Thermal characteristics of aluminum nanoparticles and oilcloths

Exothermic behavior of aluminum nanoparticles (ANP) in aqueous medium of various pH values and oilcloths (OC) composed of linseed oil, SAE 10W-40 engine oil, or SAE 20W-50 engine oil in cotton or nylon was studied. The experimental results revealed that for ANP hydrolysis, a deviation of pH value from 7 yielded a decrease in onset temperature (Tonset), peak temperature, no return temperature, self-accelerating decomposition temperature, time to T(onset), time to maximum rate (TMRad), and activation energy. Also, reaction order and frequency factor increased as pH value deviating from 7. For decomposition of oily materials, Tonset of OC was lower than that of pure oil, suggesting that cotton and nylon enhanced the combustibility of the three oils. Besides, total enthalpy of OC was larger than that of the corresponding pure oil. Nylon-based OC produced larger total enthalpy than cotton-based OC, while the latter yielded shorter oxidative induction time (OIT) than the former. Moreover, reasonable discrepancy between experimentally determined OIT and theoretically estimated TMRad was obtained. Hydrolysis of damped ANP and decomposition of OC could be derived from heat accumulation, leading to release of a considerable amount of thermal energy at relatively low Tonset.