Effect of zinc-levulinic acid chelate compounds formed in furfuryl alcohol polymer concrete

Abstract

As part of an experimental programme to develop high early strength water-compatible furfuryl alcohol (FA) polymer concrete (PC) composites, the polymerization heat resulting from the use of various mineral and organic acid initiators was measured using a differential scanning calorimeter. The results indicated that, of the several initiators evaluated, the use of 1,1,1-trichlorotoluene (TCT)-zinc chloride (ZnCl2) system to cure a FA-water-saturated aggregate system yielded the highest early strength and the highest polymerization heat. The ZnCl2 solution used as part of the two-component initiator systems had a significant effect on the rate of polymerization of the FA monomer and the thermal stability of the composite. The latter resulted from an increase in the stiffness of the polymer chains due to the formation of zinc-FA chelate compounds. These were formed through reactions between the bivalent metallic Zn2+ ions dissociated from the ZnCl2 solution and the strongly ionized carboxyl groups of levulinic acid yielded by the cleavage of furan rings in an acidic medium. The thermal polymerization activation energy of FA monomer combined with the TCT-ZnCl2 system was calculated to be 98.6 kJ mol−1. The glass transition temperature, T g, and thermal decomposition heat of the system were 62° C and 220 kJ kg−1, respectively.