This document summarizes a study on the mechanical properties and kinetics of weight loss of polypropylene waste plastic under isothermal conditions at low temperatures (80-140°C). The study found that even very low weight loss (0.3% by mass) significantly affected tensile strength, breaking strength, strain and yield strength due to evaporation of volatile substances. Kinetic parameters like activation energy, pre-exponential factor and reaction order were calculated at different temperature ranges and weight loss levels. The activation energies were low, indicating a physical rather than chemical degradation process at these temperatures. The order of reaction changed from 1 to 2 as weight loss increased from 0 to 0.9, in line with literature. Mechanical properties