Evaluation of the synthesis variables' effect on the properties of PUF/ENB microcapsules using experimental design

Polymers and polymeric composites are constantly susceptible to damage due to the emergence of microcracks which may compromise the structure as well as the useful life of the material during use. Thus, self-healing systems have been increasingly studied and the use of polymeric microcapsules is one of the effective solutions for repairing damage during application. In this work, poly (urea-formaldehyde) microcapsules (PUF) containing 5 ethylidene 2 norbornene (ENB) as core material were prepared by in situ polymerization. To do so, a experimental design Plackett-Burman (PB) was used to evaluate the effect of seven entrance variables of the process on the properties of the obtained microcapsules. The evaluated responses were average diameter, the encapsulated content, synthesis yield, thermal stability temperature and degradation temperature. It was observed that the stirring speed and the emulsifier amount presented the most significant effects for all analyzed parameters on the analyzed response variables. The high curvature significance observed in the Pareto charts for some of the variables indicated that microcapsules with satisfactory properties can be obtained in the central points. None of the analyzed parameters were statistically significant for the synthesis yield and encapsulated content at a confidence level of 90%.

Automated summary

This study prepared poly (urea-formaldehyde) microcapsules by in situ polymerization and evaluated the effects of seven input variables on the properties of the microcapsules. The results showed that stirring speed and emulsifier amount had the most significant effects on the properties of the microcapsules.