Dissolution window in in situ polymerization preparation of polyamide single-polymer composites

Single-polymer composites (SPCs) are promising composite materials in which the reinforcement and matrix have the same chemical composition. In situ polymerization shows a broad application potential for producing SPCs due to its wide temperature window. However, the dissolution of fiber reinforcements in the liquid monomer destroys the oriented chain structure of the fibers and affects the properties of SPCs. In this study, the polymerization time was adjusted by varying the activator dosage. The influence of the dissolution of fibers on the properties and the structure of SPCs was investigated. The maximum tensile strength was achieved at the highest activator dosage. A longer duration was required for the polymerization due to the low-activator dosage, which led to the destruction of the oriented chain structure and the formation of a large amount of oligomers on account of the dissolution. Eventually, SPCs showed a low strength and a high deformation at break. In order to realize a good reinforcing effect, a sufficiently large dissolution window must be created by reducing the polymerization time. This study enhanced our understanding of the structure–property relationships of SPCs and provided a way to improve their mechanical characteristics.