جستجوی مقالات مرتبط با کلیدواژه « polymer » در نشریات گروه « شیمی »

This article explores the insights provided by infrared (IR) spectroscopy into the optical properties and surface morphology of polyethylene (PE) polypropylene (PP), and polyvinyl chloride (PVC) films. Notably, IR spectroscopy can identify absorption lines attributed to various functional groups in addition to those associated with lower-density linear polyethylene. The specific characteristics of IR spectra for linear low density polyethylene are influenced by polymer processing conditions, branching, and monomer content. Moreover, the IR spectrum of PVC offers valuable information about its molecular structure and composition. Comparatively, polypropylene (PP) films exhibit higher absolute light transmission in the ultraviolet and visible spectrum when contrasted with films based on PE and PVC. The utilization of atomic force microscopy (AFM) and IR spectroscopy reveals that heat-induced decomposition and subsequent cooling do not impact the surface roughness or thickness of the films, confirming the retention of structural and electrophysical attributes.

Easy operation, eco-friendliness, and high capacity are the advantages of using hydrogelbased membranes in water treatment, medicine, drug delivery, wound care products, and protective clothing. In the present work, we tried to prepare bio-films with antimicrobial ability by incorporating of Cu ions in chitosan and poly vinyl poly Pyrrolidone. The prepared film was characterized by the thermal gravimetric analysis (TGA), Fourier transforms infrared spectroscopy (FT IR), scanning electron microscopy with X-ray microanalysis (SEM-EDS), and X-ray powder diffraction. The antimicrobial ability of the prepared film was confirmed due to the analysis of antibacterial assay results by using gram-positive and gram-negative bacteria. Based on the achieved data, the prepared multifunctional bio-film could be a considerable candidate in packing industry, especially in medical compounds, tissue engineering, and pharmacology.

Today, due to the industrialization of human societies and the need to use fossil fuels as much as possible, the face of most cities in the world has become black and dirty due to pollution and fats from these fuels. In proportion to the progress of societies, the discovery of nano-sized materials can be the solution to many problems. Among them, two types of self-cleaning and hydrophobic coatings have been developed, which are based on hydrophobic properties, but with the difference that self-cleaning coatings are possible. Clean surfaces only by sunlight. By creating a coating of this material on the exterior of buildings and various structures, it is possible to decompose existing pollution, which are mostly hydrocarbon compounds, only by using sunlight. In addition to creating anti-water properties, nano self-cleaning solutions are very effective with the use of statin light that removes dust from surfaces. One of its applications is to use as anti-fog and self-cleaning materials. The hydrophilic properties of its materials allow water to spread completely on the surface instead of remaining as small droplets. Therefore, it can achieve anti-fog and self-cleaning effects. In these compounds, the catalyst can have self-cleaning and anti-fog effects. The complementary combination of PEG and 2SiO2 can improve such catalyst efficiency as crystal structure, crystal size, porosity level, and surface area.

In this research, we develop and prepare some of the polymers based on polythioesters using cetrimide as an ionic liquid and phase transfer catalyst. All of the polymers were prepared through the reaction of 5,5'-methylenebis (1,3,4-oxadiazole-2-thiol) with five types of diacyl chloride derivatives in the presence of cetrimide as phase transfer catalyst in the mixture of water and chloroform at room temperature. The chemical structure of synthesized polymers was determined using 1H NMR and 13C NMR spectroscopy. The mechanical and thermal stability of the synthesized polymers were investigated. In addition, using DFT calculation, the chemical optimization of synthesized polymers was presented. Moreover, the catalytic activity of cetrimide was compared with four types of ionic liquid with phase transfer catalyst roles. Additionally, the application of synthesized polymers in bone cement was investigated.

Plasticizers is a type of organic materials that can be enhanced to polymers for improving their several characteristics; for example, mechanical properties and pliantness. Plasticizers are veritably significant for the construct of polymeric membrane for potentiometric methods, a significant type of sensors for electrochemical methods. The suitable application of plasticizers in the formulation of membranes for preparing electrodes. The character of the plasticizer effects fundamental operation pointers of the ion-selective membrane electrodes; for example, slope, selectivity, and the area of linear reply. A plasticizer in the membrane formulation has to be well-matched with the ionophore and polymer and have a small solubility and an upper lipophilicity in solution as aqueous. The selection of the high-quality plasticizer for the improvement of a membrane special to an accurate ion ordinarily includes experimental assessments to discover the ionophore with the plasticizer having suitable response properties of the ion-selective electrodes are acquired. Some instances of choosing good suited plasticizer for the formulation of selective electrodes responsive have been given for organic and inorganic ions.

