General Properties
Short Name:
Name:
PVC-U
Polyvinyl Chloride (Unplasticized)
PVC-U, sometimes also designated rigid PVC, is polyvinyl chloride without the addition of plasticizer. The letter U stands for unplasticized. As with PVC-P, thermoplastic processing of PVC-U should take place on special corrosion-resistant systems and take the decomposition temperature of PVC (HCl formation) into account. For the compounding or extrusion of PVC powder, counter-rotating twin screw extruders are used to keep the mechanical stress of the shear-sensitive polymer to a minimum. In the same way as for PVC-P, the degree of gelation serves as a quality criterion for PVC-U that is directly linked to the impact strength.
Structural Formula
Properties
| Glass Transition Temperature | 80 to 90°C |
|---|---|
| Melting Temperature | - |
| Melting Enthalpy | - |
| Decomposition Temperature | 285 to 315 / 460 to 475°C |
| Young's Modulus | 2700 to 3000 MPa |
| Coefficient of Linear Thermal Expansion | 60 to 80 *10-6/K |
| Specific Heat Capacity | 0.84 to 1.171.3 J/(g*K) |
| Thermal Conductivity | 0.13 to 0.29 W/(m*K) |
| Density | 1.38 to 1.55 g/cm³ |
| Morphology | Amorphous thermoplastic |
| General properties | High mechanical stability, stiffness and hardness, good chemical resistance, good electrical and insulating properties, low tendency to stress cracking, good weatherability, low humidity absorption |
| Processing | Extrusion, inject moulding, blow moulding, calendering, chip removing process |
| Applications | Building industry (e.g. window profiles (with stabilizers), pipes), mechanical and apparatus engineering, electrical engineering, packaging industry |
NETZSCH Measurement
| Instrument | DSC 204 F1 Phoenix® |
| Sample Mass | 10.82 mg |
| Isothermal Phases | 5 min |
| Heating/Colling Rates | 10 K/min |
| Crucible | Al, pierced lid |
| Atmosphere | N2 (40 ml/min) |
Evaluation
Due to the missing plasticizer, the glass transition of the entirely amorphous plastic PVC-U occurred at much higher temperatures, compared to PVC-P; in the present case at approx. 84°C (in both heatings, midpoint) with a step height (Δcp) of 0.32 J/(g·K) in the 2nd heating. The slight waves, overlapping the glass transition step in the 1st heating, are probably due to stress in the material that is dissipated during thermal treatment.