Five different types of Dow epoxy blends were studied with differential scanning calorimetry. Each epoxy blend consists of a flexible epoxy resin, DER 736 or DER 732, with one of four different rigid epoxies, DER 317, DER 331, DER 332 and DEN 431, crosslinked by 1,4-bis (3-aminopropyl)-piperazine (BAPP). Longitudinal and shear wave acoustic properties of these epoxy resin blends as a function of the composition were measured at room temperature and an ultrasonic frequency range. All moduli and Poisson's ratios were calculated by using longitudinal velocity, shear velocity and density. These systems all have similar behavior. By increasing the amount of flexible epoxy in a mixture of hard and flexible epoxies a critical composition was found (∼50% by weight for DER 736 and ∼30% for DER 732), below which the acoustic properties, the elastic moduli and Poisson's ratios kept an almost constant value, and above which the velocities, impedances and all moduli decreased, whereas attenuations and Poisson's ratios increased gradually. Many epoxy materials ranging from soft and flexible to hard and rigid have been obtained by epoxy blend technology. Some of them have been applied to make 1-3 composites for medical ultrasound transducers.
- Epoxy Blends,
- Acoustic Properties,
- Poisson's Ratio
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