Decabromobiphenyl oxide–aluminum hydroxide system as a flame retardant for styrene–butadiene rubber

Styrene–butadiene rubber (SBR) was treated with decabromobiphenyl oxide (DBBO) and/or aluminum hydroxide [Al(OH)₃] as a flame retardant. The flammability of the resulting system was determined by the limiting oxygen index method. The effect of the added flame retardants on the maximum torque (MH), curing rate, and tensile properties was also evaluated. The results showed, particularly, that DBBO was a more effective flame retardant than was Al(OH)₃. On the other hand, this brominated compound reduced the modulus of elasticity while its effect on the maximum torque was insignificant. Moreover, the addition of DBBO was found to decrease the curing rate of SBR. In contrast, Al(OH)₃ significantly increased the maximum torque and also markedly reduced the modulus of elasticity. Moreover, the effect of the treatment with Al(OH)₃ on the curing rate was found to be insignificant. The flammability measurement of the SBR treated with different mixtures of the two flame retardants indicated that the two compounds reacted slightly antagonistically. The addition of Al(OH)₃ to DBBO in a mixture that was applied to SBR remedied some negative impacts on the mechanical properties when DBBO was added separately to the rubber. The value of the maximum torque of SBR increased and the curing rate slightly increased as well. Meanwhile, the values of the modulus of elasticity were not affected. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 2134–2139, 2000     

On the positioning of revolute‐joint robot manipulators

A new technique is introduced for obtaining the sets of joint‐motor‐displacements which correspond to a desired spatial pose at the end‐effector of a revolute‐joint manipulator. The properties of rotation are exploited and a new local coordinate notation is introduced to obtain the required solution. The proposed technique leads to two simplified sets of linear equations which correspond to the kinematic behavior of both the arm and the wrist. These two sets of equations have been manipulated further to obtain polynomial solutions for both manipulator structures. © 2000 John Wiley & Sons, Inc.     

High‐performance flexible epoxy/ZnO nanocomposites with enhanced mechanical and thermal properties

Flexible epoxy/ZnO nanocomposites were prepared using different loadings of ZnO nanoparticles (NPs) and nanotubes (NTs) via in situ curing of epoxy with polyoxyethylene diamines (ED₆₀₀). ZnO precursor was synthesized via precipitation method and ZnO NPs with an average size of 25 nm were used in the preparation of the nanocomposites. ZnO NTs with an average outer diameter, length of 200 nm and 2.4 µm respectively, were prepared by the wet method (hydrothermal method). The morphology, structure, and composition of the nanocomposites were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FT‐IR), and thermo‐gravimetric analysis (TGA). The effect of morphology and content of nano‐ZnO materials on the thermal and mechanical properties of flexible epoxy was studied. In addition, the hardness and indentation depth were calculated by means of nanoindentation. Results showed that the mechanical and thermal properties of flexible epoxy were enhanced by incorporation of ZnO nanostructure into the polymer matrix. POLYM. ENG. SCI., 57:932–946, 2017. © 2016 Society of Plastics Engineers     

Antimicrobial evaluation of novel buccoadhesive films containing Myrrh extract

This study describes the formulation of new buccoadhesive films containing Myrrh extract as a natural and safe antimicrobial agent to give a long local medication. Buccoadhesive films of Myrrh extract were developed using solvent evaporation technique. The fabricated Myrrh extract films were evaluated for their palatability, weight, surface pH, and their content uniformity. In addition, tensile strength and the percentage of elongation of the films as well as in vitro mucoadhesive time were determined. Also, the films were tested for their antimicrobial activities. Obtained results showed that the tested films are elegant in appearance and have neutral pH, palatable by volunteers and have good tensile strength and elasticity. They also exhibited antibacterial activities against different types of bacterial strains as well as antifungal activity against Candida albicans.     

Effect of Solvent,Preheating Temperature,and Time on the Ultrasonic Extraction of Phenolic Compounds from Cold‐Pressed Hempseed Cake

The effect of different solvents (aqueous methanol [70%, v/v], aqueous acetone [80%, v/v], and a solvent mixture [MA] of aqueous methanol [70%, v/v] and aqueous acetone [70%, v/v] in a ratio of 1:1 [v/v]), preheating temperatures (140, 160, and 180°C), and times of exposure (5, 15, and 30 min) on the ultrasonic extraction of the main phenolic compounds from hempseed cake (Cannabis sativa) was investigated. A simplified new high‐performance liquid chromatography (HPLC) method was developed to identify and quantify the main phenolics (namely, N‐trans‐caffeoyltyramine and cannabisin B) in the extracts. Two other main compounds, numbered 3 and 4 , were also detected. The results showed that the nature of the extracting solvent had a significant (P < 0.05) impact on the ultrasonic extraction of phenolic compounds. The acetone extracts exhibited the highest total phenolic content (TPC), followed by MA and methanol. The preheating temperature and time of exposure enhanced the TPC for all solvents examined. The main phenolics, N‐trans‐caffeoyltyramine, cannabisin B, and compound 3 , were positively affected by the temperature and time of exposure, irrespective of the solvents used. In sharp contrast, compound 4 appeared to be thermally sensitive: increasing preheating time and temperature decreased the yields of this compound. This study demonstrated that acetone was the most effective extracting solvent and that preheating enhanced the yield of the main phenolics.     

