Studying Reactivity Relationships of Copolymers N-naphthylacrylamide with (Acrylicacid and Methylacrylate)

            The organation ⁄monomer N-naphthylacrylamide (NAA) was prepared; subsequently the synthesized monomer was successfully copolymerized with acrylicacid (AA) and methylacrylate (MA) by free radical technique using dry benzene as solvent and benzoyl peroxide (BPO) as initiator. The overall conversion was kept low (≤ 10% wt/wt) for all studies copolymers samples. The synthesized monomer and copolymers were characterized using Fourier transform infrared spectroscopy (FT-IR), and their thermal properties were studied by DSC and TGA. The copolymers compositions were determined by elemental analysis. Kelen-Tudes and Finmman-Ross graphical procedures were employed to determine the monomers reactivity ratios. The derived reactivity ratios (r1, r2) are: (0.048, 0.687) for (NAA-co-AA) and (0.066, 0.346) for (NAA-co-MA). Based on the average reactivity ratios, sequence distribution of monomers in the copolymers and the microstructure of copolymers were calculated by statistical method and found that these values are in agreement with the derived reactivity ratios

Synthesis and properties of vinylpyrrolidone / (trimethoxysilyl) propyl methacrylate gels containing different amounts of crosslinking agent

High conversion copolymers containing 90 wt % of N-vinylpyrrolidone (NVP) and 10 wt % of 3-(trimethoxysilyl)propyl methacrylate (TMSPM) with 0, 1, 2, 3 and 4 wt % (in conversion to mass of NVP/TMSPM) of ethylene glycoldimethacrylate (EGDMA) as crosslinker have been successfully synthesized. Proton nuclear magnetic resonance (1H NMR) and Fourier transform infrared spectroscopy (FT-IR) were employed to characterize the resulting copolymers. The effect of EGDMA amount on the mechanical and thermal properties, swelling parameters, clarity, and oxygen permeability of the prepared xerogels and hydrogels were studied. 3 wt % of EGDMA is required to obtain clear xerogels and hydrogels. The water content (EWC), volume fraction of polymer (φ2) and weight loss during swelling decrease with increasing EGDMA content. Young’s and shear modulus (E and G) increase as EGDMA content increases, the values of E and G are 0.570–3.531 MPa and 0.217–1.359 MPa, respectively. The hydrogels were characterized in terms of modulus crosslinking density (ve and vt) and polymer-solvent interaction parameters (χ). The results are 0.220–0.613 mol/dm3 for ve, 0.105–0.441 mol/dm3 for vt, and 0.595–0.822 for χ. Thermal properties enhance by adding EGDMA whereas the oxygen permeability (P) of hydrogels decreases from 48.6 to 44.3 as water content decrease from 70.3 to 55.1

Synthesis of Multifunctional Polymers Based on Tert-Butyl Acrylamide/Octyl Acrylate as Lubricant Additives and Adsorbents for Copper Ion from Aqueous Solution

تحضير بوليمرات متعددة الوظائف مشتقة من البيوتيل اكريلامايد والاوكتيل اكريلات كمضافات لزيوت التشحيم وممتزات لايون النحاس من المحلول المائيTwo homopolymeric and three copolymeric additives for base oil were synthesized using octyl acrylate (OA) and tert-butyl acrylamide (TBA) monomers. The two additives named P1 and P2 are the homopolymers of TBA and OA, respectively, whereas copolymeric additives named Co1, Co2, and Co3 were synthesized by varying the ratios of TBA:OA as 1:3, 3:1 and 1:1, respectively. The prepared polymers were characterized by Fourier Transform Infrared (FTIR). Based on the solubility of synthesized polymers in base oil and reactivity ratios of TBA/OA copolymer (0.222, 0.434) calculated by Fineman-Ross method, P2, Co1, Co2 and Co3 were selected to evaluate their performance as pour point depressant (PPD), viscosity improver (VII), and anticorrosion additives in base oil. Additives P2 and Co1 showed the best performance as (PPD) and (VII) whereas Co2 and Co3 revealed the best performance as anticorrosion additives. The flash point of base oil increased as a concentration of polymeric additives increased in the base oil. In addition to study the performance of synthesized polymers as lubricant additives, the capability of polymers for removing CuII from synthetic wastewater was also investigated. Different parameters such as pH of solution, contact time, and CuII concentration were changed in order to study their effect on adsorption capacity of polymers. Generally, polymers with high TBA content such as P1, Co2, and Co3 showed good performance in removing CuII

