Buy Recycled Material
PlastikCity is designed for use by the plastics sector, so we will concentrate on recycling at the industrial level. This involves unwanted or scrap plastic items being converted back into useable feedstock. It does not involve the collection and processing of household waste.
This will be mainly offcuts (perhaps from thermoforming) and scrap components generated by plastic processing companies. They need to be pre-sorted, clean and free from items such as metal fasteners.
For example, companies may buy raw materials in non-returnable plastic containers.
Examples would be products that have been replaced or upgraded, or surplus stock that needs to be removed to free up warehousing space.
A good example would be damaged wheelie bins collected by a local authority, supermarket crates or gas/water piping.
General post-consumer items
Coat hangers, fridge plastics, cable reels, CD cases, seed trays, automotive parts such as car bumpers.
Common material grades that are recycled
ABS • EPS • HDPE • LDPE • PA (Nylon) • PC • PC/ABS • PET • PETG • PMMA • PP • PS • PVC
Depending on the quality of the bought-in material, it may need to be sorted by polymer type, screened for metal contaminants and washed. If scrap products are pre-sorted by grade and colour, this is far more attractive to both the reprocessor and the end-user.
There are three common ways that material is processed so that it can be reused.
It is common practice to blend the recycled content with virgin material to achieve a more uniform specification (for example, MFI range). An exact colour can be specified by quoting a RAL number or other similar industry nomenclature. Other common additives include UV and heat stabilisers, lubricants to aid processing, or anti-static agents.
Providing quantities are sufficient, companies such as those listed in the PlastikCity category for Sell Your Scrap Plastic will tender for your stock. Depending on your location, collections are sometimes available. If you are generating waste product continuously, suitable stillages may be provided for you to fill.
If you are a plastic processing company, PlastikCity also has companies that offer a Toll Granulation service, meaning they can collect your scrap product, reprocess it, and then return it to you in a useable form.
Biodegradable polymers should not be confused with recyclable grades. They are designed to break down into basic and harmless chemical compounds at the end of their serviceable life. To be classed as fully biodegradable, a polymer must be reduced to carbon dioxide, water and biomass within a defined period. The standard quoted (EN 13432:2000) is most often 90% breakdown within 6-months.
The environmental conditions under which each material will degrade varies greatly. The necessary conditions determine the designation of the materials, e.g.:
The most popular grade currently in general use is PLA, an Aliphatic Polyester derived from fermenting biomass products such as sugar cane or beet, corn etc. This material will fully degrade, but only by using an industrial composting process with specific processing parameters and duration. Other products are water-soluble and will readily degrade in a household composter. An example would be milk protein-derived products.
Typical applications for biodegradable polymers involve single-use products, particularly ones that can enter the environment, e.g. through littering. Water-soluble grades are commonly used for their functionality, e.g. washing pouches that need to quickly release their contents in a washing machine or dishwasher.
Downsides of these polymers include:
When specifying a biodegradable material, consideration should be given to both the products application and its end of life outcome. For example, a single-use plastic cup will only need a relatively short life-span once used, and because it may end up as litter, should ideally degrade with extended exposure to and moisture.
Using additives to make standard polymer grades biodegradable
There are also specialist additives that can be formulated into standard polymer grades such as petrochemical-derived PP or PE. The main reason most plastics aren't readily degraded relates to their closed structure and solid form, meaning that water and/or microbes cannot penetrate. These additives are designed to remain dormant for a period of time, but then open up the structure of the plastic at the appropriate time in a product's life-cycle. This is typically achieved through a specific type of microbial attack, for example, the high concentrations of bacteria found at landfill sites. Once the additive has broken down, pores are left in the plastic material, allowing microbes to penetrate and attack the structure.
In everyday use, the additive is not subjected to high concentrations of these microbes, and can often be readily recycled. Only when entering the waste disposal system will biodegradation commence.