Facile synthesis of novel 6-methyl-5-phenyl-2-sulfido-1,2,3,5-tetrahydro-4H[1,2] oxazolo[4′,5′:5,6]pyrano[2,3-d][1,3,2]diazaphosphinines

A number of 6-methyl-5-phenyl-2-sulfido-1,2,3,5-tetrahydro-4H[1,2]oxazolo[4′,5′: 5,6]pyrano[2,3-d][1,3,2]diazaphosphinines 4–11 were synthesized via an interaction of tetraphosphorus decasulfide and Lawesson’s reagent under different conditions with 6-amino-3-methyl-4-phenyl-4H-pyrano[3,2-d][1,2]oxazole-5-carbonitrile (3). The reaction mechanisms for these products were discussed. Structures of the newly synthesized products were established on the basis of elemental analysis and spectral data.     

Towards superior permeability and antifouling performance of sulfonated polyethersulfone ultrafiltration membranes modified with sulfopropyl methacrylate functionalized SBA-15

A non-solvent induced phase separation (NIPS) process was used to fabricate a series of sulfonated polyethersulfone (SPES) membranes blending with different concentrations of SBA-15-g-PSPA with the applications in the ultrafiltration (UF) process. SBA-15 was modified with 3-methacrylate-propyltrimethoxysilane (MPS) to form SBA-15-g-MPS. It was further modified with the charge tailorable polymer chains by reacting with 3-sulfopropyl methacrylate potassium salt. The nanoparticles were uniformly dispersed and finger-like channels were developed within the membrane. The adding of surface modified SBA-15-g-PSPA nanoparticles has significantly improved membrane water permeability, hydrophilicity, and antifouling properties. The pure water fluxes of the composite SPES membranes were significantly higher than the pristine SPES membrane. For the membrane containing 5% (mass) of SBA-15-g-PSPA (MSSPA5), the pure water flux was increased dramatically to 402.15 L·m^-2·h^-1, which is ~1.5 times that of MSSPA0 (268.0 L·m^-2·h^-1). The high flux rate was achieved with 3% (mass) of SBA-15 nanoparticles with retained high rejection ratio 98% for natural organic matter. The results indicate that the fashioned composite membrane comprising SBA-15-g-PSPA nanoparticles have a promising future in ultrafiltration applications.     

Role of exergy in increasing efficiency and sustainability and reducing environmental impact

The use of exergy is described as a measure for identifying and explaining the benefits of sustainable energy and technologies, so the benefits can be clearly understood and appreciated by experts and non-experts alike, and the utilization of sustainable energy and technologies can be increased. Exergy can be used to assess and improve energy systems, and can help better understand the benefits of utilizing green energy by providing more useful and meaningful information than energy provides. Exergy clearly identifies efficiency improvements and reductions in thermodynamic losses attributable to more sustainable technologies. A new sustainability index is developed as a measure of how exergy efficiency affects sustainable development. Exergy can also identify better than energy the environmental benefits and economics of energy technologies. The results suggest that exergy should be utilized by engineers and scientists, as well as decision and policy makers, involved in green energy and technologies in tandem with other objectives and constraints.     

Blending of natural rubber with linear low-density polyethylene

Blends of natural rubber (NR) with linear low-density polyethylene (LLDPE) were prepared by melt blending of the materials in a plasticorder mixer at various temperatures around the melting point of LLDPE and at various mixing rates. The optimum processing conditions were a temperature of about 135°C and a mixing rate of 55 rpm. The tensile properties, stress and strain, of the blend had improved significantly with the addition of liquid natural rubber (LNR) into the blend. For blends with compositions around 50% NR, about 10–15% LNR produced the most significant improvement in the physical properties. Welldispersed plastic particles in a rubber matrix were strongly indicated in these samples. Scanning electron micrographs (SEM) of the samples also indicated an increase in the homogeneity of the mixes with the addition of LNR. A single glass transition temperature of about?55°C for the blend was observed via dynamic mechanical analysis (DMA). Interfacial linking between the NR and LLDPE phases was attributed to the presence of active groups on the polyisoprene chain of LNR, which induced the interphase reaction between the NR and LLDPE phases. © 1995 John Wiley & Sons, Inc.     

Molecular Weight Determination of Palm Olein Polyols by Gel Permeation Chromatography Using Polyether Polyols Calibration

Natural oil polyols have been intensively developed and successfully used for the production of various polymers, notably polyurethanes. The need to access the average molecular weight (MW) and the MW distribution (MWD) has led to the efforts to have a precise and reliable determination method. A series of commercial polyether polyols, with well‐defined MW, was used as a gel permeation chromatography (GPC) calibration standard to determine the MW of palm olein polyols. This GPC analysis was compared to the one calibrated against the commercially available polystyrene (PS) standards and to the number‐average molecular weight (M_n) obtained via vapor pressure osmometry (VPO) technique. For example, the M_n obtained for palm olein polyol E‐135 calibrated against polyether polyols was 2,537 Da, which was closer to the M_n via VPO (1,618 Da), than the M_n obtained using PS as calibration standards (3,836 Da). Hence, this GPC analysis using polyether polyols as calibration standards can offer reassured determination of MWD of palm olein polyols.