The Preparation And Reach Of Poly (Urea-Formaldehyde) Microcapsules

Microcapsulated healing agent in the self-healing polymer material is theability to heal cracks autonomicallt with a structural polymeric stuff. Thishealing is accomplished by incorporating amicrocapsulated healing agent and acatalytic chemical trigger within an expoxy. When cracking nicks coming for thepolymer structure, the embedded microcapsules are releasing the healing agentinto the crack plane through capillary action. In addition, this healing agent istriggered by contact the embedded catalyst with bond the crack faces.This paper discusses the development of self-healing material. In particular,recent developments in the microcapsule technology and mirocapsulated healingagent in polymer system. Current research is focused on the main fuction, rawmaterial, synthetic method, characterization of microcapsules and so on.Recording to the application of microcapsules in recent years, this article makethe conclusion of the development on self-healing composites withmicrocapsules embedded in polymericmatix as well as the background, sense ofmeaning, the way of production.In this paper, the kinds of microcapsules were synthesized by in-situpolymerization in an oril-in-water emulsion with urea and formaldehyde as theraw shell material,and opoxy resin(E-51) as the core material.The physical andchemical properties were investigated by optical microscopy(OM), scanningelectron microscopy(SEM),Fourier-transform infrared spectrometer(FTIR) andthermogravimetry analysis(TGA).In order to get the suitable microcapsules forthe self-healing material, technological parmarters such as the mixing rate, thetype of the surfactant,the reactin temperation, the reaction time and the final pHvalue are optimized experimrntally in order to control the size distribution of themicrocapsulrs.The optimum conditions are as follow:mass ratio of the core material to the shell material:0.8︰1；surfactant:sodium dodecylbenzenesulfonate(DBS)；reaction temperature:50～60℃:reaction time,2h; final pHvalue:2.0～3.0. The microcapsule surface morphologies are better when acidificationtime and hesting rate are properly increased, The microcapsule size decreasesand its distribution narrows with the increasing of agitation rate.The poly(urea-formaldehyde) microcapsules E-51synthesized in thisexperiments possessed excellent physical properties, such as surface morphology,microcapsules size. Change the single phase of the microcapsule.