Summary 1: Ehylene and Addition polymer chapter

Seite 1

Petroleum contains gas fractions ethylene; ethene.

2 ways to crack petroleum; catalytic and thermal

catalytic cracking; invoves a ctalsyt (zeolite) and temperatres around 500 degrees celscius; using both temperature and catalyst

thermal cracking; 750 degrees elsius, using only high temperature

all ethylene molecules have a doubble bond and by breaking it we can create ethanol, ethylene oxide, vinylchloride, styrene, ethylene glycol, vinyl acetate

ethanol is a disinfectant, ethylene glycol is an antifreeze, the others are plastics

compare alkane with alkenees using bromine water; cyclohexane/ene are liquid at room temp. The alkane due to its electron rich double bond will decolourise bromine water and the alkane will stay the same, except when exposed to UV light

ehtylene is a monomer from which polmers are made. I

Polyethylene is an ADDITION polymer; monomers propagate chain by adding on end to end, NO atoms are lost and the double bond is broken

Production of polyethylene forms LDPE and HDPE . LDPE involves FREE RADICAL polymerisation (intiation-by a free radical, propagation-, termination- 2 long chains come together or temp and pressure is lowered) LDPE is BRANCHED and amorphous and HDPE involves the Zieggler-Natta process where a catalyst is used (metallocene catalyst) which breaks the double bond and attaches itself to the linear chain/ polymer

Vinyl chloride is common name, its systematic name is CHLOROETHENE (one hydrogen is substituted for a chlorine atom)

Styere is common name, systermatic name is ETHYLBENZENE or PHENYLETHENE (one hydrogen is substituted for benzene ring)

Both styrene and vinyl chloride become POLY when the molecules join together to form a polymer

HDPE is a linear molecule, strong bonds, high tensile strenght, hard plastics including construction hats

LDPE is a brachned molecule, weaker bonds, more flexible, sandwich bags or plastic bags

Polystyrene have big benzene rings which make it stiff and tough

Polyvinylchloride, chemical chlorine groups make it chemically resistnat, if you add plasticisers (additives) you can make it water and heat resistant as well as flexible, so used for things like tubing pipe and raincoats

Condesation polymer is when monomers join together and a small molecule is lost, usually water or ammonia