Effects of processing parameters on physical properties ofpoly ( urea-formaldehyde) microcapsules of epoxy resin

A series of microcapsules were prepared by in-si tu polymerization with poly (urea-formaldehyde) as theshell material and the mixture of epoxy resin E-51 and butyl glycidyl ether (501 # ) as the core material. The effect sof the processing parameters , including the mass ratio of core material to shell material , final p H value , agitationrate , acidification time and heating rate , on the state of microencapsulation , the microcapsule size and it s dist ribution were discussed by L16 (45 ) orthogonal experiment . The physical properties of microcap sules were investigatedusing scanning elect ron microscopy (SEM) and optical-photographic microscopy (OM) . The state of microencapsulation is dramatically dependent on the mass ratio of core material to shell material and final p H value. Themicrocapsule surface morphologies are better when the acidification time and heating rate are properly increased.The microcap sule size decreases and it s dist ribution narrows with the increasing of agitation rate. The optimum conditions are as follows : the mass ratio of core material to shell material is 0. 8∶1 , final p H value is 2. 0～4. 0 , acidification time is 2. 0～3. 0 h , heating rate is 0. 17～0. 25 ℃·min^-1 , and agitation rate is 325～350 r·min ^-1 .