Polymers & Fibres
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What are 2 kinds of fibre examination?
1) visual: material, colour, physical features, width 2) spectroscopic: material, dye, delustrant
How are synthetic polymer fibres made?
Take molten/dissolved polymer and pass it through very small holes. Polymer solidifies when it comes through the holes (extrusion). Fibre shape & size depends on the hole
What are 2 ways to identify synthetic polymers?
1) Which polymer: Infrared spectrum by microspectrophotometry 2) Colour: Analysis of dye by chromatography
What is a limitation when identifying synthetic polymers?
cannot be individualised, but can be traced to one manufacturer, at one period of time
What are the 3 phases of hair growth?
Anagen phase: growth phase, up to six years. Hairs pulled out will contain DNA in the root (follicle tissue) Catagen phase: transitional phase as growth slows & stops (2-3 weeks) Telogen phase: root has shrivelled & hair can fall out (2-6 months). Not enough DNA
When examining the cross section of hair, what are the 3 parts and how can it characterise its owner?
Cuticle: species identification Cortex: requires expert judgement to be individualised, but 11% wrong. colour, size, distribution, density Medulla: characteristic of species
What is hair analysis? How does it work?
Since chemicals are deposited as hair grows, hair can record one’s exposure to chemicals. Cut hair off at scalp and cut them into regular segments (representing different time periods). Analyse
What are 3 ways to analyse fibres?
1) microscopy 2) chromatography 3) spectroscopy