Slime

One of the most popular school holiday "science projects" is to make slime by adding an aqueous solution of borax to PVA glue. Young children, and adults, can have hours of fun playing with this oozey slime, discovering some of its interesting properties along the way.

But what is slime and why should we be interested in it?

Read this edition of AUS-e-NEWS to find out more.

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Polymerize or Polymerise?

A polymer is produced when lots of monomers bond together. Monomer has Greek roots, mono meaning one and mer meaning parts. Polymer also has Greek roots, poly meaning many and mer meaning parts.

So  we can form a verb that means to produce a molecule of many parts. Because the words monomer and polymer have Greek roots, we should use the "ize" suffix, that is, polymerize. Yet, particularly in Australia,  the Latin "ise" suffix is used to produce the verb polymerise.

The word, polymerise, would have a Greek root (poly, many), a French root (mer, sea), and a latin suffix (ise). This would appear to suggest that to polymerise would be to make many seas. On the other hand, a monomer would be just one sea.

Merde!

Why is polyvinyl chloride an addition polymer?

Question: Why is polyvinyl chloride an addition polymer?

Answer:

1. An addition polymer is produced in an addition polymerization reaction.

2. In an addition polymerization reaction, the double bonds (C=C) in the monomer molecules open up so that one monomer molecule can "add on to" another monomer molecule to make a longer chain resulting in a polymer.

3. When vinyl chloride monomers (chloroethene monomers, CH₂=CHCl) join together in an addition polymerization reaction the polymer product is polyvinyl chloride, -(-CH₂-CHCl-)_n-

Find out more about addition polymerisation at https://www.ausetute.com.au/polymers.html

Find out more about polyvinyl chloride at  https://www.ausetute.com.au/pvc.html

Classification of Organic Reactions

Organic reactions are reactions in which the reactants and products are carbon-containing compounds, or organic compounds.
The chemical reactions that organic compounds take part in can be classified as:

• substitution reactions
• addition reactions
• elimination reactions
• oxidation reactions
• reduction reactions
• polymerisation reactions
• rearrangement reactions

AUS-e-TUTE has just added new resources including  a tutorial, game and test with worked solutions to help you identify and classify these types of organic reactions. AUS-e-TUTE Members should log-in to use these new resources.

If you are not an AUS-e-TUTE, a free-to-view tutorial is currently available at https://www.ausetute.com.au/organicrxn.html

polytetrafluoroethene

Polytetrafluoroethene is a very useful polymer. You can can find it encasing electrical wires, being sprayed out of a can of lubricant, and as the non-stick covering on your baking tray. So what is this remarkable polymer? How is it made? What are its properties and uses?
Find out the answers to these and other questions at AUS-e-TUTE.
AUS-e-TUTE members should log-in to view the polytetrafluoroethene tutorial, play the game and take the test and exam.
If you are not a member, you can access a "free-to-view" tutorial at https://www.ausetute.com.au/ptfe.html

Water-Soluble Plastic

I buy boxes of dishwasher detergent containing plastic bags filled with the detergent. I place these bags straight into the dishwasher. When the dishes are clean and I remove them from the machine there is no trace of either detergent or the plastic bag that held it.

What happened to the plastic bag?

Can plastic dissolve in water?

Find out in the December 2018 edition of AUS-e-NEWS, AUS-e-TUTE's free, quarterly, newsletter for chemistry students and teachers. 

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Polylactic Acid

The London Organizing Committee of the Olympic and Paralympic Games (LOCOG) was committed to making 2012 the very first "zero-waste" Olympic and Paralympic Games.

11 million attendees produced 8,500 tons of solid waste, mostly in the form of plastic packaging.

8,000 tons of this plastic waste was transported to a site where it was composted within 9 weeks and subsequently used to fertilize local crops.

That's right!

There are plastics that can be composted, and the plastic used at the London Olympic Games was the most common compostable plastic which is known as polylactic acid or PLA.

And the chemistry of polylactic acid (PLA) is the subject of this edition of AUS-e-NEWS, AUS-e-TUTE's free quarterly newsletter.

