SMMA

Styrene methyl methacrylate is a transparent copolymer consisting of styrene units, the monomer of polystyrene, and methyl methacrylate units, the monomer of the also transparent PMMA. In many versions of SMMA a rubber phase has also been added to make the material very tough or ductile.

The rubber component is an acrylic rubber dispersed in the SMMA matrix. A dispersed rubber phase usually makes the material opaque (as in ABS), but in this case, by cleverly selecting the ratio of S and MMA units, the optical refractive index of the SMMA matrix is ​​made equal to that of the rubber component, which enables visible light to pass undisturbed. Impact-resistant SMMA can be used as an alternative to PC and other transparent polymers, although the temperature resistance is lower.

Specific characteristics
Density:

approx. 1.05g / cm3.

Mechanical properties:

Modulus around 2 GPa, depending on the amount of rubber, strength around 35 MPa. High elongation at break and high toughness in impact resistant blends with rubber. Pure SMMA has a higher modulus and strength, but much lower elongation and toughness.

Thermal properties:

Tg approx. 100 °C, HDT around 70 °C.

Chemical resistance:

Good resistance to sterilization with ethylene oxide and gamma radiation. Slightly better resistance to alcohols and other hydrocarbons than ABS and PS.

Color / surface:
Colorless transparent with a high light transmission. Glossy surface and easy to color and print.

Processing
Injection moldable at temperatures between 190 ° C and 240 ° C.

Applications
Consumer items: clothes hangers, toys, games, impact-resistant CD and DVD boxes, water (filter) jugs, storage boxes, computer equipment, kitchen utensils, office supplies, etc. Packaging: cosmetics packaging Medical: medical equipment and packaging Retail: sales displays

Source: Promolding B.V.