UNLABELLED: Potassium chlorate has long been utilized as an excellent oxidizing agent in pyrotechnics and explosives. As mixtures of potassium chlorate and any type of combustible material can be explosive, there is a potential risk of misuse in homemade explosives. Unlike commercial explosives, homemade chlorate and oil mixtures do not have a constant composition, which limits their understanding. This study reports the effects of two types of oil (motor oil and cooking oil) and their ratios (ranging from 2.5% to 40.0% (w/w)) on the explosive properties of such mixtures. The impact sensitivity was highest at a motor oil ratio of 5%. The friction sensitivity increased with an increasing oil ratio, reaching a maximum at an oil ratio of ~22.5%, and was close to those of primary explosives. The motor oil mixtures exhibited higher sensitivity than the cooking oil mixtures at oil ratios of 25.0% or less. A 10% oil mixture, which was close to the ratio of oxygen balance equal to zero, detonated in weak confinement, such as a paper cylinder. The highest detonation velocities in a polypropylene tube were ~2 300 and 2 550 m/s at a 10% ratio of motor oil and cooking oil, respectively. The velocities of the metal case wall, measured by photonic Doppler velocimetry, reached ~1 100 m/s near the end of acceleration. These results show that homemade chlorate and oil mixtures are capable of detonation and quite sensitive over a wide range of oil ratios, with sufficient power to cause damage in the vicinity. KEY POINTS: Simple mixtures of potassium chlorate and oil can be used as a homemade explosives.Oil types and ratios considerably affect the sensitivity and detonation velocity.Mixtures are sufficiently potent to generate hazardous fragments.Long-term storage causes an internal oil gradient.Mixtures with wide-ranging oil ratios can have highly sensitive points.

Explosion Investigation Section 2nd Department of Forensic Science National Research Institute of Police Science Chiba Japan

Institute of Energetic Materials Faculty of Chemical Technology University of Pardubice Pardubice Czech Republic

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