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Many processes can be used to remove toxic pollutants from wastewater. Adsorption process has been an important issue in water pollution control. In this research, work describes a facile procedure for synthetizing two polyampholytes through chemical modification of polyethyleneimine and their efficacy as adsorbent materials. The presence of amino and sulfonic acid groups in both polyelectrolytes gives them the property of ionic exchange, classifying them as polyampholytes. The adsorptive properties of both polyelectrolytes were evaluated in aqueous solutions with two acid dyes, Congo Red (DR28) and Eriochrome Black (MB11), and two basic dyes, Malachite Green (BG4) and Methylene Blue (BB9). These dyes possess anionic or cationic groups that interact electrostatically with these new polyampholytes that allow the adsorption. The kinetic study of adsorption for both polyelectrolytes, with all dyes, fits well with the pseudo second order model, demonstrating the chemisorption process. The adsorption percentage of both polyelectrolytes with cationic dyes is closer to 100%. The polyampholytes show adsorption capacity values ranging, with cationic dyes, from 270 to 416 mg g−1, as conventional ion exchange resins. [ABSTRACT FROM AUTHOR]

An experiment for the calculation of the degree of double bond conversion, after a polymerization reaction, of photopolymerizable liquid monomers using FTIR-ATR spectroscopy is reported. The experiment was successfully conducted with undergraduate students in materials engineering during the Fundamentals of Polymeric Material course. Students synthesized a Bis-GMA and TEGDMA copolymer through radical chain polymerization using visible light as the energy source (photopolymerization). Through the quantitative analysis of two absorption bands in the FTIR spectra of the monomer and the polymer, the ?C-C of the alkene group at 1638 cm[superscript -1] and the ?C-C of the aromatic ring at 1610 cm[superscript -1], students calculated the degree of double bond conversion after the polymerization reaction. Students acquired competencies in the synthesis and qualitative and quantitative characterization of polymeric materials through FTIR spectroscopy.

Mexico has important kaolin deposits, which must be assessed to obtain products with a high commercial value, such as kaliophilite as raw material for biodiesel production. Two kaolins, A and B, with approximate SiO2:Al2O3 ratios of 1 and 1.2, respectively, were used as raw materials to produce kaliophilite. Both kaolins were obtained from the municipality of Agua Blanca in the State of Hidalgo, Mexico. Kaolins are a source of Al and Si for the synthesis of kaliophilite through an alkali fusion process at 700 °C followed by ultrasonic treatment at 28 kHz to different times and for Kaolin-KOH ratios of 1:1 and 1:1.2 (mass: mass). The kaolins as received and the alkaline mixtures heat and ultrasonically treated were analyzed using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS). The most suitable kaolin for synthesizing kaliophilite was kaolin A with the Si/Al mass ratio of approximately 1, which exhibited a higher crystallinity index range from 54 to 79.6%. Higher KOH concentrations promote the amorphous material formation decreasing the kaliophilite amount. The crystallinity index was increased when the time of ultrasonic treatment was increased. [ABSTRACT FROM AUTHOR]

The mineralogy and thermal properties of two kaolin clay samples from Agua Blanca (Hidalgo-México) were determined by XRD, SEM-EDS, TGA-DSC techniques. Kaolin clay A contains a higher Al2O3 and lower impurities (K2O, TiO2, Fe2O3) amount than kaolin clay B, while the SiO2 amount is similar for both kaolin clays. A theoretical approach was carried out by a thermodynamic analysis considering the chemical composition of both kaolin clay samples with the FactSage 7.3 software. Stability phase diagrams were obtained to different K2O content from 0.1 to 3 wt % and temperatures in the range from 600 to 1600°C based on the chemical composition of the kaolin clay samples. The main mineralogical compounds predicted are andalusite (Al2O3·SiO2), K-Potash feldspar (K2O·Al2O3·6SiO2), and the SiO2 polymorphs (quartz, tridymite, and cristobalite) with small amounts of ferricpseudobrookite (Fe2O5Ti), and rutile (TiO2). As K2O content is increased, the amounts of mullite and tridymite decrease meanwhile the potash feldspar is increased at high temperatures. A liquid phase is formed at around 1350 and 1400°C for the kaolin clay samples A and B, respectively. The viscosity of the melt is increased for the evaluated K2O additions to 1400, 1500, and 1600°C. [ABSTRACT FROM AUTHOR]

Biopolymers have undergone growing development in the last twenty‐five years because of their important applications in several areas of medicine. Monomers Bis‐GMA and MMA are widely used in either the teeth restoration or complete substitution, respectively. This work reports the design and synthesis of allyl‐3,5 bis(((allyloxy)carbonyl)oxy)benzoate (35DACBzA) and its evaluation as an eluent for Bis‐GMA in dental resin composites and as a crosslinking agent for MMA. The resin formulated with monomer 35DACBzA showed polymerization shrinkage 40% lower than control. Besides, it presented a degree of conversion 27% greater, water sorption 53% lower, and solubility 80% lower than the composite resin used as control. When 35DACBzA monomer was used as MMA crosslinker, copolymer showed a thermal stability 100 degrees greater than the MMA homopolymer. This proves that monomer 35DACBzA may be used as an eluent for Bis‐GMA in the formulation of dental resin composites with a high degree double bond conversion, less polymerization shrinkage, and less aqueous sorption as well as a crosslinking agent for methacrylic polymers with greater thermal stability. POLYM. COMPOS., 39:E342–E350, 2018. © 2017 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

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This study investigated the antibacterial activity, bond strength to dentin (SBS), and ultra-morphology of the polymer–dentin interface of experimental adhesive systems doped with pyrogallol (PY), which is a ubiquitous phenolic moiety that is present in flavonoids and polyphenols. A universal adhesive containing 4-META and 10-MDP was used in this study. PY behaves as an antioxidant and anti-cancerogenic agent and it was incorporated into the adhesive at different concentrations (0.5 and 1 wt.%). The antibacterial activity and SBS were analyzed and the results were statistically analyzed. The ultra-morphology of the polymer–dentin interface was assessed using scanning electron microscopy (SEM). At 24 h, a lower antibacterial activity was observed for the control adhesive compared to those with 0.5% and 1% PY. No difference was seen in SBS between the three groups at 24 h. After 6 months, the SBS of the 0.5% PY adhesive was significantly lower than the other tested adhesives. The specimens created with 1% PY adhesive presented a higher bond strength at six months compared with that found at 24 h. No morphological differences were found at the polymer–dentin interfaces of the tested adhesives. Pyrogallol may be incorporated into modern universal adhesive systems to preserve the polymer–dentin bonding interface and confer a certain degree of antibacterial activity. [ABSTRACT FROM AUTHOR]