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Composites have been prepared from devulcanized waste ethylene propylene diene monomer (W-EPDM) rubber by blending with low-density polyethylene (LDPE) in a twin-screw extruder. W-EPDM was treated separately by optimized microwave and ultrasonic radiation. Effect of compatibilizer such as ethylene octane elastomeric copolymer (POE) on the enhancement of mechanical properties of composites was also studied in addition to the radiation treatment. The enhancement of tensile strength (TS) and elongation at break of composite with microwave-treated W-EPDM were increased up to 41% and 62%. Corresponding values were found 44% and 68% for ultrasonic treatment. Higher amount of energy during microwave treatment induced larger and localized cavity formation on the surface of composite results reduction of TS as confirmed from surface morphology study. On the contrary, encapsulation effect of POE only found to be useful to enhance TS of the composites up to 30% with untreated W-EPDM and LDPE. No significant additional strength increase over microwave and ultrasound treatment was found upon using POE. The encapsulation effect of POE disappeared when radiation was applied. FTIR and DMA study revealed the existence of only physical interaction upon microwave and ultrasound treatment. POLYM. ENG. SCI., 55:533-540, 2015., INTRODUCTION As a consequence of rapid growth of rubber-based industries, the amount of waste rubber components has also been increasing since the last few years. The systematic recycling of large [...]

This study is carried out on the effect of processing conditions including preparation methods, ultrasonication, film thickness, and thermal annealing on the thermal, mechanical, and piezoelectric properties of copolymer of poly(vinylidene difluoride-trifluoroethylene) (P(VDF-TrFE)J. Free-standing films and films on substrates are prepared by solvent casting and spincoating, respectively. The results obtained by differential scanning calorimetry show that the Curie transition of the copolymer films was influenced by the preparation methods, with very little difference in the melting transition. The difference was attributed to a less uniform distribution of TrFE comonomer units within the crystalline and amorphous regions of the spin-coating films. However, no effect of the preparation methods on the piezoelectric properties of the films was observed. It is also found that the short ultrasonication, film thickness higher than critical value of crystallization of P(VDF-TrFE) (about 100 nm), and drying before annealing did not have a significant effect on the properties of the films. Surprisingly, the ultrasonication had a clear impact on the relaxations at high temperature of the polymer chains. In addition, this study indicates that a short annealing by 10 min at 140°C was enough to obtain well-crystallized films, which is interesting from the industrial point of view., INTRODUCTION Since the discovery of its strong piezoelectric activity in 1969 by Kawai [1], poly(vinylidene fluoride) (PVDF) and its copolymers, in particular the copolymers of vinylidene difluoride and trifluoroethylene P(VDF-TrFE) [...]

In this work, the effect of processing conditions on the production of an intumescent flame-retardant system is studied in polypropylene-based compounds. Two distinct procedures were used: ultrasonic assisted single screw (with a static mixer die) and twin screw extrusion. The flame-retardant, thermal, mechanical, morphological, and rheological properties were measured. It was found that the flame-retardant intumescent content can be diminished from 30 phr (as usually used) to 21 phr using the application of ultrasonic waves during extrusion and with the addition of chemically modified clay to obtain a VO classification according to UL94-V standards. In addition, the processed materials presented improvements in the mechanical properties such as impact resistance (Izod Notched), strain at break and tenacity upon ultrasound application. The online application of ultrasound through a die that produces extensional flows improved greatly the dispersion and distribution of the particles of the intumescent system and the chemically modified clay in the polymer matrix. POLYM. ENG. SCI., 53:2018-2026, 2013. © 2013 Society of Plastics Engineers, INTRODUCTION Intumescent systems have been widely studied due to their effectiveness as flame-retardant additives. (1-3). These systems have been formulated with various polymers, such as PU, EVA, SBR, PE, LDPE, [...]

The reaction of maleic anhydride (MAH) grafted onto propylene-based copolymer (DP) without adding any initiator was conducted through ultrasound assisted extrusion in this article. The effects of ultrasound power, die temperature, and MAH content on the grafting degree and efficiency were studied. With increasing ultrasound power, the grafting degree and efficiency of DP-g-MAH increase. The presence of ultrasound with higher power and lower die temperature is beneficial to increase the grafting degree and efficiency. The increase of MAH content can increase the grafting degree but reduce the grafting efficiency. Based on the results of melt flow index, dynamical ideological, gel permeation chromatograph (GPC), and Fourier transform infrared spectroscopy (FTIR) tests, the mechanisms of the grafting reaction were proposed. POLYM. ENG. SCI., 52:51&-524, 2012. © 2011 Society of Plastics Engineers, INTRODUCTION As one general way to polarize polyolefin (PO), maleic anhydride (MAH) is grafted onto macromolecular chains of PO in solid (1), (2), solution (3), (4), or melt (5-13), PO [...]

