Types of Fibres Flashcards
What is Synthetic Fibres
man made fibres spun from synthesized fibre forming polymers.
Regenated fibres are
man made fibres that have been produced from naturally occuring polymers by a technique that includes the regeneration of polymer structure.
Subdivisons of Natural Fibres
Animal (protein)
Vegetable (cellulose)
Mineral (asbestos)
Characteristics of Fibre Polymers
- Linear molecular chains which possess some degree of extension to the fibre axis.
- Streamlined molecular chains.
- The molecular chains should be flexible and hence impart extensibility to the fibres.
- Have a high molecular weight
What is dry spinning?
Involves dissolving the polymer into a solution that can be evaporated.
What is wet spinning?
Involves dissolving polymer into a solvent which and the polymer solution is extruded through spinneret into a solvent-non solvent mixture
What is melt spinning?
Involves melting the polymer then extruding it through a spinneret where it is then drawn out to create spools.
Source of Vegetable/ Cellulose Based Fibre?
- Seed
- Stem/Bast
- Leaves
What are examples of seed fibres?
Cotton, Kapok and Brazil Nut
What are examples of stem fibres?
Flax and Hemp
What are examples of leaf fibres?
New Zealand Hemp, Sisal and Aboca
Sources of Animal/Protein Based Fibre?
Goat, Camel, Rabbit, Sheep and Silkworms
What is goat hair most famously used for?
Goat Hair is used to create cashmere.
What fibres are rabbit fur mainly mixed with?
Nylon and Wool
What is responsible for the higher specificity gravity of Nomex over nylon?
Nomex is made of aromatic polyamides called aramids. Aramids have an almost perfect polymer chain caused by its molecular linearity and hydrogen bonding. These chains is the reason for it’s higher specificity of gravity.
Between Nomex and Nylon which of the two fibres would be more useful for application in a floatation device?
Nylon would be the more useful because of its low moisture regain as a result of it’s crystalline structure.
Why do fibre wrinkle?
Fibre wrinkle through the process of wetting then drying. When a fibre is wet the weaker chains within the fibre will break and upon drying will reconnect in a different area of the fibre.
Why are some aramids suitable for high performance products?
Aramids are extremely strong, resistance to breaking, stretching, heat and some chemicals.
Compare the properties of nylon and polyester. Say why nylon is more suitable for making stockings than polyester. Why do we see more nylon than silk stockings?
Polyester and Nylon have many things in common like they are both strong, resistance to abrasion, thermally stable and able to hold a good setting treatment. However, nylon has a better elasticity recovery than that of polyester which would make it more suitable for stockings. Polyester would require twice as much force to stretch.
What is responsible for the higher modules of polyester over nylon?
Polyester has para substituted benzene ring that makes it crystalline and stiff.
What properties of silk causes it to dissolve in cuprammonium hydroxide unlike other animal fibres?
Silk is cellulose based fibre unlike its other animal based fibres as a result it readily dissolves in cuprammonium hydroxide.
What are the benefits of garments made of alpaca have over the garments made of wool?
Garments made of alpaca are known to be hypoallergenic unlike garments made of wool. This means many people may have a hypersensitive reaction to wool versus alpaca fibre.
Why is it that white cotton fibre are of little evidential value?
White fibre is manufactured in bulks on a daily basis and is one of the mot commonly used fibres out there as a result it is difficult for examiners to differentiate where this evidence might have originated from.
What are the benefits of spinning in the manufacturing of synethic and regenerated fibres?
Spinning is a good way of making strong fibres because it allows inter polymer forces of attraction between polymers to maximise.
