Preparation And Characterazation Of Micro-capsules Containing Organic Peroxide Initiator With High Storage Stability

The microcapsules were prepared by in situ polymerization technology with poly(urea-formaldehyde) (PUF) as a shell material and cumene hydroperoxide (CHP) as core material. The microcapsules could be applied in machinery industry, electronic industry, electric industry and other fields. In this thesis, the effect of the structure of stabilizers on microencapsulation process was investigated, as well as the formation mechanism and determining factors for the synthesis of microcapsules.The microcapsules were prepared with sodium dodecyl benzene sulfonate (SDBS), sodium dodecyl sulfate (SDS), hydroxypropyl methyl cellulose (HPMC), gum acacia (GA), styrene-maleic anhydride copolymer (SMA), and poly(vinyl alcohol) (PVA) as stabilizers or without stabilizer. The microcapsules only could be synthesized by using PVA as stabilizer. And the morphology of capsules became better with lower alcoholysis degree of PVA. However, the morphology and particle size distribution of capsules became worse and larger as the content of stabilizer PVA was insufficient. And the O/W surface tension seemed to be no effect on the encapsulation of core material.The pH value of system decreased at first, then rose to a stable value under the polymerization reaction of PUF. And the changes of pH value became larger with faster heating rates. There were no obvious differences on the morphology of final microcapsule product with different heating rates. The interaction between stabilizer and PUF with surface stability was investigated by comparing the microencapsulation process with different initial particle size of oil droplets. Rotation rate was not a key factor which determined the particle size of microcapsules prepared, and the polymerization rate of PUF decreased with lower rotation rate which made the turbulent intensity of the system lower.The microcapsule yield was lower and core content increased by increasing core/shell ratio. As the core/shell ratio reached to 6:1.5, the shell of microcapsules became too thin to sustain the core material so that the microcapsules cracked under filtration step. The utilization ratio of shell material increased as its usage increased. The microcapsule prepared had a regular shape, and it owned a rough outer surface and a smooth inner layer. The thickness of the inner layer shell was 643 nm. Comparing with the microcapsule product Loctite 23419 from Loctite Company, the microcapsule prepared in this thesis had good thermal stability no matter it was placed separately or mixed with the anaerobic adhesive monomer. The prepared microcapsule product had its application prospect since it could form anaerobic adhesive mixed with Loctite 23418 although its mechanical performance was as high as the Loctite product.