# @stem_antics on Instagram

- **Type:** Video
- **Original URL:** https://www.instagram.com/p/DWKzNkJkazC
- **Gondola URL:** https://gondola.cc/posts/61935602-stem-antics-instagram
- **Thumbnail:** https://img.gondola.cc/tr:w-,h-,fo-auto/postThumbnails/54ab99396e.jpg
- **Posted:** 2026-03-22T01:46:14.000+00:00
- **Account Owner:** Stem Antics (@stem_antics) — https://gondola.cc/stem_antics

## Caption

Stress whitening occurs due to microstructural changes under mechanical deformation, especially in semi-crystalline polymers.

When a polymer is bent beyond its elastic limit, localized plastic deformation begins. This leads to:
	•	Formation of crazes: microvoids bridged by fibrils
	•	Cavitation within amorphous regions
	•	Alignment and stretching of polymer chains

These features create interfaces with different refractive indices (polymer vs air voids). Light hitting these regions undergoes strong scattering (Mie scattering regime when feature sizes are comparable to visible wavelengths ~400–700 nm).

Key factors influencing whitening:
	•	Polymer type (amorphous vs semi-crystalline)
	•	Strain rate and temperature
	•	Degree of crystallinity
	•	Presence of additives or plasticizers

Importantly, stress whitening is often a precursor to fracture, since craze formation concentrates stress.

In some engineered materials, this effect is actually used as a visual indicator of mechanical fatigue or overstress.

#stemeducation #stemantics #stem #engineering #engineeringexplained

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- **Likes:** 175
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## Tags

engineering, stem, stemeducation, engineeringexplained, stemantics

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