New Plastic Films Can Deflect or Trap Heat from Sunlight

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New Plastic Films Can Deflect or Trap Heat from Sunlight

The research team explained that their plastic films were made up of inexpensive plastic polyethylene / Photo by Sergey Ryzhov via 123RF

 

Plastic and warmer temperatures are major problems in any part of the world today. But a team of researchers found a way to make plastic agents fight the heat. They developed new plastic films that remain cool when exposed to sunlight, and these are compatible with a wide range of applications.

The new plastic films were developed by an international team of scientists led by the Massachusetts Institute of Technology. Their new materials could keep its temperature substantially cool despite exposure to the Sun's heat and radiation. They published the results in the journal Optical Materials Express.

 

New Plastic Films to Combat Rising Temperatures

During summer, people tend to use more electricity compared to any other season. In the United States, the cost of electricity surges like a tsunami in summer because people need to use cooling appliances more often at a longer time. Sometimes, people even keep their appliances like air conditioners and electric fans turned on for 24 hours a day, according to Call Me Power.

At The Optical Society, researchers announced their newly developed plastic films that could be a potential solution in keeping homes, buildings, and people cool when the temperature rises. Their materials have been tested to be bendable and lightweight, which could help their incorporation in clothing and wearable items. Also, the films come in different colors to match whatever surface needs cooling.

A team of researchers found a way to make plastic agents fight the heat / Photo by James Martin via 123RF

 

"Materials used for wearable technologies and architecture applications require simultaneous control of multiple properties to combine visual appeal with thermal comfort. We accomplished this challenging balance by creating the first plastic-based flexible material that combines various optical properties with passive thermal regulation via both conduction and radiation," explained Svetlana Boriskina, the lead author of the study and a researcher at MIT.

The research team explained that their plastic films were simply made up of inexpensive plastic polyethylene. But what provided the capability to handle temperature was the effects of nanoparticles, which also gave out the variety of colors.

 

How They Created the Plastic Films

Normally, manufacturers have to separately optimize color and temperature management properties in materials. However, separate optimization can take time and may even increase the cost of production.

So, the team altered the properties of inexpensive plastic polyethylene by stretching them to different degrees. When they examined the stretched material, they discovered that they could change the optical, mechanical, and thermal properties of the polyethylene.

First, they noticed that the stretching forces the polymer chains to align in one direction parallel to each other. This part has made the material unique compared to other types of plastic. Next, the stretching and alignment of the chains altered its typical properties. After the stretching, the polyethylene films exhibited higher thermal conductivity, enhanced broadband transparency, decreased haze, improved melting temperature, and better tensile strength.

To create a variety of colors, the team implanted different nanoparticles into the polymer. They embedded these tiny particles before the stretching process. Aside from producing various colors, the nanoparticles could deliver additional effects to the polymer.

 

If nanoparticles with visible light absorption were used, the particles would prevent warming up under the Sun as the plastic absorbs visible light, but not infrared solar heat. But if the nanoparticles with infrared light scattering were applied, the plastic films would be able to trap heat.

As such, the nanoparticles say what the plastic films do when it comes to light and heat, while the stretching process determines how heat conductive and how flexible they will be. It also means that they can be used on clothing, smart wearable items, and architectural products without using electricity.

Tests conducted on the plastic films in a solar lab showed that films with dark silicon nanoparticles expressed temperature of 20 degrees Celsius cooler than a black reference paper. Also, the dark silicon nanoparticles could spread heat laterally. The spread of heat promotes cooling in parts exposed to light.

 

Could The Plastic Films Recycle Waste Plastic?

When it comes to recycling the vast number of plastic on land and in oceans, the answer may be a yes if it concerns a type of plastic. Polyethylene is a thermoplastic or a plastic that responds to heat and can melt at a specific temperature.

 

In the study, the classification of the plastic films is ultra-high molecular weight polyethylene, modified with organic and inorganic nanoparticle inclusions. On the other hand, the most common type of plastic in plastic bottles, soda bottles, and other materials designed to keep food and liquid is polyethylene terephthalate, while low-density polyethylene for shopping bags and similar items.

According to Ryedale District Council, PETE plastics are commonly recycled while LDP is sometimes recycled. And even if they can be recycled, current strategies cannot even recycle 50 percent of the total plastic production per year.

So, at this time, the new plastic films cannot support the recycling of ultra-high molecular weight polyethylene until commercialization. The researchers will need to conduct further studies if they can simply create the films out of recycled materials or out of other plastic types to confirm its potential in solving plastic pollution.

Still, the new films will prove to be useful on a larger scale if they work in keeping households and buildings cool in the era of climate change. The cooling will significantly help reduce overall electricity consumption in industrial, commercial, and residential areas, and decrease the consumption of water as people will no longer have to shower more than necessary.

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