نشریه علوم و فناوری رنگ
سال هجدهم شماره 1 (پیاپی 67، بهار 1403)

Introducing new uses for agricultural waste is important to prevent environmental pollution and reduce waste disposal costs. The oleaster, often called the Russian olive, has culinary and medicinal applications, but its byproducts (seeds and peel) are frequently thrown away. Oleaster and its components are tannin-rich and can be used as mordants in dyeing. The extraction process was carried out in the presence of ethanol and was evaluated by analytical methods (FTIR and DSC). The percentage of phenolic compounds in peel and seed of oleaster fruit was obtained by the TPC method at 81.2 and 45.5 mg/ml, respectively, which indicates the possibility of using these extracts as mordants. Dyeing was done using Reseda extract on wool yarns. Alum was utilized as a low-risk mineral mordant with a concentration of 5% to evaluate natural mordants' effectiveness. The dyeing method with a 40% concentration of Oleaster peel and reseda extract yields the greatest K/S (19.47). Finally, the dyed samples were evaluated regarding color and fastness properties.

The study of the rheology of polyvinyl chloride plastisol is important because, at first, it is in a paste state and is usually applied by spraying. Moreover, controlling the gel and melting processes is possible by using rheology. This research investigated the rheological behavior of plastisols, including shear thinning behavior, thixotropy and gelation behavior. Also, long-term ageing was studied and it was found that plastisols turn into gel at a constant temperature for a long time period according to the concept of time-temperature superposition. Finally, the relationship between the samples' thixotropy and yield stress was evaluated to study the physical gel structure. The results confirm that thixotropy and yield stress in PVC plastisols are the same due to the fundamental physics and this is related to the strength of the microstructure.

Cinnabar was one of the most common red pigments throughout history and was obtained naturally and artificially. Considering this pigment's importance and wide application in Persian artworks, this research will attempt to study the identification characteristics of natural and artificial cinnabar by microscopic and spectroscopic methods. Therefore, the research tries to answer the question, what are the identifying characteristics of the cinnabar resulting from its making methods in old Persian recipes? Natural cinnabar was prepared from the historical bazaar of Tabriz, and artificial kind was made based on different old Persian recipes from the 12th to the 19th centuries. After applying the necessary processes on samples, including acid washing with pomegranate juice and lemon juice, the identification characteristics of the pigment in pure form and combination with gum and animal glue binders were investigated using a polarized light microscope, Raman spectroscopy, SEM-EDX, and reflective spectrophotometer. The results show that despite the difficulty of separating artificial and natural cinnabar with a light microscope, they separate by SEM images based on their morphology differences. Also, EDX analysis makes it possible to identify them according to the ratio of sulfur to mercury due to impurities in natural cinnabar. Analysis of the Raman spectrum with an emphasis on the 253 cm-1 band can be an important indicator for identifying cinnabar pigments without interfering with binding effects. However, the distinction between natural and synthetic pigments requires statistical analysis.

This research modified the degummed silk yarn with β-cyclodextrin (β-CD) using Succinic acid (SUA). Then, the modified silk yarn was dyed with three different acid dyes through usual (with acid) and unusual (without acid) methods. The surface modification and inclusion complex were characterized by well-known analyses such as Fourier transform infrared (FTIR), attenuated total reflectance-FTIR (ATR-FTIR), Scanning electron microscope (SEM), X-ray diffraction (XRD), and UV-visible. Results show that the presence of the β-CD has markedly enhanced the dye adsorption, and also, the acid has an effective role in the dye adsorption mechanism. The improvement of dye adsorption can be related to chemical (H-bonding and ionic) and physical (inclusion complex and encapsulation into tridimensional polymeric network) interactions. In addition, the β-CD had no negative effect on the color fastness (wash, light, and rubber) of the modified silk samples, so the color fastness of most samples remained unchanged or did not show a noticeable decrease.

This research aims to study two Qajar papier-mache penboxes to identify the pigments used in their decoration. Micro-Raman spectroscopy was employed with three laser-excitation wavelengths of 457, 532, and 785 nm to identify these pigments. Additionally, due to weak Raman scattering in one of the pigments, reflectance microspectrophotometry was utilized. The results of this study demonstrated that these penboxes, which were coated with oil-resin varnish (Kaman-oil), used ultramarine blue, chrome green (mixture of lead chromate and a blue pigment), red lead, carbon black, and cochineal pigments for decoration. Furthermore, evidence of using white lead, especially in the highlighted areas for attaching golden leaf, was found. All the identified pigments are commonly found in Iranian art and the Qajar period, and this study can greatly contribute to understanding their application in artistic decorations and cultural heritage. Conversely, including chrome green in one penbox and the ornamental technique attributed to Abu-Talib Modaresi Hamadani in the other suggests that both works were likely created after the mid-19th century.