Carbon black is commonly used as a filler in the rubber industry. However, it can cause serious damage to human health and to ecosystems. Today, reducing the use of this substance via alternative materials is receiving increased attention. Clay minerals such as montmorillonite can be substituted for carbon black as environmentally friendly fillers for rubber compounds. The uniform dispersion of montmorillonite and its compatibility with the rubber matrix are the main principles for using this material in the rubber industry. To this end, montmorillonite was surface treated with various dosages (1.0, 1.5 and 2.0 wt.%) of polypropylene glycol. The surface-treated montmorillonites were investigated using attenuated total reflection Fourier-transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy and X-ray diffraction analysis. The results indicated that the treatment expanded the interlayer spaces of the montmorillonite and improved surface hydrophobicity. The untreated and treated montmorillonites were used with carbon black as dual fillers in natural rubber/styrene butadiene-based compounds. The cure characteristics, thermal stability, some mechanical properties and dispersion states were evaluated. The curing study indicated a faster optimum cure time, scorch time and increased torque difference for the rubber compounds filled with surface-treated montmorillonites. Thermal analysis of the rubber compounds illustrated that the interval between the initial and final temperature of decomposition could be increased via the treatment. Surface-treated montmorillonite samples, especially the sample containing 1 wt.% polypropylene glycol, showed improved abrasion resistance, resilience and compression set values.

Surface sulfurization of Cu(In,Ga)Se2 (CIGSe) absorbers is a commonly applied technique to improve the conversion efficiency of the corresponding solar cells, via increasing the bandgap towards the heterojunction. However, the resulting device performance is understood to be highly dependent on the thermodynamic stability of the chalcogenide structure at the upper region of the absorber. The present investigation provides a high-resolution chemical analysis, using energy dispersive X-ray spectrometry and laser-pulsed atom probe tomography, to determine the sulfur incorporation and chemical re-distribution in the absorber material. The post-sulfurization treatment was performed by exposing the CIGSe surface to elemental sulfur vapor for 20 min at 500°C. Two distinct sulfur-rich phases were found at the surface of the absorber exhibiting a layered structure showing In-rich and Ga-rich zones, respectively. Furthermore, sulfur atoms were found to segregate at the absorber grain boundaries showing concentrations up to ~7 at% with traces of diffusion outwards into the grain interior.

Ti6Al4V alloys usually need to undergo some kind of surface treatment to enable good bone growth and implant integration. In this work, three treatments that modify the titanium alloy surface were studied with the aim of promoting osteogenic differentiation of human-embryonic-stem-cell-derived mesenchymal progenitors (hESC-MPs). The surface treatments used were mechanical polishing and electropolishing for 4 or 12 min in an H2SO4/HF/glycerine solution. The samples were characterised by atomic force microscopy, profilometry, X-ray photoelectron spectroscopy, and wettability. Samples were seeded with hESC-MPs in osteogenic media, and the cell number and alkaline phosphatase activity were measured. The electropolishing surface treatments influenced the nanometric morphology and wettability. However, the electropolished surfaces contributed in the same way as the mechanically polished surface to osteogenic differentiation, indicating that differentiation was strongly influenced by microroughness, which did not differ among the treatments used in the present work.