Describe the phases of hair growth

1

Learning Objectives

Identify synthetic and natural polymers

Explain the methods used to identify fibres and dyes

3

4

Define “Polymer”

2

1

Describe how hair analysis helps

to identify species and individuals

5

2

A long chain molecule made

up of many repeating units

What is a polymer?

Monomer

3

May be made up of two different monomers

What is a polymer?

Co-polymer

Ethylene

Polyethylene

4

Polymers

Polyethylene or polythene

Polymerise

5

Polymers

Polypropylene

Polystyrene

Formation in a similar way to

the polymerisation of ethylene

Propylene monomer

Styrene monomer

6

Polymers

Polyethylene, polypropylene and polystyrene

Not good for making fibres

7

Co-polymer

Nylon

Nylon-6,6

8

Nylon

Diaminohexane

Adipic acid

9

Fibre examination

Wool, nylon, cotton, etc.

Microscopic to determine type

Spectroscopic analysis of fibre

Physical features

3

2

1

Shape

10

Fibre examination

Delustrant

Chemicals added to reduce shine

5

Colour

4

Spectroscopic analysis of the dye

More chemical components analyzed

Better individualization of fibre

Natural fibres vs synthetic fibres

11

Polymers

Natural fibres

Synthetic fibres

From chemical industry

From plants and animals

Made by Extrusion

12

Synthetic polymer fibres

Fibre shape and size

depends on the hole

13

Microscopic examination

allows for identification of

Manufacturer

Trilobal fibre

Synthetic polymer fibres

Batch of material

IR spectrum

14

Identification

Analysis of

chemical

constituents

IR Microscope

Microscope

IR spectrometer

IR microscope

15

Jeffrey

MacDonald

U.S. Army, Fort Bragg, N.C.

16

Jeffrey MacDonald

Convicted of murdering

his wife and daughters

Beaten and stabbed

to death at home

Jeffrey MacDonald

Murders done by a group of drug addicts

17

Defense

No evidence of anyone else in the house

Broke into the house

MacDonald found guilty

Additional evidence used at the appeal

18

Defense

Fibre from the crime scene

No match to victims’ clothes

Evidence of an intruder

19

IR comparison

From Mrs.

MacDonald

Claimed to be

from attackers