Investigation of degradation of polypropylene in soil using an enzymatic additive

Abstract

Polypropylene (PP) has been widely used industrially in several sectors, mainly in the use of packaging of different products. Thus, this has been accumulated in our environment due to the incorrect disposal and its high resistance toward degradation, causing an array of environmental impacts. With this, one alternative that has been explored to minimize the problems intensified by these residues is the use of pro-degrading additives. Therefore, the aim of this work is to evaluate the degradation process of PP blends in soil using enzymatic additive. The soil degradation experiment was done for 6 months; monthly collected samples were checked for alterations on the material properties during that time. The extent of PP degradation with enzymatic additive was compared to an organic additive by techniques of FTIR, TGA, DSC, carbonyl index (CI), and crystallinity. From the obtained results it was observed that the additives influenced the degradation of PP. In addition, the enzymatic additive caused more significant changes in the CI (increase of 3693%), crystallinity (variation of 18.7%), and structural characteristics, indicating a greater influence on the degradation process in relation to the organic additive. In this way, this work has had an important role in the research and development of biodegradable materials with the aim of minimizing the effects induced by plastic waste in the environment.

Natural freshwater degradation of polypropylene blends with additives of a distinct nature

“…Comparing the results obtained in this work with the previous work [13], it can be highlighted that in both degradation media (freshwater and soil), the blends with enzymatic additive show more pronounced results after 180 days of testing. However, the use of the lowest percentage (2%) of PP with enzymatic additive shows the largest increase in CI after 30 days in soil (3693%), while blends of PP with the highest percentage of enzymatic additive (8%) show the largest CI increase in freshwater (1395%).…”

“…Due to problems in relation to the plastic waste that reaches rivers, lakes and other aquatic springs of the large freshwater reserve placed in Brazil, there is a need to look for alternatives to mitigate this problem. One alternative that has been explored is to obtain degradable polyolefins, which have with special additives called pro-oxidants or degraders, in order to accelerate and improve the degradability of polymers [13,14]. Among existing additives, the most commonly used are transition metals, but there are problems related to this type of additive as they have the potential to cause negative effects after disposal [15].…”

“…In our group's previous work [13], the soil degradation of polypropylene with a pro-degrading additive (without the presence of heavy metals) of an enzymatic nature was published, which demonstrated a higher activity when compared to 1 3 Polymer Bulletin (2021) 78:2025-2042 organic additives. As there are few published studies that evaluate degradation in aqueous media [17][18][19], this work aims to investigate the degradation behaviour of PP with commercial additives without metals (enzymatic and organic) in freshwater and compare the results with the previous work [13], due to the different characteristics between soil and water, such as luminosity and temperature.…”

Fungal Enzymes Involved in Plastics Biodegradation

“…Although some studies reported the involvement of fungi in polypropylene biodegradation, so far none have investigated the use of fungal enzymes in the biodegradation of PP [101,178,214,216,231,232]. Investigating which microorganisms are able to degrade PP and the identification of their enzymes would be an interesting and useful area of further research.…”

Abiotic and biotic degradations of a LDPE blend in soil of South Brazil landfill

“…After that, it allows molecular weight decrease and addition of oxygenated groups on PE surface, which are easily metabolized by microorganisms [17]. Biodegrading additives are composed since natural substances (enzymes or natural polymer) to synthetic polymers containing ester, hydroxyl or ether groups, which are prone to hydrolytic cleavage by microorganisms [19,21] In our group's previous work [22] degradation process in soil of polypropylene (PP) blends with 2-8% (w/w) of two biodegrading additives (organic and enzymatic) was evaluated over 6 months. Both additives had influence on PP degradation with 2% of additive (low percentage), indicating acceleration of this process by their action.…”