Recently, researchers have suggested the use of membranes to separate gases. They found that using Pebax polymer was very suitable for gas separation. This polymer has good properties and good solubility for carbon dioxide absorption. One of the challenges for researchers is how to turn this polymer into a thin layer for usage as a membrane. Therefore, several methods and solvents have been used to make this membrane. Researchers have calculated the carbon dioxide permeability of this polymer and obtained different results. One of the reasons for the non-uniform permeability results for this gas could be the difference in the method of making the thin film. The use of different methods and solvents affects the physical and chemical properties of this polymer. Perhaps the most important parameters during membrane construction are temperature and drying time. In this research, we want to investigate the effect of these two parameters on the final performance. Thus, the membranes were evaluated by XRD, FT-IR, FESEM, and mechanical strength analyses. Finally, the effect of the parameters on the permeability of carbon dioxide and methane was calculated and compared by the Taguchi method.

In this work, PP+CdS/ZnS transparent hybrid polymer nanocomposites were synthesized and studied. The nanocomposites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive (EDS), and UV-spectroscopy analysis. It was found that the bandgap of PP+1%CdS/ZnS; PP+3%CdS/ZnS, and PP+5%CdS/ZnS; PP+10%CdS/ZnS nanocomposites is 5.2 eV, 5.1 eV, 4.6 eV, respectively. SEM analysis showed that the ZnS and CdS nanoparticles are evenly distributed in the polymer matrix. Furthermore, the average size of nanoparticles in the PP+3%CdS/ZnS, PP+5%CdS/ZnS nanocomposite is 40-54 nm, 29-56 nm, respectively. Photoluminescence properties of hybrid PP+CdS/ZnS nanocomposites were also investigated. It was established that introduction of ZnS and CdS semiconductor nanoparticles into the polypropylene matrix leads to expanding the region of the spectral sensitivity of hybrid nanocomposites. The photosensitivity of PP+CdS/ZnS nanocomposite films was also investigated.

We report the formation and characterization of PEG stearate (PEG)-coatedChitosan (CS) nanoparticles. Chitosan nanoparticles were synthesized usingtripolyphosphate (TPP) via the ionic crosslinking method. Preparation of PEGStearate-grafted Chitosan is essential to improve the biocompatibility and watersolubility of Chitosan. The size and morphologies of Chitosan nanoparticleswere measured with transmission electron microscopy and scanning electronmicroscopy. Sizes of Chitosan nanoparticles were in the range of 150-200nm. The particle size and zeta potential of PEG Stearate-coated Chitosanhad been measured at 187.5 nm by Photon Correlation Spectroscopy (PCS).Drug entrapment efficiency (EE) was obtained to be 99%. The purpose of thepresent work was to develop a new nanoparticle system, consisting of polymericnanoparticles coated with PEG Stearate. The modification procedure led to areduction in the zeta potential values, varying from +43.3 mV for the uncoatedparticles to +20 mV for that of PEG Stearate-coated Chitosan. PEG Stearatecoated nanoparticles were more stable due to their polymer coating layer whichprevented aggregation of Chitosan nanoparticles. Consequently, it is possible thatthe PEG Stearate surrounds the particles reducing the attachment of enzymesand further degradation of the polymeric cores. Properties nanoparticles wereaffected by the preparation variables and the coating layer. Chitosan nanoparticlesshowed a smooth surface and globular shape. In this study, we explored therelease behavior of levothyroxine was affected by the coating layer. Coatingsurface leads to a decrease in the burst release effect compared to uncoatednanoparticle due to gradual release of adsorbed levothyroxine from PEG coatedChitosan nanoparticles.

