Facile preparation of epoxidized soybean oil-hexanediamine resin for fabrication of pressure-sensitive adhesives

Due to the massive consumption of petroleum-derived resources, it is imperative to develop biomass adhesives to replace traditional petroleum-derived materials. The current work deals with the possibility to undergo crosslinking of epoxidized soybean oil (ESO) using hexanediamine (HDA) via one-pot method to produce a pressure-sensitive adhesive, poly(epoxidized soybean oil)-hexanediamine (PESH). The chain growth reaction between ESO and HAD involved the ester group in ESO be destroyed via aminolysis, as evidenced by Fourier Transform Infrared Spectroscopy (FTIR) and 1H Nuclear Magnetic Resonance (1H NMR). The bonding properties of PESH pressure-sensitive adhesive were studied by rolling ball method, shear strength and 180° peeling. The results revealed that the initial viscosity, adhesion persistence and peeling were significantly improved when the molar ratio of ESO to HDA was 1:3. At the same time, the PESH adhesive exhibited good bonding performance under water, especially with PVC substrates, in which the underwater bonding strength can reach 1043 KPa. In addition, PESH adhesive with high crosslinking degree presented excellent resistivity at high voltage. It can be implied that the addition of HDA can acquire the PSA antifungal action. All the results support that at a molar ratio of ESO to HDA of 1:3, it is easier to produce robust crosslinked network structure with overall upgraded properties. Conclusively, the developed PESH adhesive can provide a good application prospect in packaging and insulating fields.