Fibres

Question 1

Natural fibres

Answer 1

aka staple fibres. plant animal mineral (asbestos the only mineral fibre)

Question 2

synthetic fibres

Answer 2

aka filament fibres. polyester nylon, glass fibre
extruded through spinneret device –> alterations give physical properties –> trilobal CSA common in nylon

Question 3

analytical work flow for fibres

Answer 3

gross exam
preliminary evaluation
physical fit
microspectrophotometry
IR spec
Raman

Question 4

caveats to fibres

Answer 4

can never state as unique
no reference databases
expensive, time consuming analysis

Question 5

SEM in fibre use

Answer 5

res = 10mn
depth of focus = high
field view = good
specimen prep = easy, rapid
relative cost = high
(used for backscattering)

Question 6

TEM in fibre use

Answer 6

res = 1nm
depth of focus = medium
field view = limited
specimen prep = skilled, slow
relative cost = high
(used for diffraction)

Question 7

Pleochroism

Answer 7

when anisotropic materials show different absorption colours when exposed to polarised light coming from different directions

Question 8

Retardation

Answer 8

2 components of light travel through crystal at different velocities (one faster than the other when inside crystal)
is the difference between the RIs of each ray

Retardation (mm) = Birefringence x Thickness (micro m ) x1000