- Issue Time
PVC has high hardness and mechanical properties. The mechanical properties enhance with the molecular weight increasing but decrease with the temperature increasing. The mechanical properties of rigid PVC (uPVC) are very good; the elastic modulus can reach 1,500-3,000 MPa. The soft PVC (flexible PVC) elastic is 1.5–15 MPa.
Thermal and fire properties
The heat stability of raw PVC is very poor, so the addition of a heat stabilizer during the process is necessary in order to ensure the product's properties. PVC starts to decompose when the temperature reaches 140 oC, with melting temperature starting around 160 oC. The linear expansion coefficient of rigid PVC is small and has good flame retardancy, the Limiting oxygen index (LOI) being up to 45 or more. The LOI is the minimum concentration of oxygen, expressed as a percentage, that will support combustion of a polymer and noting that air has 20% content of oxygen.
PVC is a polymer with good insulation properties, because of its higher polar nature the electrical insulating property is inferior to non polar polymers such as polyethylene and polypropylene.
Since the dielectric constant, dielectric loss tangent value, and volume resistivity are high, the corona resistance is not very good, and it is generally suitable for medium or low voltage and low frequency insulation materials.
PVC is chemical resistant to acids, salts, bases, fats, alcohols therefore it is used in sewerage piping. It is also resistant to some solvents, mainly uPVC, plastified PVC is in some cases less resistant to solvents. For example PVC is resistant to fuel, some paint thinners. Some solvents may only swell it or deform it but not disolve PVC, but some of them may damage it like tetrahydrofuran or acetone.