The cationic nickel(II) complexes [(η-C3H5)Ni(SbPh3)2][B(3,5-(CF3)2C6H3)4] (2) and [(η3C3H5)Ni(SbPh3)2][Al(OC(CF3)3)4] (3) were prepared and their polymerization activities in aqueous systems were compared with [(η-C3H5)Ni(η-BHT)][B(3,5-(CF3)2C6H3)4] (1) (BHT ) 3,5-di-tert-butyl-4-hydroxytoluene). Cispolybutadiene is formed in nonaqueous solution polymerization. The presence of water decreases ...

Mechanical properties of products produced with the Fused Deposition Modeling (FDM) process are known to be dependent on bead direction, especially when short fiber reinforcement is added to the polymer filament feedstock. As a result, the structural performance of fiber-filled FDM parts is expected to be improved by simultaneously computing preferred deposition directions while optimizing the ...

The ability to control wave propagation in highly deformable layered media with elastic instability-induced wrinkling of interfacial layers is presented. The onset of a wrinkling instability in initially straight interfacial layers occurs when a critical compressive strain is achieved. Further compression beyond the critical strain leads to an increase in the wrinkle amplitude of the interfacia...

Unstabilised bisphenol A polycarbonate samples were aged under UV radiation for periods of up to 3000 hours. The samples were then characterised using FTIR/ATR, GPC, SEM, microscopy, light transmission and colour changes. The changes in optical properties were related back to the changes in the polymer microstructure and composition. In this study, the molecular weight of polycarbonate was seen...

Unlike conventional Polymer Optical Fibre (POF), single -mode Microstructured Polymer Optical Fibre (MPOF) can easily be fabricated, as required for many nonlinear applications. It was demonstrated that tungsten electrodes for poling and measuring the electro -optic coefficient could be incorporated in the PMMA fibre during the draw process. Lengths of up to 70m of this fibre were produced. For...

a key parameter for the application of polymer gels in water shut off treatment is the adsorption of polymer gel onto the rock surface. so, the adsorption properties of a nanocomposite hydrogel were discussed in this research by crosslinking of sulfonated polyacrylamide/sodium montmorillonite aqueous solutions with chromium triacetate. the x-ray diffraction patterns indicated that exfoliated ty...

Albert J. van Reenen and Omar Sultan Department of Chemistry and Polymer Science, University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa Reprint requests to Dr. A. J. van Reenen. Fax: +27-21-8084967. E-mail: [email protected] Z. Naturforsch. 2007, 62b, 362 – 366; received November 1, 2006 Dedicated to Prof. Helgard G. Raubenheimer on the occasion of his 65th birthday TwoC2-symmet...

Guide regeneration techniques have been recently used to heal soft and hard tissue defects. In this approach, scaffolding plays an important role. Hydroxypatite (HA) resembles the natural bone mineral and has shown good bone bonding properties. In this work, porous polyurethanes have been prepared by a thermally induced phase separation technique. Freeze drying of the separated polymer/solvent ...

Unique properties of nanohybrid composites based on different types of porous polymer matrices doped with fluorescent nanoparticles (quantum dots, QDs) are determined by the combination of the mechanical properties of the host matrix (flexibility, chemical stability, etc.) and a high luminescence intensity and extreme stability of QDs. Here, we report on the preparation, optical and microstruct...

Polymers are the products of processes and their microstructure can be changed significantly by the reactor systems employed, especially for nonlinear polymers. The Monte Carlo simulation technique, based on the random sampling technique, is used to explore the effect of reactor types on the branched polymer structure, formed through free-radical polymerization with simultaneous long-chain bran...