Reaction kinetics of cassava starch graft anionic/nonionic-type polymer internal curing agents

Abstract

Internal curing can help to improve the durability of concrete by preventing and minimizing initial cracks due to autogenous shrinkage and plastic shrinkage. Using a reliable internal curing agent is essential to the effectiveness of the internal curing process. This paper investigates the reaction kinetics of a starch graft anionic/nonionic-type polymer. The results demonstrate that initiator monomer concentration, and starch concentration are positively correlated with graft reaction rate Rp. Based on the research, the kinetics equation of this cassava starch graft anionic/nonionic-type polymer has also been developed, which coincides well with the law of free radical polymerization. The obtained Rp equation is a first-order dependence of the monomer concentration and the square root of the initiator concentration. And Rp is further correlated to the reaction temperature based on a sigmoid function instead of a linear function. It is also found that the polymerization reaction is characterized by the coexisted disproportion termination and coupling termination.

Keywords

• free radical polymerization
• graft reaction rate
• kinetics
• growth sigmoid curve
• internal curing agent