Commonly Recycled Polymers (PET, HDPE, LDPE, PP, PS) - Polymer Identification & Properties
A quick-reference table for the five most commonly recycled plastic polymers — PET, HDPE, LDPE, PP, and PS — showing their Resin Identification Code (RIC), full name, key physical characteristics, and typical waste sources.
| Resin Code | Polymer Name | Key Characteristics | Common Waste Sources |
| 1 (PET) | Polyethylene Terephthalate | High clarity, strong moisture barrier, high strength. | Water/soda bottles, food jars, polyester clothing. |
| 2 (HDPE) | High-Density Polyethylene | Opaque, tough, chemical resistant, high melting point. | Milk jugs, shampoo bottles, detergent containers, crates. |
| 4 (LDPE) | Low-Density Polyethylene | Flexible, transparent/translucent, high impact resistance. | Grocery bags, shrink wrap, squeeze bottles, liners. |
| 5 (PP) | Polypropylene | High heat resistance, stiff, fatigue resistant. | Yogurt tubs, bottle caps, microwaveable trays, car parts. |
| 6 (PS) | Polystyrene | Rigid and brittle (GPPS) or foamed (EPS). | Disposable cutlery, CD cases, Styrofoam packaging. |
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How to read this table
- Resin Code is the number inside the recycling triangle symbol printed on plastic products — used for quick visual sorting.
- Key Characteristics describe physical properties relevant to recycling processing and end-use application quality.
- Common Waste Sources are the product types where each polymer most frequently appears in the urban waste stream.
About this table
Before a plastic waste material can be recycled, it must be identified and sorted by polymer type. Mixing different polymers in a recycling line degrades the output material. This table is the starting-point reference for that identification process — covering the five polymers that form the majority of India's plastic waste stream: PET, HDPE, LDPE, PP, and PS.
PET (Resin Code 1) — Polyethylene Terephthalate — is the clear, tough polymer used in water bottles, soda bottles, and food jars. Its high clarity and moisture barrier make it a premium recycled material (rPET) for both food-contact bottles and polyester fibre. HDPE (Code 2) — High-Density Polyethylene — is the opaque, chemically resistant polymer in milk jugs, shampoo bottles, and industrial crates. Its high melting point (130–135°C) makes it durable in outdoor applications.
LDPE (Code 4) — Low-Density Polyethylene — is the flexible film polymer in grocery bags, shrink wrap, and liners. It is soft and transparent to translucent, with high impact resistance but low stiffness. LDPE film is one of the harder polymer streams to recycle because it tends to wrap around shredder and granulator components rather than being cleanly cut. PP (Code 5) — Polypropylene — is the heat-resistant, stiff polymer used in yogurt tubs, bottle caps, microwaveable trays, and automotive parts. PP tolerates temperatures up to approximately 160°C, making it suitable for applications that PET and HDPE cannot handle.
PS (Code 6) — Polystyrene — comes in two commercial forms: General Purpose Polystyrene (GPPS), which is rigid and brittle (used in CD cases and disposable cutlery), and Expanded Polystyrene (EPS), the white foam packaging material. PS is the most problematic of the five for mechanical recycling — GPPS is brittle and shatters into fine particles, while EPS has very low bulk density, making collection and transport economics challenging.
Key insights
- PET (Code 1) and HDPE (Code 2) are the highest-value polymers for mechanical recyclers because their clean sources (bottles, jugs) produce high-purity sorted feedstock.
- LDPE film (Code 4) requires special granulation and washing equipment because it wraps around rotating components instead of being cleanly cut.
- PS (Code 6) is the most difficult of the five for mechanical recycling — GPPS shatters into dust and EPS has low bulk density, creating collection and processing economics problems.
- PP's heat resistance (up to 160°C) makes it useful in applications where PET and HDPE fail — but mixed-colour PP is typically downcycled into non-food applications.
Methodology & sources
Polymer properties listed are standard physical characteristics from polymer science literature. Resin Identification Codes (RIC 1–6) are the international standard coding system. Waste source descriptions reflect typical sources in urban mixed waste streams in India. Actual waste-stream composition varies by city and collection method.
Related data tables
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