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

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