Tribological Properties of Carbon Nanotube and Carbon Nanofiber Blended Polyvinylidene Fluoride Sheets Laminated on Steel Substrates

Nanostructured carbon dispersed polymer nanocomposites are promising materials for tribological applications. Carbon nanofiber (CNF) and carbon nanotube (CNT) dispersed polyvinylidene fluoride (PVDF) nanocomposite was prepared by chemical synthesis route. Morphology and microstructure of well-dispersed CNF and CNT in PVDF were specified by scanning electron microscope and X-ray diffraction, respectively. Moreover, chemical and functional characteristics were examined by Raman spectroscopy and FTIR investigation. The friction coefficient of PVDF nanocomposite laminated on steel substrate decreased with an increase in the dispersed quantity of CNF and CNT. The friction coefficient of PVDF is approximately 0.27; however, the addition of carbon nanomaterial in PVDF will further decrease the friction coefficient between 0.24 and 0.17. This value was significantly less in CNT dispersed PVDF nanocomposite. This could be explained by easy shearing and rolling action contact interfaces.

FTIR INVESTIGATION ON CRYSTALLINITY OF HYDROXYPROPYL METHYL CELLULOSE-BASED POLYMERIC BLENDS

Two series of polymeric blends have been prepared based on hydroxypropyl methyl cellulose (HPMC)/polyacrylic acid (PAA) (1:1, 1:2, 1:3, 1:4) and HPMC/sodium alginate (SA) (1:30, 2:30, 3:30, 4:40) and investigated by Attenuated Total Reflectance–Fourier Transform Infrared Spectroscopy (ATR-FTIR). IR analysis confirmed the interaction between the polymeric components in the blend and the degree of structural organization. Crystallinity changes in the blends were observed as a function of a number of experimental parameters, such as temperature, composition and HPMC concentration, by determining the quantitative crystallinity indexes: Total Crystallinity Index (TCI), Lateral Order Index (LOI) and Hydrogen Bond Index (HBI).

Multi-Level Evaluation of UV Action upon Vitamin D Enhanced, Silver Doped Hydroxyapatite Thin Films Deposited on Titanium Substrate

Hydroxyapatite Ca10(PO4)6(OH)2 (HAp) is an important bioactive material for bone tissue reconstruction, due to its highly thermodynamic stability at a physiological pH without bio-resorption. In the present study, the Ag:HAp and the corresponding Ag:HAp + D3 thin films (~200 nm) coating were obtained by vacuum deposition method on Ti substrate. The obtained samples were exposed to different UV irradiation times, in order to investigate the UV light action upon thin films, before considering this method for the thin film’s decontamination. The effects of UV irradiation upon Ag:Hap + D3 are presented for the first time in the literature, marking a turning point for understanding the effect of UV light on composite biomaterial thin films. The UV irradiation induced an increase in the initial stages of surface roughness of Ag:HAp thin film, correlated with the modifications of XPS and FTIR signals. The characteristics of thin films measured by AFM (RMS) analysis corroborated with XPS and FTIR investigation highlighted a process of recovery of the thin film’s properties (e.g., RMS), suggesting a possible adaptation to UV irradiation. This process has been a stage to a more complicated UVA rapid degradation process. The antifungal assays demonstrated that all the investigated samples exhibited antifungal properties. Moreover, the cytotoxicity assays revealed that the HeLa cells morphology did not show any alterations after 24 h of incubation with the Ag:HAp and Ag:HAp + D3 thin films.

FTIR INVESTIGATION OF PIGMENTS AND BINDER OF PAINTED WALLS IN HERITAGE MONUMENTS

Studies of materials used for works of art and cultural monuments throughout the history contribute to the comprehensive understanding of particular cultures, their technological achievements and customs over time. Investigations of the authenticity of objects and the interventions they may have endured over time keep an important role for their successful restoration and preservation. A three-layer sample of the colored wall decoration from Ottoman Ćejvan Ćehaja mosque from Mostar, Bosnia and Herzegovina was investigated by FTIR spectroscopy. The plaster was identified as gypsum-lime binder. Inorganic pigments were found in two layers, reddish-brown mixture of Fe2O3 and MnO2 and green pigment recognized as viridian, Cr2O3 ∙ 2H2O. The upper layer of "golden color" is found to be a physically compact piece of gold foil or leaf whose fixation method meets both the Ottoman and "west" mode of binding. The mode of adhesion by animal glue could be the result of decoration immanent to Islamic culture, but also to reconstruction from the late 19th century during the Austro-Hungarian rule in Bosnia.