Condendation polymers! (2 Viewers)

[apryl]

i have been doing some reveision and got stuck on this question.

(A)explain what it mean by the term condensation polymer
(B)describe the reaction invovled in the formation of a condensation polymer

and if its not stretching thr friendship this one also had me confused:

oweing to its high reactivity, ethylene can be turned into poly(ethylene):
(a) what type of polymer is poly(ethylene)
(b)outline the steps in the production of high OR low density poly(ethylene)

thanks guys

 

[wanton-wonton]

i have been doing some reveision and got stuck on this question.

(A)explain what it mean by the term condensation polymer
(B)describe the reaction invovled in the formation of a condensation polymer

and if its not stretching thr friendship this one also had me confused:

oweing to its high reactivity, ethylene can be turned into poly(ethylene):
(a) what type of polymer is poly(ethylene)
(b)outline the steps in the production of high OR low density poly(ethylene)

thanks guys

I hope you're not serious about these questions, they are very basic.

1. A condensation polymer is a long chain molecule produced from smaller molecules (monomers) via the removal of a small molecule (often water).

I can't really distinguish between a and b since they sort of co-relate.

2. Ethylene is a addition polymer.

The first step in the production of polymer is initiation, where the ethylene molecules are activated so that they are willing to react together. This part involves the use of a radical (organic peroxide) to break the first C=C double bond. Once the chain is initiated, it grows off by a process of chain propagation, in which the ethylene monomers come together in a head to tail arrangement. When sufficient ethylene monomers have been linked, termination occurs.

LDPE is made by subjecting ethene to high pressures, resulting molecular collisions which results as a highly branched polymer.

 

[Dreamerish*~]

(A) A condensation polymer is a polymer that forms by the elimination of a small molecule (usually water) from the monomers as they are joined by their functional groups. For example, cellulose:

... HO-C₆H₁₀O₄-OH HO-C₆H₁₀O₄-OH H ...​

which produces the polymer:​

... -O-C₆H₁₀O₄-O-C₆H₁₀O₄-O- ...​

The 2 H atoms and O atom which are not in bold are eliminated during the process of condensation polymerisation of glucose (C₆H₁₂O₆) into cellulose.

(B) The reaction involved in condensation polymerisation is the formation of the same type of chemical bond as when proteins form. Two functional groups join together, eliminating a small molecule. Another example is nylon-6(polyamide):

... H₂N-(CH₂)₅-COOH H₂N-(CH₂)₅-COOH H ...​

which forms the polymer:​

... -HN-(CH₂)₅-CO-HN-(CH₂)₅-CO-HN-(CH₂)₅-CO-HN- ...​

Bonds are formed when the ends of each monomer is joined with the end of a neighbouring monomer. The carboxylic acid group (-COOH) combines with an amine group (H₂N-) to form what is called an amide link (-CO-NH-).

(a) Polyethylene is an addition polymer. An addition polymer is one which is formed without the loss of any atoms. It involves the opening of a double bond in the monomer in order to join onto neighbouring monomers.

(CH₂=CH₂)_n --> n[ -CH₂-CH₂- ]

The double bond between the C atoms open up and join onto the neighbouring C atoms.

(b) The gas phase process is used to make LDPE. A high pressure of (1000 - 3000 atms) and a high temperature of about 300ºC is used, along with an initiator - an organic peroxide. The produce has significant chain branching. In this process the initiator is not strictly a catalyst because it gets incorporated into the actual polymer formed - one initiator molecule per one or two polymer molecules - per 2000 or 3000 monomer units.

The Ziegler-Natta process is used to make HDPE. It uses only a few atms and temperatures of about 60ºC. It uses a catalyst which is a mixture os titanium(III) chloride and a trialkylaluminium compound. This process forms unbranced polyethylene molecules which are able to pack together in a nice orderly fashion.

Wonton beat me to it. Be nice, wonton.

 

[azza_3761]

A) A condensation polymer is formed by monomers combining together, condensing out small molecules (such as water) as the polymer chain forms.

B) See diagrams on http://www.kcpc.usyd.edu.au/discovery/9.2.2/9.2.2_Condensation.html

a) Addition polymer
b) High pressure (1000-3000 atmospheres) and high temperature (300° along with an initiator (an organic peroxide, a compound containing an O-O group or sometimes oxygen gas is used). The product has significant chain branching. This means that at some carbon atoms one hydrogen atom is replaced by an alkyl group. Consequently the alkane chains cannot pack close together or in an orderly way: this is called low density polyethylene (LDPE).

The second process uses pressures of only a few atmospheres and temperatures of about 60°C and uses a catalyst which is a mixture of Titanium (III) chloride and a trialkylaluminium compound. The Ziegler-Nltta process as it is called forms unbranched polyethylene molecules which are able to pack more closely together in an orderly fashion. This product is more crystalline and has a higher density than the branched chained product.

 

[wanton-wonton]

(b) The gas phase process is used to make LDPE. A high pressure of (1000 - 3000 atms) and a high temperature of about 300ºC is used, along with an initiator - an organic peroxide. The produce has significant chain branching. In this process the initiator is not strictly a catalyst because it gets incorporated into the actual polymer formed - one initiator molecule per one or two polymer molecules - per 2000 or 3000 monomer units.

The Ziegler-Natta process is used to make HDPE. It uses only a few atms and temperatures of about 60ºC. It uses a catalyst which is a mixture os titanium(III) chloride and a trialkylaluminium compound. This process forms unbranced polyethylene molecules which are able to pack together in a nice orderly fashion.

Wonton beat me to it. Be nice, wonton.

That's impossible. An your answer to b) is very...specific. I shall use it.

a) Condensation polymer

That's wrong. The syllabus states 'identify polyethylene as an addition polymer..blah blah blah'.

 

[velox]

hah wanton u stole neos avatar.