Storage stability and solubility of poly(urea‐formaldehyde) microcapsules containing A‐olefin drag reducing polymer

Microcapsules containing α-olefin drag reducing polymer were prepared by in situ and interfacial polymerization with urea, formaldehyde, and styrene as shell materials, respectively. IR spectrums of prepared shells indicated the formations of poly(urea-formaldehyde) and polystyrene in the microencapsulating process. The morphologies of uncoated particles and microcapsules were observed by scanning electron microscopy (SEM) which proved that the α-olefin drag reducing polymer particles were effectively coated. For the purpose of determining the stability of microcapsules in transportation and storage, the static pressure experiment was carried out and lasted for 6 months. In this process, microcapsules with polystyrene as shell material stuck together after 3 months; however, those with poly(urea-formaldehyde) kept the state of particles. The thermal characteristics of uncoated particles (core), poly(urea-formaldehyde) (shell), and microcapsules with that as shell material were characterized by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) which proved that thermal stable temperature of microcapsules containing α-olefin drag reducing polymer with poly(urea-formaldehyde) as shell material was below 225°C, and the mean heat absorbed by microcapsules in the temperature increasing process was 1.5–2.0 W/g higher than that by cores. The evaluation of drag reducing rate of microcapsules showed that the microencapsulating process had no influence on the drag reduction of α-olefin drag reducing polymer. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011