| Tenacity (gpd) | High Tenacity | Normal Tenacity | Staple |
| Dry | 6-7 | 4.5-5.5 | 3.5-4 |
| Wet | 6-7 | 4.5-5.5 | 3.5-4 |
| Elongation (%) | |||
| Dry | 12.5-7.5 | 25-15 | 40-25 |
| Wet | 12.5-7.5 | 25-15 | 40-25 |
| Density | 1.38 | 1.38 | 1.38 |
Moisture Regain
At 65% RH and 70 deg F--> 0.4%
Because of low moisture regain, it develops static charge. Garments of polyester fibres get soiled easily during wear.
Thermal Properties
Polyester fibres are most thermally stable of all synthetic fibres. As with all thermoplastic fibres, its tenacity decreases and elongation increases with rise in temperature. When ignited, polyester fibre burns with difficulty.
Shrinkage
Polyester shrinks approx 7% when immersed in an unrestrained state in boiling water. Like other textile fibres, polyester fibres undergo degradation when exposed to sunlight.
Its biological resistance is good as it is not a nutrient for microorganisms.
Swelling and Dissolving
The fibre swells in 2% solution of benzoic acid, salycylic acid and phenol.
Alcohols, Ketones, soaps, detergents and drycleaning solvents have no chemical action on polyester fibres.
Chemical Resistance
Polyester fibres have a high resistance to organic and mineral acids. Weak acids do not harm even at boil. Similarly strong acids including hydrofluoric acids do not attack the fibres appreciably in the cold.
Uses of Polyester
1. Woven and Knitted Fabrics, especially blends.
2. Conveyor belts, tyre cords, tarpaulines etc.
3. For filling pillows
4. For paper making machine
5. Insulating tapes
6. Hose pipe with rubber or PVC
7. Ropes, fish netting and sail cloth.
