Observation and modeling of environmental stress cracking behaviors of high crystalline polypropylene due to scent oils

Environmental stress cracking (ESC) is a common phenomenon that affects commercially available polymeric materials exposed to liquid agents under external loading, and it is one of the most common causes of their unexpected long-term failure. In this study, ESC behavior of high crystalline polypropylene (HCPP) was studied through modified notched constant tensile load testing using two different scent oils as environmental agents. The relationship between total lifetime of the material and initial stress intensity factor was determined. Despite the similar molecular structures of the scent oils, they caused a remarkable lifetime difference for the material within a certain loading range. Swelling tests were also conducted in order to define diffusion coefficients for the scent oils without any loading. From these results, the diffusion coefficients for the two scent oils into the HCPP were modeled according to the initial stress intensity factor.