Synthesis and Performance Evaluation of Novel Nitrogen‐Containing PVC Heat Stabilizer Oligo‐Uracil

Two novel nitrogen‐containing organic heat stabilizers for PVC, 1,5‐triuracil (5‐SU) and 1,6‐triuracil (6‐SU), were successfully synthesized from 5‐chlorouracil and 6‐chlorouracil, respectively, by oligomerization reaction. The molecular structures were characterized by FTIR and NMR techniques. Then, the thermal stability performance of 5‐SU and 6‐SU was investigated in detail by Congo red test, thermogravimetric analysis, thermal aging test, conductivity test, and torque rheology test. The results demonstrate that both 5‐SU and 6‐SU have much superior thermal stability compared to those in the literature, including the commercial calcium–zinc heat stabilizers. The thermal stability of 6‐SU is better than that of 5‐SU. The thermal stabilization time of 6‐SU is measured to be not less than 200 min. However, there is an antagonistic rather than a synergistic effect between 5‐SU/6‐SU and CaSt 2 . Both 5‐SU and 6‐SU have certain UV‐absorbing ability to improve the UV weathering resistance of PVC. The results of optical density measurements show that the PVC material with 5‐SU/6‐SU is able to inhibit the growth of S. aureus . When the bacteria are incubated up to 12 h, the inhibition rate of 5‐SU is 9%, while that of 6‐SU is 33.3%. The stabilizing effect of 5‐SU and 6‐SU on PVC is achieved by substituting the defective sites in PVC material.