Radical Polymerization Kinetics of Hexyl Methacrylate in Dimethylsulfoxide Solution

In this study, we conducted a series of polymerization studies of hexyl methacrylate in dimethyl sulfoxide with (0.1 - 0.4) mol dm-3 of monomer and (1 10-3 – 4 10-3) mol dm-3 of benzoyl peroxide as initiators at 70 °C. Using the well-known conversion vs. time technique, the effects of initiator and monomer concentration on the rate of polymerization (Rp) were studied. An initiator of order 0.35 was obtained in accordance with theory and a divergence from normal kinetics was detected with an order of 1.53 with respect to monomer concentration. The activation energy was determined to be (72.90) kJ mol-1, which does not correspond to the value of most thermally initiated monomers. The observed value of activation energy suggests that propagation and termination reactions have equal activation energy and the difference between them is nearly zero. The average degree of polymerization (DPn) decreased as benzoyl peroxide concentration increase whereas an increase in solvent polarity has slightly increased rate of polymerization value

Geometrically Nonlinear Free Vibration Analysis of Cylindrical Shells Using high Order Shear Deformation Theory-A Finite Element Approach

A nonlinear finite element model for geometrically large amplitude free vibration analysis of laminated composite shallow cylindrical shell panel is presented using high order shear deformation theory (HSDT). The nonlinearity is introduced in the Green – Lagrange sense. The effects of different orthotropic ratios, thickness ratio, curvature ratio and boundary condition are study also frequency ratio (nonlinear frequency to linear frequency) of cylindrical shell are determined as function of shell amplitude ratio

Effect of Crack and Cutout on Vibration Characteristics of A Laminated Composite Plates Using Nonlinear Finite Element Analysis

A nonlinear finite element model for geometrically large amplitude free vibration analysis of composite laminated plate using high order shear deformation theory used in this work. The aim of the study is to analyze the effect of the stationary crack and hole on the free vibration of composite plate those in which the singularity due to presences of crack is modeled, so that stress field at the tip of the crack is properly represented. The results are computed for different crack, hole size, material orthotropy and different boundary condition. Finally the discrepancy of the results was 29.8249% when considered the severe nonlinearity

Vibration Analysis of Laminated Composites Using Experimental and Genetic Algorithms Optimization Technique

In this paper, damage detection for different types of defects (delamination, crackand hole) in the composite laminate plate and cylindrical shell be used to characterizethe vibration behavior experimentally which used two types of load (plus and sineload) to find the frequency response. To this end, some plates and cylindrical shellsare made using hand-lay-up process. Glass fiber is used as a reinforcement in theform of bidirectional fabric and general purpose polyester resin as matrix for thecomposite material of plates and cylindrical shells. From the results, the damagedetection by using the Genetic algorithms is investigated. Also, these experiments areused to validate the results of free vibration obtained from the finite elementsprogram

Enhancement of Polyacrylic Acid/Silicon Carbide Nanocomposites’ Optical Properties for Potential Application in Renewable Energy

