Development and Characterization of Phosphate Glass Fibers and Their Application in the Reinforcement of Polyester Matrix Composites.

This study focused on the production and characterization of phosphate glass fibers (PGF) for application as composite reinforcement. Phosphate glasses belonging to the system 52P2O524CaO13MgO (11-(X + Y)) K2OXFe2O3YTiO2 (X:1, 3, 5) and (Y:0.5, 1) were elaborated and converted to phosphate glass fibers. First, their mechanical properties and chemical durability were investigated. Then, the optimized PGF compositions were used afterward as reinforcement for thermosetting composite materials. Polyester matrices reinforced with short phosphate glass fibers (sPGF) up to 20 wt % were manufactured by the contact molding process. The mechanical and morphological properties of different sPGF-reinforced polyester systems were evaluated. The choice between the different phosphate-based glass syntheses (PGFs) was determined by their superior mechanical performance, their interesting chemical durability, and their high level of dispersion in the polyester matrix without any ad sizing as proven by SEM morphological analysis. Moreover, the characterization of mechanical properties revealed that the tensile and flexural moduli of the developed polyester-based composites were improved by increasing the sPGF content in the polymer matrix in perfect agreement with Takayanagi model predictions. The present work thus highlights some promising results to obtain high-quality phosphate glass fiber-reinforced polyester parts which can be transposed to other thermosetting or thermoplastic-based composites for high-value applications.

Micro- and nano-structures of cellulose from eggplant plant (Solanum melongena L) agricultural residue.

Currently, agriculture sector produces enormous quantity of residues, creating severe environmental problems. These agricultural residues are rich in lignocellulosic fibers, making them sustainable sources to produce high added-value materials. This investigation aims to transform the eggplant plant residue (EPR) into purified cellulose microfibers (CMF) and cellulose nanocrystals (CNC). CMF with a yield of 54 %, diameter of 13.6 µm and crystallinity of 71 % were successfully obtained from raw EPR using alkali and bleaching treatments. By subjecting CMF to phosphoric and sulfuric acid hydrolysis, phosphorylated (P-CNC) and sulfated (S-CNC) were produced. P-CNC and S-CNC exhibited an aspect ratio of 89.4 and 74.2, zeta potential value of - 39.4 and - 28.7 mV, surface charge density of 116.7 and 218.2 mmol/kg cellulose and a crystallinity of 73 % and 80 %, respectively. Herein, the obtained cellulosic structures with excellent properties could be used in various applications, such as bio-derived fillers for polymer composites development.

Stipa tenacissima L.: A New Promising Source of Bioactive Compounds with Antioxidant and Anticancer Potentials.

BACKGROUND: Stipa tenacissima L. (S. tenacissima), called Esparto grass, is a cultivated species used for industrial purposes, including textile production. This species has never been studied for its medical potential before, nor has it been used in traditional medicines. It is thus fitting that the present study aimed to investigate the pharmacological potential of S. tenacissima. To achieve this goal, this work was conducted to study the chemical composition, antioxidant properties, and antiproliferative effects of S. tenacissima against cancerous cell lines, including the human colorectal adenocarcinoma cell line (HT-29) and human breast adenocarcinoma cell line (MDA-MB-231). Fractionation and characterization of S. tenacissima extract showed the presence of promising bioactive fractions. The fractions obtained from S. tenacissima extract exhibited interesting antioxidant properties, with IC50 values ranging from 1.26 to 1.85 mg/mL. All fractions, such as F1, F2, F3, and F4, induced an important antiproliferative effect on the cancer cell lines MDA-MB-231, scoring IC50 values ranging from 63.58 ± 3.14 to 99.880 ± 0.061 µg/mL. These fractions (F1, F2, F3, and F4) also exhibited a potent antiproliferative effect versus HT-29 cell lines, with IC50 values ranging from 71.50 ± 4.97 to 87.500 ± 1.799 µg/mL. Therefore, S. tenacissima could constitute a new natural source of bioactive compounds that can be used for therapeutic purposes to fight cancer and free radical damage.

Development and potential performance of prepolymer in corrosion inhibition for carbon steel in 1.0 M HCl: Outlooks from experimental and computational investigations.

