The morphological structure observed in the microscope of the polyester obtained by the melt spinning method has a circular cross section and no special longitudinal structure. Filamentous fibril tissue can be observed under an electron microscope.
Shaped fibers can change the elasticity of the fiber, giving the fiber a special luster and bulkiness, and improving the fiber's cohesive and covering ability as well as anti-pilling and static reduction. For example, the triangular fiber has a glittering effect; the five-lobed fiber has a lustrous luster, a good feel, and is resistant to pilling; the hollow fiber has a small density inside and a good warmth.
Folded aggregate structure
The thickness of the polyester folded chain crystal measured by electron diffraction is about 10 NM, and the length of the polyester single base is 1.075 NM. Therefore, the thickness of the platelet is considered to be equivalent to the single base length of 9 polyester molecules. However, the polyester macromolecular chain length is about 1.075*130 (average degree of polymerization) = 140 NM, and it can be seen that the polyester platelet macromolecular chain must take a folded chain structure. The folding may occur at the -CH2-CH2- segment because the flexibility of the chain is good and it is easy to bend.
In addition, since the polyester macromolecule can also form an extended chain crystal (fibrillated crystal). It can be seen that the polyester internal folded chain crystal and the fibril crystal coexist. The two crystal ratios vary depending on the draw ratio and heat setting conditions.