How Is PET Recycled? Process, Challenges, and Quality Testing
polyethylene terephthalate PET plastic material testing in laboratoryPolyethylene terephthalate (PET) is the most widely recycled plastic worldwide, with established collection and processing infrastructure driven by beverage bottle deposit systems and curbside recycling programs. PET’s recyclability is a key sustainability advantage for the packaging industry, and material testing ensures that recycled PET (rPET) meets the quality standards required for food-contact and other demanding applications. For companies seeking PET and rPET testing at a US-based testing lab, Infinita Lab provides comprehensive polymer analysis through its accredited laboratory network.
The PET Recycling Process
Collection and Sorting
PET bottles and containers are collected through curbside programs, deposit systems, and commercial waste streams. Automated sorting using near-infrared (NIR) spectroscopy separates PET from other plastics, with additional color sorting to separate clear from colored PET.
Washing and Flaking
Sorted PET is shredded into flakes, washed to remove labels, adhesives, and food residue, and subjected to hot caustic washing and friction washing to achieve the purity required for food-grade recycling.
Reprocessing
Clean PET flakes are dried, melted, and either extruded into pellets for injection molding and fiber spinning, or processed through solid-state polymerization (SSP) to restore intrinsic viscosity for food-contact bottle applications. Chemical recycling (glycolysis, methanolysis) produces virgin-quality monomers for the highest-quality applications.
Testing Recycled PET
Quality testing includes intrinsic viscosity (ASTM D4603) for molecular weight, DSC thermal analysis (ASTM D3418), contamination and color measurement, acetaldehyde content for food-contact safety, tensile properties (ASTM D638), and FTIR identification to confirm material purity.
Why Choose Infinita Lab for PET Recycling Testing?
At the core of this breadth is our network of 2,000+ accredited labs in the USA, offering access to over 10,000 test types. From advanced metrology (SEM, TEM, RBS, XPS) to mechanical, dielectric, environmental, and standardized ASTM/ISO testing, we give clients unmatched flexibility, specialization, and scale. You are not limited by geography, facility, or methodology—Infinita connects you to the right testing, every time.
Looking for a trusted partner to achieve your research goals? Schedule a meeting with us, send us a request, or call us at (888) 878-3090 to learn more about our services and how we can support you. Request a Quote
Frequently Asked Questions (FAQs)
Can PET be recycled into food-contact packaging? Yes. FDA-approved recycling processes (including solid-state polymerization and chemical recycling) produce rPET that meets food-contact safety requirements. Many beverage brands now use 25–100% rPET content in their bottles.
What is intrinsic viscosity testing for PET? Intrinsic viscosity (IV) per ASTM D4603 indicates PET molecular weight. Higher IV means higher molecular weight and better mechanical properties. Bottle-grade PET requires an IV of 0.72–0.86 dL/g.
What is solid-state polymerization? SSP heats PET pellets below their melting point under vacuum or inert gas to increase molecular weight (IV). This process restores recycled PET to bottle-grade specifications after the molecular weight reduction that occurs during mechanical recycling.
What is chemical recycling of PET? Chemical recycling breaks PET back into its monomers (terephthalic acid and ethylene glycol) through glycolysis, methanolysis, or hydrolysis. These monomers are purified and repolymerized into virgin-quality PET.
What contaminants affect rPET quality? PVC contamination causes degradation and discoloration. Acetaldehyde affects taste in beverage applications. Colored PET limits end-use options. Metal and adhesive contamination reduce mechanical properties. Testing screens for all these contaminants.
