The present article deals with the preparation and characterization of pure and lead oxide (PbO) nanoparticles embedded polyvinyl alcohol (PVA) films by using a colloidal processing technique. PbO nanoparticles were successfully synthesized using the simple precipitation method. Polymer/ceramic‐based flexible and self‐standing films were obtained and further characterized using various analytical techniques. The mechanical and dielectric properties were also investigated. The Fourier Transform Infrared Spectroscopy (FTIR) results indicate that the structural characterization of PVA is strongly affected by the incorporation of PbO. Thermal analysis results indicate that the thermal stability of the PbO‐doped PVA film has improved as compared with the neat PVA film. The mechanical property of nanocomposites has improved significantly due to an increase in filler loadings, indicating that a good interaction exists between PbO nanoparticles and PVA matrix. The dielectric constant of PVA/PbO nanocomposites has significantly improved with comparatively low dielectric loss values, indicating that the nanocomposites can be considered as an attractive material for embedded capacitor applications.
Acrylic impact modifier (ACR), one kind of methyl methacrylate–butyl acrylate copolymer with a core–shell structure, was prepared by seed emulsion polymerization. The weight ratio of core–shell ranges from 85.5/14.5 to 71.9/28.1. Then PLA/ACR blends were prepared with a constant ratio of 80/20. The effect of core–shell ratio of ACR on toughening PLA was investigated. Torque analysis revealed that the torque values of PLA/ACR blends increased with increasing shell content of ACR. The impact strength of PLA/ACR blends reached the highest value of 77.1 kJ m −2 when the core–shell ratio of ACR was 79.2/20.8. Transmission electron microscope (TEM) photographs revealed that ACR was dispersed uniformly in the PLA matrix. Scanning electron microscopy (SEM) suggested that the plastic deformation and cavitations were the major toughening mechanism for the PLA/ACR blends. The shell partition PMMA of ACR was partially miscible with PLA from dynamic mechanical analysis.
Multiwall carbon nanotubes (MWCNTs) reinforced composites for electromagnetic (EM) absorption are reviewed. Here, four types of nanostructured radar absorbing materials (RAMs) were discussed including MWCNTs polymer composites, magnetic nanostructures decorated MWCNTs polymer composites, nonmagnetic nanostructures decorated MWCNTs polymer composites, and honeycomb‐coated MWCNTs as RAMs. Challenges hindering the practical applications of such composites have been discussed. It has also been highlighted that MWCNTs decorated with magnetic and dielectric nanostructures are effective for broadband lightweight absorbing materials.
A global computer model has been developed for starve‐fed nonconventional single‐screw extrusion. The model has been built by combining a new melt conveying model with recently developed melting models. Mixing screw equipped with dispersive mixing element of Maddock has been considered as an example for modeling. Extensive fully three‐dimensional non‐Newtonian Finite Element Method (FEM) computations have been performed to model the melt flow in mixing elements. Screw pumping characteristics have been computed and modeled for these elements at various power law indices. These characteristics have been implemented into the global model of the process. Computations were made for low‐density polyethylene at various operating conditions. Fill factor, pressure, temperature, and melting profiles were simulated and validated experimentally. It has been confirmed by computation and experimentation that melting in starve‐fed single‐screw extruders is totally different compared with melting in flood‐fed extruders. It is faster, and the screw length needed for melting extends with an increase of the flow rate. The screw is fully filled for some distance from the die only and starved beyond it. This distance is dependent on the flow rate and screw speed.
