Elongated soy protein isolate-poly(D, L-lactide-co-glycolic acid) microcapsules prepared using syringe filters and their effect on self-healing efficiency of soy protein-based green resin

Abstract

A self-healing soy-based resin lled with soy protein isolate (SPI) containing poly(D, L-lactide-co-glycolic acid) (PLGA) microcapsules (MCs) was prepared. MCs were prepared using a syringe lter via a membrane emulsi cation technique. Using this method, spherical (diameter of about 1.30 μm) and elongated MCs (aspect ratios up to 20) could be produced. Tensile properties and self-healing e ciencies of resins were characterized for both MC morphologies in terms of strength recovery and toughness recovery. While both MCs could successfully heal cracks, spherical MCs were seen to compromise the tensile properties of the resin, whereas elongated MCs demonstrated some mechanical enhancement. Overall results showed that elongated MCs having a higher aspect ratio resulted in slightly better selfhealing performance as well as a mechanical improvement. The results also show that higher MC loading results in higher self-healing e ciency.

Self‐healing efficiency of cinnamaldehyde‐crosslinked soy protein resins with elongated soy protein microcapsules

“…Figure 2 shows various steps involved in the self‐healing test. The conditioned MC‐CA‐SPI resin sheets were laser‐cut to the final dimensions of 32 mm × 30 mm × 2 mm, as shown in Figure 2a, as per ASTM E647‐08, with slight modification 14,15,55 . At 10 mm below the precrack tip, a 40‐deg arc was also laser cut.…”

“…The conditioned MC-CA-SPI resin sheets were lasercut to the final dimensions of 32 mm  30 mm  2 mm, as shown in Figure 2a, as per ASTM E647-08, with slight modification. 14,15,55 At 10 mm below the precrack tip, a 40-deg arc was also laser cut. The purpose of including the arc was to capture and arrest the cracks from propagating further than 10 mm during the self-healing test.…”

“…One of the effective solutions to prevent the microcracks from growing to catastrophic levels is through autonomous self-healing, which allows materials to recover from damages at the microstructural level. [1][2][3]8,14,15 This self-healing characteristic not only extends the life of the materials but also enhances the safety of the products as well as the users.…”

“…Cracks and microcracks are the main culprits for premature failure of polymers and composites when they operate under extreme environments such as high stress/strain, cyclic loading, humidity, or oxygen‐rich conditions. One of the effective solutions to prevent the microcracks from growing to catastrophic levels is through autonomous self‐healing, which allows materials to recover from damages at the microstructural level 1–3,8,14,15 . This self‐healing characteristic not only extends the life of the materials but also enhances the safety of the products as well as the users.…”