Glass Transition of LDPE and PP under High Quasi-Hydrostatic Pressure in Room Temperature

Physical properties such as heat capacity, relaxation time and viscoelastic state will change before and after the glass transition temperature of the polymers. Changes in the physical properties of polymers such as low-density polyethylene (LDPE) or polypropylene (PP) under high quasi-hydrostatic pressure will affect the insulation performance of the cables. At the same time, increasing the pressure is equivalent to lowering the temperature, and studying the glass transition pressure of the polymers in room temperature can better study the physical properties of polymers and the insulation performance of the cables. In this paper, we will measure the deformation of polymer planar samples under high quasi-hydrostatic pressure and draw the stress-strain curve of LLDPE, copolymerized PP and homopolymerized PP under high quasi-hydrostatic pressure to obtain the glass transition pressure in room temperature.