Predicting & Preventing Runaway Chemical Heating

The chemical industry is evolving rapidly and becoming increasingly complex. As demand for plastics, sustainable polymers, and high-performance materials continues to surge, manufacturers are encountering an ever-growing array of unstable chemicals. Peroxide-based initiators, olefinic monomers, and other reactive compounds essential to polymer production can pose significant safety challenges if not properly managed. With global plastics production projected to grow at least 5% annually through 2030, the stakes are rising for chemical producers who must find safer, smarter ways to handle these materials.

This Chemical Engineering Progress Magazine article by Exponent's Brian Ott, Nicholas Welchert, Laurent Delafontaine, Matevz Frajnkovic, and Ali Reza — featured on the cover of the Feb. 2025 issue — presents a practical screening methodology designed to help manufacturers assess, predict, and mitigate the risks connected to unstable chemicals. By combining heat transfer modeling with chemical kinetics analysis, the method enables engineers to evaluate how materials behave under real-world conditions such as storage, transportation, and processing. This integrated approach allows companies to pinpoint where thermal runaway might occur and design more effective controls before problems arise.

The article explores how unstable chemicals generate heat as they react or decompose, and how those reactions can accelerate dangerously when the environmental temperature climbs. Inhibitors and cooling systems are commonly used to slow these processes, but once an inhibitor is consumed or refrigeration fails, the chemical may quickly enter a self-heating reaction. The presented screening method helps operators model these dynamics, considering variables such as container size, insulation, ambient conditions, and reaction kinetics.

Heat transfer plays a critical role in determining stability. The authors describe scenarios ranging from a one-gallon drum to a 55-gallon insulated drum. Smaller, uninsulated containers tend to dissipate heat quickly, keeping temperatures close to ambient levels. Larger or insulated containers, however, lose heat more slowly — allowing internal reactions to build heat that can trigger a runaway event. By modeling parameters such as the overall heat transfer coefficient (U) and the wetted surface area (AS), engineers can better understand whether a particular storage configuration promotes safe dissipation or hazardous accumulation of heat.

The methodology also incorporates kinetic data gathered through accelerating rate calorimetry (ARC), which tracks how quickly materials begin to self-heat as temperature rises. Applying a zeroth-order reaction model, the authors calculate key parameters like the time to maximum rate (TMR) and self-accelerating decomposition or polymerization temperatures (SADT/SAPT). These indicators help identify the critical temperature ranges at which materials become unstable — invaluable information for shipping, storage, and process safety assessments.

Most importantly, the article demonstrates how this screening method integrates into broader risk assessments. By considering variables such as ambient temperature, agitation energy, and insulation, engineers can predict temperature behavior over time and design operational safeguards — for instance, automatically shutting off agitators before a system reaches a danger threshold.

The screening methodology outlined in the article gives chemical manufacturers a vital early-warning system that does not just aim to prevent accidents but can also support more efficient, informed, and resilient production. As the industry continues to push boundaries in polymer chemistry, adopting advanced thermal and kinetic screening tools will be essential to keeping both innovation and safety in balance.

From the publication: "The screening method presented in this article will help assess the risks associated with producing, handling, storing, and transporting unstable materials, in addition to identifying processes that require additional analysis."