Generally, poly maleic anhydride has a relative molecular weight of 400~800, while polymaleic anhydride using the solvent method (PMA-s) has an average molecular weight of about 1000 because PMA-s is based on polymerization and hydrolysis of maleic anhydride in the solvent phase.

Maleic anhydride has good solubility in organic solvents due to the principle of similar compatibility. Maleic anhydride can be well polymerized into long chain polymaleic anhydride in organic solvent. However, polymaleic anhydride (PMA-s) prepared by the solvent method has a high molecular weight, but a loose structure, resulting in low density. In contrast, water is a polar solvent. Maleic anhydride in water can not form long-chain poly maleic anhydride, but the polymaleic anhydride formed (PMA-w) has a compact structure and high density.

The polymaleic anhydride solvent method (PMA-s) and the polymaleic anhydride hydrolysis method (PMA-w) are different in molecular weight and density and in scale inhibition and dispersion effect.

The Polymaleic anhydride solvent method (PMA-s) has a better effect in water treatment, especially when the dosage is low.

CAS No.:


Structure Formula:

polymaleic anhydride


ItemPolymaleic Anhydride water method (PMA-w)Polymaleic Anhydride solvent method (PMA-s)
AppearanceLight yellow to brown red transparent liquidAmber liquid
Molecular weight300-800600-1500
Solid content, %48.0 Min.48.0-52.0
Bromine value, mg/g80 Min.
pH value (1% aqueous solution)2.0-3.0
Density (20℃), g/cm31.22-1.251.16-1.22
pH value (stock solution)2.0 Max.
Viscosity (25℃)/cps10.0-60.0


Polymaleic anhydride (PMA-s) still has good scale inhibition and dispersion effect on carbonate below 300 ℃. The scale inhibition time can reach 100 hours. Because of its excellent scale inhibition and high-temperature resistance, HPMA-s is widely used in flash distillation devices of seawater desalination, low-pressure boilers, steam locomotives, crude oil dehydration, water, and oil pipelines, and industrial circulating cooling water.

Polymaleic anhydride (PMA-s) can also be used as the main component of advanced cleaning agents. For example, it can be used as a rinsing agent for textiles to reduce the ash content of textiles. In addition, the agent has a certain corrosion inhibition effect and has a better effect when compounded with zinc salt. PMA-s can also be used as a cement admixture and a saline-alkali soil conditioner.

When HPMA-s is used alone, the concentration is generally 1~15 mg/L, and it is often used in combination with organic phosphonates, which have good compatibility. Polymaleic anhydride is compatible with organic phosphonic acids and quaternary ammonium salts and is not affected by chlorine and other oxidizing biocides under normal use conditions. Therefore, it will not cause environmental pollution.

Packing and Storage:

200L plastic drum, IBC(1000L), customers’ requirement. storage for one year in a shady room and dry place.

200l plastic drum  1000l IBC

Safety Protection:

Acidity, Avoid contact with eye and skin. Once contacted, flush with water.