Development and performance evaluation of silk fibroin fiber reinforced epoxy composites for lightweight structural components

This research presents the development and comprehensive performance evaluation of silk fibroin fiber reinforced epoxy matrix composites prepared from natural fibers of Bombyx mori (Bm), Antheraea pernyi (Ap), and Samia cynthia ricini (Sr). High volume fraction composites up to 68 vol% were prepared by vacuum-assisted resin impregnation and hot pressing. The effects of different kinds of silk fibers and fiber volume fractions on the mechanical, thermal, and microstructural properties of the composites were examined. Tensile tests showed a significant improvement over neat epoxy, and the values of tensile strengths for Bm, Sr, and Ap are 36.5 ± 2.5 MPa, 67.8 ± 3.8 MPa, and 98 ± 5.0 MPa, respectively, along with tensile modulus values ranging from 8.0 to 8.6 GPa. The flexural strengths for Bm, Sr, and Ap are 228, 210, and 250 MPa, and the flexural modulus values are 3.5-4.5 GPa. The impact strength values are up to four times higher, reaching a value of 28.5 kJ/m² for Ap. The interlaminar shear strengths are more than doubled compared to neat epoxy. Dynamic mechanical thermal analysis tests showed that the storage modulus retention and thermal stability are improved. The A. Peryii silk fiber-reinforced epoxy composite material possesses a balanced combination of properties, and this study confirms that silk fibroin fiber-reinforced composites are sustainable, high-performance fiber-reinforced composite materials.