Styrene maleic anhydride

Styrene maleic anhydride
IUPAC name	Poly(Styrene-co-Maleic Anhydride)
Other names	SMA; Xiran
Identifiers
CAS number	9011-13-6 Y
Properties
Molecular formula	(C8H8)n-(C4H2O3)m
Molar mass	Variable
Appearance	crystal clear polymer
Density	1.080 g/cm³
Solubility	Soluble in alkaline solutions and polar organic solvents
Refractive index (nD)	1.577
Y (what is this?)  (verify) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Styrene maleic anhydride , also known as SMA or SMAnh , is a synthetic polymer that is built-up of styrene and maleic anhydride monomers. The monomers are built in randomly making it a random copolymer. It is formed by a radical polymerization using an organic peroxide as the initiator. The main characteristics of SMA copolymer are its transparent appearance, high heat resistance, high dimensional stability, and the specific reactivity of the anhydride groups. The latter feature results in the solubility of SMA in alkaline (water-based) solutions and dispersions.

SMA is available in a broad range of molecular weights and maleic anhydride (MA)contents. In a typical combination of those two properties SMA is available as a crystal clear granule that can be used in a broad range of applications. SMA polymers with a high molecular weight are widely used in engineering plastic applications, normally in the impact modified and optional glass fibre filled variants. Alternatively, SMA is applied using its transparency in combination with other transparent materials like PMMA or the heat resistancy to heat-boost other polymers materials like ABS or PVC. The solubility of SMA in alkaline solutions makes it suitable for various applications in the field of sizings (paper), binders and coatings. The specific reactivity of SMA makes it a suitable agent for compatibilizing normally incompatible polymers (e.g. ABS/PA blends).

SMA producers

There are only a few commercial suppliers of SMA polymers. The major producers are Polyscope Polymers (Xiran), Sartomer (SMA) and Nova Chemicals (Dylark). While the Sartomer product range covers low molecular weight products with high MA contents (and sometimes chemically modified), the Nova materials are high molecular products with low MA content (and mainly impact modified) and Polyscope's Xiran product range covers the area in between (with some overlap; also in impact modified grades). Each of those products have their own specific features.

References

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