Composites made from polymers and nanoparticles have promise to be effective solar collectors and thermal energy storage devices due to benefits including improved thermal characteristics and increased structural stability. This study intends to fabricate polyacrylic acid/silicon carbide (PAA−SiC) nanocomposites and examine the optical properties for use in solar collectors and thermal energy storage (TES) fields. The optical properties of PAA−SiC nanocomposites are investigated within the wavelength between 340 and 840 nm. The findings indicate that an increase in SiC concentration in the PAA aqueous solution to 50 g/L at a wavelength of λ = 400 nm causes an increase in the absorption by 50.2% besides a reduction in transmission by 6%. Furthermore, the energy band gaps were reduced from 3.25 eV to 2.95 eV to allow for the transition, and subsequently reduced from 3.15 eV to 2.9 eV to allow for forbidden transition as a result of the increasing SiC concentration from 12.5 g/L to 50 g/L. The optical factors of energy absorption and optical conductivity were also enhanced with a rising SiC concentration from 12.5 to 50 g/L. Specifically, an improvement of 61% in the melting time of PAA−SiC−H2O nanofluids is concluded. Accordingly, it can be said that the PAA−SiC−H2O nanofluids are suitable for renewable energy and TES systems

Isotherms, kinetics, and thermodynamics of boron adsorption on fibrous polymeric chelator containing glycidol moiety optimized with response surface method

A fibrous boron chelator containing glycidol moiety (PE/PP-g-PVAm-G) was prepared by radiation induced grafting of N-vinylformamide (NVF) onto polyethylene/polypropylene (PE/PP) non-woven sheet followed by hydrolysis and immobilization of glycidol moiety. The glycidol density was controlled by optimization of the reaction parameters using the Box-Behnken design of response surface methodology (RSM). The properties of the PE/PP-g-PVAm-G were evaluated using Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM) and energy dispersive x-ray (EDX) analysis, X-ray diffraction (XRD) and thermal gravimetric analysis (TGA). A maximum glycidol density yield of 5.0 mmol·g−1 was obtained with 11.8 vol%, 78.9 °C and 109.4 min for glycidol concentration, reaction temperature and time, respectively. The isotherms, kinetics, and thermodynamic behavior of boron adsorption on the optimized chelator were investigated. The boron adsorption was pH-dependent and attained a maximum adsorption capacity of 25.7 mg·g−1. The equilibrium isotherm proceeded by Redlich–Peterson model whereas the kinetics was best expressed by the pseudo-second-order equation. The thermodynamic analysis revealed that boron adsorption is endothermic and spontaneous. The fibrous chelator demonstrated high boron selectivity and strong resistance to foreign ions with uncompromised regeneration efficiency after five adsorption/desorption cycles. The PE/PP-g-PVAm-G chelator seems to be very promising for boron removal from aqueous media

α-Mangostin from cratoxylum arborescens (Vahl) blume demonstrates anti-ulcerogenic property : a mechanistic study

Cratoxylum arborescens (Vahl) Blume is an Asian herbal medicine with versatile ethnobiological properties including treatment of gastric ulcer. This study evaluated the antiulcerogenic mechanism(s) of α-mangostin (AM) in a rat model of ulcer. AM is a prenylated xanthone derived through biologically guided fractionation of C. arborescens. Rats were orally pretreated with AM and subsequently exposed to acute gastric lesions induced by ethanol. Following treatment, ulcer index, gastric juice acidity, mucus content, histological and immunohistochemical analyses, glutathione (GSH), malondialdehyde (MDA), nitric oxide (NO), and nonprotein sulfhydryl groups (NP-SH) were evaluated. The anti-Helicobacter pylori, cyclooxygenase-2 (COX-2) inhibitory effect, and antioxidant activity of AM were also investigated in vitro. AM (10 and 30 mg/kg) inhibited significantly (P < 0.05) ethanol-induced gastric lesions by 66.04% and 74.39 %, respectively. The compound induces the expression of Hsp70, restores GSH levels, decreases lipid peroxidation, and inhibits COX-2 activity. The minimum inhibitory concentration (MIC) of AM showed an effective in vitro anti-H. pylori activity. The efficacy of the AM was accomplished safely without presenting any toxicological parameters. The results of the present study indicate that the antioxidant properties and the potent anti-H. pylori, in addition to activation of Hsp70 protein, may contribute to the gastroprotective activity of α-mangostin