Determining whether a material is polypropylene (PP) involves a few simple tests, given its unique properties. First, check for a recycling symbol with the number 5 inside and the letters "PP" beneath it, which is a direct indicator of polypropylene. Another method is the density test; PP floats in water since it's less dense (0.855-0.946 g/cm³). Additionally, consider performing a burn test in a controlled environment: polypropylene burns with a yellow flame and produces a faint, sweet smell, distinguishing it from other plastics. However, remember to exercise caution with the burn test due to health and safety concerns. These tests, combined with observing the material’s characteristics such as its resistance to chemicals, staining, and its semi-rigid nature, can help identify polypropylene.

Polypropylene (PP) is a thermoplastic polymer known for its versatility and wide range of applications, from packaging materials to automotive components. The softening point of polypropylene, often referred to as its Vicat Softening Point, is a crucial thermal property indicating the temperature at which PP begins to deform under a specific load. Typically, this softening point for polypropylene ranges between 150°C and 160°C (302°F and 320°F). This temperature can vary depending on the specific type of polypropylene—whether it's homopolymer, copolymer, or a particular blend designed for enhanced qualities like impact resistance or clarity. Understanding the softening point is essential for determining polypropylene's suitability for various applications, especially those involving exposure to heat. It is also critical in processing techniques such as injection molding or extrusion, where precise temperature control is needed to achieve the desired product properties.

Joining PVC pipes involves a process known as solvent welding. First, ensure the pipe ends are clean and dry. Apply a primer to both the pipe end and the inside of the fitting to prepare the surfaces. Once the primer has dried, apply a liberal amount of PVC cement to the same areas. Quickly insert the pipe end into the fitting with a slight twisting motion to spread the cement evenly and hold it in place for a few seconds to ensure a strong bond. It's crucial to work quickly as the cement sets fast. Avoid using the pipeline for at least 24 hours to allow the joint to cure fully.