SODIUM POLYNAPHTHALENE SULFONATE

SODIUM POLYNAPHTHALENE SULFONATE

Sodium polynaphthalene sulfonate (SPNS) functions as an emulsion stabilizer, surfactant – dispersing agent, and a surfactant – hydrotrope in cosmetic products. It is used as a raw material in the production of admixtures for the construction industry and is one of the basic ingredients for formulation of chemical admixtures for concrete and mortars. It is defined as the sodium salt of the product obtained by the condensation polymerization of 2-naphthalene sulfonic acid and formaldehyde.

2 CHEMICAL NAME AND IDENTIFICATION

Chemical Name (IUPAC): Naphthalenesulfonic acid, sodium salt, polymer with formaldehyde
CAS RN: 9008-63-3
Molecular formula: (C10H8O3S.CH2O.Na)x [This substance is a polymer.]
Molecular weight: Unknown
Synonyms: Sodium polynaphthalene sulfonate; naphthalenesulfonic acid, sodium salt, polymer with formaldehyde; sodium naphthalenesulfonate-formaldehyde copolymer; naphthalenesulfonic acid sodium salt/formaldehyde polymer; formaldehyde/naphthalenesulfonic acid.

3 PHYSICO-CHEMICAL PROPERTIES

According to Hampshire Chemical Corp. (1995), SPNS is made by reacting naphthalene with sulfuric acid under conditions of heat and pressure. Formaldehyde and water are then added to produce the acid polymer under the same conditions of heat and pressure. Caustic is added to the acid polymer resulting in the final product (CIR, 2003).
SPNS is tan or amber in powdered form and brown in liquid form. It is completely soluble with a density of 400 – 700 kg/m3 . The substance has a percent (%) volatility of 3 % to 7 % water (CIR,
2003).

4 Effect

Four naphthalene sulfonate formaldehyde condensate (FDN) fractions with different molecular weights were obtained by fractionation using ultrafiltration and their Molecular weight distributions and the contents of sulfonic group were tested separately by mass spectrum and element analysis. The effects of four FDN fractions on the property of cement and mortar were studied. It is found that FDN with higher molecular have better workability. When the mass dosage of FDN gotten through 30000 member size is 0.5%, the water-reducing ratio of mortar is up to 16%, increases by 4% than that of original FDN. At the same time, the compressive strength of responded mortar is rised by 30% compared with blank sample after 7 days, accompanying with flexural strength increases by 23%. FDN with higher molecular has some retarding effect comparing with the lower, and can help the formation of uniform and densely thin rod-shaped ettringite during cement hydration early by scanning electron microscope (SEM).