The Story Behind Plastic Bottles and their Recycling Codes

Most people are familiar with the little number on the bottom of recyclable plastic bottles. However not everyone knows what those numbers mean about the materials used in the packaging. Many polymers can be used to produce rigid packaging but poly(ethylene terephthalate) — known as PET — is the primary plastic material used to produce bottles for beverages, such as carbonated soft drinks, water or juices. That’s because of PET’s excellent clarity, moderate gas barrier, and good recycling, mechanical and sensorial performance. In order to differentiate the most commonly used plastic packaging materials present on the market and help recyclers facilitate the recovery of post-consumer plastics, the Society of Plastics Industry (SPI) introduced a resin identification coding system called “SPI code” in 1988. At that time, six resins had been considered the most used plastics in producing rigid packaging, and a number from 1 to 6 was assigned.... Read more