Chemistry Reference
In-Depth Information
Table 7.4
Approximate melting points of polyamides
Nylon
MP (
C)
Repeat unit
3
-(CH
2
)
2
-CO-NH-
320-330
4
-(CH
2
)
3
-CO-NH-
260-265
5
-(CH
2
)
4
-CO-NH-
260
6
-(CH
2
)
5
-CO-NH-
215-220
7
-(CH
2
)
6
-CO-NH-
225-230
8
-(CH
2
)
7
-CO-NH-
195
9
-(CH
2
)
8
-CO-NH-
197-200
10
-(CH
2
)
9
-CO-NH-
173
11
-(CH
2
)
10
-CO-NH-
185-187
12
-(CH
2
)
11
-CO-NH-
180
13
-(CH
2
)
12
-CO-NH-
173
From various literature sources
trimerization of butadiene using Ziegler-Natta type catalysts. One patent reports using polyalkyl-
titanate and dialkylaluminum monochloride [
69
]:
3
The cyclododecatriene is then converted to lauryl lactam by different processes. One of them
consists of hydrogenation of the cyclic triene, followed by oxidation to a cyclic ketone, conversion to
an oxime, and rearrangement by the Beckmann reaction to the lactam:
O
[H]
[O]
etc.
Another process utilizes photonitrosation:
OH
NOCl
h
ν
[H]
N
Beckmann
rearrangemen
t
H
2
SO
4
O
N
H
There are still other processes, but they lack industrial importance. Nylon 12, like nylon 11, exhibits
low moisture absorbency, good dimensional stability, and good flexibility at low temperatures.
Preparations of other nylons were reported from time to time in the literature. For one reason or
another, however, they have not developed into industrially important materials. Thus, for instance, for
some time now it has been known that
can be prepared from erucic acid that is found in crambe
and rapeseed oils. The polymer is supposed to be quite similar to nylon 11, though lower melting.
The melting points of the nylons describe above are summarized in Table
7.4
.
nylon 13
