Acoustic Properties

Abstract

This article covers the use of acoustics as a molecular probe of polymer structure and describes various acoustic applications of polymers. Sound speed and sound absorption measurements in polymers are useful both as a probe of the molecular structure of polymers and as a source of engineering design properties. Enough theory and experimental details are given to make the presentation understandable, but the emphasis is on the experimental results for polymers. Most of the presentation is for small‐amplitude waves in solid polymers. References to some specialized topics are given.

Review on Structural Health Evaluation with Acoustic Emission

“…In contrast to polymers, in which hysteretic effects due to molecular rearrangements are dominant [18], ultrasonic attenuation of crystalline metals and ceramics mainly comes from absorption, Rayleigh scattering, and stochastic scattering [26,80]. Absorption effect is similar to polymers with linear frequency dependence, though mechanisms are different.…”

“…The same phenomena at lower frequencies are referred to as structural damping and a recent review relative to composite materials [17] provides useful backgrounds. This topic is also indirectly related to the mechanical properties of polymers since most polymers exhibit viscoelastic behavior and strong acoustic damping [18,19].…”

“…For example, Treviso's review [17] mentioned no complex elastic moduli works, and Castaings and Hosten [48,49] ignored low frequency damping studies. Still, an identical physical mechanism governs vibration energy loss in polymers like PMMA and epoxy [18,19].…”

A Comprehensive Report on Ultrasonic Attenuation of Engineering Materials, Including Metals, Ceramics, Polymers, Fiber-Reinforced Composites, Wood, and Rocks

“…As data from some reports were given as ranges in [7], the total tabulated data count exceeded 80, but this number was still less than 200 for only about 40 different types of materials. Most polymer data, with about 50 being available in [9][10][11], were not included, in part because the test frequency was in the low kHz region or below and was often unidentified. Technical standards for their measurements and validation were also inadequate [12,13].…”

Acoustic attenuation characteristics of surface‐modified polymeric porous microspheres

“…6) lowered down the TL level oppositely. This outcome implies that in additional to the interfacial attenuation mechanisms (reflection, scattering, mode transfer, and friction), 16,17 attenuation through absorption counts on an appropriate matching between the viscoelastic property of each individual bead (of the testing disk) and frequency of incident sound wave at a given temperature. It is more likely that the presence of a layer of Ni nanoparticles on the three kinds of pristine microspheres enhances the interfacial attenuation mechanisms but weakens the bulk absorption capacity of the beads at the same time.…”