Partially hydrolyzed polyacrylamide (HPAM) is widely employed in enhanced oil recovery (EOR) process. However, its effectiveness is hindered by degradation of polymer molecules during flow through injection lines, valves and reservoir. This degradation leads to a decrease in average molecular weight and subsequently reduces the solution’s viscosity and viscoelastic properties, impacting its effectiveness on displacing oil. Our research characterized the degree of mechanical degradation of HPAM solutions using shear and extensional rheology. We induced degradation by flowing the solutions through a valve with varying constriction and flow rates and through a microfluidic porous medium model. Our findings reveal that the addition of silica (SiO2) nanoparticles has a negligible effect on the shear and extensional viscosities of fresh solutions and minimizes the mechanical degradation of HPAM solutions. The rheological properties of HPAM solutions with SiO2 nanoparticles are not significantly affected by mechanical degradation, suggesting that incorporating nanoparticles could enhance the efficiency of polymer injection in EOR processes by stabilizing HPAM solutions. In addition, our study explored oil displacement flow using both fresh and degraded HPAM polymer solutions in microfluidic devices used as models of porous media. The findings suggest that fresh HPAM is more efficient in displacing oil than degraded HPAM. Furthermore, the addition of silica nanoparticles into degraded NPs-HPAM solutions resulted in a 9-13 percent increase in oil recovery, highlighting the enormous potential of nanoparticles in enhancing EOR processes.