Chapter 15: Problem 39
Cite the primary differences between addition and condensation polymerization techniques.
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Chapter 15: Problem 39
Cite the primary differences between addition and condensation polymerization techniques.
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In your own words, briefly describe the phenomenon of viscoelasticity.
Briefly explain how each of the following influ\(\Theta\) ences the tensile or yield strength of a semicrystalline polymer and why: (a) molecular weight (b) degree of crystallinity (c) deformation by drawing (d) annealing of an undeformed material
List the two molecular characteristics that are essential for elastomers.
For each of the following pairs of polymers do the following: (1) State whether it is possible to determine whether one polymer has a higher melting temperature than the other; (2) if it is possible, note which has the higher melting temperature and then cite reason(s) for your choice; and (3) if it is not possible to decide, then state why. (a) Branched polyethylene having a numberaverage molecular weight of \(850,000 \mathrm{~g} / \mathrm{mol}\); linear polyethylene having a number-average molecular weight of \(850,000 \mathrm{~g} / \mathrm{mol}\) (b) Polytetrafluoroethylene having a density of \(2.14 \mathrm{~g} / \mathrm{cm}^{3}\) and a weight-average molecular weight of \(600,000 \mathrm{~g} / \mathrm{mol}\); PTFE having a density of \(2.20\) \(\mathrm{g} / \mathrm{cm}^{3}\) and a weight-average molecular weight of \(600,000 \mathrm{~g} / \mathrm{mol}\) (c) Linear and syndiotactic poly(vinyl chloride). having a number-average molecular weight of \(500,000 \mathrm{~g} / \mathrm{mol}\); linear polyethylene having a numberaverage molecular weight of \(225,000 \mathrm{~g} / \mathrm{mol}\) (d) Linear and syndiotactic polypropylene having a weight-average molecular weight of 500,000 \(\mathrm{g} / \mathrm{mol}\); linear and atactic polypropylene having a weight-average molecular weight of \(750,000 \mathrm{~g} / \mathrm{mol}\)
Make two schematic plots of the logarithm of relaxation modulus versus temperature for an amorphous polymer (curve \(C\) in Figure \(15.8\) ). (a) On one of these plots, demonstrate how the behavior changes with increasing molecular weight. (b) On the other plot, indicate the change in behavior with increasing crosslinking.
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