Chemistry of Polyester

Chemistry Connections

Hopewell Valley Student Podcasting Network

Chemistry Connections

The Chemistry of Polyester Shirts & Their Impact On The Environment

Episode #1

Welcome to Chemistry Connections, my name is Dorothy Wong and I am your host for episode #1 called The Chemistry of Polyester Shirts & Their Environmental Impact. Today I will be discussing the structure of polyester, how it is made, why it is used to make shirts, and its impact on the environment.

Segment 1: Introduction to Polyester

Polyester is a type of polymer.

Polymers are chains of thousands of monomers, forming a single big molecule.

• Monomers are smaller molecules that can react with each other to form polymer chains.
• The process is called polymerization.
• It is amorphous - polymer chains are randomly bunched together.
• The bonds within polymers are covalent (intramolecular forces),
• The bonds between polymers are dipole-dipole and London Dispersion (intermolecular forces).

Polyesters, in particular, are made by mixing an alcohol with a carboxylic acid.

• This reaction forms an ester functional group which is distinguished by the atom chain C-O-O.
• Another property of polyester in general is that it is a thermoplastic polymer - can be remelted and remolded.

Most Common Polyester: Polyethylene Terephthalate

• Also known as PET or #1 Recycling Plastic
• Properties: High strength, low shrinkage, chemical resistance → This makes it ideal for plastic containing and clothes.

Segment 2: The Chemistry Behind Polyethylene Terephthalate

Process Of Making Polyethylene Terephthalate Fiber

• A condensation reaction occurs between ethylene glycol and dimethyl terephthalate.
• This ends up becoming a monomer, containing the ester functional group COO (trait of a polyester as stated before).
• The monomers react once more with dimethyl terephthalate to form the polymer (PET).
• Molten polyethylene is formed into long strands that cool and dry.
• They are then broken up again, melted, and spun into fibers.
• The final product is polyester fibers that can be dyed and turned into clothing.

Chemical Bonding Within Polyethylene Terephthalate

• Covalent Bonds
• Explain what covalent bonding is:
• This sort of bonding occurs when neither of the two atoms want to part with their own electrons, causing them to share.
• This can be found by finding the difference in electronegativity.
• One pair of shared electrons makes a single bond, two pairs of sharing electrons make a double bond, three pairs of shared electrons make a triple bond.

Amorphous Solid

• Benzene ring limits the mobility of the groups attached
• The polymer chains cannot properly arrange themselves in a crystalline structure, contributing to its amorphous structure (blame on the benzene ring)
• Amorphous nature allows for transparent appearance → what you see in plastic water bottles
• Shirts → They are not transparent, but dyes are added to them to get the desired color

Segment 3: Personal Connections

I am interested in the environment, and the different factors that negatively affect it.

I went to a sustainable polymers camp this past summer. I was intrigued by the large reach that plastic has on the environment. One talk that really caught my eye was the one about microplastic. In this lecture, the professor (Anne McNeil) mentioned that millions of microplastic particles from the synthetic material of shirts are released into the environment for every laundry load. Because I was aware that polyester was one such synthetic material, I thought it would be interesting to look at its structure and properties. It is interesting to see how this is the case.

Thank you for listening to this episode of Chemistry Connections. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com.

Sources:

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

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

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

https://www.compoundchem.com/2022/12/15/football-shirt-2022/

https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Supplemental_Modules_(Organic_Chemistry)/Esters/Reactivity_of_Esters/Polyesters

https://www.sciencedirect.com/topics/chemistry/polyester-fiber

https://www.sciencedirect.com/topics/chemistry/polyethylene-terephthalate

https://www.sciencedirect.com/topics/chemistry/covalent-bond#:~:text=A%20covalent%20bond%20consists%20of,two%20nuclei%20are%20bonding%20electrons.

https://sewport.com/fabrics-directory/polyester-fabric#:~:text=Chemically%2C%20polyester%20is%20a%20polymer,be%20derived%20from%20other%20sources.

https://www.newworldencyclopedia.org/entry/Polymer

https://study.com/academy/lesson/polyethylene-terephthalate-structure-uses.html

List your sources here. Make sure they are linked. Wikipedia cannot count for more than 50% of your sources.

Music Credits

Warm Nights by @LakeyInspired

Subscribe to our Podcast

• Apple Podcasts
• Spotify
• Google Podcasts
• Stitcher

Connect with us on Social Media

• @theHVSPN

Research

Polyesters:

• Type of polymer - a chain of monomers; a singular molecule made up of thousands of covalently bonded atoms
• Amorphous
• Manufactured by mixing an alcohol and carboxylic acid
• Contains the ester functional group
• Thermoplastic polymer, meaning that it can be remelted and remolded
• Most well known polyester is polyethylene terephthalate
• Also known as PET
• Recycling Number: 1

Polyethylene Terephthalate

• Properties: high strength, low shrinkage, chemical resistance → great for clothing
• Used for food and drink containers, plastic bottles, and clothing
• 
• Intermolecular Forces: dipole-dipole forces between carbon and oxygen atoms, london dispersion forces
• Process of Making Polyethylene Terephthalate:
• Condensation reaction between ethylene glycol and dimethyl terephthalate
• Ends up becoming a monomer, containing the ester functional group COO (trait of a polyester)
• Monomer reacts once more with dimethyl terephthalate to form the polymer