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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