Mechanically strong and fully transparent PMMA composite with greatly improved toughness and impact strength incorporating PEBA nanofibrils

Abstract

Improving the tensile toughness and impact strength of poly(methyl methacrylate) (PMMA) involves a trade-off, the improvements often come at the expense of reduced tensile strength, stiffness, transparency, and other crucial properties. In this article, we report a facile method to enhance the tensile toughness and impact strength of PMMA simultaneously, without sacrificing its tensile strength, stiffness, transparency, glass transition temperature, and scratch resistance. We demonstrate that the inclusion of only 3 wt% of polyether block amide elastomer (PEBA) nanofibrils (diameters ranging from ∼ 20 to 164 nm) in PMMA and ∼ 0.6 wt% of a random ethylene-glycidyl methacrylate copolymer (E-GMA) selectively at the interface resulted in a remarkable increase of ∼ 169 % in its elongation at break, ∼188 % in tensile toughness, and ∼ 87 % in notched Izod impact strength. Importantly, by incorporating such a minimal content of rubbery materials, these improvements were attained without compromising any of its major properties. Herein, we also demonstrate that multiple crazing was the primary toughening mechanism in the composites at a slow deformation speed (i.e., tensile testing), while rubber cavitation and subsequent ductile shear yielding of the surrounding matrix (enabled by the presence of E-GMA at the interface) was the most dominant at a high deformation speed (i.e., notched Izod impact testing). The high-performance composites presented herein possess immense potential for use in applications requiring a unique combination of attributes such as high strength, stiffness, tensile toughness, impact strength, and optical transparency.