Preparation Of Epoxy-based Porous Material With Uniform Pores And Its Application In Membrane Emulsification Technology

Membrane emulsification is an unique technology for the preparation of uniform emulsions.The porous membrane,as a core part of membrane emulsification technology,influents largely on the emulsification results.The membrane pore size,pore size distribution,pore type,porosity and surface property are all key factors.SPG(Shirasu porous glass)membrane is the most commonly used membrane in membrane emulsification technology.However,its applications in W/O and alkaline systems are limited due to the strong hydrophilicity and poor alkali resistence.To solve this problem,a hydrophobic and alkali-resistant epoxy-based porous material with three-dimensional bicontinuous skeleton structure was prepared and applied in membrane emulsification in this dissertation.There are five main sections in this dissertation.(1)Epoxy-based porous(EP)material based on a copolymer of diglycidyl ether of bisphenol A(DGEBA)and 4,4'-diaminodicyctoexylmethane(DDCM),was prepared by chemically induced phase separation,wherein polyethylene glycol 200(PEG200,P)and N,N-dimethylformamide(DMF,D)were chosen as poor and good solvents.The isothermal/non-isothermal curing kinetics of DGEBA/DDCM/P and DGEBA/DDCM/P-D systems were studied,and the changes of enthalpy and modulus during the curing reaction were investigated.With optical microscope(OM)and scanning electron microscopy(SEM),different phase separation processes and the resulted phase structures were observed.By the construction of the pseudo phase diagrams of DGEBA/DDCM/P and DGEBA/DDCM/P-D systems,the evolution of the phase structure was elucidated.(2)In order to regulate the morphology of EP material to obtain the bicontinuous skeleton structure,we studied the effects of solvent concentration,molecular weight of poor solvent,types and concentration of good solvent,weight ratio of the monomer to curing agent and reaction temperature on the process of chemically induced phase separation in epoxy-based system.Then,the regulation mechanism of phase structure was interpreted with the pseudo phase diagram.(3)Aiming at the controlling of the pore size of bicontinuous structure,the effects of the porogens concentration and compostion,reaction components composition and reaction temperature on the pore size of EP material were studied.Meanwhile,the changes of glass transition temperature(Tg)and thermal degradation temperature(Td)of EP material along with the pore size changing were investigated.The relationship between the system composition and the pore size of EP material was analyzed by response surface methodology.Various pore sizes(0.5 ?m-15 ?m)of EP material with bicontinuous skeleton structure was prepared.To obtain larger size of bicontinuous skeleton structure,the secondary phase separation in the process of chemically induced phase separation was studied.The forming technology of EP material and the related problems were studied and discussed.Tubular and sheet-like membranes were prepared by the improved lathe method.(4)SPG membranes modified by KP-18C and GRT-350,were used to prepare W/O emulsions.It was found that,the modified layer of SPG membrane was destoried in different degrees after 3-4 circles.Different with SPG membrane,EP material was hydrophobic and could be directly used in W/O system.Meanwhile,EP material had 3D bicontinuous skeleton structure,narrow pore size distribution(C.V.=19.9%)and high porosity(57.91%.v/v).The self-made EP membrane was firstly used in membrane emulsification technology for water-in-oil(W/O)emulsions.Uniform agarose microspheres(d=16.53 ?m,C.V.=11.8%)and Ca-alginate microspheres(d=0.56 ?m,C.V.=11.4%)were prepared successfully.(5)In alkaline system,uniform W/O emulsions could not be obtained with SPG membrane modified by KP-18C or GRT-350,due to the weak resistence of modified layer to alkali.However,EP material was alkali resistant(resistant to 1M NaOH).Uniform small-sized KGM microspheres(d=7.47 ?n,C.V.=15.35%)were obtained by applying EP membrane in alkaline system.It was found that emulsions coalescence and flocculation occurred frequently in the curing process.due to the high interface energy and sedimentation velocity of KGM emulsions.By the optimization of the amount of surfactant,the viscosity of KGM solution,the composition of oil phase and the addition methods of curing agent,the emulsions stability was improved,and the flocculation and coalescence phenomena were alleviated.In summary,the reaction kinetics and phase separation kinetics in the process of chemically induced phase separation of epoxy system,had been systematically investigated and the influencing mechanisms of the key factors were analysed.A kind of alkali-resistant and hydrophobic epoxy-based porous material with three-dimensional bicontinuous skeleton structure and uniform pores was prepared.The membrane with this material was successfully used in W/O and alkaline systems of membrane emulsification technology,and different kinds of polysaccharide microspheres with uniform particle size were prepared.