What causes white plastic to yellow?

For one of the most commonly used plastics, polyethylene, it's long been suggested that ultraviolet (UV) light — the same light that gives us sunburns — initiates reactions in the backbone of the polymer's structure that cause the yellow color change.

acs.org - Shining light on why plastics turn yellow - American Chemical Society

What are 5 instruments playing together called?

Quintet—Quintets are five musicians performing together, pieces of music meant to be played by five musicians, or a piece of music that includes...

Last updated Sep 28, 2022

Is it good to have a piano in the house?

In fact, research has shown that playing the piano can improve mood, memory, motor skills, concentration, focus, reading comprehension, math...

Last updated Aug 1, 2019

Promotion

“Could Superficial Chiral Nanostructures Be the Reason Polyethylene Yellows as It Ages?”

ACS Applied Polymer Materials

If you own a retro gaming console or have an old roll of packing tape, you’ve seen how plastics turn yellow as they age. Though the cause of this color change has long been attributed to the formation of molecules that act as dyes — the actual chemical changes that take place remained unexplained. Now, researchers reporting in ACS Applied Polymer Materials have identified surface-based chiral nanostructures as the potential culprit. Understanding how and why polymers degrade with age is key to designing alternatives that can avoid these pathways, allowing plastic products to have a longer lifespan. For one of the most commonly used plastics, polyethylene, it’s long been suggested that ultraviolet (UV) light — the same light that gives us sunburns — initiates reactions in the backbone of the polymer’s structure that cause the yellow color change. However, though chemical changes to polyethylene’s polymeric backbone have been observed after exposure to UV light, those new structures cannot account for polyethylene’s yellowing. One emerging way to intentionally modify the color and the ways that plastics interact with light is to create nano-sized “supramolecular” structures on their surfaces that impact plastics’ properties in a controllable way. Inspired by these surface-based technologies, Margaret M. Elmer-Dixon, Melissa A. Maurer-Jones and colleagues wanted to see if such nanostructures formed unintentionally by UV light could be the cause of polyethylene yellowing. The researchers first investigated if potential structures formed on yellowed polyethylene films’ surfaces interacted with circularly polarized light, a type of light whose waves travel with a right- or left-handed rotation. The amount of circularly polarized light absorbed by the film in these experiments changed depending on the film’s orientation, suggesting that the yellowed plastic contains new chemical structures that are chiral, that is, they are directional and aren’t identical to their mirror images. Additional experiments showed that most of the degradation during film yellowing occurred on the surface of the films. The team concluded that chiral chemical structures on the surfaces of the polyethylene films are formed during exposure to UV light and are a potential cause for the yellow color of old plastics. They say that these insights could help researchers design plastic products that last longer before becoming unsightly or unusable. The authors acknowledge funding from the University of Minnesota, Duluth, the University of Minnesota McKnight Foundation, and the U.S. Department of Energy.

Is 61 keys enough for Fur Elise?

It's possible to play the first two movements of Fur Elise by Beethoven on a 61 key-keyboard, but the third and final movement will need at least...

Last updated May 28, 2018

Which pianos appreciate in value?

Grand pianos are the most collectable because they are the most rare and tend to offer superior acoustics. Apr 8, 2013

Last updated Feb 15, 2018

Join almost HALF A MILLION Happy Students Worldwide

Promotion

How do you know if a piano needs to be restrung?

If the piano sounds tinnier and less deep, and seems to have lost some of its resonance, it's most likely time for restringing. As well, if the strings are too stretched and hard, it could be from too many tunings.

taylorpianorestorations.com - How to Know When Your Piano Needs Restringing

Piano strings can last as long as the instrument itself depending on a number of factors. If the piano is kept in the right environment, has a set of high-quality strings, and has not been played more than several hours a week, the strings may last for decades. On the other hand, if the piano has had heavy use, or exposure to excessive dust and moisture, the strings may lose their tone in less than 10 years. If the piano sounds tinnier and less deep, and seems to have lost some of its resonance, it’s most likely time for restringing. As well, if the strings are too stretched and hard, it could be from too many tunings. In extreme humidity the strings become rusty lose their richness, and when dust penetrates the strings it deadens their sound. It may also be time to replace the strings if the piano’s pinblock–the part that grips the tuning pins to keep the piano in tune– has loosened. Sometimes it’s necessary to replace the strings as well as the pinblock. In general, when repairs are needed to the piano’s soundboard and bridges, it is often necessary to remove the piano’s strings. If your piano is significantly valuable, it pays to have its strings restrung. If you think you may have an issue with the strings in your piano, visit TaylorPianoRestorations.com to find out more about piano restringing in Richmond, VA. Taylor Piano Restorations tunes, moves, rebuilds, and refinishes pianos throughout Central Virginia.

Where are Flemish people from?

Belgium The term Flemings (Dutch: Vlamingen) is currently mostly used to refer to the ethnic group native to Flanders (the northern half of...

Last updated Mar 18, 2018

What is the fear of scary music called?

Fear of loud noise is referred to as phonophobia, sonophobia, or ligyrophobia. This condition is not caused by hearing loss, or any type of hearing...

Last updated Aug 3, 2019

Promotion

How do smart people think?

Incredibly intelligent people use the power of intuition to make decisions. They don't ignore existing facts or data, but they also know that there...

Last updated Feb 27, 2019

Promotion

Is Für Elise easy or hard?

intermediate The full version of Fur Elise is considered reasonably difficult, broadly an intermediate piece around grade 5, but a shorter...

Last updated Aug 27, 2021