INSTITUTUL NAÅ¢IONAL DE CERCETARE-DEZVOLTARE - ICECHIM

2. Multifunctional materials and nanocomposites - PMODIFICATION OF PHYSICAL-MECHANICAL PROPERTIES BY THE PRESENCE OFFLEXIBLE CHAINS IN EPOXY NETWORKSThe National Institute for Research & Development in Chemistry and Petrochemistry –ICECHIM 202 Spl.Independentei , 0060021, Bucharest, RomaniaLADANIUC Magdalena Adriana, DUMITRACHE Liviu, GABOR Raluca,PAVEN HoriaDue to a large versatility, epoxy resins have many uses in various fields such as paints andvarnishes, adhesives, casting and encapsulation resins, engineered materials andstabilizers[1, 2,3]. However, epoxy resins based on bisphenol A (DGEBA) have the disadvantageof a high rigidity. One of the ways to improve this feature is to introduce flexible chains intheir molecular structure [4].In this study as flexible structures were considered small polyether molecular chains.Depending on the molar ratio used resulted in two types of molecular structures including:-terminal hidroxyl groups produced by the use of excess glycol;-epoxy terminal groups produced by the use of excess resine.Accordingly, by product were synthesized and the flexibility effect induced by them on threedimensionalepoxy network. Given the relatively high viscosity, modified epoxy resines were homogenized.Hot diaminodifenil type hardener methane (DDM) and resin-hardener mixture was poured into teflonmoulds, the specimen being crosslinked according to the temperature program as: 7h/60 0 C, and 7h/120 0 C. Thesamples obtained were physico-mechanical characterized (density, tensile strength, elongation,flexural strength, impact strength, hardness Shore) and were assessed against unmodified resineproperties. Comparative analysis of physical-mechanical properties and DMA have found thatthe introduction of flexible chains in epoxy resine structure produces a variation of physicaland mechanical characteristics as result of long chains of polyethter and mixing ratio of weightconcentrations.It was also found that the physical and mechanical properties of the produced resinssynthesized with terminal hydroxyl groups do not produce the same sharp decline as withepoxy resines epoxy terminal groups. 21. CLAYTON, A.M., Epoxy resins-chemistry and technology, 2nd Edition, Ed. Marcel Dekker, New York, 1988, p.3682. POSSART, G., PRESSER, M., PASSLACK, S., GEIB, P.L., KOPNARSKI, M., BRODYANSKI, A., STEINMANN, P., J. Adhesion and Adhesives, 29, 2009, p.4783. MOTAWIE, A.M., SHERIF, M.H., BADR, M.M., AMER, A.A., SHEHAT, A.S., Australian J. Bas. Appl. Sci., 4(6), 2010, p.13764. LADANIUC, M.A., DUMITRACHE L., RADITOIU V., RADITOIU A., HUBCA G., U.P.B. Sci. Bull. - B, 73(1), 2011, p.49