The high density polyethylene (HDPE) and polyamide 6 (PA6) blend melts with a droplet-matrix microstructure were investigated using ultrasonic diagnosis system. The blend composition, as well as the particle size of the dispersed PA6 phase controlled by adding various amounts of the reactive compatibilizer HDPE grafted with maleic anhydride (HDPE-g-MAH), was, respectively, correlated with the ultrasonic velocity and attenuation. The results showed that ultrasonic velocity was insensitive to the particle size but varied linearly with the blend composition. However, the decrease of ultrasonic attenuation with the increasing content of HDPE-g-MAH suggested that the attenuation depended greatly on the particle size. Further investigations revealed that there was a good linear relationship between the excess attenuation and the size of the dispersed phase. Our results present that ultrasonic technique may be served as a promising technique for exploring phase morphology of polymer blends during processing. POLYM. ENG. SCI., 52:338-345, 2012. ©2011 Society of Plastics Engineers, INTRODUCTION The phase morphology of multiphase polymer blends, as well as its evolution, is a basic issue in polymer processing area (1). The size, shape, spatial distribution, and time evolution [...]

Ultrasonic atomization was conducted using 2.4 MHz ultrasound generator to produce polymeric particles from the solutions of water-soluble polymers like poly (ethylene oxide) (PEO), poly(vinyl alcohol) (PVA), and poly(vinyl pyrrolidone) (PVP). In the series of solutions containing these polymers of various molecular weights, the shear viscosity and surface tension were varied; such differences, however, could not account for the observed trends in the atomization behavior. It was found that the availability of droplet formation and size of the droplets depend strongly on the extensional characteristics of polymer solutions along with the apparent extensional viscosities and the longest relaxation times. The extensional properties of polymer solutions were effectively measured by capillary breakup extensional rheometry (CaBER) and provided a rational basis to understand the essential role of fluid viscoelasticity in ultrasonic atomization. POLYM. ENG. SCI., 51:2446-2452, 2011. ©2011 Society of Plastics Engineers, INTRODUCTION Ultrasonic atomization is a useful way to produce fine droplets ranging from a few microns to submicrons depending on the mechanical construction of atomizers and physicochemical properties of the [...]

Characterization of high-intensity focused ultrasound (HIFU) systems using ex vivo tissues is an important part of the preclinical testing for new HIFU devices. In ex vivo characterization, the lesion volume produced by the absorption of HIFU energy is quantified as operational parameters are varied. This paper examines the three methods used for lesion-volume quantification: histology, magnetic resonance (MR) imaging, and numerical calculations. The methods were studied in the context of a clinically relevant problem for HIFU procedures--that of quantifying the change in the lesion volume with changing sonication time. The lesion volumes of sonicated samples of porcine liver were determined using the three methods, at focal intensities ranging from 800 W/[cm.sup.2] to 1700 W/[cm.sup.2] and sonication times between 20 s and 40 s. It was found that histology consistently yielded lower lesion volumes than the other two methods, and the calculated values were below magnetic resonance imaging (MRI) at high applied energies. Still the three methods agreed with each other to within a [+ or -] 10% difference for all of the experiments. Increasing the sonication time produced much larger changes in the lesion volume than increasing the acoustic intensity, for the same total energy expenditure, at lower energy (less than 1000 J) levels. At higher energy levels, (around 1500 J), increasing the sonication time and increasing the intensity produced roughly the same change in the lesion volume for the same total energy expenditure. [DOI: 10.1115/1.4001739] Keywords: HIFU, MRL lesion size, sonication time, histology

SONOLITHOGRAPHY: 3D PRINTING WITH SOUND Scientists from the Universities of Bath and Bristol have shown that it's possible to create precise, predetermined patterns on surfaces from aerosol droplets or particles, [...]

