Yes, there are side reactions in polypropylene polymerization, which can affect the yield and properties of the produced polymer. One common side reaction is chain termination, which limits molecular weight. Another is chain transfer, especially to monomer, leading to branches in the polymer chain. This branching can affect the crystallinity and melting point of the polypropylene. Additionally, unsaturated end groups can form due to β-scission, influencing polymer stability. To minimize these side reactions, precise control over reaction conditions such as temperature, pressure, and catalyst concentration is vital. Advances in catalyst design, particularly with metallocene and Ziegler-Natta catalysts, have significantly reduced the impact of these side reactions, allowing for the production of more uniform and predictable polypropylene materials.

PVC pipes are commonly available across a wide range of retail platforms, both in physical stores and online. Hardware stores, home improvement centers like Home Depot or Lowe's, and plumbing supply stores are prime locations for finding PVC pipes in various sizes and types suited to different applications, from plumbing to construction and DIY projects. Online marketplaces like Amazon and eBay also offer the convenience of home delivery, often with a broad selection. Prices and availability can vary, so it may be beneficial to shop around. When purchasing, it's vital to know the specific type (e.g., Schedule 40, Schedule 80) and size (diameter) needed for your project to ensure compatibility and meet any regulatory requirements.

Titanium dioxide is generally considered safe for use in food, cosmetic, and sunscreen products by the FDA. However, there have been some concerns raised about its safety when inhaled in significant amounts over a long period, such as in occupational exposure scenarios. The International Agency for Research on Cancer designated inhaled titanium dioxide as a possible human carcinogen based on animal studies, but admits evidence is limited. Therefore, moderate use is likely not harmful, but continuous inhalation might be. Always use products as directed to ensure safety.