Multifunctional nanocomposites represent a new class of multiphase materials containing dispersion of nanosized filler materials such as nanoparticles within the polymer matrices. In this study, a polyaniline@polyxanthonetriazole@Fe 3 O 4 (PANI@PXT@Fe 3 O 4 ) trilayered nanocomposite was synthesized successfully through emulsion polymerization of PANI in the presence of a dilayered magnetic polyxanthone triazole (PXT@Fe 3 O 4 ) composite. Nuclear magnetic resonance, Fourier transform infrared, X‐ray diffraction, scanning electron microscopy, thermal gravimetric analysis, and vibrating sample magnetometry were used for characterization of synthesized materials. The antioxidant and antibacterial activities of PANI, PXT, PXT@Fe 3 O 4 , and PANI@PXT@Fe 3 O 4 trilayered nanocomposite were investigated by 2,2‐diphenyl‐1‐picryl‐hydrazyl free radical (DPPH • ) and inhibition zone assays, respectively. Summing up, the results showed a synergic effect on thermal stability, antioxidant, and antibacterial activities of the PANI@PXT@Fe 3 O 4 trilayered nanocomposite. Consequently, the developed PANI@PXT@Fe 3 O 4 trilayered nanocomposite is a suitable candidate for biological applications.
Poly(ε‐caprolactone) microparticles containing embelin ( PCLE ) are prepared by electrohydrodynamic atomization ( EHDA ) and emulsion‐solvent evaporation techniques. Microparticles are characterized in terms of drug state, drug‐loading capacity, encapsulation efficiency, morphology and in vitro release in different mediums. Physicochemical, morphological, and thermal characterization is presented. Kinetic analysis is performed. EHDA microparticles present higher size, surface area, and encapsulation efficiency. The release profiles combine a high initial release, followed by a slow‐controlled release stage. Electrosprayed PCLE presented characteristics such as size (3.14 ± 0.05 μm), zeta potential (−49.22 ± 2.88 mV ) and release profiles that could be attractive for the development of microcarriers for pulmonary administration of embelin.
In this research, the preparation of nanocomposites (NCs) containing nonaggregated nanoparticles (NPs) was studied. Alumina NPs were functionalized by two coupling agents, citric acid and ascorbic acid. NCs of poly(vinyl chloride) (PVC) doped with varying amounts of modified Al 2 O 3 NPs were synthesized via the ultrasonication method. The X‐ray diffraction confirmed that the structure of the modified Al 2 O 3 NPs was still preserved in a pure crystalline phase with the hexagonal structure. Surface morphology showed a picturesque network structure due to the existence of hydrogen bonds in the modified Al 2 O 3 . It also proved good dispersion of NPs in the polymer matrix in nanoscale.
Solubility of poorly water‐soluble drugs is one of the most emerging issue associated with these drugs to form a suitable dosage form that will provide desired pharmacological response. Their low solubility causes elimination of most of the drug from body as such, and desired therapeutic levels are not achieved. Polymers are major players in these formulations, e.g., chitosan, polyvinyl pyrolidone, polyvinyl alcohol, β‐cyclodextrin, etc. β‐Cyclodextrin is one of the most efficient polymer among all of these to work as a carrier for these drugs to enhance solubility. In the present work, microparticles were prepared by different techniques to enhance solubility of rosuvastatin calcium. Microparticles were evaluated for Fourier transform infrared spectroscopy (FTIR), thermal analysis, dissolution studies, powder X‐ray diffraction (PXRD), scanning electron microscopy (SEM), and stability studies to confirm enhancement in solubility. Different in vitro kinetic models such as zero order, first order, Higuchi, and Korsmeyer–Peppas were applied to determine the release behavior of drug from prepared formulations. Results were statistically analyzed by the one‐way ANOVA test, and the p value was determined to check significant results. Results of PXRD had shown that drug nature was changed from crystalline to amorphous, and FTIR and thermal analysis confirmed that the complex was formed between drug and β‐cyclodextrin. SEM images had shown that microparticles had small size loaded with drug. Results had shown that formulation F3 prepared by solid dispersion of drug and β‐cyclodextrin in 1:3 had achieved maximum release of drug 97% within 45 min.
