The Physical Properties of Polyester Fibre

physical property

1.Color: polyester fiber is generally milky white with mercerization. To produce Matt products, the matting agent TiO2 should be added before spinning. To produce pure white products, the whitening agent should be added. To produce colored yarn, the pigment or dye should be added into the spinning melt.

2.Surface and cross section shape: The surface of conventional polyester is smooth and the cross section is nearly round. If the profiled spinneret is used, it can be made into fibers with special cross-section, such as triangular, Y-shaped, hollow and so on

3.Density: when polyester is completely amorphous, the density is 1.333g/cm3. It is 1.455g/cm3 when fully crystallized. Generally, polyester has higher crystallinity, and the density is 1.38 ~ 1.40g/cm3, which is similar to wool (1.32g/cm3).

4.Moisture regain: the moisture regain of polyester is 0.4% under standard condition, which is lower than that of acrylic (1% ~ 2%) and nylon (4%). Polyester has low hygroscopicity, so its wet strength decreases less and the fabric washability is good; However, the electrostatic phenomenon is serious during processing and wearing, and the air permeability and moisture absorption of the fabric are poor.

5.Thermal properties: softening point t of polyester is 230-240 degrees Celsius, melting point TM is 255-265 degrees Celsius, decomposition point t is about 300 degrees Celsius. Polyester can burn in the fire, curl and melt into beads, with black smoke and fragrance.

6.Light resistance: its light resistance is second only to acrylic fiber. The light resistance of polyester is related to its molecular structure. Polyester only has a strong absorption band at 315 nm, so the strength loss is only 60% after 600 hours of sunlight exposure, which is similar to that of cotton.

7.Electrical properties: polyester has poor conductivity due to its low moisture absorption, and its dielectric constant is 3.0 ~ 3.8 in the range of – 100 ~ + 160 degrees Celsius, so it is an excellent insulator.