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e1
QUESTIONS
1. One powerful chemical species is the isocyanates
group. In this chapter we have discovered that the iso-
cyanates group is important in the synthesis of poly-
2. Polyurethanes are important biomaterials; however,
these polymers are also commercially relevant in
other applications. Describe at least two instances
3. The case study presented in this section focuses on the
use of PUs as pacemaker leads. Find another medical
ANSWERS
1. Isocyanates readily react with active hydrogen atoms.
Such hydrogens are often attached to oxygen, nitro-
gen, or sulfur. In all cases, the reaction results in an
addition reaction where the active hydrogen migrates
an amine. This amine often further reacts with
isocyanates to form urea bonds.
d. Isocyanates can react with carboxylic acids. This
an amide bond.
e. Isocyanates can react with urethane hydrogen or
urea hydrogen to form allophanate and biuret
applications are given below.
a. An example of polyurethanes used in everyday life
spandex can be stretched up to six times their
original dimension and return to their original
shape.
b. Polyurethanes are often used as varnishes, specifi-
cally for hardwood floors. The PUs used in this
application form hard, durable, and abrasion-
CHAPTER I.2.2.A
Polyurethanes