This paper is aimed at studying the effect of the grade and the granulometry of poly(lactic acid) (PLA) on its processability by rotational molding. Two PLA grades were considered: a low melt flow rate (MFR), high viscosity, material, characterized by an excellent quenchability, leading to a completely amorphous structure of rotomolded samples; a high MFR, low viscosity, material, characterized by a lower quenchability, leading to a semicrystalline structure of rotomolded samples. Three different granulometries were considered: a coarser one, that is, the pellets as received, intermediate size pellets produced by extrusion followed by pelletizing, and a powder obtained by grinding of as received pellets. Besides the different dimensions, the intermediate size pellets also experienced a supplementary extrusion step, which induced some degradation in the material. For both grades and three granulometries, void‐free prototypes were obtained, which indicate a very efficient sintering process, attributed to the low viscosity of all PLA grades. As a consequence, the modulus of the rotomolded samples was found to be unaffected by the PLA grade or granulometry. In contrast, the strength was shown to be more significantly dependent on quenchability than on the grade. To obtain an adequately high strength, an amorphous structure must be developed during cooling. Finally, the supplementary extrusion step experienced by the intermediate size pellets was shown to significantly decrease the strength of prototypes, as a consequence of the thermal degradation induced by this additional processing step.
We present an experimental study on the microcapsule‐based semi‐intrinsic self‐healing behavior of low viscosity epoxy resin used in Resin Transfer Molding ( RTM ) process. The microcapsules containing RTM epoxy resin are prepared using in situ polymerization of urea‐formaldehyde. Single type of microcapsules with six different agitation rates is prepared, resulting in microcapsules with a mean diameter ranging from 52 to 202 μm. The thermal characteristics of each microcapsule batch are investigated using Differential Scanning Calorimetry ( DSC ) and Simultaneous Thermal Analysis ( STA ). In addition to thermal characterization tools, Fourier Transform Infrared Spectroscopy ( FTIR ) is also used as a qualitative technique to determine the composition of microcapsules. The mechanical properties of the self‐healing specimen such as Mode‐I fracture toughness and flexure strength are assessed by a universal testing machine, and the obtained results are compared with the findings in literature.
The thermal conductivity of poly(trimethylene terephthalate‐ block ‐poly(tetramethylene oxide) copolymer (PTT‐PTMO)–based nanocomposites filled with the hybrid system of nanofillers, including single‐walled carbon nanotubes (SWCNT) and graphene nanoplatelets (GNP) is studied. At the same loading, SWCNT provided greater thermal conductivity enhancement when added to thermoplastic elastomer matrix when compared to GNP. Moreover, SEM images showed that SWCNT and GNP were well dispersed in PTT‐PTMO, suggesting that in situ polymerization is a highly efficient method for preparing hybrid nanocomposites with low loading of carbon nanofillers. To further improve thermal conductivity of PTT‐PTMO–based nanocomposites, a hybrid SWCNT/GNP was used. When the ratio of SWCNT to GNP was 5:1, i.e. 0.5 wt% of SWCNT and 0.1 wt% of GNP, the PTT‐PTMO–based nanocomposites exhibited the highest thermal conductivity of 0.30 W/m·K, higher than that filled with SWCNT and GNP alone. This suggests that the combination of two types of nanofillers, which differ in shape, allows obtaining the synergistic effect for the thermal conductivity enhancement of PTT‐PTMO.
Nanosized chromium oxide Cr 2 O 3 was prepared and mixed with polyvinyl alcohol (PVA) to produce nanocomposite films. X‐ray diffraction (XRD) and transmission electron microscopy were performed to study the crystallinity and size of nano‐Cr 2 O 3 . Based on the results, the average particle size of the Cr 2 O 3 was found to be 29 nm. The effects of nanosized chromium oxide Cr 2 O 3 concentration and gamma dose on the structural and optical properties of PVA have been studied. The resultant effect of Cr 2 O 3 concentration on the properties of PVA has been investigated using XRD and UV spectroscopy. The results reveal that the addition of Cr 2 O 3 to PVA up to 0.80% leads to a more compact structure of PVA, resulted in an improvement in the isotropic nature of the polymer samples due to the increase in the refractive index. In addition, the effect of gamma irradiation on the 0.50% Cr 2 O 3 /PVA nanocomposite has been investigated. Samples from the 0.50% Cr 2 O 3 nanocomposite were irradiated with gamma doses in the range 200–1 kGy. It is found that the irradiation in the dose range 200–800 Gy causes cross‐linking that increases the amorphous regions and gives polymer resilience.
