Dynamic mechanical properties epoxy resins

The epoxy resin formed by tetraglycidyl 4,4 -diamino diphenyl methane and 4,4 -diamino diphenyl sulfone was characterized by dynamic mechanical analysis. Epoxy specimens were exposed to varying dose levels of ionizing radiation (0.5 MeV electrons) up to 10,000 Hrads to assess their endurance in long-term space applications. Ionizing radiation has a limited effect on the mechanical properties of the epoxy. The most notable difference was a decrease of approximately 40°C in Tg after an absorbed dose of 10,000 Mrads. Sorption/desorption studies revealed that plasticization by degradation products was responsible for a portion of the decrease in Tg. 

Wilson, W.T. "Effect of Radiation on the Dynamic Mechanical Properties of Epoxy Resins and Graphite Fiber/Epoxy Composites", 1986, Ph.D. Thesis, North Carolina State University, Raleigh, NC. 

Ozonization of lignin forms derivatives of muconic acid that have the unique chemical structure of conjugated double bonds with two carboxyl groups. These derivatives have great potential for chemical modification. The ozonized lignin of white birch was soluble in epoxy resin at 120°C, and the free carboxyl groups were found to react with epoxide. This paper discusses developmental work on the preparation of pre-reacted ozonized lignin/epoxy resins the dynamic mechanical properties of cured resins and preliminary results of the application of these resins as wood adhesives. 

Structures and Dynamic Mechanical Properties of Epoxy Resins Cured... 

A number of papers deals with the dynamic mechanical properties of cured epoxy resins1 -5) and with the effect of the structure of basic resins and the degree of cross-linking s 8>. 

In this review, the effect of the cured epoxy resins on the dynamic mechanical properties of epoxy resins is discussed. 

The mechanical properties and dynamic mechanical properties of the cured epoxy resins are governed by their structures. 

Table 3. Dynamic mechanical properties and flexural strength of diamine cured epoxy resins...

Table 6. Dynamic mechanical properties for epoxy resin cured with acid anhydrides...

The dynamic mechanical properties of three epoxy resins cured with diphenyl-methane diisocyanate (MDI) are shown in Fig. 15. Since these resins consist of many bulky cyclic structures, Tg (a-dispersion) is above 200 °C and the transition region is wide. In the DEN 431 —L-MDI resin, Tg is higher than 300 °C. The resin is expected to be highly heat-resistant51). 

On the other hand, many studies on dynamic mechanical properties at temperatures lower than room temperatures have been reported 5,7 63,64). For example, a small (3 transition near —50 °C has also been observed in epoxy resins. Cuddihy 65,661 observed a (3 transition in resins cuted with different hardeners such as DETA, MPDA, HHPA, pyromellitic dianhydride (PMDA), and tris(dimethylaminomethyl)-phenol (DMP-30) (Fig. 19). The larger the size of the P transition, the higher the impact strength (Table 8). 

Epoxy film samples were prepared with the DGEBA-TETA and N-5208 resins. Detailed Information on the DGEBA-TETA and N-5208 resin cure and sample preparation has been previously provided (2,4). Films of the N-5208 resin were made with a curing agent concentration of 25 PHR-DDS (4) 14 PHR TETA was used for curing the DGEBA epoxy (2). Dynamic mechanical properties for films were measured on strip samples cut to nominal 0.02 cm x 0.3 cm x 6.0 cm dimensions. 

Mijovic, J. Tsay, L.L. Correlations between dynamic mechanical properties and nodular morphology of cured epoxy resins. Polymer... 

Reddy, C. S. and Das, C. K. 2006. Effects of epoxy resin-modified zinc-ion-coated nanosUica on structural, thermal and dynamic mechanical properties of propylene-ethylene copolymer. Polymer International 55 923-929. 

Rajabi Laleh, and Malekzadeh Ghodratollah. Effects of bismaleimide resin on dielectric and dynamic mechanical properties of epoxy-based laminates. Iran. Polym. J. 15 no. 6 (2006) 447-455. 

Chen HT, Gao J, Wang G, Shi SQ, Zhang SB, Cai LP (2004) Effect on temperature on calcium carbonate deposition in situ on bamboo fiber and polymer interfaces. Wood Fiber Sci 46 1-12 Datta C, Basu D, Baneijee AN (2002) Mechanical and dynamical mechanical properties of jute fibers-Novolac-Epoxy composite laminates. J App Polym Sci 85 2800-2807 Garea SA, Nicolescu A, Deleanu C, lovu H (2010) New nanocomposites based on epoxy resins reinforced with modified montmorillonite. Int J Polym Anal Charact 15 497-508 Ghosh P, Mitra PS, Baneijee AN (2003) Photopolymerization of methyl methacrylate with the use of bromine as photoinitiator. J Polym Sci Polym Chem Ed ll(8) 2021-2030 Jia N, Li SM, Ma MG, Sun RC, Zhu L (2011) Green microwave-assisted synthesis of cellulose/ calcium silicate nanocomposites in ionic liquids and recycled ionic liquids. Caibohydr Res 34 2970-2974... 

Lewis, A.F. Doyle, M.J. Gillham, J.K. Effect of cure history on dynamic mechanical properties of an epoxy-resin. Polym. Eng. Sci. 1979, 19, 683-686. 

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