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Abstract In this work, low-density polyethylene/high-density polyethylene/thermoplastic starch (LDPE/HDPE/TS) films were prepared with different compositions to obtain environmentally friendly materials. LDPE/HDPE/TS blends, at ratios of 95:5:15, 90:10:15, 85:15:15, 85:15:20, 85:15:25, [...]

The relationship between career resin of carbon black (CB) masterbatch and the performance of bimodal polyethylene pipes (PE100) under ultraviolet (UV) irradiation and the long-term stability of black PE100 with different comonomer content have been investigated. For this purpose, two different CB masterbatches varying in carrier resin were selected and added to two PE100 pipes. Samples were exposed to UV irradiation, and then thermal, mechanical, and rheological properties were explored using differential scanning coloriemetry (DSC), tensile, and rheometry analyses. Additionally, Fourier transformed-infrared spectroscopy (FTIR) has been performed to characterize the structural changes of PE100 samples under UV irradiation. According to rheological results, the PE100 sample containing more comonomer underwent a higher degree of degradation. Thermal and mechanical results reveal that the masterbatch composed of highdensity polyethylene (HDPE) as carrier resin has a better influence on PE pipes' UV stability with less comonomer content. KEYWORDS carbon black, HDPE, photodegradation, pipe, rheology, UV irradiation, UV stability, 1 | INTRODUCTION Easy to install, light, flexible, and corrosion-free are the features that have made polyethylene (PE) pipes a material of choice for the network of gas and water [...]

Mixed matrix membranes (MMMs) are brought up as prospecting media to sweeten natural gas in recent decades. But the majority of experiments have conducted on CO2/CH4 gas pair separation, and H2S removal from CH4 through MMMs has been paid less consideration. Thereupon, polycarbonate (PC) permeability and permselectivity as a polymer with inherent gas transport properties and two PC-based MMMs containing octylsilane (OS) and polydimethylsiloxane (PDMS)-modified nanosilica were investigated under various operational conditions for this gas couple. The influence of operational parameters including transmembrane pressure, feed temperature, H2S inlet concentration and physical aging on the permeability of mixed gas and selectivity of the H2S/CH4 pair was assessed. It was observed that addition of silica nanoparticles causes more H2S permeability and selectivity. As a result, it can be used for methane upgradation. Membranes fabricated with PDMS-modified nanosilica showed the highest permeability of H2S and also the superior selectivity of H2S/CH4. Therefore, it could be possibly applied to mitigation of H2S concentration in the outlet gas stream. [ABSTRACT FROM AUTHOR]

Polymers are used in various industries and, particularly in the medical industry, the use of skin-friendly, biocompatible materials is essential. In this field, using natural and biocompatible carbonaceous materials to replace petroleum-derived materials is the most efficient solution. In this study, which was performed in two phases, polyurethane foam made from natural polyol obtained from rapeseed oil (RPO) and containing silver (Ag) nanoparticles for use in wound dressings was prepared and examined. In the first phase, bio-based polyurethane was prepared via a specific method and characterized using Fourier-transform infrared and nuclear magnetic resonance analysis. Polyol foams were prepared using different ratios of natural polyol to a petroleum based polyol. The results of the water absorption test showed that PF-NPO-35 (containing 35% natural polyol) has a 145% absorption rate. The water vapor transfer rate test was also conducted on this sample, giving results in the range of 8–9 mg cm−2 h−1, which is a suitable range for a wound dressing application. After selecting PF-NPO-35 as the optimal sample, different amounts of Ag nanoparticles were added to this sample and the final foams with different percentages of Ag nanoparticles were prepared. The antibacterial properties of the samples showed that PF-NPO-35-Ag-7 (7% Ag nanoparticles) was more sensitive to Escherichia coli than to Staphylococcus aureus. Increasing the amount of Ag nanoparticles improved the antibacterial properties. Cytotoxicity tests also showed that all samples containing Ag nanoparticles survived for 48 h. High levels of cell viability were observed in the presence of the synthetic foams. In the animal tests, the healing process of the wounds treated with a sample containing silver nanoparticles showed improved progress after 14 days. [ABSTRACT FROM AUTHOR]

A new method of fabricating thin film composite (TFC) membranes is presented through a one‐step co‐casting technique. In this method a dense layer of poly(ether‐block‐amide) (PEBAX‐1657) was formed on a porous support of polyethersulfone (PES) in one step by immersing the cast films in a coagulation bath of n‐hexane. To assess the impact of silica (SiO2) nanoparticles on characteristics of the fabricated membranes, dual‐layer nanocomposite membranes containing 2.5, 5, and 7.5 wt% of SiO2 nanoparticles in the dense layer were also prepared. Physical and mechanical properties of membranes were evaluated using scanning electron microscopy (SEM), Fourier transformed infrared spectroscopy, X‐ray diffraction, water contact angle and tensile strength measurements. SEM images revealed that a defect‐free top‐layer was formed on a porous substrate and both layers were adhered together properly. These images also showed that sub‐layer's microstructure was affected by addition of SiO2 nanoparticles to the PEBAX matrix. Gas permeation properties of membranes were recorded for pure CO2 and CH4 at room temperature and pressures in the range of 4–6 bars. Addition of SiO2 nanoparticles up to 5 wt% enhanced CO2/CH4 selectivity of the membranes, while at higher SiO2 nanoparticles loading (7.5 wt%), the selectivity was reduced. [ABSTRACT FROM AUTHOR]

Hindered amine light stabilizers (HALS) are widely used chemical stabilizers for preventing polymer degradation. In this study, the effects of type of HALS and its content in high‐density polyethylene (HDPE) over the stabilization process are investigated employing density functional theory (DFT) and experimental approach. The electrophilicity index of four types of commercial HALS are compared by DFT to select the most effective one. Besides, the HDPE sample containing a phenolic antioxidant and different contents of the selected HALS are experimentally exposed to UV irradiation. The effect of HALS content on the changes in chain microstructure and molecular weight of HDPE are evaluated using gel permeation chromatography and frequency sweep rheometry. In the absence of HALS, HDPE suffers degradation and the phenolic antioxidant causes chain scission. However, by adding HALS, the chain branching and crosslinking mechanisms are predominant. The results of FTIR, DSC, and tensile analyses follow similar trends, revealing that the best stabilization performance corresponds to adding 600 ppm HALS to HDPE. [ABSTRACT FROM AUTHOR]