Preparation and characterization study on maleic acid cross-linked poly(vinyl alcohol)/chitin/nanocellulose composites

In the quest on improving composite formulations for environmental sustainability, maleic acid (MA) cross-linked poly(vinyl alcohol) (PVA)-α-chitin composites reinforced by oil palm empty fruit bunch fibers (OPEFB)-derived nanocellulose crystals (NCC) had been successfully prepared. Based on the Fourier transform infrared (FTIR) spectroscopic analysis, it was proven that molecular interactions of the cross-linker to the polymeric networks was through conjugated ester linkage. Differential scanning calorimetry (DSC) showed that the influence of MA was minimal toward crystallization in the PVA/chitin/NCC composite. Maximum tensile strength, elongation at break and Young's modulus of the respective PVA/chitin/NCC composites were achieved at different content of MA, dependent on the PVA/chitin mass ratio. Among all compositions, a maximum Young's modulus was achieved at 30 wt% MA loading in PVA/chitin-30/NCC, amounting to 2,413.81 ± 167.36 MPa. Moreover, the mechanical properties and selected physicochemical properties (swelling, gel content, and contact angle) of the PVA/chitin/NCC composites could be tailored by varying the chitin content (10–30 wt%) and MA content (10–50 wt% based on total mass of composite). In brief, this chemically cross-linked PVA-based biocomposites formulated with sustainable resources exhibited tunable physicochemical and mechanical properties.     

Preparation of poly(methyl methacrylate-co-ethylene glycol dimethacrylate-co-glycidyl methacrylate) walled thermochromic microcapsules and their application to cotton fabrics

This study focused on fabrication of the thermochromic microcapsules and their application to the cotton fabric. In this study, thermochromic systems composed of crystal violet lactone, bisphenol A, and 1-tetradecanol were prepared and microencapsulated by emulsion polymerization method in poly(methyl methacrylate-co-ethylene glycol dimethacrylate-co-glycidyl methacrylate) wall. The microcapsules were analyzed by Fourier transform infrared spectroscopy, scanning electron microscope, transmission electron microscope, differential scanning calorimetry, and thermogravimetric analysis. Their thermoregulating property was tested by T-history test. The results revealed that microcapsules with smooth surfaces, core–shell structured, and spherical shape were successfully produced. The latent heat storage capacity of the microcapsules decreased from 202 J g⁻¹ to 167 J g⁻¹ when their shell/core ratio changed from 0.5/1 to 2/1. Microcapsules were adequately had sufficient thermal resistance to the temperatures they will encounter during their application to textile products and their usage. According to the UV–visible spectroscopy analysis and color measurements, the microcapsules exhibited reversible color change from blue to colorless and vice versa. Besides, the microcapsule impregnated fabric was able to absorb latent heat energy of 21.79 J g⁻¹ at around 35 °C and had cooling effect. According to the colorimetric parameters, the fabric was at blue color at room temperature and became colorless when heated to the temperature above the melting point of thermochromic system. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48815.     

Synthesis and characterization of Y (In,Mn) O3 blue pigment using the complex polymerization method (CPM)

In this paper, a new synthetic pathway is proposed for the system YIn_1-xMn_xO₃, a bright blue inorganic pigment, discovered in 2009. Blue pigment samples with increasing concentration of Mn³⁺ (x?=?0.08, 0.12 and 0.16) were prepared using the complex polymerization method (CPM) and compared with those synthesized via solid state reaction. All powders, the amorphous precursor from CPM and the starting materials for solid state method, were calcined at 1000, 1100, 1200 and 1300?°C for 12?h, and the resulting blue pigments were characterized by X-ray diffraction (XRD), colorimetric system CIE L*a*b* and Near infrared (NIR) reflectance measurements. XRD patterns and Rietveld Refinement show that the lowest temperature at which single hexagonal phase (isostructural to YInO₃) is formed is 1000?°C for CPM method and 1300?°C for conventional solid state method, respectively. The L*a*b* values demonstrate that the coloration of powders prepared by CPM exhibit temperature dependence below 1300?°C, a color shade shift from grayish blue to intense deep blue is observed when heating the samples from 1000 to 1300?°C. Blue pigments obtained by CPM have smaller particle size due to low temperatures and excellent near-infrared reflectance comparable to those by solid state method. Thus, providing advantages for application process and energy efficiency.     

Effect of the cultivation mode on red pigments production from Monascus ruber

In submerged cultures performed in chemically defined fermentation medium containing glucose and glutamate, the growth and production of water‐soluble red pigments and citrinin by the filamentous fungus Monascus ruber were studied under various carbon/nitrogen (C/N) ratios. The specific production of the red pigments was optimal at a glucose/glutamate ratio of about 10 and then steadily decreased at higher C/N ratio. In contrast, the production of the mycotoxin increased with increased C/N with an optimum in the range of 30–45. In a fed‐batch mode, it was also found that the production of pigments was not favoured in fed‐batch mode by feeding the medium with glucose while keeping the C/N ratio lower than 10. This low production likely resulted from concurrent high accumulation of L‐malic acid that was reported to inhibit this production. In contrast, this mode of cultivation was rather favourable for the production of the mycotoxin.     

