Chemistry Reference
In-Depth Information
(b) An operator makes up this mixture and forgets to add the ethylene gly-
col. He tries to run the reaction to completion. At what extent of con-
version will he notice the results of this omission?
7-6 Nylon-11 is poly(11-aminoundecanoic acid). This polymer has a crystal
melting point around 190
C and has lower water absorption than nylon-
6,6 or nylon-6. It can be used to make mechanical parts, packaging films,
bristles, monofilaments, and sprayed and fluidized coatings.
H
220°C
nCH
2
N
CH
2
COOH
N
CH
2
C
O
+ nH
2
O
10
10
n
In the step-growth polymerization of this monomer
(a) How much monomer (in terms of weight fraction of the reaction mix-
ture) is lef
t w
h
en
90%
of
the functional groups have reacted?
(b) Calculate M
n
;
M
w
, and M
z
of the reaction mixture at this stage.
7-7
Poly(ethylenoxy benzoate) is a fiber-forming polymer produced by the fol-
lowing sequence of reactions:
O
KOH
HO
+ CO
2
HO
COOH
CH
2
CH
2
CH
3
OH
(1)
COOH
C
HOCH
2
CH
2
O
HOCH
2
CH
2
O
OCH
3
O
OCH
3
Δ
(2)
n HOCH
2
CH
2
O
C
O
OCH
2
CH
2
O
C
O
+
nCH
3
OH
n
The polymer synthesis is a step-growth polymerization. The fiber is
meltspun at 250-270
C and has silklike properties.
(a) When the extent of reaction (2) is 60%, what is the number average
degree of polymerization of the reaction mixture?
(b) What weight fraction of the reaction mixture is polymer under these
conditions?
(c) What is the weight average degree of polymerization of the polymer?
7-8 The polymer of Problem 7-7 becomes too viscous to spin conveniently
when its number average molecular weight exceeds 5
0,0
00. Show a practi-
cal way to adjust the polymerization recipe so that M
n
does not exceed
this value.
