Synthesis of Lanthanum 2-aminonicotinate Acid on Heat Stability of PVC
Lanthanum 2-aminonicotinic acid(2-LANA)was synthesized by the double decomposition reaction of 2-aminonicotinic acid(2-ANA),lanthanum nitrate and sodium hydroxide,and its effect on the thermal stability of polyvinyl chloride(PVC)was studied.The results showed that 2-LANA improved the thermal stability of PVC,and extended the static and dynamic stability time of PVC to 27 min and 27.45 min,respectively.2-LANA is compounded with zinc stearate(ZnSt2),calcium stearate(CaSt2),and pentaerythritol(PE)in one or more ways to investigate the thermal stability of its composite heat stabilizer.When 2-LANA∶ZnSt2∶PE=2∶1∶2,its static and dynamic thermal stability time are 66 min and 64.91 min,respectively,and the apparent activation energy(Ea)of PVC degradation is 169.73 kJ/mol,indicating that it can make the PVC degradation reaction more difficult to occur.When 2-LANA∶Ca/Zn stabilizer∶PE=1∶1∶3,its discoloration resistance,rheological and mechanical properties are the best,which makes PVC more stable and ductile during processing.It shows that 2-LANA has obvious synergistic effect with other stabilizers.2-LANA can effectively absorb the HCl gas released from PVC during thermal degradation and generate LaCl3,which can effectively prevent the fracture of C—Cl on PVC chains and C—H connected with chlorine,reduce the generation of conjugated double bonds,slow down the discoloration of PVC,inhibit the generation of HCl,and delay the thermal degradation of PVC to a certain extent.
Lanthanum 2-aminonicotinate acidPolyvinyl chlorideThermal stabilityCompoundApparent activation energy of degradation
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