Week 11: The Crispness Design Space

Turning Module 9's glass transition into a map — temperature and moisture bounding a crisp region on two sides, and why a cracker in humid air softens.

10 May 2027

Outline#

• Recap: Module 9 gave us a single glass-transition boundary, crossed once as a crust fries. This lecture reframes the same physics as a state diagram with a target region on it, not one boundary crossed once.
• Building the temperature-versus-moisture map live: a crisp region bounded above by temperature and, separately, bounded by moisture — two distinct ways to leave the crisp state, not one.
• Why a cracker left in humid air softens at constant room temperature: moisture uptake alone can cross the same glass-transition boundary that heat crosses in Module 9, from the other side.
• Using the Crispness Phase Diagram live to compare two specimens’ stability margins — how much moisture or temperature headroom each one has before it leaves the crisp region.
• Setting up Module 12: this map gives a target region. The capstone asks which formulation or process choice actually moves a specimen toward it.