Syntheses and Electrochemistry of Monosubstituted Carbonyl Complexes of Low Valent Ruthenium

The reactions of Ph2MeP and PhMe2P with (PPh3)4RuCl2 yield (PPh2Me)4RuCl2 and (PPhMe2)4RuCl2, respectively. These complexes have been shown by conductivity studies to be dissociated in acetonitrile and exist as [(PPh2Me)4RuCl(CH3CN)]Cl and [(PPhMe2)4RuCl(CH3CN)]Cl. When carbon monoxide was bubbled into these solutions, monocarbonyl complexes were obtained. Elemental analyses, 1H NMR, 31P NMR, infrared spectroscopy, conductivity measurements, and polarography were used to analyse the products, (PPh2Me)2RuCO(CH3CN)Cl2 and (PPhMe2)3RuCOCl2. The structures of the complexes were elucidated and in each case two phosphine ligands were trans and two chloride ligands were cis. Conductivity measurements established that the chloride ligands remain coordinated in acetonitrile. The redox properties of (PPh2Me)4RuCl2, (PPhMe2)4RuCl2, (PPh2Me)2RuCO(CH3CN)Cl2 and (PPhMe2)3RuCOCl2 in acetonitrile indicated that these compounds were reduced irreversibly with the uptake of two electrons. Phosphine ligand exchange with the solvent led to the presence of at least two electroactive species in solution. The exchange of phosphine ligands decreased the ease of the reduction of the complexes by 300- 350 mV. The half-wave potentials in solution indicate that the electron density around the metal was not changed appreciably by substituting PPh2Me and PPhMe2. Attempts to reduce (PPh2Me)2RuCO(CH3CN)Cl2 and (PPhMe2)3RuCOCl2 with 1 % Na-Hg amalagam yielded mixtures of compounds that appeared as a brown powder and an intractable oil, respectively. Characterization of these zerovalent products was not accomplished. The electrochemical synthesis of (PPh3)4Ru(η2-CH3CN)⋅CH3CN was carried out electrochemically. When the complex was heated under reflux in hexane, an air-sensitive unsaturated compound, identified as (PPh3)4Ru was obtained. The exact nature of the complex was not established

Syntheses and Electrochemistry of Monosubstituted Carbonyl Complexes of Low Valent Ruthenium

The reactions of Ph2MeP and PhMe2P with (PPh3)4RuCl2 yield (PPh2Me)4RuCl2 and (PPhMe2)4RuCl2, respectively. These complexes have been shown by conductivity studies to be dissociated in acetonitrile and exist as [(PPh2Me)4RuCl(CH3CN)]Cl and [(PPhMe2)4RuCl(CH3CN)]Cl. When carbon monoxide was bubbled into these solutions, monocarbonyl complexes were obtained. Elemental analyses, 1H NMR, 31P NMR, infrared spectroscopy, conductivity measurements, and polarography were used to analyse the products, (PPh2Me)2RuCO(CH3CN)Cl2 and (PPhMe2)3RuCOCl2. The structures of the complexes were elucidated and in each case two phosphine ligands were trans and two chloride ligands were cis. Conductivity measurements established that the chloride ligands remain coordinated in acetonitrile. The redox properties of (PPh2Me)4RuCl2, (PPhMe2)4RuCl2, (PPh2Me)2RuCO(CH3CN)Cl2 and (PPhMe2)3RuCOCl2 in acetonitrile indicated that these compounds were reduced irreversibly with the uptake of two electrons. Phosphine ligand exchange with the solvent led to the presence of at least two electroactive species in solution. The exchange of phosphine ligands decreased the ease of the reduction of the complexes by 300- 350 mV. The half-wave potentials in solution indicate that the electron density around the metal was not changed appreciably by substituting PPh2Me and PPhMe2. Attempts to reduce (PPh2Me)2RuCO(CH3CN)Cl2 and (PPhMe2)3RuCOCl2 with 1 % Na-Hg amalagam yielded mixtures of compounds that appeared as a brown powder and an intractable oil, respectively. Characterization of these zerovalent products was not accomplished. The electrochemical synthesis of (PPh3)4Ru(η2-CH3CN)⋅CH3CN was carried out electrochemically. When the complex was heated under reflux in hexane, an air-sensitive unsaturated compound, identified as (PPh3)4Ru was obtained. The exact nature of the complex was not established

Effect of fiber length on thermomechanical properties of short carbon fiber reinforced polypropylene composites