Stabilization of polypropylene (PP) against thermal oxidation during its melt processing and service life, due to its susceptibility to oxidation, is of great importance from both scientific and industrial points of view. The present work was devoted to synthesize a new antioxidant for polypropylene through esterification reaction between thymolphthalein and stearic acid. The occurrence of the reaction was confirmed by Fourier transform infrared (FT-IR) spectroscopy, size exclusion chromatography and melting point measurements. The reaction product was proved to be a mixture of thymolphthalein mono- and di-stearate. It was also shown that the esterification of thymolphthalein, in addition to lowering its polarity, lessens its melting point significantly from 246 to 186 °C, hence, helping the synthesized additive to be mixed with the polymer more favorably in comparison to thymolphthalein. Differential scanning calorimetry demonstrated that the new additive improves stability of the polymer in melt state, significantly. Moreover, oven ageing experiments revealed that the additive stabilizes the polymer against oxidation outstandingly in solid state and its efficiency is comparable to that of SONGNOX 1010, which is a powerful commercially used antioxidant for the polymer.

Stabilization of polypropylene (PP) against thermal oxidation, due to the susceptibility of this commodity polymer to oxidation, is of great importance from both scientific and industrial points of view. The present work aimed at preparing a new polymeric antioxidant for polypropylene, which has no tendency toward migration from the polymer. Accordingly, a diacid (phenylmalonic acid), which has a labile hydrogen atom and can act as a hydrogen donor antioxidant, was polymerized with 1,4-phenylenediamine to render a polyamide. Occurrence of the reaction was confirmed by FT-IR spectroscopy, differential scanning calorimetry (DSC), gel permeation chromatography and thermogravimetric analysis (TGA). The synthesized polyamide was melt-mixed with PP and its uniform distribution in the matrix was verified by the yellowness index measurements. Oxidation onset temperature and oxidative induction time of the samples using DSC proved that the additive enhances stability of the polymer remarkably in melt state. However, its stabilization efficiency is not as outstanding as that of SONGNOX 1010; a conventional antioxidant for PP. But oven ageing experiments followed by FT-IR spectroscopy revealed that the synthesized antioxidant amends thermo-oxidative stability of the polymer in solid state with an eminent efficiency which is even better than that of SONGNOX 1010. Furthermore, its remarkable stabilization activity was proved by DPPH method. Finally, the synthesized polyamide’s potential, as an efficient antioxidant for PP, especially in the long-term stabilization, was assigned to the presence of the two different hydrogen donor groups, i.e. allylic and amine hydrogen atoms, in the molecular structure of the new antioxidant.

The work entails the viscometric study of a common plant gum found in Nigeria (Acacia Senegal) blended with polyacrylamide (PAM). The gum was purified after collected and mixed in specific ratios of 10:90, 30:70, 50:50, 70:30 and 90:10 with PAM, before they were subjected to rheological study. The intrinsic, relative and specific viscosity for the bends were determined and presented in the research work. The plots of the relative viscosity against concentration of the gums at different temperature vary significantly at higher concentration, while the viscosity for gum Arabic/PAM (90:10) showed the most distinct variation between different temperatures. The result was found to be agreement with some other similar research in the literature. PAM was found to be more viscose than gum Arabic at both temperatures, while the viscosity index such as intrinsic, specific and relative viscosity for the synergistic combination between the polymers were found to decrease as we increased the composition of gum Arabic within the blend.

Batteries are a major technological challenge in this new century as they are a key method to make use of energy efficiently. Nowadays Lithium-ion batteries (LIBs) appeared to be one of the most important energy storage technologies. Today’s Li-ion technology has conquered the portable electronic markets and still on the track of fast development. The success of lithium-ion technology will depend largely on the cost, safety, cycle life, energy, and power, which are in turn determined by the component materials used for its fabrication. Accordingly, this review focuses on the challenges of organic based materials and prospects associated with the electrode materials. Specifically, the issues associated with organic based batteries, advances and prospects are presented. This review aims to summarize the fundamentals of the polymer-based material for lithium-ion batteries (LIBs) and specifically highlight its recent major advancement in material design, challenges, performance and finally its prospects. We anticipate that this Review will inspire further improvement in organic electrolyte materials and the electrode for the battery as energy device storages. Some of these concepts, relying on new ways to prepare electrode materials by the use of eco-efficient processes, on the use of organic rather than inorganic materials in order to overcome environmental issues associated with their use. Organic electrodes are important for solid electrode batteries because they can make device cost-effective, allow flexibility, and can also enable the use of multivalent ions without the problems typically associated with inorganic compounds.

