Naphthalene formaldehyde sulfonates molecular weight

The fluid loss and thickening time characteristics of the cement slurry is altered, either by increasing the molecular weight of the lignin by cross-linking with formaldehyde or epichlorohydrin or by adding agents such as sodium sulfite, sodium metasilicate, sodium phosphate, and sodium naphthalene sulfonate. 

The material is produced from naphthalene by oleum or sulfur trioxide sulfonation under conditions conducive to the formation of the h sulfonate. Subsequent reaction with formaldehyde leads to polymerization and the sulfonic acid is neutralized with sodium hydroxide [17] or lime. The process is illustrated in Fig. 2.2. The value of n is typically low but conditions are chosen to get a proportion of higher-molecular-weight product as it is believed to be more effective [18]. The quantity of sodium sulfate by-product formed by the neutralization of excess sulfonating reagent will vary depending on the process used, but can be reduced by a subsequent precipitation process using lime [19]. 

Salts of Formaldehyde-Naphthalene Sulfonate Although it was the first WRA referred to in the literature, it has been used in major applications only since the early 1970s. The material is obtained by oleum or sulfur trioxide sulfonation of naphthalene. The reaction of the product results in polymerisation [26]. If the material obtained is of low polymerisation, it does not result in air-entrainment. However, if they are of high molecular weight they do not result in air-entrainment. 

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