As a model herbicide, paraquat (PQ) was intercalated into montmorillonite (MMT) and clinoptilolite (CL) clays at different concentrations. FT‐IR, XRD, and SEM techniques were used to characterize the structures of the prepared formulations. The prepared PQ/clay samples were further encapsulated with alginate (Alg) polymer. After characterization, the potential application was verified through release of PQ from PQ/clay and PQ/clay/Alg formulations. According to the results, the release of PQ from PQ/MMT was slower than the release from the PQ/CL system. The presence of the alginate polymer in PQ/clay/Alg capsule beads caused the system to liberate PQ in a more controlled release manner than PQ/clay samples. Furthermore, the release data were fitted to empirical equations to estimate the kinetic parameters. The results suggested the feasibility of the use of clay/Alg formulations for controlled release of herbicides in agricultural applications.
Magnetic molecularly imprinted polymers (MMIPs) were synthesized for selective recognition and rapid enrichment of indole from a model fuel. The MMIPs were synthesized by precipitation polymerization and a surface molecular imprinting technique, using indole as the template molecule, Fe 3 O 4 nanoparticles as magnetically susceptible components, methylacrylic acid as the functional monomer, and ethylene glycol dimethacrylate as a cross‐linker. The properties of the MMIPs were characterized by Fourier‐transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, vibrating sample magnetometry, and thermogravimetric analysis. The adsorption capacity of indole–molecularly imprinted polymers (MIPs) was 50.25 mg g −1 at 303 K and reached adsorption equilibrium in a short time. Experimental data were modeled with a pseudo–second‐order, Langmuir isotherm model. The selective adsorption performance of MIPs was favorable.
Thermal and mechanical properties and fouling resistance of polyamide thin‐film composite ( PA ‐ TFC ) membranes modified with amino‐cyclodextrins and diethylamino‐cyclodextrins are investigated. It was found that the decomposition temperatures of the modified membranes were 500°C and were not significantly different with those of the unmodified membranes. Differential scanning calorimetry ( DSC ) studies showed that the modified membranes with heating melting temperatures in the range 112.5–113.8°C were more crystalline than the unmodified membranes due to the presence of cyclodextrin derivatives on the interfacial layer. The crystallization temperatures ( T c ) were found to range between 128.75 and 129.03°C and the glass transition temperatures ( T g ) ranged between 78.67 and 79.33°C. The modified PA ‐ TFC membranes were found to have comparable ultimate tensile strengths ( UTS ) to the unmodified membranes, except for the membranes modified with amino‐ β ‐ CD s, with a UTS of 20.00 ± 0.50 MP a. The PA ‐ TFC membranes had a lower water uptake percentage due to their enhanced crystallinity. However, these materials had a higher water permeate flux due to the hydrophilic nature of the modified membranes enhanced by the rich hydroxyl groups on the CD s. The modified PA ‐ TFC membranes also exhibited high Mg SO 4 salt rejection and fouling resistance capacities compared to unmodified membranes. Different pH levels resulted in different fouling resistance patterns of the membranes. Therefore, the membranes modified with functionalized CD s were thermally and mechanically stable, had enhanced crystallinity, high divalent salt rejection and fouling resistance under different pH conditions.
Adding organic–inorganic hybrid nanoparticles is a potential way to enhance room temperature ionic conductivity and mechanical strength of solid polymer electrolytes (SPEs). In this work, a new nanocomposite solid polymer electrolyte (NSPE) based on poly(ethylene oxide)–lithium bis(trifluoromethane sulfonyl) imide (PEO 12 –LiTFSI) incorporating polyhedral oligomeric silsesquioxane–poly(ethylene glycol) (POSS–PEG( n = 4)) hybrid nanoparticles has been prepared and reported the effect of POSS–PEG( n = 4) hybrid nanoparticles on thermal, mechanical, and electrical properties of (PEO 12 –LiTFSI) SPE. Results from X‐ray diffraction and differential scanning calorimetry studies indicated that the conductivity increase was due to the decrease in crystallinity upon the addition of lithium salt and POSS–PEG hybrid nanoparticles into the SPE system. The mechanical properties of PEO 12 –LiTFSI SPE tended to increase with the addition of POSS–PEG( n = 4) nanoparticles up to 10 wt% and decreased afterwards. The NSPEs having solid state show quite high ionic conductivity (1.45 × 10 −4 S/cm at 30°C), which is about 7.44 times of magnitude larger than that of the matrix polymer (PEO 12 –LiTFSI) electrolyte (1.95 × 10 −5 S/cm at 30°C).