Diglycidyl amino benzene (DGAB) epoxy prepolymer was investigated using Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopy. Then, we highlighted the usefulness of DGAB epoxy prepolymer to improve the resistance of carbon steel (CS) in hydrochloric acid (1.0 M HCl) using weight loss (WL), electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), scanning electron microscope (SEM), atomic force microscopy (AFM), density functional theory (DFT) and complexation calculations, molecular dynamics (MD) and meansquaredisplacement (MSD) simulations. Highest inhibitory efficiencies for the WL, EIS and PDP methods at 10-3 M of DGAB are 90.8, 96.3 and 95.9%, respectively. SEM and AFM micrographs demonstrated that the epoxy prepolymer could effectively block the acid attack by chemisorption on the surface of the carbon steel, the high correlation coefficient and low Standard Deviation (SD) and low Sum of Squares (SS) value gave the best fit for Langmuir isotherm. PDP data suggested that the epoxy prepolymer could provide excellent corrosion performance and showed a mixed-type inhibitor with predominant cathodic effectiveness. Investigate of the inhibitory layer and the potential mechanism was conceptually evaluated using DFT, MD simulations, radial distribution function (RDF) and mean square displacement (MSD).

Development rheological and anti-corrosion property of epoxy polymer and its composite.

Epoxy polymer, namely, decaglycidyl pentamethylene dianiline of phosphorus (DGPMDAP) was synthesized in three steps. The synthesis of epoxy polymer DGPMDAP was investigated by nuclear magnetic resonance spectroscopy, rheological analysis, scanning electron microscope (SEM), stationary and transient electrochemical methods (PDP and EIS), respectively. The rheological properties of composite (DGPMDAP/MDA/TiO2) without and with different percentages of titanium dioxide (0%, 5%, 10% and 15%) increase with both the increase in frequency and with rate of load of titanium dioxide. Besides, SEM micrographs shows a good dispersion of the titanium dioxide charge in the composite (DGPMDAP/MDA/TiO2) elaborated. The results of PDP show that epoxy polymer DGPMDAP acts as mixed type inhibitor and reaches maximum corrosion inhibition efficiency reaches 92 % at 10-3 M. Besides, EIS results indicate that DGPMDAP act as good inhibitor for carbon steel in 1 M HCl solution and its efficiency reaches 91 % at 10-3 M of DGPMDAP. Furthermore, the adsorption of DGPMDAP on carbon steel surface obeyed Langmuir isotherm.

Epoxy pre-polymers as new and effective materials for corrosion inhibition of carbon steel in acidic medium: Computational and experimental studies.

Present study is designed for the synthesis, characterization and corrosion inhibition behavior of two diamine aromatic epoxy pre-polymers (DAEPs) namely, N1,N1,N2,N2-tetrakis (oxiran-2-ylmethyl) benzene-1,2-diamine (DAEP1) and 4-methyl-N1,N1,N2,N2-tetrakis (oxiran-2-ylmethyl) benzene-1,2-diamine (DAEP2) for carbon steel corrosion in acidic medium. Synthesized DAEPs were characterized using spectral (Nuclear magnetic resonance (1H NMR) and Fourier transform infrared-attenuated total reflection (FTIR-ATR)) techniques. Viscosity studies carried out at four different temperatures (20-80 °C) increase in temperature causes significant reduction in their viscosities. The anticorrosive properties of DAEPs differing in the nature of substituents, for carbon steel corrosion in 1 M HCl solution was evaluated using several experimental and computational techniques. Both experimental and computational studies showed that inhibitor (DAEP2) that contains electron releasing methyl (-CH3) showed higher protectiveness as compared to the inhibitor (DAEP1) without substituent (-H). Electrochemical results demonstrate that DAEPs act as reasonably good inhibitors for carbon steel in 1 M HCl medium and their effectiveness followed the sequence: DAEP2 (92.9%) > DAEP1 (91.7%). The PDP results show that the diamine aromatic epoxy pre-polymers molecules (DAEPs) act as mixed type inhibitors. Electrochemical study was also supported using scanning electron microscopy (SEM) method were significant improvement in the surface morphology of inhibited (by DAEPs) metallic specimens was obtained. Results derived from computational density functional theory (DFT) and molecular dynamics (MD) simulationsand studies were consistent with the experimental results derived from SEM, EIS and PDP electrochemical studies. Adsorption of the DAEPs obeyed the Langmuir adsorption isotherm model.