Unit 2 - Lecture 10 Topic 1 Flashcards
What are the three categories of manufactured fibres?
Regenerated, synthetic, and inorganic.
Regenerated fibres:
Produced from naturally occurring polymers (cellulose or protein) e.g. acetate, triacetate, viscose, lyocell.
Give examples of synthetic fibres:
Acrylic, nylon, and polyester.
Give examples of inorganic fibres:
Glass, carbon, and metal.
What are the steps of fibre spinning?
- Raw material (cellulose, protein, or synthetic polymer) is dissolved and made into a thick solution. This part of the process is called dope or melt
- Extrude dope or melt through spinneret to form fibre
- Solidify fibre by coagulation, evaporation, or cooling
- Filaments are then either: Kept as filament length or cut into staple lengths
Melt Spinning:
The polymer is melted, spun into air, and cooled.
Dry Spinning;
Used on polymers sensitive to heat, they are dissolved by a solvent, spun into warm air, and then the solvent evaporates.
Wet Spinning:
A polymer is dissolved by chemicals, spun into a chemical bath, and then coagulated.
What are the five general ways to modify fibres?
- Changing the shape/size of the spinneret
- Modify molecular structure/crystallinity
- Additives in dope or polymer
- Modify spinning process
- Combine two polymers in single fibres/yarn
Why is spinneret size important?
Finer fibres are used for apparel, medium-large used for interior textiles, and the largest is for ropes and fishing lines.
Microfibres vs macro fibres:
Microfibre: denier <1. Macrofibre: denier >1
Why might someone change the cross-sectional shape of a fibre in a spinneret?
To alter lustre, allow wicking, and adjust opacity.
Why might someone modify a spinneret to produce hollow fibres?
To increase insulation.
How would someone increase the strength of a fibre after its been extruded from the spinneret?
Drawing/stretching to increase alignment/orientation occurs before the fibre has hardened.
Give an example of a delusturing pigment:
Titanium dioxide.
