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Interesting fact

Nylon was first introduced around 1939 and was in high demand to make stockings. However, as World War 2 progressed, nylon was used more and more to make parachutes, and so stockings became more difficult to buy. After the war, when manufacturers were able to shift their focus from parachutes back to stockings, a number of riots took place as women queued to get stockings. In one of the worst disturbances, 40 000 women queued up for 13 000 pairs of stockings, which led to fights breaking out!

Polymers

  1. The following monomer is a reactant in a polymerisation reaction:
    1. What is the IUPAC name of this monomer?
    2. Give the structural formula of the polymer that is formed in this polymerisation reaction.
    3. Is the reaction an addition or condensation reaction?
  2. The polymer below is the product of a polymerisation reaction.
    1. Give the structural formula of the monomer in this polymer.
    2. What is the name of the monomer?
    3. Draw the abbreviated structural formula for the polymer.
    4. Has this polymer been formed through an addition or condensation polymerisation reaction?
  3. A condensation reaction takes place between methanol and methanoic acid.
    1. Give the structural formula for...
      1. methanol
      2. methanoic acid
      3. the product of the reaction
    2. What is the name of the product? (Hint: The product is an ester)

The chemical properties of polymers

The attractive forces between polymer chains play a large part in determining a polymer's properties. Because polymer chains are so long, these interchain forces are very important. It is usually the side groups on the polymer that determine what types of intermolecular forces will exist. The greater the strength of the intermolecular forces, the greater will be the tensile strength and melting point of the polymer. Below are some examples:

  • Hydrogen bonds between adjacent chains Polymers that contain amide or carbonyl groups can form hydrogen bonds between adjacent chains. The positive hydrogen atoms in the N-H groups of one chain are strongly attracted to the oxygen atoms (more precisely, the lone-pairs on the oxygen) in the C=O groups on another. Polymers that contain urea linkages would fall into this category. The structural formula for urea is shown in [link] . Polymers that contain urea linkages have high tensile strength and a high melting point.
    The structural formula for urea
  • Dipole-dipole bonds between adjacent chains Polyesters have dipole-dipole bonding between their polymer chains. Dipole bonding is not as strong as hydrogen bonding, so a polyester's melting point and strength are lower than those of the polymers where there are hydrogen bonds between the chains. However, the weaker bonds between the chains means that polyesters have greater flexibility. The greater the flexibility of a polymer, the more likely it is to be moulded or stretched into fibres.
  • Weak van der Waal's forces Other molecules such as ethene do not have a permanent dipole and so the attractive forces between polyethene chains arise from weak van der Waals forces. Polyethene therefore has a lower melting point than many other polymers.

Questions & Answers

are you sure u wantd to ask tht or u wantd to say " how many bonds are there in alkane nd their names?" ?
Frank Reply
I also think that's what she meant 'coz I don't really understand her question
LINDOKUHLE
yeah nd if that's th case , there are only single bonds wch I could say one of em tht I know is methane
Frank
I mean methane,ethane they end up to what
Sylvia
well I also assume ths is wah u lookin for .. methane , ethane , propane, butane, pentane, hexane , Heptane, octane , nonane , decane . is ths wah u wanted ?
Frank
how many alkane are there n there names
Sylvia Reply
what's the difference between work and power ?
Elago Reply
Greetings Science Geniuses what is involved in fractional distillation of air?
Busuma Reply
what are the types of van der waals forces
Amahle Reply
weak van Der Waal forces 1.London forces 2.Dispersion forces 3.weak dipole dipole strong van Der Waal forces 1.hydrogen bonding 2.strong dipole-dipole forces
Zethu
please define saturated
Zethu Reply
compounds which there's no bonds between hydrocarbon atoms
Ruth
compounds which don't have double bonds or triple bonds between them
Hlengiwe
and they can be divided into two equal parts
Hlengiwe
what does the air in the atmosphere
Sujit Reply
How to calculate a frictional force if not given in the information?
SIBO Reply
what is not given in the problem?
Jhandy
Determine first the force between the surface and the object (N) then find the coefficient of friction with respect to the surface. Then multiply those two (N and Coefficient of Friction)
Jhandy
re read the statement there must something to use for calculation in the statement
Tandiswa
is it necessary to draw an arrow over vector quantities?
Busuma Reply
Yes. Because vector quantities consist of magnitude and direction. The arrow, which must include its head, tells you the direction of your quantity/es.
Jhandy
What is the monomer
Lindiwe Reply
it is a molecule that can be bonded to other identical molecules to form a polymer
Kwanda
need help in paper 2
Avuyile Reply
yes
Zethu
what do you need?
Zethu
what is important about molecules
Nozipho Reply
The four molecules of life are proteins, carbohydrates, lipids and nucleic acids. ... Without any of these four molecules, a cell and organism would not be able to live. All of the four molecules of life are important either structurally or functionally for cells so they are important in most cases
Nozipho
so it always has to be four molecules
Mbali
Hey guys i need help wit paper one
Mpho
why mass not change
Allan Reply
because it is irreversible
Jiluis
Hi Allan the reason why mass never change Is because of its interaction with Higgs field never change.
LUTHO
what is different between work and power in details
Andiswa Reply
When a force is exerted to an object and causes it to move in the direction of the force the work is done whereas power is the rate at which work is done.
ISRAEL
can you please help me to understand this topic of work and power
Hlayiselo
i also want to be helped
Tobeka
work occurs when force causes an object to move a certain distance while power is the work done at that specific time ..
Elago
and the difference can be simply simply that " work is in jouls while power is in walts
Elago
Why is alcohol flameable?
Moloto Reply
What is interconversion reaction for? ... under substitution reaction
Moloto
alcohol is flammable because the electrons in the CH and CC bonds are high energy compared to the electrons in OH and CO bonds of the product
Zethu
is carboxylic acid or alcohol need more heat to over come intermolecular forces?
Mpeh
carboxylic acid has higher boiling point compared to alcohol . carboxylic acid are two sited for H- bonds and alcohol is one sited for H- bonds. carboxylic acid needs more energy to break it's intermolecular forces compared to alcohol.
Zethu
heat under reflux .....it suitable for which type of reaction....btwn Addition,Elimination n Substitution reactions...?
Sqiniseko

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Source:  OpenStax, Siyavula textbooks: grade 12 physical science. OpenStax CNX. Aug 03, 2011 Download for free at http://cnx.org/content/col11244/1.2
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