This trick can be explained in many ways. There are three possibilities: 1. Atomic number of titanium: 222. Number of natural isotopes of titanium: 53. Number of protons in a titanium atom: 22.

PP, a hydrophobic material primarily used for drainage purposes, boasts a significantly lower hygroscopicity compared to highly hygroscopic materials like nylon. In fact, under ambient conditions, PP only absorbs less than 0.03% of its weight in moisture. This impressive resistance to moisture makes it a popular choice for waterproof packaging, textiles, and automotive parts.

While polypropylene can be modified through copolymerization or blending with other materials to enhance its compatibility with water or moisture, it is crucial to keep it dry during processing to avoid compromising its mechanical properties or performance.

Polypropylene is often identified by the resin identification code number 5. This coding system was developed by the Society of the Plastics Industry (now the Plastics Industry Association) in 1988 to facilitate recycling by categorizing plastics by their polymer type. Number 5, with its "recycling triangle" around it, signifies polypropylene (PP). Polypropylene is a versatile plastic used in various applications such as packaging, textiles, automotive components, and reusable containers. It is known for its strength, resistance to chemicals, and flexibility. The identification code helps in the sorting process during recycling, making it easier for recycling facilities to separate and process materials efficiently. Understanding these codes is crucial for proper recycling practices and environmental sustainability.

[Polypropylene is identified by the resin code number 5, aiding recycling and indicating its use in myriad applications due to its versatile properties.]