Ballistic Response of Polydicyclopentadiene vs. Epoxy Resins and Effects of Crosslinking

摘要

The ballistic performance of polydicyclopentadiene (pDCPD) was investigated and compared to two epoxy resins that a have similar glass transition temperature (T_g) to pDCPD. The ballistic performance of these materials (at an effective stain rate of 10~4-10~5 s~(-1)) was characterized by determining the kinetic energy of the projectile where there is a 50% probability that the projectile will penetrate a witness foil behind the sample (KE_(50)). The ballistic performance of pDCPD showed a 300-400% improvement over the structural epoxy resins. Typical, highly crosslinked epoxy networks become brittle at low temperatures, but pDCPD has a superior ballistic performance over a broad temperature range from (-55 to 75°C), despite having a glass transition temperature of 142°C, which characteristic of structural resins. pDCPD also exhibited a room temperature glassy storage modulus of 1.7 GPa, making pDCPD a potential structural resin that can overcome the structural vs. energy dissipation trade-off that commonly exists with some conventional crosslinked polymers. Quasi-static measurements of pDCPD when compared to epoxy resins suggested that the performance of pDCPD relates to higher fracture toughness and lower yield stress relative to typical epoxies, while molecular dynamics simulations comparing pDCPD to epoxy resins suggest that the performance of pDCPD is due to the lack of strong non-covalent interactions and the facile formation of nanoscale voids.