Phase epoxy

FTIR(CHCl3 cm-1) 1237 (in phase epoxy) 933-817 (out of phase epoxy). 

However, the single-phase epoxy nitrile adhesive achieves its high peel strength by bulk elongation. Other properties, such as heat and chemical resistance, are generally degraded as they are when other flexibilizers or plasticizers are added to the epoxy. The two-phase version of this adhesive hybrid solves many of these problems. 

Phase Separation of Two-Phase Epoxy Thermosets That Contain Epoxidized Triglyceride Oils... 

The preparation and characterization of the VR and ESR liquid rubbers and of the two-phase epoxy thermosets were described in detail previously (3-6). DGEBA is a solid epoxy resin (Epon 825) from Shell Chemical Company. ESO and ELO are commercial products from Atochem. Samples of VO and crambe oil were obtained from the U.S. Department of Agriculture. All other reagents and solvents were purchased from Aldrich Chemical Co. and Fisher Scientific Co. and used without additional purification. 

Preparation of Two-Phase Epoxy Thermosets. Two-phase epoxy thermosets were prepared from homogeneous stoichiometric mixtures of DGEBA and diamine (DDM or DDS), which contained varying amounts of liquid rubber (ESR or VR). The rubber was dissolved first in DGEBA at 70 °C. Then the diamine (DDM or DDS) was added and the mixture was stirred at 70 °C until the diamine dissolved (about 15 min). The homogeneous (one-phase) transparent mixture was then degassed before it reached its cloud point (phase separation). The formulations cross-linked with DDS were cured at 150 °C for 2 h, whereas the formulations cross-linked with DDM were cured first at 75 °C for 4 h and then at 150 °C for 2 h. 

Morphology. The morphology of the fracture surface of the two-phase epoxy thermosets was examined by scanning electron microscopy (SEM, Amray model 1000B). SEM specimens were sputter-coated with a thin film of gold. 

Dirlikov, S. I. Frischinger Z. Chen. Phase separation of two-phase epoxy thermosets that contain epoxidized triglyceride oils. Chem. Ser. 1996, 252, 95-108. 

Rag Raghava, R. S. Role of matrix-particle interface adhesion on fracture toughness of dual phase epoxy-polyethersulfone blend. J. Polym. Sci. Part B Polym. Phys. 25 (1987) 1017-1031. 

Two-phase epoxy thermosets have been prepared as follows Vernonia oil was initially B-staged with amines. For this purpose a mixture of 100 g of vernonia oil and 25.63 g of 4,4 -methylenedianiline (DAPM) have been... 

Figure 3. Electromicrograph of two-phase epoxy resin matrix based on Epon 825 and isophorone diamine and liquid phase of vernonia oil (20%).

Our initial results indicate improved fracture toughness (Kic) for thus modified epoxy resins. Since vernonia oil is practically resistant to water, the resulting two phase epoxy resins are expected to have lower water absorption. Also, the introduction of vernonia oil into the commercial epoxy resin will eventually result in a price reduction. 

Single-phase epoxy thermoset resins were obtained using polyphenylene ether telechelic macromonomers. Incorporation of the macromonomers into the epoxy matrix results in improved performance of the epoxy resin. The Tg and toughness was higher and the dielectric constant and loss factor are reduced. 

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