Effects of chain length of polyether amine on interfacial adhesion of carbon fiber/epoxy composite in the absence or presence of polydopamine bridging platform.

[Display omitted] • Without PDA, longer chain length of polyether amine leads to higher IFSS. • Longer chain favors molecular interlocking and penetration into epoxy matrix. • With PDA, the effect of chain length on IFSS is less obvious. • The complementary interaction mechanisms in improving IFSS is discovered. To understand the complementary mechanisms between molecular interlocking and covalent interconnection that affects interfacial shear strength (IFSS), the adherence of polyether amine with varying chain length onto the surface of carbon fiber in the absence or presence of bio-derived adhesive polydopamine (PDA) as a bridge was subtly designed and studied. Without PDA, up to 25.6% and 34.7% increases in IFSS relative to untreated CF was achieved respectively for shorter and longer molecular chain of polyether amine. The longer chain length encourages molecular interlocking with epoxy molecules and produces a higher penetration depth into epoxy matrix, thus giving a larger increase in IFSS. In the presence of PDA, 39–42% IFSS increase by analogy to CF is observed due to the synergistic effects of hybrid interfacial interactions, the increasing rigidity of interphase and the improved wetting behavior. While, in this case, impact of chain length becomes less noticeable, which is mainly attributed to the trade-off between the enhanced chemical cross-linking points and the less molecular entanglement with resin. [ABSTRACT FROM AUTHOR]