TG studies of a composite solid rocket propellant based on HTPB-binder

Thermal decomposition kinetics of solid rocket propellants based on hydroxyl-terminated polybutadiene-HTPB binder was studied by applying the Arrhenius and Flynn-Wall-Ozawa's methods. The thermal decomposition data of the propellant samples were analyzed by thermogravimetric analysis (TG/DTG) at different heating rates in the temperature range of 300-1200 K. TG curves showed that the thermal degradation occurred in three main stages regardless of the plasticizer (DOA) raw material, the partial HTPB/IPDI binder and the total ammonium perchlorate decompositions. The kinetic parameters E-a (activation energy) and A (pre-exponential factor) and the compensation parameter (S-p) were determined. The apparent activation energies obtained from different methods showed a very good agreement.

A Validated Stability-Indicating LC Method for Orbifloxacin in the Presence of Degradation Products

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Characterization of natural rubber/gold nanoparticles SERS-active substrate

Natural rubber/gold nanoparticles membranes (NR/Au) were studied by ultrasensitive detection and chemical analysis through surface-enhanced Raman scattering and surface-enhanced resonance Raman scattering in our previous work (Cabrera et al., J. Raman Spectrosc. 2012, 43, 474). This article describes the studies of thermal stability and mechanical properties of SERS-active substrate sensors. The composites were prepared using NR membranes obtained by casting the latex solution as an active support (reducing/establishing agents) for the incorporation of colloidal gold nanoparticles (AuNPs). The nanoparticles were synthesized by in situ reduction at different times. The characterization of these sensors was carried out by thermogravimetry, differential scanning calorimetry, scanning electron microscopy (SEM) microscopy, and tensile tests. It is suggested an influence of nanoparticles reduction time on the thermal degradation of NR. There is an increase in thermal stability without changing the chemical properties of the polymer. For the mechanical properties, the tensile rupture was enhanced with the increase in the amount of nanoparticles incorporated in the material. © 2013 Wiley Periodicals, Inc.

Estudo da cinética de cristalização e de degradação de compósitos nanoestruturados de poliamida 6,6/nanotubos de carbonos

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Modificação superficial de fibras de juta com descarga corona para melhora da aderência com matriz poliéster

Seeking alternatives for the total or partial substitution of synthetic fibers for natural fibers, with reinforcement in polymeric materials, this work was conducted with the objective of evaluating the treatment with corona discharge on the adherence of juta fibers with resin. The fibers were exposed to corona discharge for 1, 5, 10 and 15 minutes, as well as after treatment with hot water, molding composites fiber-reinforced with filaments treated for 10 and 15 minutes, and without the treatment. The chemical structures were evaluated by spectrometry in the region of Fourier transform infrared with attenuated total reflection (FTIR/ATR), observing the formation of a new band and the increase in the absorption of groupings with oxygen. The thermal analyses, such as thermogravimetry (TG) and differential scanning calorimetry (DSC) revealed the degradation of cellulose, hemicellulose and lignin. The microstructural characterization by scanning electron microscopy (SEM) showed changes in the surface of the fiber, such as roughness, superficial depressions, surface degradation and cavity formation. The adhesion of the fibers was evaluated by the pullout test, allowing us to verify the increase in adhesion strength after treatment with corona discharge. In conclusion, the treatment with corona discharge changes the surface of the juta fibers, resulting in better adherence with the resin.

Caracterização térmica de sacarose de cana-de-açúcar: amostras de padrão de referência, comercial e purificada

Pós-graduação em Química - IBILCE

Estudo de degradação térmica e caracterização de lodos provenientes de diferentes sistemas de tratamento de esgotos

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estudo termoanalítico e caracterização no estado sólido dos anti-hipertensivos: atenolol, besilato de anlodipino e maleato de enalapril

Pós-graduação em Ciência e Tecnologia de Materiais - FC

Caracterização e estudo do comportamento térmico de ligninas extraídas de bagaço de cana-de-açúcar e resíduos sólidos urbanos

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Aging of red wines made from hybrid grape cv. BRS Violeta: Effects of accelerated aging conditions on phenolic composition, color and antioxidant activity

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Flame retardant properties of the bark powder of Anadenanthera peregrina var. falcata (Benth.) Altschul (angico) studied by coupled thermogravimetry-Fourier transform infrared spectroscopy

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Processamento e caracterização de compósito fibra de sisal/resina epóxi via RTM

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Comportamentos, térmico e mecânico, de compósitos de polipropileno e resíduo da hidrólise enzimática do bagaço de cana de açúcar

Pós-graduação em Engenharia Mecânica - FEG

Obtenção e caracterização térmica de compósitos nanoestruturados de resina fenol-furfurílica/CNT

Pós-graduação em Engenharia Mecânica - FEG

Thermal and structural properties of commercial dental resins light-cured with blue emitting diodes (LEDs)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)