polymers 9Eb Flashcards
Examples of polymers
①Rubber ②PVC(polyvinyl chloride) ③ Nylon ④polypropene ⑤Polythene
Rubber
Rubber is a polymer obtained
from certain tress.
Rubber properties
Rubber is soft and sticky
when hot, but it is hard and
brittle when cold.
rubber vulcanisation
Rubber is heated with sulfur
and a reaction occurs that
forms cross-links between
the long molecules.
New properties of rubber after vulcanisation
These cross links make the
rubber harder and tougher
and stops its properties
changing with temperature.
Physical properties of polymers
Polymers are generally strong, flexible, non conductors of heat, durable and unreactive.
How are polymers formed?
Polymers are formed by joining together many small molecules called monomers .This can be done using added polymerization.
what are most synthetic polymers made from?
Most synthetic polymers are made from crude oil.
How are polymers elastic?
The long coiled molecules go back to their original shape when stretched making polymers elastic.
Where is poly(vinyl chloride) used and why?
It is used for covering electric cables as it is flexible, strong and a non-conductor of electricity.
Where is poly(ethene) used and why?
It is used for plastic bags and buckets as it is strong, flexible and durable.
What are the two ways in which cross-links are useful
①If cross-links are formed between chains it make the polymer harder and less easy to melt.
②Vulcanisation uses sulfur to form cross-links in rubber molecules to make it harder and less easy to melt.