Carbon fiber reinforced composites have all the ideal properties, leading to their rapid development and successful use for many applications over the last decade. In this paper, short carbon fiber reinforced polypropylene (SCF/PP) composite were prepared with melt blending and hot-pressing techniques. The thermomechanical properties of this composite were investigated taking into account the combined effect of mean fiber length. Thermal stability of the composite was studied via the thermal gravimetric analysis (TGA) and dynamic mechanical analysis (DMA) was used to measure the damping properties of the composites. Finally it can be shown that an increase in fiber length can enhance the thermal stability of SCF/PP composites and improve the damping properties as well

Effect of fiber treatment on mechanical properties of kenaf fiber-ecoflex composites

The composite material based on whole stem kenaf fiber (WSK) and Ecoflex (biodegradable thermoplastic) were prepared by melt blending technique and characterized. The composites were prepared using different fiber loadings and the fiber was treated with various concentrations of NaOH solution by soaking for 3 h. The compounding of composite were carried out at different fiber loadings (10%, 20%, 30%, 40%, 50%) using Brabender internal mixer at 130°C for 10 min. The composites were then pressed using compression molding to produce biodegradable kenaf/Ecoflex sheets. The effects of kenaf fiber loading and NaOH treatment of WSK fiber surface on mechanical properties was examined. The results showed that 40% fiber loading improved the tensile strength properties and WSK fiber treated with 4% NaOH was found to enhance tensile and flexural properties compared with untreated fiber. The FTIR characterization showed that alkali treatment removes hemicellulose and lignin from WSK kenaf fiber surface

A review on nano fibre technology in polymer composites

The enormous attention and interest by both academics and industrial field for greener, biodegradable and renewable materials implicate a persuasive trends towards the encroachment of nano-materials science and technology in the polymer composite field. Nanocomposites creates high impacts on the development of nano materials with advanced features to solve potential risks with their wider industrial applications. Nano fibres are highly engineered fibres with diameters less than 100 nm that offer several advantages over conventional fibres. One dimensional (1D) nanostructure fillers such as carbon nanofibre and cellulose nanofibre are the most common, promising and unique for developing multifunctional nanocomposites with better properties and extensive applications compared to micro size fibres. Nano fibre technology brings revolution by providing products that are completely safe, truly greener, reliable and environmentally friendly for industries, researchers and users. This review article is intended to present valuable literature data on research and trend in the fields of carbon and cellulose nano fiber, nanocomposites with specific focus on various applications for a sustainable and greener environment

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

Morphology, thermal and mechanical properties of biodegradable poly(butylene succinate)/poly(butylene adipate-co-terephthalate)/clay nanocomposites

Sodium montmorillonite (Na-MMT) was successfully modified by octadecylamine (ODA) through a cation exchange technique that showed by the increased of basal spacing of clay by XRD. The addition of the organoclay into the PBS/PBAT blends produced intercalated-type nanocomposites with improvements in tensile modulus and strength. The highest tensile strength of nanocomposite was observed at 1 wt% of organoclay incorporated. A TGA study showed that the thermal stability of the blend increased after the addition of the organoclay by 1 wt%. SEM micrographs of the fracture surfaces show that the morphology of the blend becomes smoother with presence of organoclay

Enhancement of tensile strength and flexibility of Polycaprolactone/Tapioca starch blends by Octadecylamine modified clay.

Polycaprolactone/tapioca starch/octadecylamine modified clay (OMMT) nanocomposites were successfully prepared by melt blending. X-ray diffraction and transmission electron microscopy (TEM) of the products showed that they are nanocomposites of a mixture intercalated and exfoliated types. In addition, the TEM also revealed that the OMMTlayers are homogeneously distributed in the polymer matrix. The presence of 1 php of OMMT improved the compatibility of the polymers in the blends which consequently increased the tensile strength of the blend of more than 60% and elongation at break of more than 1,000%

Fabrication of epoxy nanocomposites from oil palm nano filler: mechanical and morphological properties

The aim of this research was to fabricate epoxy nanocomposites by utilizing the developed nano filler from oil palm mills agricultural wastes oil palm empty fruit bunch (OPEFB) fibers for advanced applications. Epoxy-based polymer nanocomposites were prepared by dispersing 1, 3, and 5 wt. % nano OPEFB filler by using a high speed mechanical stirrer through hand lay-up technique. The mechanical (tensile and impact) properties and morphological properties of nano OPEFB/epoxy nanocomposites were examined and compared. Morphological properties were analyzed by transmission electron microscopy (TEM) and scanning electron microscopy (SEM) to look at the dispersion of the nano OPEFB filler in the epoxy matrix. The tensile and impact properties of nanocomposites increased until 3% nano filler loading, but beyond 3% they decreased. Overall mechanical properties reached maximum values for 3% loading, due to better stress transfer owing to homogenous dispersion of nano OPEFB filler within epoxy matrix. The observed results were also confirmed by SEM and TEM micrographs