Bags made primarily from plastic (common plastics include polypropylene, polyester, nylon, etc.) are indispensable items in people's daily lives, often used to carry other items. They are widely used due to their advantages of being inexpensive, extremely lightweight, spacious, and easy to store.
Cybertron discovered the plasticity of nitrocellulose and found that items made from it were also waterproof. He took great interest in using it to create beautiful rice bowls, cups, bottles, and teapots. He admired these masterpieces and even wrote a letter to his good friend, the renowned scientist Faraday, about this unexpected discovery. Unfortunately, Faraday did not pay much attention at the time, until the emergence of a photographer. Photographer Alexander Parkes had many hobbies, and photography was one of them. In the 19th century, people could not buy ready-made photographic film and chemicals as they do today; they often had to make what they needed themselves. Therefore, every photographer also had to be a chemist.
Common food plastic bags are mostly made from polyethylene film, which is non-toxic and thus suitable for storing food. Another type of film is made from polyvinyl chloride (PVC). While PVC itself is non-toxic, the additives used based on the film's purpose are often harmful to humans and can be toxic. Therefore, such films and the plastic bags made from them are not suitable for storing food. To distinguish between polyvinyl chloride plastic bags and polyethylene plastic bags, the following simple method can be used.