Deformation and Fracture Behaviors of Tough Plasticized Poly(vinyl butyral) across Broad Temperature and Strain Rate Ranges

Understanding the deformation and fracture behaviors of amorphous polymers, particularly those toughened via dynamic bonds, is crucial for their practical applications and further material design. In this study, the amorphous plasticized poly(vinyl butyral) (p-PVB) is chosen as a model system, characterized by heterogeneous distribution of hydrogen bonds, strong dynamical asymmetry, and exhibiting stretch-induced phase separation. Through measuring and examining the time–temperature superposition principle on viscoelastic modulus in dynamic mechanical analysis (DMA) tests, hysteresis energy in loading–unloading tests, rupture work in uniaxial tensile tests, and fracture toughness in pure shear tests across broad strain rate and temperature ranges, we have specifically elucidated the critical roles of bulk viscoelasticity and stretch-induced phase separation on the energy dissipation during the deformation and fracture of p-PVB. In p-PVB, the stretch-induced phase separation makes a significant contribution to its fracture energy dissipation, retards crack propagation, and enlarges the fracture strain. The systematic investigations in this work not only enable the prediction of the mechanical behaviors and energy dissipation pathway of p-PVB products, such as the interlayer films used in laminated glass, but also provide guidance for designing amorphous polymers with similar structures and great energy dissipation capability during deformation and fracture.