The Chemistry of Sheep Wool

Introduction

YouTube Video



I did my project on the chemistry of sheep wool.  Sheep wool is the fibrous protein on the outside of a sheep’s body.  I chose to do my project on sheep wool because sheep have been a part of my life since I was little.  My life has been affected by sheep because since I started showing them in 4-H I have had to learn everything about them.

Composition of ...

  • Lanolin C48H69NO6

  • Hydrogen

  • Oxygen

  • Nitrogen

  • Carbon

  • Sulfur HOOCCH(NH2)CH2S-SCH2CH(NH2)COOH

  • Ash:  potassium, sodium, calcium, aluminum, iron, silica, sulfate, carbonate, phosphorus pentoxide, and chloride

Main Chemicals, Compounds, Components

Lanolin is oil that secretes from the sebaceous glands and makes the wool soft.  It is a mixture of esters, diesters, hydroxy esters, high-molecular-weight lanolin acids, and high-molecular- weight lanolin alcohols.  Alcohols are composed of aliphatic alcohols, sterols which are cholesterol and dihydrocholesterol, and trimethyl sterol which are lanosterol and dihydrolanosterol.  Acids are composed of normal, iso, anteiso, and hydroxy acids.  The alcohol in lanolin is composed of 25.8% aliphatic alcohols, 38% cholesterol, 27.1% trimethyl sterols, and 5.9% hydrocarbons and undetermined.  The acids are 12.1% normal acids, 22.1% iso acids, 26.3% anteiso acids, 27.1% alpha-hydroxy acids, 5.1% omega hydroxy acids, and 7.3% are unknown.


Sulfur makes up 3.7% weight of sheep wool.  The sulfur content is because of cystine.  Cystine is a double amino acid which contains two sulfur atoms with a disulfide bond:  HOOCCH(NH2)CH2S-SCH2CH(NH2)COOH


Chemistry's Role

Wool is a fibrous protein known as keratin.  The different proteins are made up of carbon, hydrogen, oxygen, nitrogen, and sulfur.  Those chemicals are combined to make different amino acids which are then linked in a ladder formation of polypeptide chains.  Sulfur content is from cystine which is a disulfide bond.  Wool has a three dimensional structure, it is held together by the hydrophobic effect and electrostatic interactions.  The hydrophobic effect is when nonpolar substances aggregate in aqueous solution, that exclude water molecules.



Background Research

Hydrogen, oxygen, nitrogen, carbon, sulfur, and ash are all elements that make up sheep wool.  Carbon makes up 50.5% weight, hydrogen makes up 6.8% weight, oxygen makes up 22% weight, nitrogen makes up 16.5% weight, sulfur makes up 3.7% weight and ash makes up .5% weight.  The ash has potassium, sodium, calcium, aluminum, iron, silica, sulfate, carbonate, phosphorus pentoxide, and chloride.

Wool is a fibrous protein known as keratin, it is made up of many amino acids.  The different proteins are made up of carbon, hydrogen, oxygen, nitrogen, and sulfur.  Those chemicals are combined to make different amino acids which are then linked in a ladder formation of polypeptide chains.  It is a keratin-type protein.  There are three distinct parts of the physical part of sheep wool.  They are the cuticle, cortex, and medulla.  The cuticle is an outer layer composed of scales and it absorbs water. The cortex is the main part and is 90% of the fibers mass.  Lastly the medulla is the center and it has a honeycomb like structure, it does contain air pockets.  Wool will eventually decompose when it is sheared off and thrown away on the ground.


Sheep use to not have wool on their bodies, they had hair like deer have today.  In 10,000 BC sheep started to becoming domesticated by the people of West Asia.  They would still use the sheep’s skin for leather clothing but most the time they would take off the the wool.  Around 5000 BC sheep began to have better wool because they would be breeded by which had the best hair.  The wool on domesticated sheep was more woolly and wild sheep have more of a hair like wool.  Wool eventually became able to spin.  Wool is easier to spin than cotton of flax so many people used wool to make clothes.  Wool was also used to make clothes because it was warm, could be color dyed easily, and it has a natural oil called lanolin in it that repels water.

Resources

http://wpage.unina.it/avitabil/testi/Lana.pdf

Elements in Sheep Wool.


http://nzic.org.nz/ChemProcesses/animal/5F.pdf

Shows the structure of wool and explains the peptide bonds. 


http://www.sheep101.info/products.html

Gives many uses for sheep wool and why it is better to use than other products.  


https://en.wikipedia.org/wiki/Wool

History of how wild sheep and domesticated sheep had different wool.  Listed the different processes on how to clean sheep wool and how they are done.  


http://www.iowasheep.com/uploads/3/3/4/8/3348193/wool_lesson2.pdf

Showed and explained the three main parts of the physical structure of sheep wool, it also gave more information on the chemical structure of sheep wool.


http://www.alluredbooks.com/sample_pages/chem_manu_cosm_3rdedit_vol3_p559_563.pdf

Chemical components of lanolin.


http://biotechlearn.org.nz/focus_stories/wool_innovations/wool_fibre_structure_and_properties

Gives a diagram starting from the outside of the fibre going all the way into the center.  

About the Author
Maya Guldborg is a junior at Billings Senior High School.  She shows sheep in 4H.  She runs cross country and swims for Senior.  Her interests are going to lake and boating, snowboarding, and riding horse.  She has not decided where she want to go to college yet but she wants to become an ER physician.
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