CHAPTER 2. ORGANICMACROMOLECULES 2.5
- In your home, find as many examples of different types of plastics that you can.
Bring them to school and show them to your group. Together, use your examples
to complete the following table:
Object Type of plastic Properties UsesMore practice video solutions or help at http://www.everythingscience.co.za(1.) 01pg (2.) 01phThermoplastics and thermosetting
plastics
ESCAK
A thermoplastic is a plastic that can be melted to a liquid when itis heated and freezes
to a brittle, glassy statewhen it is cooled enough. These properties of thermoplastics
are mostly due to the fact that the forces between chains are weak. This also means
that these plastics can beeasily stretched or moulded into any shape. Examples of ther-
moplastics include nylon, polystyrene, polyethylene, polypropylene andPVC. Thermo-
plastics are more easilyrecyclable than some other plastics.
Thermosetting plastics differ from thermoplastics because once they have been formed,
they cannot be remeltedor remoulded. Examples include bakelite, vulcanised rubber,
melanine (used to makefurniture), and many glues. Thermosetting plastics are gener-
ally stronger than thermoplastics and are better suited to being used in situations where
there are high temperatures. They are not ableto be recycled. Thermosetting plastics
have strong covalent bonds between chains andthis makes them very strong.
Activity: Biodegradable plastics
Read the article below and then answer the questions that follow.Our whole world seemsto be wrapped in plastic. Almost every product we
buy, most of the food we eat and many of the liquids we drink come encased
in plastic. Plastic packaging provides excellentprotection for the product, it is
cheap to manufacture and seems to last forever. Lasting forever, however, is
proving to be a major environmental problem.Another problem is thattradi-
tional plastics are manufactured from non-renewable resources - oil, coal and