Biodegradation plastics’ life cycle

Patel, M. (2005). Environmental life cycle comparisons of biodegradable plastics. Chapter 13. In Handbook of Biodegradable Polymers, ed. Bastioli, C. Shawbury, UK Rapra Technology Ltd. pp. 431 184. 

When looking at the life cycle of biodegradable plastics, two aspects are of particular importance the end-of-life options and the use of renewable resources in the material production (the major part of the currently available biodegradable plastic products are made of blends of fossil-based polymers and polymers derived from biomass). 

In terms of the product life cycle analysis, a new product or polymer would generally require about thirty years from the research and development stage before becoming a commodity product when millions of tonnes are produced annually for mainstream application. In 2005, the biodegradable plastics industry has about fifteen to twenty years of development time behind it and has now reached the market introduction stage. 

Process design the CER includes articles which discuss the creation of products having lower environmental impact, (e.g. target-specific agrochemicals and biodegradable plastics from corn starch). Life cycle analysis is also discussed. 

The correct balance has to be found between the durability of the packaging needed for the preservation of packed food during its shelf-life, and the expected biodegradability at the end of the life cycle. Addition of nanocomposites in PLA can improve barrier properties for food applications and increase degradation in compost conditions [217]. On the other hand, plasticizers are commonly added to promote flexibility of PLA but degradation increases, and food shelf life is often negatively affected by increasing plasticizer content [89]. 

Over the past decade, researchers and citizen advocates have developed several tools to assist in decision making about plastics selection. The plastics pyramid (Fig. 5.1] developed by Thorpe and Van der Naalde in 1998 was an early attempt to visually display the life cycle hazards of different plastics to assist in materials selection. This ranking focused on the toxicity of the material, considering production hazards, use of harmful additives, hazards in use, and disposal hazards. In this pyramid, bio-based polymers form the bottom of the pyramid, indicating they are most preferable, as they are made from renewable resources, and theoretically are biodegradable and compostable (Rosalia et al., 2012]. 

Polylactic acid (PLA) has caught the attention of polymer scientist and proving to be a viable alternative biopolymer to petrochemical based plastics for many applications. PLA is produced from lactic acid, that is derived itself from the fermentation of corn or sugar beet and due to its biodegradation ability, PLA presents the major advantage to enter in the natural cycle implying its return to the biomass. The life-cycle of PLA is shown in Fig. 11.1. 

Produced from renewable resources Living organisms—E. coli, yeast, plants, and animals—can be designed to produce protein-based polymers. Protein-based polymers can be produced with renewable resources. They can be prepared without resorting to toxic and noxious chemicals, and they can be programmed for a desired biodegradation. For example, they can mean food for the fishes rather than death to marine life, as occurs with present plastics. Thus, protein-based polymers can be environmentally friendly for their complete life cycle, from production to disposal. 

Chaffe, C. and Yaros, B. (2007) Life Cycle Assessment for Three Types of Grocery Bags - Recyclable Plastic Compostable, Biodegradable Plastic and Recycled,... 

Sustainable plastics can include biobased, biodegradable, and recycled plastics. LCAs will be used to provide a scientific explanation of sustainable plastics. The content of the book includes definitions of sustainability and sustainable materials, evaluations of the environmental concerns for industry, definitions of life cycle assessments, explanations of biobased and recycled plastics, and examples of sustainable plastics as defined by LCAs. 

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