The effect of crosslink and reinforcement of hydroxymethylated kraft lignin on bromobutyl rubber - I: effect of hydroxymethylated kraft lignin content

摘要

Phenol/formaldehyde (resole) resins are important curatives for unsaturated elastomers and give the vulcanizates with very thermally stable crosslinks. The structure of hydroxymethylated lignin is similar to that of resole due to the fact that both of them contain the same functional groups, ie. Ortho-hydroxymethyl groups. Pine kraft lignin was hydroxymethylated by reaction with formaldehyde. Bromobutyl rubber (BIIR)/hydroxymethylated kraft lignin (HKL) compounds without any other additives were vulcanized at the temperature of 165°C. Rubber processing analysis (RPA) and equilibrium swelling analysis indicate that vulcanization of BIIR/HKL compound occurs. With increasing HKL content, the crosslink density increases. In addition to good aging resistance properties, BIIR/HKL vulcanizates show high mechanical properties. At 100/50 BIIR/HKL ratio, the tensile strength and the tear strength of the vulcanizate reach maximum values. Scanning electron microscope (SEM) analysis demonstrates that the diameters of HKL phases dispersed in BIIR are less than 300 nm. It is clear that HKL performs as both effective curative and reinforcing agent for BIIR.