The study aims for potential utilization of red mud (an industrial waste) to be utilized as a wear‐resistant material. Investigations on mechanical and wear characteristics of red mud epoxy based homogeneous and their functionally graded materials (FGMs) developed with an intent of probable application in tribological systems are presented. The influence of significant operational parameters, material parameters, and their subsequent influences among themselves are explored. A specially designed experimental series is performed on a pin‐on‐disk machine with three different sliding velocities 105, 209, and 314 cm/s under three different loading conditions of 20, 30, and 40 N and compares the experimental results with the reported theoretical wear model. Artificial neural network approach is also applied to the wear data for subsequent validation. The comparative study indicates that although the homogeneous composites and FGMs exhibit relatively inferior mechanical properties, the sliding wear performance of the FGMs is better than homogeneous composites. It is also found that out of all synthesized composites FGMs exhibit the maximum impact strength and tensile modulus, which clearly indicates that the gradation achieved because the centrifugation technique enhances the crack arresting capability of the materials. The measured Young's moduli of homogeneous composites and FGMs were compared to standard theoretical prediction models. The measured moduli values showed good harmony with those predicted from Halpin–Tsai and Kerner models. Transmission electron microscopy microstructures confirm the continuous graded dispersion of red mud particles in the matrix.
This research reports synthesis of novel graft copolymers of oatmeal (OAT‐ g ‐PMMA) using a methyl methacrylate monomer via the “microwave‐assisted ” technique which were applied as matrices. The synthesized matrices were used to develop the bioavailability of model drug (5‐amino salicylic acid (5‐ASA)) for colon‐targeted delivery. Characterization of novel synthesized matrices includes intrinsic viscosity, 13 C‐CP/MAS solid‐state NMR spectroscopy, FTIR, DSC, SEM, TGA, UV, and elemental analysis. In vitro release studies of 5‐ASA were performed in simulated gastric medium (pH 2) and simulated intestinal medium (pH 7 and 7.4). The release rate of 5‐ASA from OAT‐ g ‐PMMA matrices was found to be slower than oatmeal in simulated gastric media. However, the reverse trend was observed in simulated intestinal medium. These results suggest that synthesized novel OAT‐ g ‐PMMA matrices are more suitable for oral delivery of applied model drug as compared to starting biopolymer (oatmeal) with special reference followed by the Fickian diffusion mechanism as a colonic drug carrier.
New ionic liquid‐mediated molecularly imprinted polymers (ILMIPs) for phthalate esters were developed in this study by the situ thermal polymerization method using methacrylic acid as a functional monomer and dibutyl phthalate (DBP) as a template. The polymer was characterized by scanning electron microscopy and Fourier transform infrared spectrometry. Batch static binding adsorption experiments were carried out to analyze its adsorption performance. The selectivity and adsorption of molecularly imprinted polymers were improved by the ionic liquids 1‐butyl‐3‐methylimidazolium hexafluorophosphate as an excellent auxiliary porogen and solvent. The adsorption process conformed to pseudo–first‐order model by kinetics analysis and Sips model by isotherm analysis. Using the prepared ILMIPs as a solid‐phase extraction (SPE) sorbent, which indicated that ILMIPs–SPE had a higher enrichment efficiency and a better selectivity for DBP, and the average recoveries of DBP at four spiked levels were in a range of 96.4–101.3% ( n = 5) with relative standard deviation (RSD) ≤6.9%.