help on 9.2 production of material (1 Viewer)

[skool_angel]

help on 9.2 production of material??

i need help!! i juss started chem n i am alreadi loss


can someone plz answer these

- identify the industrial source of ethylene from the cracking of some of the fractions from the refining of petrolem

-outline the steps in the production of polyethylene as an example of a commericially and industrially important polmer

-and finally what are the properties of vinyl chloride and styrene

 

[Ozz^E]

New member i see: welcome skool_angel...lets see wat i can do for u.

OK

1. Thats simply identify so: Ethene is industrially sourced from various fractions - produced by fractional distillation - of crude oil via a process known as catalytic cracking.

Note: next syllabus point deals with process more deeply.

2. Two ways of manufacturaing polyethene:

- In the older gas phase process, high pressures and temperatures are used along with an initiator whose function is to decompose and from reactive free radicals which add onto the ethene monomer and break the double bond. This forms LDPE as there is significant chain branching.

- The newer process uses pressures of only a few atmospheres, temperatures of about 60 degrees celcius and a catalyst (mixture of titanium(III) chloride and tialyklaluminium compound). This produces HDPE as the molecules are able to pack closely together forming a more crystalline product.

3. Vinyl Chloride: Chloride side groups stiffens chian by preventing rotation. High degree of crystallinity (lack of chain branchhing) leadsing to high density, a higher boiling point and thus a relatively hard and tough polymer. Dipole-dipole interactions between chloride groups ensures a closed packed rigid polymer. Note: PVC is susceptible to UV radiation, needs stabilisers.

Styrene: Styrene side group increases chain stiffness and makes polymer quite hard. The absence of cross-linkages ensures easy moulding

Note: be sure to link properties to uses.

There...hows that.

 

[skool_angel]

thanQ veri much!!

 

[Ozz^E]

welcome....