Epoxy polymer, rubber-modified

Bauman, A.D., High-value engineering materials from scrap rubber. Rubber World, 212, 30, 1995. Bagheri, R., Wilbams, M.A., and Pearson, R.A., Use of surface modified recycled rubber particles for toughening of epoxy polymers, Polym. Eng. Sci., 37, 245, 1997. 

Although the main use of impact modifiers is with thermoplastics, thermosets also benefit. The agent is added at the monomer stage. Thus epoxy polymers can be made less brittle by the addition of rubbers. Care has to be taken that the high temperature properties of the thermoset are not compromised. 

Sue HJ, Garcia-Meitin El (1996) Fracture behavior of rubber-modified high-performance epoxies. In Arends CB (ed) Polymer toughening. Marcel Dekker, New York, p 131... 

In the same manner, with decreasing of diffusion coefficient and interaction parameter, the spinodal is reached during the evolution of the system in the pregel stage. The very low values of interfacial tension in rubber modified epoxies (interfacial tension of polymer-polymer-solvent system were reported in range of 10-4-10-1 mN/m) therefore lead to an NG mechanism for phase separation. 

Fig, 3. Transmission electron micrograph of osmium-tetroxide stained section of a typical rubber-modified epoxy thermosetting polymer... 

Fig. 6. Stress-intensity factor, KIc, at the onset of crack growth as a function of temperature for unmodified and rubber-modified epoxy polymers 81...

Turning to the multiphase thermosetting epoxy polymers (Table 2), then for the rubber-modified materials the greater fracture resistance arises from a greater extent of energy dissipating deformations occurring in the material in the vicinity of the crack tip 1 -8-35.38). The deformation processes are ... 

Fig. 14. Crack opening displacement, 8te, as a function of test temperature for a rubber-modified epoxy polymer 44)...

The theory has been examined by measuring the ratio K,c/Klcs as a function of j/g, as shown in Fig. 17. The theoretical lines have been fitted to the experimental points by choosing suitable values of the critical distance, c, which is the only fitting parameter. The agreement between theory and experiment has been found to be equally good for many different epoxy polymers cured with many different hardeners, both unmodified 44- 45,51), rubber-modified 45) and containing glass particles 22) and even, under certain circumstances, for structural adhesive joints S3). Values of critical stress, ct,c, and distance, c, for various epoxy materials, obtained from bulk and... 

Fig. 17a and b. Variation of Klc/Klcs ratio with j/e44 a Unmodified, simple epoxy polymer b Rubber-modified epoxy polymer AO values of q deduced from Eq. (6) A.0 measured values ofp Full curve Theoretical relation from Eq. (12)... 

Daly, J., Pethrick, R. A. Rubber-modified epoxy resins 2. Dielctric and ultrasonic relaxation studies, Polymer, 22, 37 (1981)... 

Glassy polymers with highercohesiveness, like polycarbonate and cross-linked epoxies, preferentially exhibit shear yielding [7], and some materials, such as rubber-modified polypropylene, can either craze or shear yield, depending on the deformation conditions [8]. Application of a stress imparts energy to a body which... 

Much work has been reported on studying the structure of thermoset resins via SAXS, especially focussing on interpenetrating network polymers (IPNs), thermoset nanocomposites, rubber-modified thermosets and thermoset-thermoplastic blends. Most recently Guo et al, (2003) have examined the use of SAXS to monitor the nanostructure and crystalline phase structure of epoxy-poly(ethylene-ethylene oxide) thermoset-thermoplastic blends. This work proposes novel controlled crystallization due to nanoscale confinements. 

Sue, H., Garcia-Meitin, E. Pickelman, D. (1996) Fracture behaviour of rubber modified high performance epoxies, in Arends, C.E. (Ed.) Polymer Toughening, New York Marcel Dekker. Sun, L., Aklonis, J. Salovey, R. (1993) Polym. Eng. Sci., 33, 1308-1319. 

The aforementioned analyses were essentially elastic in nature. However, Huang and Kinloch (7,8) developed a two-dimensional, plane-strain model to analyze the stress fields around the dispersed rubbery particles in multiphase, rubber-modified epoxy polymers. The epoxy matrix was modeled as either an elastic or elastic-plastic material. Their work revealed that the plane-strain model predicted higher stress concentrations within the glassy polymeric matrix than the axisymmetric model. Furthermore, they successfully applied their... 

