Synthesis of novel polyimides from dianhydrides with flexible side chains - Polyimides and Other High Temperature Polymers - page 82

Figure 10. DSC thermograms of C 8 -FDA.

are summarized in Table
5. Most of the X-ray measurements agree in that only weak reflections show up in
the typical wide-angle region (2

The X-ray reflections of polyimides from C m -OADA

>10°). On the other hand, the diffractograms ex-
hibit at least one strong reflection in the middle angle region 2

θ

θ =2~8°. This re-

flection is particularly strong and sharp in both C 12 -series and C 8 -series but is

relatively broad in the case of C 4 -series.

series, the resulting layer distances (d)
were also plotted versus the number of carbon atoms in the alkyloxy side chain
and its slope was 1.7. From these facts, it is thought that these polyimides have
loose-layered structures because the layer distance (d in Table 5) is larger than the
theoretical layer spacing calculated from the fully extended and completely inter-
digitated side chains.

In completely amorphous C m -MDA