Unplasticised Polyvinyl Chloride - Unplasticised PVC - UPVC

It is an amorphous commodity thermoplastic that can be colorless and transparent but is much more commonly pigmented. It is strong, stiff, and inherently flame retardant with relatively good chemical resistance (solvents are its weak area, particularly stress cracking therein).

It has good UV resistance and barrier properties but a limited operational temperature range, and unless modified it becomes brittle at 5 °C with an upper continuous use temperature of 50 °C. As additive-free PVC begins to decompose before it melts, it can only be melt processed by the use of copolymers or the addition of stabilizers (or by the addition of plasticizers which gives rise to products of different properties).

Polymer Type

Thermoplastic

Advantages

Cheap, good acid and alkali resistance.  Flame-retardant.  Stiff and strong.  Can be transparent.  Good vapour barrier properties.  Good UV resistance.

Disadvantages

Difficult to melt process, requires modification.  Limited solvent stress cracking resistance.  Becomes brittle at (c 5 °C (40 °F) ) unless impact modified.  Low continuous service temperature of 50 °C (120 °F).

Applications

Pipe and pipefittings, building products e.g. gutters, cladding, window frames.  Bottles, film, LP records, floor tiling

While PVC is extensively used as cable insulation, this is generally made from plasticized grades (or sometimes from cross-linked PVC for minimum flammability).

Typical Properties

Property Value
Density (g/cm3) 1.4
Surface Hardness RR110
Tensile Strength (MPa) 51
Flexural Modulus (GPa) 3
Notched Izod (kJ/m) 0.08
Linear Expansion (/°C x 10-5) 6
Elongation at Break (%) 60
Strain at Yield (%) 3.5
Max. Operating Temp. (°C) 50
Water Absorption (%) 0.1
Oxygen Index (%) 45
Flammability UL94 V0
Volume Resistivity (log ohm.cm) 14
Dielectric Strength (MV/m) 14
Dissipation Factor 1 kHz 0.025
Dielectric Constant 1 kHz 3.1
HDT @ 0.45 MPa (°C) 70
HDT @ 1.80 MPa (°C) 67
Material. Drying hrs @ (°C) 2 @ 75
Melting Temp. Range (°C) 150 - 220
Mould Shrinkage (%) 0.4
Mould Temp. Range (°C) 20 - 40

Source : Abstracted from Plascams

For more information on Plascams please visit RAPRA Technology Ltd.

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