RUDN University biologist tested the resistance of bioplastics to aggressive environment
Bioplastics are an alternative to ordinary plastics. They are obtained from waste of plant and food industry. The safe composition allows using them as filters for gases and liquids, as “sponges” for cleaning reservoirs and medical implants. Depending on the field of use, bioplastics are exposed to different environmental factors — light, water, temperature, and the physiological environment. It is still not known how the external environment affects the nanostructure of bioplastics products. The RUDN University biologist found out how the environment affects the nanofibers of two plastics of organic origin: polylactide and polyhydroxybutyrate.
“We obtained the electrospun ultrathin fibers based on thermoelastic biopolyesters. Both of them produced from the naturally abundant renewable resources, namely, polylactide and polyhydroxybutyrate. But our main aim was not to obtain the fibers themselves, but to determine whether their properties are preserved under the impact of aggressive environmental factors”, Alexandre Vetcher, PhD, Deputy Director of the Scientific-educational centre “Nanotechnologies” of RUDN University
Biologists obtained six types of fibers from polyhydroxybutyrate powder and polylactide granules by electrospinning method. The polymer solution was placed in a high-voltage electrostatic field, which “pulled” the solution into thin jets. After cooling, they turned into fibers. Six types of finished fibers differed in the content of polymers in the composition-pure polylactide and polyhydroxybutyrate and their blends in different ratios.
RUDN University biologists have studied the impact of water, physiological environment (internal environment of the body) and ozone on the resulting nanofibers. It turned out that the water vapor absorption depends on the polymer structure. The higher the proportion of polylactide, the more water the fibres absorb: up to 1% of the sample weight. Scientists used a phosphate buffer to simulate the internal environment of a living organism. Polylactide fibers lost more than 50% of their mass in solution over 21 days, and samples with a high polyhydroxybutyrate content lost less than 15%. Also, polymers with a high content of polylactide absorbed ozone molecules more quickly when treated with a stream of this gas and as a result of such intense oxidation they were destroyed. Ozone penetrated the fibers with a 50:50 ratio of the two polymers the fastest.
“We demonstrated that biodegradable nanofibers, which are characterized by a crystalline structure, are more resistant to decomposition by water and ozone. Now it is necessary to test these materials for resistance to UV light and microorganisms in order to determine the optimal applications for each type of fiber”, Alexandre Vetcher, PhD, Deputy Director of the Scientific-educational centre “Nanotechnologies” of RUDN University.
The results are published in the journal Polymers
RUDN University chemist proposed a new method to create catalysts on a porous silicon matrix with metal nanoparticles. Efficient catalysts for organic reactions are obtained, for example, for the synthesis of vanillin, which is in demand in the food and perfume industry.
When talking about COVID-19, television, newspapers, magazines, and social media turn to battle metaphors that make the fight against the pandemic feel like a war. Also, the coronavirus is often discussed in an excessively alarming and threatening tone. This problem is so acute that there is even the term for that — infodemia. It describes the panic in the media and social networks. A linguist of RUDN University studied how such a language affects the notions of people regarding COVID-19.
Ecologists of the RUDN University showed that one of the methods used to detect the soil organic matter turns out to be ineffective after precipitation. Studies have shown that the impact of rain on the surface of arable soils leads to a decrease in the accuracy of modelling of organic matter content by 70%. The ecologists also suggested the way to compensate for this negative phenomenon and increase the accuracy of calculations to 84%.