Molecular structure and chemical stability of PVC film
PVC, or polyvinyl chloride, is a polymer compound formed by polymerization of vinyl chloride monomers. Its molecular chain is mainly composed of carbon-carbon bonds and carbon-chlorine bonds, among which the presence of chlorine atoms is a major feature of the PVC molecular structure. As a strong electronegative element, chlorine atoms can enhance the interaction between molecular chains, thereby giving PVC film a higher hardness and mechanical strength. More importantly, the introduction of chlorine atoms also significantly improves PVC's resistance to a variety of chemical substances.

The chemical stability of PVC film is mainly reflected in its tolerance to corrosive media such as acids, alkalis, and salts. The presence of chlorine atoms changes the distribution of electron clouds on the PVC molecular chain, enhancing the molecule's defense against external attacks. For example, in an acidic environment, chlorine atoms can effectively neutralize some hydrogen ions and slow down the degradation rate of PVC; under alkaline conditions, the chlorine-carbon bonds in the PVC molecular chain are relatively stable and not prone to hydrolysis and rupture. In addition, PVC film also shows good corrosion resistance to common inorganic salt solutions, thanks to its dense molecular structure and the protective effect of chlorine atoms.

Application in the chemical and pharmaceutical fields
It is precisely based on the above-mentioned excellent chemical stability that PVC film has found a wide range of applications in the chemical and pharmaceutical industries.

In the chemical industry, PVC film is often used as a lining material for equipment such as storage tanks, pipes, valves, etc., effectively isolating corrosive chemicals and protecting the basic structure from erosion. Especially when dealing with high-risk substances such as strong acids, strong alkalis, and organic solvents, the corrosion resistance of PVC film is particularly important. It can not only extend the service life of the equipment, but also reduce safety accidents and environmental pollution caused by leakage.

The pharmaceutical industry has extremely high requirements for the purity and chemical stability of materials. PVC film is widely used in pharmaceutical packaging, such as blister packaging, infusion bags, capsule shells, etc., because of its non-toxic, odorless, and chemically inert characteristics. In these applications, PVC film can not only effectively isolate oxygen, moisture and microorganisms in the air, maintain the stability and shelf life of the drug, but also avoid the potential impact of impurities generated by the decomposition of the material itself on the quality of the drug.

Environmental considerations and future trends
Although PVC film has excellent chemical stability, with the increasing global awareness of environmental protection, environmental issues in the production, use and waste treatment of PVC materials have also received increasing attention. Therefore, developing environmentally friendly PVC substitutes or improving PVC production processes to reduce harmful substance emissions has become an important direction for industry development. For example, by adding bio-based plasticizers and developing degradable PVC composite materials, the aim is to improve the environmental friendliness of PVC products.