PSI - Issue 40

Ivetta Varyan et al. / Procedia Structural Integrity 40 (2022) 445–449

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Ivetta Varyan at al. / Structural Integrity Procedia 00 (2019) 000 – 000

result, to the emergence of a number of related environmental problems. If nothing is done, in the near future this situation can lead to disastrous consequences. To solve this problem, much attention has been paid to the development of biodegradable polymers from renewable sources. Once in waste, such polymers are able to undergo a biodegradation process, which is the process of changing the chemical structure of the polymer from a more complex to a simpler one under the influence of various biological factors, such as soil bacteria, mold fungi and various atmospheric microorganisms. The end products of a biodegradation process typically include CO 2 , CH 4 , water, biomass and other natural substances that have a positive effect on environmental balancing. Repeated attempts to create new, fully biodegradable polymers with attractive commercial production costs and acceptable performance characteristics have so far been unsuccessful. Therefore, it is becoming increasingly clear that the best solution to the problem of environmental pollution from plastic waste is to develop technologies to convert already commercially used plastics into biodegradable ones. Thus, the modification of a polymer by introducing additives that trigger the rapid degradation of the polymer makes it possible to obtain composite materials with increased degradability after their life cycle. At the same time, the profitability of the production of such composite materials is expected to be high due to the absence of expensive synthesis steps in the production cycle. In this case, the presence of a synthetic polymer in the composite provides the required operational and technological properties, as well as the possibility of reuse. In turn, the type of additive determines the rate of polymer biodegradation. The use of natural fillers obtained from the waste of agricultural production can significantly reduce the cost of such materials, which makes their profitability even higher. For example, in a number of works, composite materials based on low and high density PE were obtained, filled with such materials as wood flour, rice husk, corn, banana flour and others. Despite a number of significant advantages of synthetic polymer composites with natural fillers, discussed above, the mechanical properties of such materials remain rather low. This prompts researchers to look for new materials for creating polymer composites with characteristics acceptable for their commercial use. In this study, a technology for the production of biodegradable materials is proposed based on low-density polyethylene with the addition of natural rubber (NR). It is shown that, with good biodegradability, such materials also have satisfactory operational physical and mechanical properties. This suggests that materials based on PE/NR composites can be used to create a wide range of products for the needs of agriculture and other industries. 2. Materials and methods To make low-density polyethylene biodegradable, raw natural rubber was used as an additive. To study the physicochemical properties of PE/NR composites, the samples were made in the form of polymer films with an NR content varying in the range of 10- 50 wt%. Compounding of the polymers was carried out at 140 °C in a Brabender mixer. Film samples were obtained b y pressing at 140 °C followed by rapid cooling to a temperature of 20 ± 2 °C. The strength characteristics and biodegradability of PE/NR mixtures of composition 100/0, 90/10, 80/20, 70/30, 60/40 and 50/50 (wt%) were determined. The mechanical properties of polymer PE/NR composites were studied using bursting test equipment from DVT Devotrans. Its principle of operation is to stretch a polymer film sample at a speed of 100 mm/min. In this case, the polymer film is deformed, and the force developed during deformation is measured. The dimensions of the polymer test samples were 10×60 mm, the thickness was 0.2 ± 0.07 mm, and the length of the working section of the samples was 40 mm. Biodegradation tests were carried out by composting PE/NR polymer film samples in synthetic soil, prepared in accordance with GOST 9.060-75. The soil moisture content was maintained at 60% throughout the testing period. This value was chosen based on the fact that it is optimal for the biological activity of microorganisms used in our tests. Biodegradation of polymer films was characterized by assessing changes in the appearance and weight of the samples after exposure to soil over time up to 18 months. 3. Results and discussion To study the effect of natural rubber additives on the biodegradability of film samples based on low-density polyethylene, laboratory tests were carried out using synthetic soil. The biodegradation of the polymer material was