Effect of butyryl substitution degree in cellulose acetate butyrate (CAB) on A3 plasticizer migration: Mechanism analysis

Plasticizer migration is a significant issue in the utilization of polymer materials. For cellulose derivatives substituted with two or more different groups, such as cellulose acetate butyrate (CAB), the varying proportions of acetyl and butyryl groups lead to different chemical structures, which influence the plasticizer migration properties. This paper investigates the effects of the butyryl substitution degree on plasticizer migration properties through experimental testing and molecular dynamics simulations. Results from experiments and simulations indicate that as the temperature increases, the plasticizer in the mixed system is more likely to migrate with the increase in CAB butyryl substitution. Microscopic and mesoscopic mechanism studies reveal that the strength of intermolecular forces between the plasticizer and CAB is not the primary reason for the differences in plasticizer migration. The main reasons could be attributed to the reduction in steric hindrance effect and plasticizer migration pathway as the degree of butyryl substitution increases.