Chemistry Reference
In-Depth Information
points on sufficient rigidity of material which is comparable to that of
polycarbonate. Impact strength on Izod is 7-8 kJ/m
2
at 23 C with notch.
The strength and durability of polysulfones keep well at high tempera-
tures. This fact opens possibilities to compete with metals in such areas
where other thermoplasts are worthless.
The possibilities of using polysulfones in parts of high-precision articles
arise from its low shrinkage (0.7%) and low water absorption (0.22% after
5.64
×
10
4
sec).
Aromatic polysulfone on the basis of bisphenylolpropane is relatively
stable to thermo-oxidation destruction, because the sulfur is in its highest
valence state in such polymers; electrons of adjacent benzene nuclei shift,
under the presence of sulfur, to the side of sulfogroups what causes the
resistance to oxidation.
The polysulfone can operate long at temperature up to 140-170 °C, the
loss of weight after 2.52
×
10
7
sec of loading at 125 °C is less than 0.25%;
polymer loses 3% of its mass after 3.24
×
10
7
sec of exposure to 140 °C
in oxygen.
The results of thermal destruction of polysulfone in vacuum have re-
vealed that the first product of decomposition at 400°C was the sulfur diox-
ide; there are also methane and bisphenylpropane in products of decomposi-
tion at temperatures below 500 °C. Therefore, the polysulfone is one of the
most stable to thermo-oxidation thermoplasts.
The articles from polysulfone possess self-attenuating properties,
caused by the nature of polymer but not of the additives. The values of
oxygen index for polysulfone lie in the range of 34-38%. Apparently,
aromatic polysulfones damp down owing to the formation of carbonized
layer, becoming porous protective cover, on their surfaces. The probable
is the explanation according to which the inert gas is released from the
polymer [8].
Aromatic polysulfone is chemically stable. It is resistant to the effect of
mineral acids, alkalis and salt solutions. It is even more stable to carbohy-
drate oils at higher temperatures and small loadings [149].
The polysulfone on the basis of bisphenylpropane also possesses high
dielectric characteristics: volume resistivity 10
17
; electric inductivity at a
frequency 10
6
Hz is 3, 1; dielectric loss tangent at a frequency 10
6
Hz is 6
×
10
-4
.
Aromatic polysulfones can be reprocesses by die-casting, by means of
extrusion, pressing, blow method [150, 151]. The aromatic polysulfones