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Polystyrene

AUS-e-TUTE has just uploaded new resources for the Polystyrene topic.
AUS-e-TUTE members should log-in to view the new tutorial, play the polystyrene game and answer the polystyrene test questions.

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Polyesters

AUS-e-TUTE has just added new resources for the Polyester topic.
Members can log-in to read the new tutorial, play the new game, take the test or the exam.

http://www.ausetute.com.au

Polymer Banknotes

Australia was the first country to successfully replace paper notes with polymer notes, beginning with the circulation of $10 polymer banknotes back in 1988. Other countries, including Brunei, Canada, Fiji, Israel, Mauritius, New Zealand, Papua New Guinea, Romania, and Vietnam, have now abandoned paper in favour of polymer banknotes. Even the Bank of England will begin circulating polymer banknotes to replace the existing paper banknotes in 2016.

Australia is still the world's leading authority and prints polymer banknotes for more than 20 other countries in the world.

But what is a polymer banknote and why is it better than a paper banknote?

Find out in the March 2014 edition of AUS-e-NEWS, AUS-e-TUTE's free quarterly newsletter.

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Turning Polyethylene Waste into Fuel

Low density polyethylene, LDPE, is used to make many things we use everyday such as plastic milk containers, cling wrap, and plastic bags. LDPE can be recycled quite easily, but a lot of LDPE ends up as rubbish in land fills.
Chemists in India have developed a commercially viable way to turn LDPE into a liquid fuel by heating the LDPE waste to between 400 and 500^oC over a kaolin catalyst which causes the long chain polymer chains to break apart. This process is known as thermo-catalytic degradation: thermo means heat, the catalyst is kaolin, and degradation means breaking apart. This thermo-catalytic degradation of LDPE produces much smaller carbon-based molecules. Gas Chromatography was used to characterise these smaller molecules, and it was found that they were mainly alkanes and alkenes between 10 and 16 carbon atoms long. This makes the mixture very similar to that found in petrochemical fuels. For example, the hydrocarbons in gasoline (petrol) typically have a chain length of between 4 and 12 carbon atoms while diesel fuel typically contains hydrocarbons with a chain length between 8 and 21 carbon atoms.

The catalyst, kaolin, is a layered, aluminosilicate clay mineral with the formula Al₂Si₂O₅(OH)₄. It acts as a catalyst by providing a large surface on which the polymer molecules can sit in an orientation favourable to the degradation under heat.

Using the kaolin catalyst at 450^oC, the thermo-catalytic degradation of 1 kg of LDPE produced 700 g of liquid fuel.

Reference:
Achyut Kumar Panda, Raghubansh Kumar Singh. Thermo-catalytic degradation of low density polyethylene to liquid fuel over kaolin catalyst. International Journal of Environment and Waste Management, 2014; 13 (1): 104 DOI: 10.1504/IJEWM.2014.058803

Further Reading:
Polythene (polyethylene): Properties, Production and Uses 
Gas Chromatography 
Alkanes: properties and uses
Alkenes: properties and uses
Ethene (ethylene): properties and uses
Silicates: structure and formula

Suggested Study Questions:

1. Give the molecular structure for ethene (ethylene).
2. Write an equation showing how ethene (ethylene) molecules can be polymerized to form polythene (polyethylene).
3. Name the type of polymerization reaction being described by the equation in question 2.
4. Explain, using a diagram of the partial structure of polythene (polyethylene), what happens when polyethylene undergoes thermo-catalytic degradation.
5. Describe the differences in the structures of alkanes and alkenes.
6. Draw a straight chain alkane with 10 carbon atoms.
7. Draw a structural isomer of the molecule in question 6.
8. Draw a straight chain alkene with 10 carbon atoms.
9. How many structural isomers of the molecule in question 8 do you think there would be? Support your answer with the structural formula for each of these structural isomers.
10. Why do you not find short carbon chain alkanes, between 1 and 4 carbon atoms long, in the liquid petrochemical fuels like gasoline (petrol) and diesel?