STMMA
STMMA copolymer beads are copolymers of styrene and methyl methacrylate with a carbon content of 69.6%. Compared with EPS, the carbon content is greatly reduced, and because STMMA contains oxygen atoms, oxygen atoms can be combined with carbon atoms, thereby further reducing the residual carbon
STMMA raw materials are mainly used in the production of castings such as valves, pipe fittings, auto parts and various mechanical parts.
STMMA series expandable copolymer resin beads have better casting properties than EPS:
Reduce the carbon defects of castings;
Reduce the surface carbon defects of steel castings;
Reduced soot;
Improve the surface finish of castings.
The EPS pattern has large shrinkage and poor dimensional stability. The STMMA pattern has low shrinkage and good dimensional stability.
EPS is mainly composed of chain links containing benzene ring, which not only has high carbon content, but also has good thermal stability of benzene ring. At high temperature (>900°C) and hypoxia, a tar-like viscous liquid is first generated, which is then cracked into carbon and hydrogen. The composition of STMMA is mainly composed of acrylate-based chains, which are zipper-type decomposition at high temperatures, and low The molecular liquid and gas are extracted through the coating and the flask, and the composition contains two oxygen atoms to take away two carbons, which further reduces the source of carbon. This is why the STMMA model material is used, and the castings are not easy to generate carbon defects and steel. The main theoretical basis for the low carbon addition on the surface of the casting and good surface finish.
Main specifications of technical performances of product:
STMMA
Main specifications of technical performances of product:
STMMA
|
Item |
Index |
| Appearance |
Opaque spherical granule |
| Range of particle size, μm |
200 ~ 800 |
| Content of volatile % |
≥7.0 |
| Content of moisture % |
≤ 0.6 |
| Main applications | Suitable for casting of aluminum, copper alloy, grey iron, nodular iron, alloy steel, mild steel and stainless steel. |
|
Name |
unit |
EPS |
STMMA |
|
Molecule |
-(C8H8)n-(C8H8O2)m- |
-(C8H8O2)-m |
|
|
Carbon |
% |
92 |
60 |
|
Crumble |
j/g.k |
-912 |
-842 |
|
Tg |
℃ |
80-100 |
100-105 |
|
Evaporation(start) |
℃ |
270-300 |
250-260 |
|
Evaporation(end) |
℃ |
460-500 |
420-430 |
Storage method of STMMA beads:
STMMA requires low-temperature refrigeration (≤10°C). For customers who do not have this condition, please store in a dry, ventilated, cool place without direct sunlight. When it is not used up after opening, remember to re-tighten the bag and cover the bucket to prevent the loss of pentane. It is best to place the beads in a designated location, and pay attention to fire prevention in the place where the beads are stored.
