADSORPTION

In this study, the bio-nanocomposite composed of chitosan and nanoclay was prepared by solution intercalation method. The membrane was subsequently fabricated by dry/wet phase separation technique. The structure of bio-nanocomposite was characterized by Fourier-transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) and scanning electron microscope (SEM). The membrane was applied to adsorb methylene blue (MB) for water treatment. The adsorption of MB was monitored through UV-Vis spectroscopy. The results showed that bionanocomposite membrane could adsorb MB up to 97.9 % in 150 min. The MB adsorption of bionanocomposite membrane was 234 times as high as the adsorption of the conventional chitosan films that is promising for environmental applications.

Synthesis, Characterization and Their Antimicrobial Activities of Boron Oxide/Poly(Acrylic Acid) Nanocomposites: Thermal and Antimicrobial Properties

Boron oxide (B2O3)/Poly(acrylic acid) (PAA) nanocomposites were synthesized by solution intercalation method, and characterized by Fourier transform infrared spectroscopy (FTIR-ATR), transmission electron microscopy (TEM), X-ray diffraction and thermogravimetric analysis (DTA/TG). The effect of boron oxide amount on the thermal stability of nanocomposites was investigated. Moreover, the antimicrobial activities of them were also determined by the serial dilution method against E. coli and S. aureus. XRD analysis showed that boron oxide was homogenously dispersed in polymer matrix; FTIR-ATR that there was interaction between PAA and boron oxide; and TEM that boron oxide particles had spherical structure, and dispersed in nano size in polymer matrix; DTA/TG that the thermal stability of polymers increased with the adding of boron oxide into polymer matrix, and changed the decomposition mechanism of PAA. B2O3/PAA nanocomposites exhibited higher decomposition temperature. The decomposition mechanisms of PAA and its nanocomposites occurred through three decomposition steps; dehydration, decarboxylation and chain scission. B2O3/PAA nanocomposites showed greater antimicrobial activity with increasing B2O3 amount.