Kinetics and mechanism of plasticized poly(vinyl chloride) films autohesion interface effect

Kinetics of bis(2-diethylhexyl)phthalate plasticized poly(vinyl chloride) (PVC) autohesion development was monitored at 373 K, 393 K, 413 K. Three regions of bonding kinetics were observed (first time) at all temperatures: adhesion increase after initial contact, constant adhesion plateau, long contact time adhesion increase. Initial adhesion increase resulted from plasticizer diffusion into interface and capillary attraction, activation energy, E-a = 66 kJ mol(-1). Plateau in adhesion kinetics is consistent with polymer segments diffusion across interface; duration decreased with temperature increase, yielding E-a = 113 kJ mol(-1). Adhesion at plateau increased linearly with temperature increase, indicating Van der Waals attraction between the PVC macromolecules in interface. Final adhesion increase was stipulated by macromolecular segments diffusion into and entanglement within interface, E-a = 109 kJ mol(-1). Scanning electron and optical microscopy confirmed plasticizer and polymer diffusion into interface (width up to 3.5 mu m). PVC segments diffusivities in plasticized PVC were derived: 1.8 x 10(-13) cm(2) s(-1) at 373 K, 1.1 x 10(-12) cm(2) s(-1) at 393 K, 6.3 x 10(-12) cm(2) s(-1) at 413 K.

Automated summary

The kinetics of autohesion development in plasticized PVC with bis(2-diethylhexyl)phthalate were studied at different temperatures, revealing three stages of bonding: initial adhesion increase, constant adhesion plateau, and long contact time adhesion increase. The diffusion of plasticizer and polymer, as well as Van der Waals attraction between PVC macromolecules, play key roles in the adhesion process. The increase in temperature results in a decrease in the duration of the constant adhesion plateau, showing an activation energy of 113 kJ mol(-1).