Progettazione di bio-plastiche compostabili innovative per la produzione di soluzioni per l’imballaggio alimentare = Design of innovative compostable bio-plastics for the manufacturing of packaging solutions

Global production of plastic has continued to rise in the past 50 years, the amount of plastic produced in the last two decades exceeds the total production of plastic in the past century. Market driven by consumerism, alongside comparatively low price of plastic materials caused demand for plastic to increase. Recovery and recycling, however, remain insufficient; millions of tons of plastics end up in landfills and mismanaged waste finds its way to the oceans. Plastic debris may take up to 450 years to degrade, causing direct and deadly effects on wildlife. The majority of plastic production is used in the packaging industry, representing 40% of demand in Europe and 42% in the United States. Plastic is an important material for the global economy, the revenue generated by the plastic industry is estimated to $ 600 billion annually. However, its growing production brings with it a series of challenges related to its production, use, and end-of-life that need to be addressed. The European Commission very recently (January 2018), communicated a strategy to tackle the issue of plastic waste. Commitments include a reduction in consumption of single-use plastics and restrictions on the use of micro-plastics, such as microbeads found in some cosmetics, furthermore, innovation efforts in the development of biodegradable plastics are encouraged. In Europe, bioplastics consumption is estimated at around 0.1–0.2% of total EU plastics consumption but the global bioplastics market is growing very rapidly. Bioplastics can potentially be used for a wide range of applications but cannot yet replace all types of petroleum-based plastics in every application, due to processing difficulties, low thermal stability or unacceptable mechanical properties. The EU Commission has always acknowledged the importance of the plastic industry and in 2017, the Commission confirmed it would focus on plastics production, working in favour of a more sustainable use and disposal of plastics. In 2018 the European Commission proposed a new EU-wide guidance to target the 10 most common plastic waste items found on European beaches. The new rules follow different criteria depending on the products they will be applied to. For example, single-use plastic products will be banned altogether from the market if alternative and affordable solutions are available, this is the case of single-use plastic cutlery, straws, drink stirrers, plates, cotton buds and sticks for balloons which will be banned from 2021. These products will all have to be made exclusively from more sustainable materials. The Commission's proposals will soon go to the European Parliament and Council for adoption. Agreements reached by the European Council and Parliament on the EU waste legislative package published by the Commission in 2015, recognise the benefits of bioplastics. Bio-based feedstock for the production of compostable plastic packaging is acknowledged as an efficient waste management option and helps to reduce the impacts of plastic packaging on the environment. Bioplastics are characterized by a circular nature, therefore substituting fossil-based feedstock with renewable resources is a key transition that is supported by legislation, in line with EU policy on Circular Economy (COM 2015/614 entitled “The missing ring. European action plan for the circular economy”). Biodegradable and especially compostable plastics may break down over the course of a few months, depending on the materials involved, thickness and the conditions of their disposal, while conventional plastics typically break down in hundreds of years. This typical trait of compostable plastics obviously eases pressures on the waste stream of plastic packaging items. Nonetheless, several aspects limit wide-spread application of biobased and compostable plastics. Firstly, most biopolymers are very sensitive to thermo-hydrolitic degradation, causing great difficulties during processing (i.e. – stickiness, molten instability, air bubbles, etc,) and a general loss of mechanical and thermal properties of such materials, which in many cases are not exceptional to start with. Secondly, achieving the same characteristics in terms of thermal stability, mechanical properties and permeability of fossil plastics such as PET, PE, PP or PS may be triggering. Among bio-derived and compostable polymers, polylactic acid (PLA) is one of the most promising biopolymers thanks to its superior mechanical properties and appreciable thermal stability compared to most bioplastics. Nonetheless, compared to conventional plastics, such as PET, PLA is still rather brittle and suffers from poor thermal resistance.