PVC, PE, PP and PS are general purpose plastics. The features of the particular plastic are determined by its chemical composition and type of molecular structure (molecular formation: crystalline/amorphous structure)
PVC has an amorphous structure with polar chlorine atoms in the molecular structure. Having chlorine atoms and the amorphous molecular structure are inseparably related. Although plastics seem very similar in the context of daily use, PVC has completely different features in terms of performance and functions compared with olefin plastics which have only carbon and hydrogen atoms in their molecular structures.
Fire retarding properties
PVC has inherently superior fire retarding properties due to its chlorine content, even in the absence of fire retardants.
Under normal conditions of use, the factor most strongly influencing the durability of a material is resistance to oxidation by atmospheric oxygen. PVC, having the molecular structure where the chlorine atom is bound to every other carbon chain, is highly resistant to oxidative reactions, and maintains its performance for a long time.
PVC is resistant to acid, alkali and almost all inorganic chemicals. Although PVC swells or dissolves in aromatic hydrocarbons, ketones, and cyclic ethers, PVC is hard to dissolve in other organic solvents. Taking advantage of this characteristic, PVC is used in exhaust gas ducts, sheets used in construction, bottles, tubes and hoses.
PVC is a chemically stable material, which shows little change in molecular structure, and also exhibits little change in its mechanical strength.
Processability and mouldability
The processability of a thermoplastic material depends largely on its melt viscosity. PVC is not suitable for injection moulding of large sized products, since its melt viscosity is comparatively high. On the other hand, the viscoelastic behaviour of molten PVC is less dependent on temperature and is stable. Therefore PVC is suitable for complex shaped extrusion profiling (e.g., housing materials), as well as calendaring of wide films and sheets (e.g., agricultural films and PVC leather).
Other properties that make PVC versatile
PVC has polar groups (chlorine), and is amorphous, therefore mixes well with various other substances. The required physical properties of end products (e.g., flexibility, elasticity, impact resistance, anti-fouling, prevention of microbial growth, anti-mist, fire retarding) can be freely designed through formulation with plasticisers and various additives, modifiers, and colouring agents. PVC is the only general purpose plastic that allows free, wide and seamless adjustment of the required physical properties of products such as flexibility, elasticity, and impact resistance, by adding plasticisers, additives, and modifiers. Since the physical properties of end products are adjustable through compounding with additives, only a few types of resin are required to cover all applications (fibre, rigid and flexible plastic, rubber, paint, and adhesive). This controllability is also extremely beneficial for recycling.