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FTIR–PCFC coupling: A new method for studying the combustion of polymers
Posted on December 9, 2013 by Henri VAHABI
New article in Combustion and Flame
Abstract
Gases released from pyrolysis and partial combustion of various polymers (low-density polyethylene, polystyrene, poly(parabromostyrene), pure and flame-retarded polypolyamide 6, cellulose, and chloroprene) were studied using a new coupling between Fourier transform infrared spectrometry (FTIR) and pyrolysis combustion flow calorimetry (PCFC).
Combustion in PCFC was monitored by modifying the combustion temperature between 600 and 900 °C. Decreasing the combustion temperature in PCFC leads to partial combustion and the evolution of CO, but also of methane, acetylene, or ethylene when temperature is very low. The evolution of these gases depends also on the polymer and on the presence of a flame inhibitor, demonstrating that flame inhibition can be studied using this method. A correlation between FTIR–PCFC and FTIR–cone calorimetry coupling was attempted via the CO/CO2 ratio. The first results show that an “isoconversion temperature” in the cone calorimeter test may be estimated. Polar gases such as chlorinated or brominated gases are not fully observed using this method due to possible adsorption in the transfer line before they reach the FTIR gas cell.
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Flame retardant and mechanical properties of epoxy composites containing APP−PSt core−shell microspheres
Posted on December 3, 2013 by Henri VAHABI
This article was published in Journal of Applied Polymer Science.
ABSTRACT
Ammonium polyphosphate (APP)–polystyrene (PSt) core–shell microspheres (CSPs) were synthesized via in situ radical polymerization. The core–shell structure was confirmed by transmission electron microscope (TEM). The results of optical contact angle measurements demonstrated a significant improvement in hydrophobicity of the modified APP. The obtained APP–PSt CSPs were added into epoxy (EP) system with various loadings. Effects of CSP on flame retardancy, thermal properties, heat release rate (HRR), smoke production, and mechanical properties of EP/CSP composites were investigated by limiting oxygen index (LOI), UL-94 tests, thermogravimetric analysis (TGA), cone calorimeter, and tensile test. LOI and UL-94 indicated that CSP remarkably improved the flame retardancy of EP composites. TGA showed that the initial decomposition temperature and the maximum-rate decomposition temperature decreased, whereas residue yields at high temperature increased with the incorporation of microspheres. Cone calorimetry gave evidence that HRR, peak release rate, average HRR, and smoke production rate of EP/CSP composites decreased significantly. The morphology of char residues suggested that CSP could effectively promote EP to form high-quality char layer with compact outer surface and swollen inner structure. Tensile strength of EP was enhanced with the addition of CSP.
© 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40218.
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Flame retardancy of polymers 