Generalized fractional magneto-thermo-viscoelasticity

The new model of the equations of the linear theory of magneto-thermo-viscoelasticity with two relaxation times and fractional heat transfer involving fractional relaxation operator is given. The resulting formulation is applied to thermal shock problems for a perfect electrically conducting half-space in the presence of a transverse magnetic field. Laplace transform techniques are used. Some essential theorems on the linear coupled and generalized theories of thermo-viscoelasticity with two relaxation times are established. According to the numerical results and its graphs, conclusion about the new theory has been constructed. The effects of the fractional relaxation operator on viscoelastic material like poly (methyl methacrylate) (Perspex) are discussed.

     

Chemical transformation of pet waste through glycolysis

PET bottle grade material makes up a significant portion of the feedstock in plastics recycling. Theoretically, there are many end users however there are few applications for less purified grades of recycled PET. The current work is aiming to investigate the transformation of recycled PET into its chemical building blocks using glycolysis to produce unsaturated polyester resin. In this regard, PET waste has been collected from different sources, mainly, beverages and bottled water. Chemical transformation has been achieved through degrading glycolysis reaction with different glycols namely, propylene glycol, diethylene glycol, triethylene glycol and mixture of diethylene glycol with propylene glycol or triethylene glycol in equal amounts. The glycolized products have been converted into unsaturated polyester (UP) after the reaction with maleic anhydride. Finally, styrene was added as a crosslinker and the obtained UP has been characterized. Factors affecting the curing process of the obtained unsaturated polyester resin have been investigated.     

Phenyl urea derivatives as organic stabilizers for rigid poly(vinyl chloride) against photo‐degradation

Phenyl urea derivatives have been prepared and investigated as photostabilizers for rigid PVC by measuring the extent of weight loss (%), the amount of gel formation as well as the intrinsic viscosity of the soluble fractions of the degraded polymer. Moreover, the efficiency of these stabilizers was evaluated from the extent of discoloration of the degraded polymer in their presence. The results indicated a reasonable stabilizing effect of these derivatives when compared with the commercially used UV stabilizers: phenyl salicylate (Salol) and methanone, 2‐hydroxy‐4‐(octyloxy)‐phenyl‐benzophenone. A synergistic effect is achieved when the phenyl urea derivatives are mixed with the UV absorbers in the ratio (75 : 25%), respectively. A radical mechanism is proposed to account for the stabilizing action of the products investigated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2217–2226, 2007     

STATE-SPACE FORMULATION TO GENERALIZED THERMOVISCOELASTICITY WITH THERMAL RELAXATION

The model of the equation of generalized thermoviscoelasticity with one relaxation time is established. The state-space formulation for these equations is introduced. The formulation is valid for problems with or without heat sources. The resulting formulation together with the Laplace transform technique is applied to a variety of problems. The solutions to a thermal shock problem and to a problem of layer media, both without heat sources, are obtained. Also, the effects of a plane distribution of heat sources on the whole and semi-space are studied. A numerical method is employed for the inversion of the Laplace transforms. Numerical results are given and illustrated graphically for each problem. Comparisons are made with the results predicted by the coupled theory.     

Equilibrium studies of ternary systems containing some selected transition metal ions, triazoles and aromatic carboxylic acids

Solution equilibria of the binary and ternary complex systems of the divalent transition metal ions Cu²⁺, Ni²⁺, Zn²⁺, and Co²⁺ with 1,2,4-triazole (TRZ), 3-mercapto-1,2,4-triazole (TRZSH), and 3-amino-1,2,4-triazole (TRZAM) and aromatic carboxylic acids (phthalic, anthranilic, salicylic, and 5-sulfosalicylic acid) have been studied pH-metrically at (25.0±0.1) °C, and a constant ionic strength I=1×10^?1 mol L^?1 NaNO₃ in an aqueous medium. The potentiometric titration curves show that binary and ternary complexes of these ligands are formed in solution. The stability constants of the different binary and ternary complexes formed were calculated on the basis of computer analysis of the titration data. The relative stability of the different ternary complex species is expressed in terms of Δ log K values, log X and R. S.% parameters. The effect of temperature of the medium on both the proton-ligand equilibria for TRZAM and phthalic acid and their metal-ligand equilibria with Cu²⁺, Ni²⁺, and Co²⁺ has been studied along with the corresponding thermodynamic parameters. The complexation behavior of ternary complexes is ascertained using conductivity measurements. In addition, the formation of ternary complexes in solution has been confirmed by using UV-visible spectrophotometry.     

Grafting of Methacrylic Acid and Other Vinyl Monomers Onto Cotton Fabric Using Ce (IV) Ion–Cellulose Thiocarbonate Redox System

Graft copolymerization of methacrylic acid (MAA) onto cotton fabric using tetravalent ceric ion (Ce^IV)–cellulose thiocarbonate redox system was investigated under different conditions including pH of the polymerization medium (1–4), ceric sulphate (CS) concentration (4–20 m mole/l), MAA concentration (1%–6%), polymerization time (1/4–2 h) and polymerization temperature (0–70°C). Results obtained indicated that the optimal conditions for MAA grafting onto cotton fabric using the said redox system consisted of: [CS], 20 m mole/l; [MAA], 4%; pH of the medium, 2; time, 2 h; temperature, 60 °C keeping a material-to-liquor ratio at 1:0. Applying optimized conditions to different monomers, namely, acrylic acid (AA), methacrylic acid (MAA), acrylamide (Aam), acrylonitrile (AN), butyl acrylate (BuA), methyl methacrylate (MMA), ethyl methacrylate (EMA) and glycidyl methacrylate (GMA) onto the same substrate, the rates of grafting followed the order: