Glass fiber-reinforced modified PDCPD composites with improving mode I and mode II interlaminar fracture toughness and impact resistance: Effects of matrix properties

During the service life of thermoset matrix fiber-reinforced polymer composites, they are susceptible to structural damage such as delamination after low-velocity impacts, thereby affecting their mechanical properties and structural integrity. Therefore, this paper adjusted the properties of polydicyclopentadiene matrix through copolymerization and incorporation of elastomers to obtain modified polydicyclopentadiene/glass fiber composites with improved interlaminar fracture toughness and impact resistance without significantly sacrificing rigidity. The results indicated that compared to polydicyclopentadiene/glass fiber, the G_Ⅰ,R increased from 2.61 kJ/m² to 4.33 kJ/m² and the G_ⅡC increased from 3.04 kJ/m² to 4.07 kJ/m² by incorporating 10 wt% cyclooctadiene and 2 phr styrene-ethylene-butylene-styrene. The energy dissipation mechanisms leading to these improvements included matrix ductile fracture, shear yielding, particle crack bridging, particle fracture, and particle debonding. Additionally, compared to polydicyclopentadiene/glass fiber, the damage area decreased under drop weight impact by incorporating styrene-ethylene-butylene-styrene. Moreover, compared with epoxy/glass fiber composites, modified polydicyclopentadiene/glass fiber composites demonstrated superior interlaminar fracture toughness and impact resistance. The interlaminar fracture toughness of modified polydicyclopentadiene/glass fiber was comparable to that of thermoplastic matrix composites. This study provided a significant method for enhancing the interlaminar toughness and impact resistance of polydicyclopentadiene/glass fiber composites by adjusting the matrix toughness.