Scientists at North Carolina State University (NCSU) have been working on a new polymer that could be the basis for lighter, cheaper and more environmentally friendly radiation shielding. Led by Da Cao, the team introduced bismuth trioxide particles into poly (methyl methacrylate) (PMMA), which was then cured with UV light to produce a very light, strong material with effective gamma-ray-blocking properties.
Protecting living organisms and delicate equipment from the effects of ionizing radiation is a major concern in a wide range of fields, including the military, commercial nuclear energy, nuclear medicine, and space exploration. The trouble is, conventional shielding tends to be very bulky, heavy, and, in the case of metals like lead, toxic.
As an alternative, scientists have been looking at polymers doped with various materials as a way of making a substitute that is relatively non-toxic, light, compact, and inexpensive to produce. In the case of the NCU proof-of-concept study, the team turned to bismuth trioxide, a very common material with a wide range of industrial and medical applications.
As part of the study, the team mixed various amounts of bismuth trioxide in uncured liquid PMMA, which sets hard under the application of UV light. According to Ge Yang, an assistant professor of nuclear engineering, this makes the material easier to manufacture than others that rely on high-temperature techniques.
"Using the UV curing method, we were able to create the compound on the order of minutes at room temperature, which holds potential for the rapid manufacturing of radiation shielding materials," says Yang. "This is an important point because thermal polymerization, a frequently used method for making polymer compounds, often relies on high temperatures and can take hours or even days to complete. The UV curing method is both faster and less expensive."
Various samples of the new material were created with bismuth trioxide concentrations of up to 44 percent. This not only greatly improved the ability of the material to shield against gamma rays, but also increased the micro-hardness of the samples by up to seven times.
“This is foundational work,” says Yang. "We have determined that the compound is effective at shielding gamma rays, is lightweight, and is strong. We are working to further optimize this technique to get the best performance from the material. We are excited about finding a novel radiation shielding material that works this well, is this light and can be manufactured this quickly."
The research was published in Nuclear Engineering and Technology.
Source: North Carolina State University