PP (Polypropylene)

PP (Polypropylene) is a semi-crystalline polyolefin with density 0.90–0.91 g/cm³ and melting point 160–168°C, produced by Ziegler-Natta or metallocene catalysis. It carries Resin Identification Code 5. In India, PP is used extensively in: woven sacks (BOPP bags for cement, fertiliser, food grains), thin-walled injection-moulded containers (cups, crates, buckets), automotive components (bumpers, door panels, battery cases), BOPP film for packaging, capacitor films, and medical disposables. India's PP consumption exceeds 5 million tonnes per year — the single largest-volume polymer in many recycling streams. Note: PP here refers specifically to Polypropylene polymer. In other contexts, PP may stand for Purchasing Power or other terms.

PP's density (0.90–0.91 g/cm³) means it floats in water, along with HDPE and LDPE — this is critical for float-sink separation. However, PP-HDPE mixed floats must then be separated by density gradient (salt solution at ~1.0 g/cm³ separates HDPE sinks from PP floats) or by NIR spectroscopy. The melting point of 160–168°C puts PP above HDPE (120–180°C overlap) but well above PET and PVC processing temperatures — mixed-polymer streams that include PP can be processed together as polyolefin blends at 200–220°C if purity grades are not critical. For colour-sorted, clean PP, recycled pellets sell at Rs 55–85 per kg; mixed colour or contaminated PP at Rs 30–50 per kg.

PP woven sacks present a particularly large and consistent industrial recyclate stream in India — cement, polymer, and fertiliser manufacturers generate thousands of tonnes of PP woven bag offcuts and used sacks annually. These are highly predictable in composition (typically >95% PP with polyester sewing thread contamination) and command prices of Rs 20–32 per kg at the baler gate. Laminated BOPP film (PP with adhesive laminate) is the more difficult stream: the adhesive layer and print reduce pellet quality and require higher wash temperatures and additive loading in the extruder. PP automotive scrap (shredder residue from vehicle recycling) is typically mixed with rubber, glass, and metal and requires aggressive separation before recycling.

For Indian recyclers, the practical opportunity in PP is the woven sack segment: steady supply from industry, relatively clean stream, established aggregator networks in industrial zones, and growing demand for rPP in non-critical applications (new woven sacks, construction sheeting, lower-spec injection moulding). A 200–500 TPD PP line processing woven sacks requires Rs 3–8 crore capex and achieves gate-to-gate margins of Rs 5–12 per kg after accounting for 8–12% material loss in washing.