Structural regulation of poly(urea-formaldehyde) microcapsules containing lube base oil and their thermal properties

Regulating the micro-structure of microcapsules containing lubricant is paramount to their properties and the subsequent self-lubrication performance of the composites. In this study, poly(urea-formaldehyde) (PUF) microcapsules containing lube base oil as lubricant have been fabricated by in-situ polymerization technology. The structure and properties of PUF microcapsules are investigated by altering the emulsifier content, homogenization time, oil viscosity and synthetic method. The content of sodium lignosulfonate, an environment-friendly emulsifier, has important regulation effect on the regularity and core content of PUF microcapsules. The homogenization time and oil viscosity directly affect the particle size and distribution of PUF microcapsules. Moreover, the oil viscosity plays an important role in regulating the morphology and thermal behavior of PUF microcapsules. Specifically, by adding low content of emulsifier (0.2 wt %), well-dispersed spherical micro capsules are obtained. Adopting 15# oil as core material and 0.2 wt % emulsifier, high core content of up to 89.2 wt % is achieved. When using lube base oil (32#, 46# oil) with high viscosity, the microcapsules show compact spherical structure and high thermal stability, with the initial decomposition temperature of up to 251.8 degrees C. This research can provide guidance for fabricating PUF microcapsules with suitable structures and performances for improving the tribological properties of different polymers.

Automated summary

The study investigates the effects of emulsifier content, homogenization time, oil viscosity, and synthetic method on the structure and properties of PUF microcapsules. It was found that emulsifier content, homogenization time, and oil viscosity play crucial roles in regulating the morphology, thermal behavior, and core content of PUF microcapsules.