PET (Polyethylene Terephthalate)

PET (Polyethylene Terephthalate) is a semi-crystalline polyester thermoplastic with density 1.38–1.40 g/cm³, glass transition temperature ~78°C, and melting point 250–260°C. It is identified by Resin Identification Code 1. In India, PET's dominant application is beverage bottles — carbonated soft drinks, water, juice — under the brand identity of a material that was entirely absent from Indian packaging before the 1990s but now exceeds 800,000 tonnes per year in consumption. Secondary applications include food-grade trays, blister packaging, and polyester textile fibre (rPET fibre is the largest single end-market for recycled PET globally).

PET's high density (1.38 g/cm³) means it sinks in float-sink water separation tanks, separating cleanly from HDPE, LDPE, and PP (all of which float), and from PVC (which also sinks but can be distinguished by flame or XRF testing). This physics makes PET relatively easy to separate in mechanical recycling. Post-collection, PET bottles are typically received baled (800–1,000 kg/bale) from MRFs. Processing: bale breaking → label and cap removal → manual colour sorting (clear > light blue > green > amber > mixed colour by value) → hot wash (80–95°C, caustic 1–2%) → float-sink → rinse → drying (moisture <0.2%) → granulation to PET flake → optional crystallisation and drying to <50 ppm moisture → extrusion or direct solid-state polycondensation (SSP) for food-grade applications. PET flake (washed, non-extruded) trades at Rs 25–45 per kg; extruded rPET pellets at Rs 60–95 per kg; food-grade rPET pellets at Rs 85–120 per kg.

The critical quality issue in PET recycling is contamination by PVC: PVC decomposes at PET processing temperatures (250°C+) releasing HCl, which attacks PET chains and creates yellow discolouration in the output — as little as 50 ppm PVC in PET causes visible yellowing. Detection methods include flame test (PVC gives green flame), XRF sorting machines (Rs 15–30 lakh per unit), and NIR spectroscopy sorters (Rs 40–80 lakh per unit). Industrial-scale PET recyclers typically deploy NIR sorters at the post-wash stage. Equally problematic is thermal degradation during reprocessing: PET is hygroscopic and must be dried to <0.02% moisture before extrusion or IV (Intrinsic Viscosity) drops sharply. The IV of food-grade rPET must be maintained above 0.72–0.80 dL/g; bottle-grade virgin PET IV is 0.76–0.84 dL/g.

For Indian recyclers, PET is the most commercially attractive post-consumer plastic: collection networks are well-established (kabadiwala to aggregator to baler), baling infrastructure exists in most cities, and the EPR credit market for PET bottles (Category I under PWM Rules) generates additional revenue of Rs 3–8 per kg on top of flake and pellet sales. A 1,000 TPD PET bottle recycling line targeting food-grade rPET pellets requires investment of Rs 15–25 crore for washing, NIR sorting, drying, and SSP equipment, but generates strong margins — food-grade rPET commands a Rs 20–40 per kg premium over standard rPET pellets.