Chemistry Reference
In-Depth Information
Table 11.4
Physico-mechanical properties of metallised PAN fibres as a
function of metal content for thermofixated PAN fibres
ww%
M
t
in
Strength
Elongation
Preservation of
PAN fibre
(g/tex)
(%)
strength (%)
Nickel-containing PAN fibres
0
11.2
21.4
44.4
0.31
13.6
17.7
54.0
0.70
13.5
21.8
53.0
1.20
14.5
16.6
57.6
Cobalt-containing PAN fibres
0
11.2
21.4
44.4
0.69
14.6
18.3
58.0
1.14
14.1
18.3
56.0
1.44
14.1
16.6
56.0
11.3
Optimisation of electroconductive
PAN-fibre production
11.3.1 Introduction
In this section, the process required to modify PAN fibres into electrocon-
ductive PAN fibres is described. Mainly, it is executed by a two-step process.
First the fibres are metallised with Ni, but its electroconductive properties
are not sufficient, so, in order to improve that property, an electrochemical
deposition (galvanisation) is then performed at a second step to add a Ni
layer of a few micrometers on top of the metallised fibres.
11.3.2 Stability of the reducing agent in aqueous solution
Prior to stability experiments, a preliminary metallisation of PAN fibres was
performed using different types of reducing agent. The metallisation itself
was performed in solutions of pH 5.5, containing 0.3 mol l
-1
of Ni(II) and
0.6 mol l
-1
of reducing agent. It was found that from sodium hypophosphite,
hydroquinone, hydrazinesulphate, hydroxylamine, sodium dithionite and
rongalite, only the latter two gave satisfactory results and were able to
reduce Ni(II) to its metallic form. Only with these two reducing agents were
PAN fibres modified into conductive fibres. Therefore, it is clear that at
this stage only sodium dithionite and rongalite will be further used in the
investigation.
