Plastic Waste

Plastics Waste

Types of Plastic Recycling:
Mechanical recycling is where the plastics, which soften on heating, are, reformed into moulding granules to make new products. The process involves collection, sorting, baling then size reduction into flake (film and sheet) or granules which may then need washing and drying. This is then re-compounded with additives and/or more virgin raw material, extruded and chopped into pellets ready for reuse.

Feedstock or chemical recycling is where the plastics are broken down into their chemical constituents usually by heat and pressure.

Types of Plastics Materials that are currently being recycled:

PE FILM POLYETHYLENE FILM
PE film is the most widely recycled plastics material in the UK. In excess of 50,000 tonnes per annum are recovered. Material suitable for recycling normally arises as scrap film or bags in film manufacturing operations, as material from pallet wrap, used bags and sacks and agricultural silage wrap. Most recycling companies require the material to be essentially clean but there are some companies, which have washing facilities and can handle soiled material. Pallet shrink-wrap may have paper labels attached and most recycling companies are interested only in material from which the paper has been removed. Companies involved in mixed plastics processing operations can accept mixed and contaminated material (e.g. some paper and tapes). Most companies are interested only in tonnage quantities but may accept smaller quantities if delivered.

PE POLYETHYLENE
Polyethylene (PE) is also widely used for applications other than film in Low Density (LDPE), Medium Density (MDPE) and High-Density (HDPE) forms. The rigidity of the material increases with increasing density. The materials are used in blow moulding applications (e.g. bottles, drums) injection mouldings (e.g. milk crates, food trays) and extrusions (e.g. water pipes and gas pipes).

PP POLYPROPYLENE
Polypropylene (PP) is widely used in textile applications and as carpets, ropes, tapes etc. In packaging it is used for film and in sheet for thermoforming. It is also used in very many injection moulding applications such as bottle crates, battery cases and car components and in some extrusion applications (e.g. waste pipes and drainage pipes). A large quantity of the material is recycled and this is estimated as being at least 25,000 tonnes per annum. This is in a large part due to the recovery of material from battery cases and bottle crates.

PVC POLYVINYL CHLORIDE
Polyvinyl chloride (PVC) exists in two main forms. When the polymer is combined with a liquid plasticiser the material is soft and this form is referred to as flexible PVC or PVC-P. It is used in a wide range of applications such as wire and cable insulation, flexible sheets and films, flooring applications etc. In the unplasticised form PVC is hard and rigid and this form is called rigid PVC or PVC-U. The main applications are pipes (e.g. rainwater goods, soil and drainage pipes) and profiles (e.g. window frames and conduit). The material is also used in packaging applications such as clear bottles (e.g. squash, water and toiletries) and as thin sheet for thermoforming (e.g. containers and blister packs). The UK recycling industry is recovering over 10,000 tonnes per annum of PVC, with most of this material arising as industrial scrap, e.g. window frame offcuts, strippings from electrical cable and skeletal waste from forming operations.

PS POLYSTYRENE
Polystyrene (PS) is used in both solid and expanded forms. In the solid form it is used as High Impact Polystyrene (HIPS) for a range of injection mouldings (e.g. garment hangers, film cassettes, audio and video cassettes). PS is also widely used in packaging applications (e.g. yoghurt pots), and most of these articles are formed from thin extruded sheet. Expanded polystyrene (EPS) is used in applications such as shaped packaging to protect sensitive equipment, as a heat insulating medium and also in some food packaging applications. Again, the quantities recycled are significant; perhaps 7500 tonnes per year.

ABS ACRYLONITRILE BUTADIENE STYRENE
The ABS polymers are based on three monomers i.e. acrylonitrile, butadiene and styrene. A feature of the materials is high impact strength and they are used in a variety of injection moulding applications with housings for electrical, electronic and telecommunications equipment (e.g. telephone handset cases) being the main area of use. The materials are also used as extruded sheet for thermoforming applications in packaging (e.g. margarine tubs) and, increasingly, for automotive components.

SPECIALIST POLYMERS
There are a number of specialist high performance plastics, e.g. nylon, acetal, polycarbonate, PPO, acrylic, polyesters etc, which are normally used in injection moulding or extrusion applications. Most of the materials which are recovered arise as industrial scrap either in the polymer manufacturing process or in the conversion (e.g. injection moulding) process. Some recycling companies specialise in one material but many handle a wide range of types.

MIXED PLASTICS PROCESSES
A few companies operate processes for the direct conversion of waste plastics into finished products. These processes may be able to utilise mixed plastics or contaminated plastics. In some processes the polyolefin materials (i.e. polyethylene or polypropylene) are required but in others it is PVC which is used.

Recyclers
There are now over 100 plastics recyclers in the UK involved in the Recycling of Plastics

Sources of Plastics for Recucling
Most of the plastics recycled are from the commercial and industrial sectors, with bottles being recovered from domestic sources. This pattern is because the main requirements for effective recycling of post-use plastics are:

• resource efficient reclamation of the post-use products
• facilities to sort and compact the reclaimed products
• end use applications for the recycled plastics materials

and these conditions are more easily met from commercial post-use waste. In addition heavily contaminated waste may requirel washing and drying facilities.

Statistics forrRecycling of Plastics
Under pressure from legislation, in particular the Packaging and Packaging Waste Directive, 94/62/EC, recycling of packaging products has increased dramatically from 1995.