By the end of this topic, you should be able to...
explain corrosion resistance, reactivity (food safe), hygroscopy and flammability.
Guiding Question
How do material properties and classifications aid material selection for a specified manufacturing process?
💡 Did You Know? In 2014, the city of Flint, Michigan switched its water supply—and within months, lead-contaminated water poisoned thousands of children, not because pipes were broken, but because chemical reactivity between water chemistry and aging infrastructure went catastrophically ignored.
Why Consider Chemical Properties?
Chemical properties determine whether materials survive—or poison—their environments over time. Corrosion resistance explains why stainless steel surgical instruments remain sterile after 10,000 sterilization cycles while carbon steel rusts overnight in humid air.
Reactivity (food safety) governs whether your water bottle leaches BPA into drinking water or remains chemically inert—a property that separates "technically functional" from "safe for human contact."
Hygroscopy (moisture absorption) determines if your wooden cutting board warps and cracks, or if your 3D-printed nylon part swells and jams after humid storage.
Flammability dictates whether furniture foam meets fire codes (preventing another Grenfell Tower disaster) or becomes an accelerant in building fires. These aren't optional considerations—they're liability boundaries.
A designer who ignores chemical properties doesn't just risk product failure; they risk lawsuits, recalls, and in the worst cases, loss of life. Understanding these properties means asking: Will this material degrade when exposed to sweat, saltwater, cleaning chemicals, UV light, or oxygen? What happens in a worst-case scenario?
Case in Point
Samsung's Galaxy Note 7 recall (2016) stemmed partially from flammability of lithium-ion battery electrolytes combined with insufficient corrosion resistance of separator materials. When micro-corrosion created internal shorts, flammable electrolyte ignited—causing phones to explode mid-flight. The $5.3 billion recall wasn't a battery problem; it was a chemical properties failure where material interactions under stress weren't adequately evaluated during design.
Learning Goals
In this topic, you'll explore how corrosion, reactivity, moisture absorption, and flammability shape material longevity and safety—learning to evaluate chemical risks proactively and select materials that remain stable, safe, and functional across their entire lifecycle in your IA project.
Linking Questions
Why is a good understanding of material properties important when designing structural systems? (A3.2)
When do the physical properties of materials restrict the ability to use certain prototyping techniques? (A2.2)
How do the properties of a material influence the choice of manufacturing techniques for a product? (A4.1)
How can the characteristics of a material limit the effectiveness of modelling and prototyping as designs are developed? (B2.2)
How important is an understanding of the mechanical properties of a material when considering structural and mechanical systems, and their applications? (A3.2, A3.3, B3.2, B3.3)
Which classifications of properties are important when developing electronic systems and their applications? (A3.4, B3.4)
How could the continued development of biodegradable materials influence designers’ ability to address aspects of design for sustainability and design for a circular economy? (C2.1, C2.2)
Why is a thorough understanding of materials key for effective product analysis and evaluation of products? (C3.1)
How do design decisions related to the properties of materials and components impact a product’s life-cycle analysis? (C3.2)