Comparison of the role of new ethers and conventional alkoxysilanes as external donors in the polymerization of propylene using the industrial Ziegler-Natta catalyst

Two new ethers were synthesized using the Williamson reaction from related alcohols and were used as external donors in propylene polymerization in the presence of the industrial diisobutyl phthalate-based MgCl₂-supported Ziegler-Natta catalyst. For comparison the propylene polymerization was carried out in the presence of silane and in the absence of external donors. The produced polymers were characterized by differential scanning calorimetry, xylene extraction, melt flow index, scanning electron microscopy and gel permeation chromatography. The isotacticity, molecular weight and molecular weight distribution, melt flow index, crystallinity degree and thermal properties of polypropylenes were influenced by the type of external donors.     

Stress distribution and hillock formation in Au/Pd thin films as a function of aging treatment in capacitor applications

Effect of quenching in different media on hillock formation and electrical resistivity has been studied in the Au–Pd layers. Oxygen was released from substrate due to substrate relaxation process. It was suggested that hillocks appear on the triple junction grain boundaries. However, lower electrical resistivity has been seen in the sample which quenched in the air. It was concluded that grain boundary scattering decreases the conductivity of the quenched films due to higher density of dislocations.     

Subpeaks in the Brillouin loss spectra of distributed fiber-optic sensors

Subpeaks in the Brillouin loss spectra of distributed fiber-optic sensors were observed for what is believed to be the first time and studied. We discovered that the Fourier spectrum of the pulsed signal and the off-resonance oscillation both contributed to subpeaks. The off-resonance oscillation at frequency /v - vB/ is the oscillation in the Brillouin time domain when beat frequency v of the two counterpropagating laser beams does not match local Brillouin frequency vB. This study is important in differentiating the subpeaks from actual strain-temperature peaks.     

Polytetrafluoroethylene Sputtered PES Membranes for Membrane Distillation: Influence of RF Magnetron Sputtering Conditions

Thin films of fluorocarbon were deposited on polyethersulfone membranes via argon plasma sputtering of a poly(tetrafluoroethylene) (PTFE) target in an RF magnetron plasma reactor. The obtained deposited ultrathin coatings had nanoscale roughnesses and high degrees of fluorination. The intensity of fluorine atom in plasma environment during fluorocarbon deposition was investigated. Depending on the deposition conditions comprising working gas pressure, applied RF power, and distance between the target and the substrate, polymeric films with different chemical compositions and/or morphologies were obtained. The morphologies of the films were analyzed by means of SEM, XPS, and AFM. The results suggested that the sputtered film deposited at a higher pressure and longer target–substrate distance and moderate RF power had a surface composition and chemical structure closer to those of the PTFE film. The treated hydrophobic PES membranes with water contact angles as high as 115° were applied for the first time in an air gap membrane distillation setup for removal of benzene as a volatile organic compound from water. The results showed that the plasma-treated membranes have a comparable or superior performance to that of commercial PTFE used in membrane distillation with similar permeate flux and separation factor after 20 h long term performance.     

Fiber optic-linear array detection spectrophotometry in combination with dispersive liquid-liquid microextraction for preconcentration and determination of copper

In this research, simple, rapid and efficient method, dispersive liquid-liquid microextraction (DLLME) combined fiber optic -linear array detection spectrophotometry (FO-LADS) was developed using a cylindrical micro-cell for preconcentration and determination of Cu(II) in samples. DLLME and FO-LADS methods have good matching conditions for being combined since FO-LADS is a suitable method for the determination of analytes in low volume of the remained phase obtained after DLLME. Molar absorptivity of complex Cu with (4-benzylp iperidineditiocarbamate potassium salt) (BPDC) was determined as 2.75 × 10⁴ L mol^-1 cm^-1 at 7nmax = 436 nm. Under the optimum conditions the calibration graph was linear in the rage of 2–70 fug L^-1 with detection limit of 0.34 fug L^-1. The proposed procedure was successfully applied to the determination of Cu(II) in real water samples and human urine sample.