May 26 2003
Background
Polyvinylidenechloride ( PVDC ) is a transparent and almost colourless thermoplastic noted for its extremely low permeability to gases. As the homopolymer begins to decompose at or marginally above its melting point (200°C), all commercially available grades are copolymers (with vinyl chloride, acrylates or nitriles) and stabilisers are also normally necessary.
Applications
The applications of Polyvinylidenechloride ( PVDC ),are predominantly packaging and barrier films, often as the barrier layer in multi-layer structures.
Key Properties
The key properties of Polyvinylidenechloride ( PVDC ) are tabulated below.
Table 1. Key properties
Chemical Resistance |
Acids - concentrated |
Good |
Acids - dilute |
Good |
Alcohols |
Good |
Alkalis |
Good |
Aromatic hydrocarbons |
Fair |
Greases and Oils |
Good |
Halogens |
Good |
Ketones |
Fair |
Electrical Properties |
Dielectric constant @ 1 MHz |
3.0 - 6.0 |
Surface resistivity ( Ohm/sq ) |
1012 - 1013 |
Volume resistivity ( Ohm.cm ) |
1012 - 1016 |
Mechanical Properties |
Coefficient of friction |
0.24 |
Hardness - Rockwell |
R98 - 106 |
Izod impact strength ( J m-1 ) |
16 - 53 |
Tensile modulus ( GPa ) |
0.3 - 0.55 |
Tensile strength ( MPa ) |
25 - 110 |
Physical Properties |
Density ( g.cm-3 ) |
1.63 |
Flammability |
Self Extinguishing |
Limiting oxygen index ( % ) |
60 |
Resistance to Ultra-violet |
Fair |
Water absorption - over 24 hours ( % ) |
0.1 |
Thermal Properties |
Coefficient of thermal expansion ( x10-6 K-1 ) |
190 |
Thermal conductivity ( W.m-1.K-1 ) |
0.13 @ 23 |
Upper working temperature (°C ) |
80 - 100 |
Properties Polyvinylidenechloride Film |
Property |
|
Value |
Dielectric Strength @ 25 µm thick |
KV.mm-1 |
160 - 280 |
Dissipation Factor @ 1 MHz |
|
0.05 - 0.08 |
Elongation at Break |
% |
30 - 80 |
Heat-sealing Temperature |
°C |
120 - 150 |
Permeability to Carbon Dioxide @ 25 °C |
x10-13 cm3.cm.cm-2.s-1.Pa-1 |
0.02 |
Permeability to Nitrogen @ 25 °C |
x10-13 cm3.cm.cm-2.s-1.Pa-1 |
0.0007 |
Permeability to Oxygen @ 25 °C |
x10-13 cm3.cm.cm-2.s-1.Pa-1 |
0.004 |
Permeability to Water @ 25 °C |
x10-13 cm3.cm.cm-2.s-1.Pa-1 |
7 |
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