Composition (type of polymeric components). The base polymer (which is to be modified) may be an amorphous polymer [e.g., polystyrene (PS), styrene-acrylonitrile copolymer, polycarbonate, or poly(vinyl chloride)], a semicrystalline polymer [e.g., polyamide (PA) or polypropylene (PP)], or a thermoset resin (e.g., epoxy resin). The modifier may be a rubber-like elastomer (e.g., polybutadiene, ethylene-vinyl acetate copolymer, ethylene-propylene copolymer, or ethylene-propylene-diene copolymer), a core-shell modifier, or another polymer. Even smaller amounts of a compatibilizer, such as a copolymer, are sometimes added as a third component to control the morphology. 

When the process involves two competitive reactions, some people prrfer to call those modified polymers interpenetrated polymer networks (IPNs) [5]. The formation of a polyether-urethane network in a loosely crosslinked poly(methyl methacrylate) matrix to increase its toughness can serve as one of the examples. From a general point of view, the analysis of the reaction-induced phase separation is the same (perhaps more complex) for IPNs than for rubber-modified epoxies or for high-impact polystyrene. 

Fig. 7. TTT diagram representing times for phase separation (doud point), gelation and vitrification for a castor-oil-modified epoxy system (4ho = 0.176) at different temperatures (Reprinted from Polymer International, 30, R.A. Ruseckaite, L. Hu, CC. Riccardi, R.JJ. Williams, Castor-oil-modified epoxy resins as model systems of rubber-modified thermosets. 2 Influence of cure conditions on morphologies generated, 287-295, Copyright (1993), with kind permission from the Society of Chemic Industry, London, UK)...

Fig. 23. Ratios (r) of amine epoxy equivalents in both phases as a function of the overall conversion of epoxide groups in the CO-modified DGEBA-EDA system (Reprinted from Polymer, 35, C.C. Ric-cardi, J. Borrajo, R.J J. Williams, Thermodynamic analysis of phase separation in rubber-modified thermosetting polymers influence of the reactive polymer polydis-persity, 5541-5550, Copyright (1994), with kind permission from Butterworth-Heinemann journals, Elsevier Science Ltd, The Boulevard, Langford Lane, Kidling-ton 0X5 1GB, UK)...

Fig. 28. SAXS intensity as a function of the scattering angle, for a rubber (ETBN) modified qmxy-amine (DGEBA-3DCM) system reacted at 50°C, at different cure tunes. (1) 80 min, (2) 105 min, (3) 130 min, (4) 180 min (Reprinted from Polymer Internationa], 32, D. Chen, J.P. Pascault, H. Sautereau, G. Vigier, Rubber-modified epoxies. II. A reaction-induced phase separation observed in-situ and a posteriori with different methods, 369-379, Copyright (15 3), with kind permission from the Society of Chemical Industry, London, UK)...

Fig. 30. Trajectories in the metastable region for different values of the interfacial tension (trajectories represent the composition of the continuous phase at different conversion levels). The simulation shows that increasing the interfacial tension leads to a decrease of the phase separation in the metastable region (Reprinted from Journal of Applied Polymer Science, 42, S.M. Moschiar, C.C Riccardi, R.J.J. Williams, D. VerchSre, H. Sautereau, J.P. Pascault, Rubber-modified epoxies. III. Analysis of experimental trends throu a phase separation model, 717-735, Copyright (1991), with kind permission from John Wiley Sons, Inc., New York, USA)...

Sue Sue, H.-J. Study of rubber-modified brittle epoxy systems. Part II Toughening mechanisms under model fracture. Polym. Eng. Sci. 31 (1991) 275-288. 

Car Cardwell, B. J., Yee A. F. Rate and temperamre effects on the fracture toughness of a rubber-modified epoxy. Polymer 34 (1993) 1695-1701. 

OOXia Xiao, K. Q., Ye, L. Effects of rubber-rich domains and the rubber-plasticized matrix on the fracture behavior of liquid rubber-modified araldite-F epoxies. Polym. Eng. Sci. 40 (2000) 2288-2298. 

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