Preparation and characterization of high-performance pollen-enhanced epoxy resin composites

In this study, natural pine pollen (bisaccate structure) and sunflower pollen (spiny surface) were adopted as eco-friendly bio-based reinforcements. Pollen/epoxy composites were systematically fabricated at low filler loadings of 0.1–0.5 wt%. The effects of pollens on the mechanical properties, UV shielding efficiency, antioxidant capacity, crystallization behavior, and thermal stability of the composite were investigated comparatively. The experimental results reveal that both pollens can form favorable physical interfacial bonding (hydrogen bonding and mechanical interlocking) with epoxy resin, inducing a partially ordered arrangement of molecular chains without altering the chemical structure or thermal stability of the matrix. The fracture stress of pine pollen/epoxy composite reaches 86.75 MPa at 0.1 wt%. In contrast, the sunflower pollen/epoxy composite achieves an optimal reinforcing effect at 0.3 wt%, with a fracture stress of 93.94 MPa. Meanwhile, the pollen/epoxy composites exhibit excellent UV resistance (transmittance decreases to 30% and 8% for UVA and UVB, respectively) and antioxidant activity (an enhancement of 38.9%). This work provides a design strategy for developing low-cost, biodegradable, high-performance green composites integrating structural and functional properties.