Evaluation of four curing agents of epoxy resin and their effects above their thermal and dinamomechanical properties
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Evaluation of four curing agents of epoxy resin and their effects above their thermal and dinamomechanical properties Aida E. García Valdez1, Ricardo Acosta Ortiz1, Lydia Berlanga Duarte1, Jorge Felix Espinosa1, Maria de L. Guillén Cisneros1 1
Centro de Investigación en Química Aplicada, Blvd Enrique Reyna Hermosillo #140, San José de los cerritos, C.P.25294, Saltillo Coahuila, México. (844)4-38-98-30 ABSTRACT Were synthesized four new hybrid hardener agents type amino tertiary functionalized with allyl groups from : l, 6-Hexanediamine, Diethylenetriamine, Trietilentriamine and Tris (2aminoethyl) amine, using the basic nucleophilic substitution mechanism, replacing bromide by amino tertiary group in the presence of tetrabutylammonium bromide as phase transfer agent, producing allyl amine corresponding: ALA-4, ALA-5, ALA-6 and TRIS respectively, which were evaluated as a hardening of epoxy resin DGEBA through photopolymerization process by UV ligth curing, adding a 10, 20 and 40% molar percentage of hybrid materials and the thiol corresponding to carry out the thiol-ene reaction (TMP TMP, PTKMP) with DMPA as initiator. The resinic materials obtained, were evaluated by the technique of dynamic mechanical analysis (DMA) at a heating rate of 5° C/min in a range from - 50° C to 150° C in nitrogen atmosphere. The formulations with hybrid hardening agent ALA 4- 20% -PTKMP and TRIS 10% -PTKMP were the materials with modulus 2289, 2971 Mpa and tgs of 102,103°C, respectively. INTRODUCTION Epoxy resin or polyepoxide is a thermosetting polymer that hardens when is mixed with a catalyst or hardener compound, containing groups amine, anhydride, hydroxyl, carboxyl or inorganic acids [1]. The mechanism of curing or hardening with tertiary amines happens through a nucleophilic attack of tertiary amine group on the epoxy methylene electrons less impediment, starting the polymerization by opening of the cycle [2]. These resins have the characteristic of being too rigid and fragile, with excellent adhesion, good electrical insulation and good resistance to moisture and attack of corrosive fluids, solvents, chemicals and high temperatures. They are used in composites reinforced with fibers, adhesives and surface coatings of metals, including applications in aeronautics by their thermal and mechanical properties listed above. Recently Thiol-ene chemistry has attracted increased attention due these polymerizations proceed rapidlly and quantitatively under mild conditions and are not inhibited by the presence of oxygen [3,4] Our interest is to reduce brittleness that have epoxy resins by adding flexible materials attached covalently by adding new hardeners, without that decrease considerably the thermal and mechanical properties that possess. The DMA analysis is the correct path to obtain information about the rigidity (modulus) and transition temperature (Tg) of the cured epoxy resins, that give us an idea about the properties of the new materials [5].
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