May 26 2003
Although unmodified Polyphenylene Oxide (PPO) is a semi-crystalline thermoplastic, all commercially available grades are blended with (high impact) polystyrene in order to improve melt processability.
A wide range of proportions, together with the use of other modifiers, results in a good range of grades with differing properties tailored to the needs of individual end-uses.
These blends are amorphous, opaque, pale grey engineering thermoplastics with a balance of properties (and cost) not unlike nylon but without nylon’s high water absorption and consequent dimensional instability.
However Polyphenylene Oxide (PPO)Modified has poor fatigue characteristics and poor solvent, though good hydrolysis, resistance.
Applications
Applications of Polyphenylene Oxide ( PPO ) include electrical and TV components, washing and dish-washing machine parts, automobile parts (especially fascias) and structural foam.
Key Properties
The key properties of Polyphenylene Oxide ( PPO )Modified are tabulated below.
Table 1. Key properties
| Chemical Resistance |
| Acids – concentrated |
Fair |
| Acids – dilute |
Good |
| Alcohols |
Fair |
| Alkalis |
Good |
| Aromatic hydrocarbons |
Poor |
| Greases and Oils |
Fair |
| Halogens |
Poor |
| Ketones |
Fair |
| Electrical Properties |
| Dielectric constant @ 1 MHz |
2.7 |
| Dielectric strength ( kV.mm-1 ) |
16-20 |
| Dissipation factor @ 1 kHz |
0.004 |
| Surface resistivity ( Ohm/sq ) |
2x1016 |
| Volume resistivity ( Ohm.cm ) |
1017 |
| Mechanical Properties |
| Abrasive resistance - ASTM D1044 ( mg/1000 cycles ) |
20 |
| Coefficient of friction |
0.35 |
| Elongation at break ( % ) |
50 |
| Hardness – Rockwell |
M78/R115 |
| Izod impact strength ( J.m-1 ) |
200 |
| Poisson's ratio |
0.38 |
| Tensile modulus ( GPa ) |
2.5 |
| Tensile strength ( MPa ) |
55-65 |
| Physical Properties |
| Density ( g.cm-3 ) |
1.06 |
| Flammability |
HB |
| Limiting oxygen index ( % ) |
20 |
| Resistance to Ultra-violet |
Good |
| Water absorption - over 24 hours ( % ) |
0.1-0.5 |
| Thermal Properties |
| Coefficient of thermal expansion ( x10-6 K-1 ) |
60 |
| Heat-deflection temperature - 0.45 MPa ( °C ) |
137 |
| Heat-deflection temperature - 1.8 MPa ( °C ) |
125 |
| Lower working temperature ( °C ) |
-40 |
| Thermal conductivity ( W.m-1.K-1 ) |
0.22 @ 23 |
| Upper working temperature ( °C ) |
80-120 |
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