# Characterization and Separation of Traditional and Bio-Plastics by Hyperspectral Devices
## 1 Introduction  
In recent years, plastics belonging to the family of organic polymers have experienced a wide commercial spread mainly due to their excellent physical and mechanical characteristics and to the availability of raw materials. Nevertheless, the use of products realized with plastics may involve potentially harmful impacts on the environment and human health, for example in the case of non-virtualous management of the products' end-of-life. These issues have directed the research into plastics with similar characteristics with respect to traditional ones, but which minimize the negative impacts resulting from their life cycle (from sourcing and manufacturing to end-of-life management). Bio-plastics are currently considered as one of the most viable alternatives to traditional plastics. Bio-plastics are materials belonging to one of the following groups: (1) bio-based (from renewable raw resources) or partially bio-based non-biodegradable plastics; (2) bio-based and degradable plastics, (3) fossil resources-based and biodegradable plastics. According to [1], a plastic material is defined as a bio-plastic if it is either bio-based, biodegradable, or features both properties. Due to this definition, in the paper we will generically refer to bio-plastics though we will investigate a bio-based and biodegradable bio-plastic, i.e., PolyLactic Acid (PLA). Though the global plastics production has almost reached 360 million tons (17% of which is produced in Europe [2]), bio-plastics represent about one percent of the total plastic produced annually. Nevertheless, the bio-plastics market is growing and is highly diversified, demonstrating how these materials are the emerging novelties in several sectors, from packaging, catering products, consumer electronics, automotive, agriculture/horticulture and toys to textiles and a number of other segments. Bio-plastics have different advantages compared to traditional plastics, such as lower carbon footprint and eco-safety [3; 4]. According to the European Commission, the potential for recycling plastic waste in the European Union remains unfulfilled. Europe generates 25.8 million tons of plastic waste per year but only 30% of it is recycled. One of the possible solutions to minimize the amount plastic waste stored on landfills and in the oceans is to encourage circular economy, according to which products, materials and raw materials circulate as long as possible, which leads to minimization of waste [5]. Though the employment of bio-plastics represents a reasonable option to get a handle on the overwhelming waste problem, this typology of plastics could disturb the current recycling of plastics and hence inhibit the closure of plastic cycles [6]. Given the current small amounts of these plastics in the market, setting up separate collection is not viable and hence bio-plastics will act as contaminants whose impact on recycling processes and products has to be carefully considered. [6] has estimated that contamination of PET by PLA could be as high as 8% by 2021, with serious effects on the quality of the recycled PET. To date the default option for the disposal of bio-based and degradable plastics is their concurrent within the organic fraction of Municipal Solid Waste (MSW) and subsequent introduction into industrial composting. Because of the similarity of products made with bio-based and degradable plastics and the ones made with traditional plastics, especially in the food sector, after use they often end up in technical recycling chains [6]. This issue must be taken into account in the stage of designing and setting up of cost-effective and efficient technologies for plastics separation in recycling plants. The separation of traditional plastic wastes in mechanical recycling plants is the process that should ensure high-quality secondary raw materials to avoid fossil resource depletion due to their use as primary raw materials.