HDPE (High-Density Polyethylene) is a strong, versatile, and recyclable thermoplastic known for its excellent chemical resistance, high impact strength, and low moisture absorption, making it ideal for milk jugs, shampoo bottles, piping, cutting boards, and 3D printing, identified by the recycling code "2". Its linear molecular structure gives it a high strength-to-density ratio, allowing for durable, yet lightweight products that are easily welded, machined, and thermoformed.