Synthesis and evaluation of several high absorbance black pigments for spacecraft thermal control coatings

Using black coatings and materials with high light absorbance that are capable of absorbing photons at visible and longer wavelengths is a very effective way to reduce unwanted stray light, also known as optical noise, within optical equipment. These lights can be greatly reduced to a reasonable level by functional and performable black coatings that are modified to absorb incident light as much as possible by their specific pigments. In the present work, several carbonaceous pigments were synthesized for the first time from wasteful materials and their optical properties in the visible and near‐infrared ranges studied. First, MCM‐48 and SBA‐15 were synthesized at different conditions and were then used as templates for carbonaceous products. SSS‐1 (the carbonic pigment synthesized by the mixture of sucrose and sodium silicate), SSS‐2 (the carbonic pigment synthesized by the mixture of sawdust and sodium silicate), and mesoporous carbon pigments (CMK‐3 and CMK‐1 with different levels of saturations) were synthesized. Finally, their structure, morphology, and optical properties were investigated by X‐ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FE‐SEM), and Diffuse Reflectance Spectroscopy (DRS). The results indicated that the SSS‐1 pigment had a lower reflectance (below 1%) than carbon black (about 2.5%) in the visible region despite it being more cost‐effective than carbon black. The mesoporous pigments showed very high light absorbance in the visible region (about 2.5%). Compared with other black pigments, the CMK‐1 was the blackest synthesized material with a very low reflectance (about 0.05% in visible region), making it an ideal candidate as a super black pigment for reducing unwanted stray light within optical equipment.     

Characterization of spray paints used in street art graffiti by a non‐destructive multi‐analytical approach

Often associated with acts of vandalism, graffiti can also be identified with the so‐called street art movement. Moreover, in the historical context of visual arts from the 20th and 21st century, graffiti spray paints feature among the materials employed in the work of representative artists such as Lucio Fontana, Richard Hamilton, Yves Klein, or David Alfaro Siqueiros. In this study, a large number of artist spray paints were analyzed by means of X‐Ray Fluorescence (XRF), Fourier Transform Infrared Spectroscopy (FTIR), spectrophotometry, and Hyperspectral Imaging (HSI). The aim of the study was to provide a chemical characterization of the main organic and inorganic components present within the spray paint formulations by means of a complementary non‐destructive approach. Titanium white, zinc white, bismuth vanadate yellow, ultramarine, strontium sulfide, iron, and copper oxides, along a series of pigments of the azo, phthalocyanine, and quinacridone classes could be identified. High amounts of barium sulfate as well as calcium‐based extenders were also detected. FTIR analysis provided important information regarding the binder composition, mainly modified alkyd resins being identified. Additional information related to the existing chromophores as well as specific binder‐pigments interactions could also be highlighted within the HSI data sets. Overall results provide new insights on the complex chemistry of this new range of materials, which could help future investigations carried on street art graffiti, contemporary murals, or mixed‐media artworks.     

A novel route to synthesize metal titanium phosphate ceramic pigments: Co,Ni, and Cu-incorporated α-Ti(HPO4)2⋅H2O from ilmenite

Solid-state reaction of α-Ti(HPO₄)₂·H₂O (α-TiP) and acetates of Co, Ni, or Cu at 500 °C and 800 °C produce a number of different metal titanium phosphate (MTiP) inorganic pigments with different colors and shades. At a given metal to α-TiP ratio and calcination temperature, the reaction produces several types of pigments such as phosphates M_0.5TiO(PO₄), M_0.5Ti₂(PO₄)₃, M₂P₂O₇, and M₃(PO₄)₃ (M = Co, Ni, and Cu) with a unique color. α-TiP, an iron free base material was prepared by digestion of high-grade natural ilmenite beach sand (FeTiO₃) with 85 wt% H₃PO₄ at 120 °C. TGA, XRD, SEM/EDX, Diffuse reflectance UV–vis, and Raman spectroscopy techniques were used for characterization. Synthesized MTiP pigments after enameling at a single fire glazing at 1100 °C for 45 min exhibit vivid colors, ranging from purple, yellow, and green with different shades.     

Synthesis of novel polyaniline/MgO composite for enhanced adsorption of reactive dye

In this investigation, the porous structure of polyaniline/MgO (PANI/MgO) composites has been successfully synthesized by in‐situ oxidative polymerization method. The as‐prepared materials were characterized by Ultraviolet–visible absorption spectroscopy, Fourier transform infrared spectroscopy, X‐ray diffraction, and scanning electron microscopy. The obtained composites, for the first time, are used as an adsorbent for the removal of the sulfonated anionic dye reactive orange 16 (RO) from aqueous solution. The equilibrium adsorption isotherms of RO on the PANI/MgO composites were analyzed by Langmuir and Freundlich models, suggesting that the Langmuir model provides the better correlation of the experimental data and maximum adsorption capacity was found to be 558.4 mg g^?1. In addition, adsorption kinetics was followed by both pseudo‐first‐order and pseudo‐second‐order, but the latter model matches the results much better than the former one. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40210.