Lecture Problem 181

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Lecture Problem 181

• Noel Godinez

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Problem Statement

• A sample of polymer has become separated from
  much of its manufacturing data. It is believed
  that the weight-averaged degree of polymerization
  is 407. The following molecular weight data were
  also reported for the sample

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Problem Statement
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Problem Statement

• From plant-processing data, the sample is either
  pure polyethylene (PE) or a 7525
  polyethylene-polypropylene copolymer (PE-PP).

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Solution

• (a) Calculate the weight-averaged molecular
  weight.

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Solution

• (b) Assuming the degree of polymerization is
  correct, calculate the number-averaged molecular
  weight.

Need to convert weight fractions to mole
fractions!!
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Solution
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Solution
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Solution

• (c) Assuming part b is correct, calculate the
  number-averaged degree of polymerization.

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Solution
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Solution

• (d) Assuming the given data are correct, is it PE
  or a PE-PP blend?

PE
PP
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Solution
Recall that this is
for the mystery polymer!
Therefore it is a 7525 PE-PP blend.