Because of the insolubility and polymeric properties of amyloid fibrils, techniques used conventionally to analyze protein structure and dynamics have often been hampered. Ultrasonication can induce the monomeric solution of amyloidogenic proteins to form amyloid fibrils. However, ultrasonication can break down preformed fibrils into shorter fibrils. Here, combining these 2 opposing effects on [[beta].sub.2]-microglobulin ([beta]2-m), a protein responsible for dialysis-related amyloidosis, we present that ultrasonication pulses are useful for preparing monodispersed amyloid fibrils of minimal size with an average molecular weight of [approximately equal to]1,660,000 (140-mer). The production of minimal and monodispersed fibrils is achieved by the free energy minimum under competition between fibril production and breakdown. The small homogeneous fibrils will be of use for characterizing the structure and dynamics of amyloid fibrils, advancing molecular understanding of amyloidosis. [[beta].sub.2]-microglobulin | dialysis-related amyloidosis | protein misfolding | analytical ultracentrifugation

This paper presents the development of a new algorithm to identify dynamic properties of concrete by comparing simulated and experimental results of nonlinear ultrasound testing. Prismatic concrete specimens with different water-cement (w/c) ratios, 0.45, 0.60, and 0.75, were prepared. The specimens were damaged progressively by loading them in compression up to 20, 40, 60, and 80% of the ultimate strength. After each load step, the load was released, and the specimens were tested for the fundamental, second-, and third-harmonic frequencies. An algorithm was developed to determine the dynamic properties of the specimen through the progression of damage. The proposed algorithm used ABAQUS to simulate the dynamic response of the specimens. A MATLAB program was used to update the material properties by minimizing the sum of squared differences between the measured and simulated harmonic frequencies. Excellent agreement was obtained between the reconstructed elastic modulus values and values obtained by testing the prisms according to ASTM C 215. Damping ratios provided by the reconstruction were observed to increase with increasing damage and with increasing w/c ratio. DOI: 10.1061/(ASCE)0899-1561(2008)20:11(700) CE Database subject headings: Algorithms; Dynamic response; Modal analysis; Optimization; Concrete; Material properties.

Articular cartilage is a biological weight-bearing tissue covering the bony ends of articulating joints. Negatively charged proteoglycan (PG) in articular cartilage is one of the main factors that govern its compressive mechanical behavior and swelling phenomenon. PG is nonuniformly distributed throughout the depth direction, and its amount or distribution may change in the degenerated articular cartilage such as osteoarthritis. In this paper, we used a 50 MHz ultrasound system to study the depth-dependent strain of articular cartilage under the osmotic loading induced by the decrease of the bathing saline concentration. The swelling-induced strains under the osmotic loading were used to determine the layered material properties of articular cartilage based on a triphasic model of the free-swelling. Fourteen cylindrical cartilage-bone samples prepared from fresh normal bovine patellae were tested in situ in this study. A layered triphasic model was proposed to describe the depth distribution of the swelling strain for the cartilage and to determine its aggregate modulus [H.sub.a] at two different layers, within which [H.sub.a] was assumed to be linearly dependent on the depth. The results showed that [H.sub.a] was 3.0 [+ or -] 3.2, 7.0 [+ or -] 7.4, 24.5 [+ or -] 11.1 MPa at the cartilage surface, layer interface, and deep region, respectively. They are significantly different (p Keywords: articular cartilage, ultrasound, elastography, biomechanics, triphasic theory, proteoglycan, fixed charge density, osmotic loading, osteoarthritis

An ultrasound in-line monitoring system that includes a homemade probe and a fast data acquisition system was used to investigate the melting behavior of linear low density polyethylene (LLDPE) in pellet form and four polyvinyl chloride (PVC) compounds in powder form in an intermeshing counter-rotating twin-screw extruder. Ultrasound signal patterns obtained from experiments revealed various melting phenomena in C-chambers, depending on materials, processing conditions, and screw configurations. The experimental results suggest that PVC particles were suspended in the polymer melt in the melting process of most PVC compounds, while melted film was still observed in the melting process of the PVC/dimethyl phthalate (DMP) system and the PVC/polybutylene adipate (PBA) system. Based on the analysis of wave attenuation, the normalized amplitude ratio K was used to characterize the melting level and uniformity across screw channels at screw speeds of 40 and 50 rpm, respectively. POLYM. ENG. SCI., 45:998-1010, 2005. © 2005 Society of Plastics Engineers, INTRODUCTION The melting process is one of the important steps for controlling processing conditions and product quality in both single- and twin-screw extrusion. The melting process in a single-screw extruder [...]

