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 and cost of analyzing polymer responses in real-time. To address this, an inexpensive and unique debris catcher has been developed, capable of safely capturing debris from hypervelocity impacts. Debris from polymers such as high-density polyethylene (HDPE), low-density polyethylene (LDPE), ultra-high molecular weight polyethylene (UHMWPE), polymethyl methacrylate (PMMA), and polycarbonate (PC) is successfully recovered from impacts with projectile velocity of approximately 5,500 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 are traceable for both HDPE and UHMWPE debris samples. The monomeric friction coefficients (ζmon) of each polymer are estimated from shear rheometry results. It is found that both ζmon and the compressive behavior of polymers caused by the shock wave need to be considered when examining the molecular responses during HVI events. Overall, the chemical structure and polymer morphology determine how polymer materials respond at hypervelocity.