2025-06-11 02:17:44
2025-06-11 02:17:44
2025-06-11 02:17:44
569317
Seriously guys, polyethylene is such a fucking cool material.
You get very different properties depending on the length of the polymer chains:
- Short chains: Low-Density Polyethylene (LDPE). This is what plastic grocery bags are made of. Easy to tear, easy to cut, lightweight.
- Long chains: High-Density Polyethylene (HDPE). This is what Tyvek (the stuff from festival wristbands, construction projects, and some USPS envelopes) and gallon milk jugs are made of. Still easy to cut, but very hard to tear.
- Very long chains: Ultra-High Molecular Weight Polyethylene (UHMWPE, also called Dyneema or Spectra). This is one of the highest strength-to-weight ratio materials that you can buy in large quantities, competitive with the strongest carbon fiber (but also you can make it into flexible fabrics and cords, which you can't do with typical carbon fiber materials), twice as strong as spider silk, ten times stronger than steel by weight. You can't even cut the stuff with normal scissors. Some bulletproof jackets are made out of it. I just bought some cheap 1000lb-rated UHMWPE cord that is 2mm thick. 550lb paracord is twice as thick, and thus has four times the cross-sectional area, for only about half the strength.
All of these variants are extremely chemically stable, chemically simple, nontoxic, blah blah blah. When would you guess that this miracle material was discovered? The answer is... 1898 (though HDPE and UHMWPE weren't synthesized until... the 50s)