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| Hesham Zakali: The material developed by an international group of scientists could become an alternative to toxic lead, for example. Photo Credit: Anastasia Kurshpel |
Polylactic acid combined with tungsten trioxide effectively blocks gamma radiation, an international group of scientists including specialists from Russia (Ural Federal University), Saudi Arabia and Egypt has found. In the future, it will be possible to create safe and biodegradable screens for protection against low-energy radiation on the basis of the new material, the researchers believe. Such screens are used in medicine, agriculture and the food industry. A description of the material has been published in the journal Radiation Physics and Chemistry.
"Polylactic acid is a non-toxic polymer of natural origin. It is inexpensive and, importantly, can be broken down by microbes when placed in an industrial plant at high temperatures. Since lactic acid is regularly produced as a byproduct of metabolism in both plants and animals, polylactic acid and its degradation products are non-toxic and safe for the environment," explains Hesham Zakali, co-author of the development and Researcher at the Department of Experimental Physics at UrFU.
Polylactic acid has become a popular plastic packaging option for everything from food and beverages to cosmetics and electronics. However, despite its significant market potential, this polymer is quite fragile: its low thermal decomposition temperature limits its use in many applications. To improve the properties of polylactic acid, it is necessary to add a filler that can adapt its properties to specific applications. Scientists have found that tungsten trioxide can be such a filler, as it increases the ability of this biopolymer to block gamma rays, improving its structure, thermal and optical properties. Tungsten trioxide is widely known to be non-toxic. It is actively used to make gas sensors, electrochromic windows, optical devices, photocatalysts, and fire-resistant fibers in "smart" windows, among others.
To create a material to shield against gamma rays, the scientists mixed polylactic acid and tungsten trioxide as a filler. Their analysis showed that the filler was sufficiently dispersed in the polylactic acid and increased its stability at high temperatures. The researchers also experimentally tested the radiation protection parameters of the improved biopolymer. They did this using a series of radioactive point sources that emitted photons with different energy levels. They found that increasing the amount of tungsten trioxide in the polylactic acid reduced the transmission of gamma rays. This filler has promising potential for improving protective materials - especially radiation shields.
"These are shields that are placed between the radiation source and people/the environment. It is important that they absorb as much radiation as possible. Radiation shields are tuned to the application to make them as effective as possible. This allows them to block a large number of photons while remaining lightweight, transparent and durable. For example, concrete effectively blocks gamma rays when mixed with certain fillers, so it has long been used for shielding. However, this material is short-lived: it cracks and loses water over time, so you have to consider the full range of its properties to improve its performance," says Hesham Zakali.
Existing materials - lead, petroleum-based plastics or concrete - can be quite dangerous, in part because of their toxicity. They are also heavy and expensive. One alternative could be material developed by an international group of scientists.
As more and more technology is created that depends on radiation, the need for materials that can block it is growing. Scientists are therefore looking at new "smart" materials with protective properties.
Published in journal: Radiation Physics and Chemistry
Source/Credit: Ural Federal University
Reference Number: chm011923_01