Analysis of the Mechanical Properties of Pristine and Thermally Aged PC/PMMA Micro and Nanolayered Films

Microlayered polymer films are synthetic polymers with biomimicking layered structures which have been successfully commercialized. Nanolayered polymer films have been developed in recent years using advanced process technology. The innovative nanolayered polymer films have more complex hierarchical systems with truly biomimic nature. There are many potential applications for the nanolayered films such as gas barrier materials and spherical gradient refractive index lens. However, as polymers possess many properties that are different from metals and other traditional materials, the mechanical properties of the polymer films can vary widely depending on the material formulation, environmental temperature, and time. In this work, standard mechanical tests have been conducted to study the relationship between the mechanical properties and the layered structures. The impact of thermal aging on the mechanical behavior of the micro and nanolayered polymer films has also been investigated experimentally. The composition of the polymer films under study are 50vol% polycarbonate (PC) and 50vol% poly(methyl methacrylate) (PMMA). The layer thickness ranges from 31 nm to 32 μm and the film thickness 50.8 μm to 254 μm. These films were thermally aged at 115°C and 125°C in a constant temperature oven for up to four weeks. The mechanical properties, including the modulus of elasticity, tensile strength and ductility, have been tested on the pristine and thermally aged films. It has been observed that the mechanical properties of the films vary with the layered structure and film thickness. The thermal aging temperature and aging time have significant effects on the overall character of the stress-strain responses. Films with different thicknesses and layer formations respond to the thermal conditions differently.