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1.
Polymers (Basel) ; 14(4)2022 Feb 16.
Artigo em Inglês | MEDLINE | ID: mdl-35215683

RESUMO

This study provides H2 gas as a renewable energy source from sewage water splitting reaction using a PMT/Au photocathode. So, this study has a dual benefit for hydrogen generation; at the same time, it removes the contaminations of sewage water. The preparation of the PMT is carried out through the polymerization process from an acid medium. Then, the Au sputter was carried out using the sputter device under different times (1 and 2 min) for PMT/Au-1 min and PMT/Au-2min, respectively. The complete analyses confirm the chemical structure, such as XRD, FTIR, HNMR, SEM, and Vis-UV optical analyses. The prepared electrode PMT/Au is used for the hydrogen generation reaction using Na2S2O3 or sewage water as an electrolyte. The PMT crystalline size is 15 nm. The incident photon to current efficiency (IPCE) efficiency increases from 2.3 to 3.6% (at 390 nm), and the number of H2 moles increases from 8.4 to 33.1 mmol h-1 cm-2 for using Na2S2O3 and sewage water as electrolyte, respectively. Moreover, all the thermodynamic parameters, such as activation energy (Ea), enthalpy (ΔH*), and entropy (ΔS*), were calculated; additionally, a simple mechanism is mentioned for the water-splitting reaction.

2.
Polymers (Basel) ; 13(19)2021 Sep 29.
Artigo em Inglês | MEDLINE | ID: mdl-34641161

RESUMO

The versatility of high-density polyethylene (HDPE) makes it one of the most used polymers for vast applications ranging from food packaging to human implants. However, there still is confusion regarding the proper selection of processing techniques to produce HDPE specimens for high-end applications. Herein, we compare the processing of HDPE by two relevant techniques: compression and injection molding. The fabricated samples were studied using uniaxial tensile testing to determine their mechanical performance. Furthermore, the microstructure of samples was analyzed using different characterization techniques. Compression-molded specimens recorded a higher degree of crystallinity (DC) using two different characterization techniques such as differential scanning calorimetry (DSC) and X-ray diffraction (XRD). With this information, critical processing factors were determined, and a general structure-property relationship was established. It was demonstrated that having a higher DC resulted in higher yield strength and Young's modulus. Furthermore, premature failure was observed in the injection-molded specimens, resulting in lower mechanical performance. This premature failure was caused due to flow marks observed using scanning electron microscopy (SEM). Therefore, it is concluded that compression molding produces superior samples compared to injection molding.

3.
Polymers (Basel) ; 12(12)2020 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-33261001

RESUMO

Herein, we report the fabrication and characterization of high-strength Kevlar epoxy composite sheets for structural application. This process includes optimization of the curing conditions of composite preparation, such as curing time and temperature, and the incorporation of nanofillers, such as aluminum oxide (Al2O3), silicon carbide (SiC), and multi-walled carbon nanotubes (MWCNT) in different weight percentages. Differential scanning calorimetry (DSC) was utilized to investigate the thermal stability and curing behavior of the epoxy, finding that a minimum of 5 min is required for complete curing under an optimized temperature of 170 °C. Moreover, mechanical characterization, including flexural and drop-weight tests, were performed and found to be in good agreement with the DSC results. Our results show that nanofiller incorporation improves the mechanical properties of Kevlar epoxy composites. Among the tested samples, 0.5% MWCNT incorporation obtained the highest mechanical strength.

4.
Environ Pollut ; 258: 113831, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31874431

RESUMO

The microparticle content of 37 common facial and body scrubs commercially available in the United Arab Emirates was analyzed. The chemical composition, ash content, physical characteristics, loading, particle size and shape of the microparticles were determined. Only 11 out of 37 products were found to have microplastic content. Many of the remaining products exhibited microparticles composed of microcrystalline cellulose and crushed walnut shells. Differential scanning calorimetry showed that microplastic products had softening points as low as 84 °C. Plastic microbeads of 2 products were found to fuse at 100 °C. The fusion altered the flotation characteristics of the microbeads of one product. Heat treatment of the product at 100 °C in the presence of silica gel led to entrainment of the silica and partial fragmentation of the beads upon cooling. This may be understood as one mechanism of fragmentation of a microplastic with a low softening point in the presence of hard soil particles under temperature cycling.


Assuntos
Cosméticos , Monitoramento Ambiental , Microesferas , Poluentes Químicos da Água , Plásticos , Emirados Árabes Unidos
5.
J Funct Biomater ; 10(1)2019 Mar 04.
Artigo em Inglês | MEDLINE | ID: mdl-30836701

RESUMO

Porous composite scaffold using an alginate and bioactive glass ICIE16M was synthesized by a simple freeze-drying technique. The scaffold was characterized using compression testing, Fourier-transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), X-ray diffraction (XRD), X-ray microtomography (XMT) and scanning electron microscopy (SEM). The bioactivity of the scaffold was evaluated by its ability to form apatite on its surface in simulated body fluid (SBF). The data collected showed evidence that the novel material produced had an appropriate pore size for osteoconduction, with an average pore size of 110 µm and maximum pore size of 309 µm. Statistical analysis confirmed that the glass filler significantly (P < 0.05) increased the collapse yield of the scaffolds compared with pure alginate scaffolds. The ICIE16M glass had an amorphous structure, favorable for bioactivity.

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