Glass Transition Temperature - The Secret to Wrinkle-Resistant Fabrics

One of the special features of our products, particularly the Aero, Apollo and Kinetic platforms is the fact that when exposed to body heat or a dryer cycle, wrinkles will naturally release without ironing. 

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While many of us may be familiar with the concept of Melting Points the temperature at which a material switches between solid and liquid phases (e.g. butter melting), an interesting phenomenon of polymers is a characteristic called Glass Transition Temperature. 

Instead of simply liquid and solid phases, there is a third, rubbery phase. 

  1. Glass State: Think of glass, it's solid and stiff at low temperatures.

    1. Glass Transition Temperature: The temperature that defines this phase change.

  2. Rubbery State: At intermediate temperatures, the material acts like rubber and can stretch and bounce back, while still retaining its shape. 

    1. Melting Point Temperature: The temperature that defines solid to liquid transition. We use this to tune PCMs to transition right at our body temperature.

  3. Liquid State: This is when a material melts from a defined shape to a liquid. 

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Let's look at these characteristics for polyester:

  • Glass Transition Temperature (Tg): 155ºF

  • Melting Point (Mp): 484ºF 

Dryer Temperature: 125ºF (Low Setting) to 145ºF (High Setting)

So as polyester gets warmer (90ºF for our skin temperature and 135ºF in the dryer), it becomes more "rubber-like". In this rubbery state, it naturally returns to the straight form of the filament fiber when it was extruded. Any bends, creases or wrinkles are thereby "released" when the material heats up. 

The fact that polyester's glass transition point is close to a dryer's temperature is a unique property that we can harness to make wrinkle-resistant fabrics.