GCSE Chemistry C2

.... betweeen moleceules determine the ..... of plastics

...... ...... bonds hold the atoms together in ...... .... . but it's the .... between ..... .... chains that determine the properties of plastic

some individual tangles chains of polymers , held together by weak intermolecular forces , are free to ...... over each other .these polymers are ......... polymers because they dont have ......-.... between chains . the forces between chains are really .... to overcome , so it's dead .... to ..... plastic . when it cools , the polymer hardens into a new shape . You can melt these plastics and ...... them as many times as you like

some plastics have strong intermolecular forces between the polymer chains , called .....-... , that hold the chains .... together . These are called ...... polymers , they have cross-links , these hold the chains together in a solid structure . theses polymers dont .... when they're ..... . thermosetting polymers are .... , .... and ....

..... polymers with different ..... and uses can also be made from the same ..... . this is done by changing the ..... ... when the polymer is made .

Low density polyethene (LDPE) is made by heating ..... to about ..... degrees centigrade under ..... pressure . Its ..... and is used for ... and ....

High density polyethene (HDPE) is made at a .... temperature and .... (with a .....) . it's more .... and is used for ... ... and .....