Thermogravimetric analysis

About: Thermogravimetric analysis is a research topic. Over the lifetime, 37248 publications have been published within this topic receiving 862144 citations. The topic is also known as: thermal gravimetric analysis & TGA.

New soybean oil–styrene–divinylbenzene thermosetting copolymers. I. Synthesis and characterization

Abstract: The cationic copolymerization of regular soybean oil, low-saturation soybean oil (LoSatSoy oil), or conjugated LoSatSoy oil with styrene and divinylbenzene initiated by boron trifluoride diethyl etherate (BF3·OEt2) or related modified initiators provides viable polymers ranging from soft rubbers to hard, tough, or brittle plastics. The gelation time of the reaction varies from 1 × 102 to 2 × 105 s at room temperature. The yields of bulk polymers are essentially quantitative. The amount of crosslinked polymer remaining after Soxhlet extraction ranges from 80 to 92%, depending on the stoichiometry and the type of oil used. Proton nuclear magnetic resonance spectroscopy and Soxhlet extraction data indicate that the structure of the resulting bulk polymer is a crosslinked polymer network interpenetrated with some linear or less-crosslinked triglyceride oil–styrene–divinylbenzene copolymers, a small amount of low molecular weight free oil, and minor amounts of initiator fragments. The bulk polymers possess glass-transition temperatures ranging from approximately 0 to 105°C, which are comparable to those of commercially available rubbery materials and conventional plastics. Thermogravimetric analysis (TGA) indicates that these copolymers are thermally stable under 200°C, with temperatures at 10% weight loss in air (T10) ranging from 312 to 434°C, and temperatures at 50% weight loss in air (T50) ranging from 445 to 480°C. Of the various polymeric materials, the conjugated LoSatSoy oil polymers have the highest glass-transition temperatures (Tg) and thermal stabilities (T10). The preceding properties that suggest that these soybean oil polymers may prove useful where petroleum-based polymeric materials have found widespread utility. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 658–670, 2001

Plasma spray deposition and high temperature characterization of ZrB2–SiC protective coatings

Abstract: Refractory metal borides are the object of special interest for aerospace applications requiring properties of chemical and mechanical resistance in ultra high temperature, such as nose and leading edges of re-entry space vehicles. The main objective of the research is the fabrication and characterization of plasma sprayed zirconium diboride–silicon carbide composite coatings and free-standing components for high temperature applications. High and low pressure plasma spray in a controlled atmosphere were selected as manufacturing techniques for the deposition of ceramic coatings. Fine ZrB2 and SiC precursors were agglomerated and preconsolidated into spherical, hollow powders for better flowability and silicon carbide thermal protection during the interaction with the plasma. Coatings and free-standing tubular specimens were fabricated and tested for high temperature behaviour. Thermogravimetric analysis, surface morphology investigation and high temperature X-ray diffraction showed that the addition of approximately 25% SiC induces a mechanism of self-protection of the ceramic material during heat treatment in oxidizing environments up to approximately 2100 K.

Removal of methyl orange from aqueous solutions by magnetic maghemite/chitosan nanocomposite films: Adsorption kinetics and equilibrium

Abstract: Magnetic maghemite (γ-Fe2O3)/chitosan nanocomposite films were prepared by solution casting method and characterized by Fourier transform infrared spectra, thermogravimetric analysis, differential scanning calorimetry and X-ray diffraction. Batch adsorption experiments were carried out utilizing the composite films to adsorb a typical azo dye, i.e., methyl orange (MO) from aqueous solutions. The effects of adsorbent dosage, solution pH, coexisting anions, and temperature were studied. Adsorption kinetic was verified by pseudo-first-order and pseudo-second-order kinetic models. Results indicated that the rate of dye adsorption followed pseudo-second-order kinetic model for the initial dye concentration range studied. MO adsorption onto magnetic γ-Fe2O3/chitosan composite films was better described by Langmuir isotherm. Thermodynamic studies showed that MO adsorption was exothermic and spontaneous in nature. Because magnetic maghemite/chitosan nanocomposite films could be recovered conveniently and possessed of excellent adsorptive property, it can be developed as an economical and alternative adsorbent to decolorize or treat dye wastewater. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012