Investigating the Molecular Responses of Polymers during Extreme Events from Captured Hypervelocity Impact Debris

Understanding the molecular response of polymers during hypervelocity impacts is crucial for improving their protective capabilities against these extreme events. However, the nature of these events increases the difficulty of real-time analysis of polymer responses. To address this, an inexpensive debris catcher has been developed that can safely capture debris from hypervelocity impacts. Debris from polymers such as high-density polyethylene (HDPE), low-density polyethylene (LDPE), ultra-high-molecular weight polyethylene (UHMWPE), poly(methyl methacrylate) (PMMA), and polycarbonate (PC) is successfully recovered from impacts with projectiles having an approximate velocity of 5800 m/s. X-ray diffraction measurements and differential scanning calorimetry are used to probe the compositions of these debris samples. These results reveal evidence of species unique to the original pristine materials. Additionally, signs of the starting polymer can be traced for both HDPE and UHMWPE debris samples. The monomeric friction coefficients (ζ_mon) of each polymer are estimated from shear rheometry. It is found that both ζ_mon and the compressive behavior of polymers caused by the shock wave need to be considered when examining the molecular responses during hypervelocity impact events. Overall, the chemical structure and morphology determine how polymer materials respond at hypervelocity.