The key properties of our unmodified THIOPLASTTM G polysulfides are elasticity and pronounced chemical resistance. This makes them ideal for their most important application as a sealant. As regards curing conditions, their behavior is uncritical. Physical properties are also easy to adapt to specific application requirements using various fillers, plasticisers and special modifying additives.
Chemistry of THIOPLASTTM G
Thioplast results from the polycondensation of bis-(2-chloroethyl-)formal with alkali polysulfide. This reaction generates long-chain macromolecules which are then cut to the required chain length by reductive splitting with sodium dithionite. The disulfide groups are at the same time converted into reactive thiol terminal groups. By introducing a trifunctional component (e.g. 1, 2, 3-trichloropropane) during synthesis, a third thiol terminal group can be added to a specific number of Thioplast molecules to determine the extent of cross-linking during the curing process. The value for n may vary between 7 and 38 depending on the amount of the splitting agent used. For particular applications, chain length and branching will have to be varied. The chemical composition of liquid G-type THIOPLASTTM is described in outline in the following structural formula:
Typical properties
All Thioplast types are medium to high viscous liquids of light brown color. The average molecular weight (calculated from the thiol terminal group content), as a measure of chain length and the degree of branching, determine the viscosity. Consequently, viscosity is the most important characteristic feature of a THIOPLASTTM G type.
Characteristic features of the Thioplast types
| Thioplast type |
Unit |
G10 |
G112 |
G131 |
G1 |
G12 |
G21 |
G22 |
G44 |
G4 |
| Molecular weight range |
g/mol |
4400-4700 |
3900-4300 |
5000-6500 |
3300-3700 |
3900-4400 |
2100-2600 |
2400-3100 |
<1100 |
<1100 |
| n |
|
23-25 |
23-25 |
30-38 |
19-21 |
23-26 |
13-16 |
14-18 |
<7 |
<7 |
| SH-contents |
% |
1.4-1.5 |
1.5-1.7 |
1.0-1.3 |
1.8-2.0 |
1.5-1.7 |
2.5-3.1 |
2.1-2.7 |
<5.9 |
<5.9 |
| Branching |
mol% TCP |
0 |
0.5 |
0.5 |
2 |
0.2 |
2 |
0.5 |
2 |
0.5 |
| Colour |
% TM |
min. 30 |
min. 30 |
min. 30 |
min. 30 |
min. 30 |
min. 45 |
min. 45 |
min. 50 |
min. 50 |
| Viscosity@25 °C |
Pa*s |
42 - 48 |
38 - 50 |
80 - 145 |
41 - 52 |
38 - 50 |
10 - 20 |
10 - 20 |
max. 1.3 |
max. 1.3 |
| Specific weight |
g/cm³ |
1.283 |
1.285 |
1.310 |
1.286 |
1.285 |
1.285 |
1.285 |
1.257 |
1.259 |
| Volatile ingredients |
% |
max. 0.3 |
max. 0.3 |
max. 0.3 |
max. 0.3 |
max. 0.3 |
max. 0.5 |
max. 0.5 |
max. 1.0 |
max. 1.0 |
| Water content |
% |
max. 0.3 |
| Sulfur content |
% |
37 - 38 |
| Free sulfur |
% |
max. 0.1 |
| Glass point |
°C |
ca. -60 |
| Flash point |
°C |
> 230 |
| Specific heat |
kJ/kg*K |
1.26 |
| Heat of combustion |
kJ/kg |
24,075 |
| Storage stability |
|
min. 3 year in closed original packaging at a temperature < 30 °C |
For detailed technical information and test formulations please see our brochures and Data sheets under Downloads.