High strength and elastic biodegradable membranes are of great demand in modern technology. Similar membranes have been developed by irradiating different weight poly (vinyl alcohol) (PVA) – hydroxypropyl guar gum (HPG) blends and followed by combining with ex situ nanosilica. Polarized light microscopic (PLM) study indicates that electron beam irradiation produced crosslinks and developed crystallinity in PVA-HPG matrix. Atomic force microscopic analysis shows that 1 wt.% nanosilica produced finer dispersion in both high and low molecular weight PVA-HPG matrix resulting nearly 4.5 times higher mechanical strength and controlled swelling-deswelling property e.g., low molecular weight PVA with 1wt% nanosilica content show swelling ratio 3.5. Greater nanosilica and PVA-HPG interaction was observed in low molecular PVA-HPG composite membranes than high molecular weight PVA-HPG composite membranes which finally showed better efficacy towards drug retention and elution under physiological condition

The new synthesized polymer named pentaglycidyl ether penta-ethoxy phosphorus (PGEPEP) was tested in the behavior of the coating on the metal substrate in a marine environment. In the first step, we developed hybrid composites by collecting two charges respectively trisodium phosphate and natural phosphate. In the second step, we applied the different hybrid composites F1 (PGEPEP/TSP), F2 (PGEPEP/NP) and F3 (PGEPEP/TSP) combined from epoxy resin and synthetic filler, natural load and both sets on E24 carbon steel in 3.5% NaCl. Finally, the gravimetric and electrochemical measurements of the composite F3 (PGEPEP/ TSP) are very encouraging and reach a maximum efficiency respectively equal to 93%, 95% and 92%.

Polyphosphotungstate (denoted as PPT) was supported on polypyrrol as organic support (abbreviated as PTT@Ppy) to produce catalytic active supported catalyst. This catalyst was characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), Field emission scanning electron microscopy (FESEM) and UV-vis diffuse reflectance spectroscopy (UV-DRS). The catalyst showed high catalytic activity in the oxidation of alkenes under optimized conditions. In this work, cyclooctene was selected as model alkene for investigation of oxidation procedure, and then under optimized condition, other alkenes were examined. The catalyst could be readily separated from the catalytic system using the centrifuging and loss of activity was negligible when the catalyst was recovered in five consecutive cycles. For this research, a statistical method called response surface methodology (RSM) has been used to economize the number of experiments and their meaningful interpretation. The effect of various factors such as catalyst amount, time, oxidant amount and temperature on oxidation of alkenes were investigated. Optimization results for 0.2 mmol cyclooctene showed that maximum oxidation efficiency 88% was achieved at the optimum conditions: catalyst amount 200 mg, temperature 63, time 5 h and oxidant = 2.15 mmol.

In this study, Copper-tetraaminophthalocyanine (CuTAP) was supported on polyvinylcholoride by reflux condition to produce heterogeneous recovarable catalyst. This catalyst was characterized using Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Scanning electron microscopy (SEM) and UV-vis spectroscopy. The results showed that the photocatalytic degradation of methyl orange was performed in mild conditions at ambient pressure and temperature under visible light. The synthesized catalyst could be readily separated from the catalytic system by centrifuging and loss of activity was negligible when the catalyst was recovered in four consecutive cycles. The effects of operational various factors such as catalyst amount, initial dye concentration and contact time on degradation of methyl orange were investigated. Optimization results showed that maximum degradation of methyl orange efficiency 98.6 % was achieved at the optimum conditions.

Poly (N-bromosuccinimide) (PNBS) as a mild, efficient, non-acidic, polymeric and heterogeneous catalyst was applied for simple conversion of epoxides into thiiranes by treatment with KSCN or (NH2)2CS at room temperature. Aliphatic and aromatic epoxides converted into their corresponding thiiranes under mild conditions. All reactions proceeded in short reaction times and afforded the corresponding products in good to excellent yields. The catalyst could be recycled and reused for several times without any deterioration in its activity. Advantages such as easy preparation of the catalyst, simple work up, excellent yields of the products and recyclability of the catalyst makes this method more useful compared to the known methodologies.