Karl Chung
September 22, 2011
Preparation and Properties of some Condensation Polymers
Introduction
Polymers can be easily produced by chemical reactions. Different polymers also have different
levels of strength other properties. In this experiment, a Phthalic anhydride-derived polyester and
a strand of nylon will be produced. Nylon strands have the ability to keeping being elongated,
where a single chain could be two or even five feet in length.
Procedure
About one cubic centimeter of phthalic anhydride was placed into a small test tube. A slightly
smaller amount of sodium acetate was also added to the same tube followed by .40 mL of
ethylene glycol. The test tube was then placed over a flame while tilted at an angle to ensure
even heating. It was heated until contents appeared yellow. Once yellow, the solution was poured
onto a glass slide where it was prodded with a sharp tip until cool to observe fiber formation. The
test tube was filled part way with acetone observed then finally filled with water and disposed of.
The next part of the procedure dealt with nylon formation. Ten milliliters of
hexamethylenediamine was measured out and poured into a small 50mL beaker. The beaker was
then tilted and 10mL of sebacoyl chloride hexane solution was slowly added forming two layers.
A paperclip was bent into the shape of a hook and was used to pull out fibers of nylon. The nylon
produced was wrapped around a glass tube and rolled up, creating one continuous strand of
nylon.
The acetone was then poured onto the nylon rope and observations were made. Next a piece of
the rope was heated over the flame and observations were taken again.
Results
Part A was conducted first. All components of the reaction were mixed together and placed over
the flame. The mixture soon melted and produced a clean liquid. The liquid started to boil and
release a gas or steam. A minute or so after, the liquid changed color to a yellow appearance; as
predicted by the laboratory procedure. When poured over a glass slide, the liquid cooled and
solidified rapidly. Fibers were only able to form during the cooling process, but after it was
completely cooled no fibers were formed. When acetone was put into the tube, it appeared that
the solid in the tube was dissolved. When filled with water it was then hard to make out the
contents of the solution.
For the second part of the procedure, all steps went according to procedure. When the nylon was
being extracted out of the beaker, the group took care in order not to break the strand. However
as we kept pulling it out and wanted to move onto the next part of the procedure, we were
quickly spinning it on the glass tube and it would still not break. Eventually the strand was cut.
Acetone was poured over the nylon with no reaction observed. When placed over a flame, the
nylon quickly shriveled.
Discussion
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Nylon was not affected by the acetone, however the polymer produced from part A was. This
suggests that nylon is thermosetting polymer and the polyester is a thermoplastic due to the
observations taken at different temperatures. The nylon chain was able to be extended as long as
the reactants were there. The polyester fibers could not extend more than a centimeter in length.
Questions
1:
Ethylene Glycol Reaction:
(C2H6O2)n + (C8H6O4)n → (C10H8O4)n + (H2O)n
Glycerin Reaction:
(C3H5(OH)3)n + (C8H4O3)n → (C11H6O3)n + (H2O)n
2:
aEthylene glycol- phthalic produced a clear polymer that was able to dissolve in acetone. Fibers
are able to be pulled out while cooling. glycerin-phthalic produced a pale yellow. This was also
able to dissolve in acetone and fibers were able to be pulled out while cooling but not after it
completely solidified.
bIf there were a 2:1 ratio of glycol and glycerin, it would be expected that longer chains of mers
could be produced due the increase in potential reactions with the carboxylic group. More
molecule interaction leads to longer chains.
3:
aC6H16N2 + C10H16Cl2O2 → C2O2(CH2)8N2H2(CH2)8
bNylon forms easily because as the chain is extended, new mers are added covalently in addition
to the attractive vanderwals force between the linear chains of nylon. The double bonds created
between oxygen molecules also contributes to the strength of the chain.
cThe purpose of using extra hexamethylenediamine was to ensure that the reaction had a
sufficient amount of reactant in order to proceed at a speed that could match the pulling of the
nylon rope from the beaker by the group members.
Conclusion
Lab successfully taught the process of condensation. The different properties of the polymers
produced shows that not all polymer reactions form the same product. The nylon was unaffected
by acetone however the polyester was easily dissolved.
References
MATERIALS SCIENCE FOR ENGINEERS
LABORATORY MANUAL
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FALL 2005
Messler, Robert W. The Essence of Materials for Engineers. Sudbury, MA: Jones and Bartlett
Learning, 2011. Print.
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