Self‐healing in high impact polystyrene (HIPS) composites via embedded non‐toxic solvent‐filled microcapsules

Polymer composites are widely used in many industries due to their desirable, and commonly superior properties. However, the replacement of damaged composite materials can be very costly and time‐consuming, motivating the development of self‐healing composites that recover their properties after a damage event. This work demonstrates the microcapsule‐based self‐healing of compression molded thermoplastic high impact polystyrene (HIPS) composites using a non‐toxic and environmentally friendly solvent, ethyl phenylacetate (EPA). EPA is incorporated within double‐walled polyurethane‐poly(urea‐formaldehyde) (PU/UF) microcapsules which are then integrated within the HIPS specimens. Flexure and fracture behavior, with and without microcapsules, is used to investigate the microcapsules' impact on composite physical properties and to determine the composite's self‐healing efficiency (up to 64%) after healing in response to fracture. Overall, this work demonstrates the inclusion of self‐healing properties in a commercially important polymer material with a non‐toxic and environmentally friendly solvent and motivates further development of thermoplastic self‐healing composites for industrial applications. Solvent‐filled microcapsuled‐based self‐healing works for compression molding processed samples.