Unit 2 - Lecture 11 Topic 3 Flashcards
Polyester:
Polyester is the most widely used fibre in the world. It consists of a long chain of synthetic polymers that is composed of 85% or more by mass of an ester of a dihydric alcohol or a diol and
terephthalic acid. It is very versatile and can be blended with many other fibre types. Polyester contributes desirable properties to fabric without interfering with the properties of the other fibre(s).
How is polyester often created?
Polyester fibres are melt spun and filaments will be drawn. It may also be textured and later cut into staple fibres. Drawing and heat settings increase crystallinity and orientation which lead to a reduction in elongation and shrinkage.
What intermolecular forces are involved in polyester?
Polyester is non-polar as it has no hydrogen bonding capability. This makes it hydrophobic. Van der Waals are very important intermolecular forces for polyester and its benzene rings give stability to the fibre as the electrons in benzene rings create strong attractive forces. It is also highly crystalline and has good orientation.
What is the cross-sectional shape of polyester?
The cross-sectional shape is round, and the fibre has smooth surface with a variety of cross-sections e.g. round, trilobal, hollow.
What is the diameter and colour of polyester?
Fibres are 12-25 μm in diameter with a white/off-white colour. Colour can be added during manufacturing or later.
What is polyester used in?
Apparel: Coats, suits, blouses, dresses, active wear
Interiors: Wall coverings, upholstery, carpets
Technical: Fiberfill, nonwoven fabrics, tire cords, sporting goods, rope, cordage, filters, geotextiles, medical applications
What is the strength and elongation of polyester like?
Polyester has high strength which remains un-altered when wet due to its highly crystalline polymer system and effective intermolecular forces between electrons of benzene rings. Polyester has low elongation as its intermolecular forces prevent slippage.
What is the elastic recovery and abrasion resistance of polyester like?
Polyester’s elastic recovery is good under low levels of stress (about 90% recovery at 2% elongation). It also has high abrasion resistance.
What is the sunlight, chemical, insect and microorganism resistance of polyester like?
Polyester is resistant to sunlight making it a good fibre choice for sun protective clothing and equipment. It’s also resistant to chemicals like dry cleaning solvents, acids and bases, and resistant to insects and microorganisms.
How does polyester wick?
Polyester’s wicking ability can compensate for low moisture absorption, but this depends on the cross-sectional shape (e.g. multi-lobal fibres). It will dry more quickly than wool or cotton.
How comfortable is polyester?
Comfort is often improved by blending with other fibres (e.g. cotton). It is low density (but heavier than nylon) and increased insulation can be achieved by altering fibre physical properties to trap air. For example, hollow fibres (x-sectional shape), staple fibres (fibre length), and microfibres all help with insulation.
What is the resiliency and cleanliness of polyester like?
Polyester has excellent resiliency and does not wrinkle in use. However, soiling can be a problem as it is oleophilic- meaning it attracts and holds oily soils on the surface.
Why does polyester pill and how is its dimensional stability?
Pills do not tend to break off due to high tenacity of fibres. Polyester has good dimensional stability and doesn’t shrink if properly heat set.
