Epoxy-functionalized polysiloxane reinforced epoxy resin for cryogenic application

Appendix S1:

Figure S1. Dimensions in mm of tensile specimen.

Figure S2. Dimensions in mm of single-edge notched bending (SENB) specimen and thefixture for flexural test.

Figure S3. Dimensions in mm of unnotchedimpact test specimen.

Figure S4. SEM micrographs of fracture surfaces of Si-epoxy composites after fracture toughness testing at RT, scale bar: 300 μm. The smooth fracture surface of neat epoxy resin indicated a typical characteristic of brittle fracture. On the contrary, the obviously rough fracture surfaces (namely the plastic deformation) were observed for the PSE modified epoxy resin, which indicated that the crack propagation paths deflected from their original planes. The reason was that the crack tip was blunted by plastic deformation and resulted in the reduction of stress concentration near the crack tip, and finally prevented the crack propagation.

Figure S5. SEM micrographs of fracture surfaces of Si-epoxy composites after fracture toughness testing at 90 K, scale bar: 300 μm. At 90 K, all specimens show a relatively smooth fracture surface, which is due to the fact that the molecular networks of epoxy resin are frozen at cryogenic temperature and result in the increase of brittleness. Compared to the neat epoxy resin, however, the PSE modified epoxy resins still present a more rough fracture, which indicate that the PSE can enhance the toughness of epoxy resin at cryogenic environment.

Table S1 Fracture toughness factor KIC of Si-epoxy composites at RT and 90 K