The thermoplastic polymer polypropylene (abbreviated PP) is widely used in many products. PP is strong and can withstand different chemical solvents, acids and bases. The resin identification code for PP is 5 and it can be recycled.
According to Transparency Market research in 2014, the global PP market was worth more than $80billion. It is expected to rise to $133.3billion by 2023.
Polypropylene Recycling is Important
PP is the most widely used plastic packaging material in America, with five billion pounds of PP being produced each year in the U.S. (2010). American Chemistry Council’s PP production and recycling statistics show that PP is not recycled at a rate of less than 1 percent.
Due to the short life span of PP-made packaging, most of these thermoplastics end in landfills as trash. According to the US Environmental Protection Agency, approximately 20% of all solid waste is made up of plastics that include PP. Products made from PP take 20-30 years to fully degrade in landfills. This is a serious concern for the environment. Plastic additives may contain toxic substances such as lead or cadmium. Research suggests that plastic products may contain cadmium, which can percolate into water and cause severe health problems in a variety of bio-systems. The burning of thermoplastics such as PP can release dioxins or vinyl chloride.
The Polypropylene Recycling Process
Recycling involves five steps: collection, sorting and cleaning. Then, reprocess the PP by melting it to make new products. The first three steps are similar to recycling other commodities. The last two steps are crucial. The reprocessing stage involves the feed of PP products into an extruder, where it melts at 4,640 degrees F (2,400 degrees C) and is cut into granules. These pellets can then be used in the manufacture of new products.
Polypropylene Recycling: Opportunities and Challenges
PP recycling is being improved continuously. Nextek Ltd., a UK-based Plastic design & recycling consulting firm and finalist in the 2013 recycling innovators forum has developed an innovative process to remove food grade polypropylene from food packaging.
Nextek’s process is two-phased. The first involves melting PP at 250 degrees Celsius (500 degrees F) to remove contaminant molecules. The second and final step involves removing any residual molecules under vacuum and solidification at 140°C (280°F). This process allows you to mix virgin PP with your products up to 50%.
The primary challenge in polypropylene recycle is to increase its rate and eliminate the harmful effects of improper disposal. As we have already mentioned, only 1% of PP can be recycled at the moment. This enormous problem can only be overcome by the development of innovative technologies.
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Proctor & Gamble and PureCycle Technologies announced a partnership in July 2017 to build a PP recycling facility in Lawrence County, Ohio. The aim was to convert polypropylene into a “virgin-like quality”. There is a huge gap in the market for recycled polypropylene. According to the Association of Plastics Recyclers, there is an annual demand for 1 Billion pounds of recycled polypropylene in North America alone. This includes 720 MILLION pounds of high-quality recycled PP.