The NSF-sponsored Center for Advanced Cement-Based Materials is actively involved in research aimed at the development of technologies for health monitoring and nondestructive evaluation of the concrete infrastructure. This paper summarizes pertinent research performed at the center. Basic findings from several new laboratory-based nondestructive evaluation techniques for concrete are reported. The described techniques are based on measurements of mechanical waves that propagate in the concrete. First, ultrasonic longitudinal wave (also called the L-wave or P-wave) signal transmission (attenuation) measurements are shown to be sensitive to the presence of damage in the form of distributed cracking in concrete. Next, experimental procedures that enable practical one-sided wave signal transmission measurements to be performed on concrete structures are described. The utility of the signal transmission measurement is demonstrated by two experimental test series; the depths of surface-opening cracks in concrete slabs are estimated and the extent and nature of autogenous healing in concrete disks are studied. Finally, an approach by which fatigue-induced damage in concrete structures is nondestructively monitored is described. Vibration frequencies are shown to be sensitive to the presence of fatigue-induced cracking in concrete specimens; changes in the vibration frequency of a concrete specimen during fatigue tests are related to the remaining fatigue life of the test specimens.

Aqueous solutions of the chlorinated C1 and C2 volatile organic compounds (VOCs) were irradiated with ultrasonic waves in a sonochemical reactor to examine the use of sonochemical destruction for removing certain VOCs from water. Solutions of carbon tetrachloride, methylene chloride, chloroform, trichloroethylene, 1, 2-dichloroethane, 1,1,1-trichloroethane and perchloroethylene were used. Results showed that the concentrations of all the solutes decreased after irradiation, and no chorinated by-products were produced. There was a concomitant decrease in pH, indicating that liberated chlorine was converted to HCl or other acid species.

Ultrasonic techniques are used in the characterization of oxidation damage in ceramic matrix composites. The angular dependence of longitudinal and transverse velocities is measured to nondestructively determine the elastic constants. The anisotropic properties of an effective fiber are determined by a micromechanical model for composites with anisotropic constituents. The experimental data also enable the determination of the effective elastic moduli of the interfacial carbon coating.

Processing of cellular polyurethane was investigated experimentally and theoretically to examine the possibility of ultrasonic foaming. Polyol resin was supersaturated with nitrogen and ultrasonic excitation was applied for copious bubble nucleation. The ultrasonic excitation resulted in good foam structure whose size distribution was uniform and less than 100 [mu]m. The ultrasonic excitation was modelled by utilizing the classical nucleation theory to predict the rate of nucleation. Theorelical results suggest that a high rate of nucleation will be obtained if the ultrasonic excitation generates large enough negative pressure. Final bubble size was calculated by considering the pressure equilibrium between inside and outside of the bubble.

Force-activated polymer 'unzips' into conductive configuration when exposed to ultrasound. Force-activated polymer 'unzips' into conductive configuration when exposed to ultrasound., Author Affiliations: Sound switches material from insulator to semiconductor Scientists have designed a polymer that can rearrange its molecular structure in response to force, altering properties including colour and conductivity. [...]

An ultrasound technique studies the effect on transient thermal contact resistance during rapid contact solidification process. An empirical correlation equation for use in molten droplet impact is introduced.

The study reveals that superimposing ultrasonic waves compared to traditional tube and wire drawing can extend the forming process limits. The analysis focuses on separating the ultrasonic effect on the surface from the volume effects.

Since concrete members with fiber-reinforced polymer (FRP) reinforcement are not as ductile as conventional structures, and since concrete in retrofitted members is often covered and not readily available for visual inspection, development of nonintrusive and nondestructive damage assessment tools is essential. Ultrasonic pulse velocity (UPV) can provide such an assessment tool, and help quantify the extent and progression of damage in concrete. Continuous UPV monitoring of a number of concrete cylinders and concrete-filled FRP tubes showed the concrete-filled tubes to have higher sensitivity at lower stress ratios as compared to plain concrete. When compared with the axial strain energy, the UPV damage index has a much better resolution for stress ratios up to about 50% of ultimate strength. This ratio depends on the thickness of the jacket. It was also shown that the UPV has a strong correlation with volumetric strains after confinement is activated. Therefore, at high levels of axial loads when the confining pressure of the jacket results in volumetric compaction, the UPV increases by about 6% of the initial pulse velocity. Repeated loading generally induces the same rate of change of UPV damage index as that of the initial loading on the virgin specimen. This phenomenon occurs irrespective of the stress ratio at which the specimen is unloaded or reloaded. A comparison of the UPV damage index with the normalized acoustic emission counts reveals that the two methods have different sensitivities at different stages of loading and could potentially complement each other as a hybrid damage assessment tool.

A mathematical model was developed for a USUV reactor that is comprised of ultrasonic cavitation (US) and ultraviolet light (UV) chambers; these chambers are connected in series. The model assumes [...]

Trichloroethylene (TCE) is one of the most frequently found groundwater contaminants in the United States and other industrial countries. This study investigated a water treatment process for TCE removal from [...]