Sonic techniques

One method used for studying the orientation of polymers which does not make use of electromagnetic radiation is that of sonic velocity or pulse propagation. This technique is particularly suited to the characterisation of orientation in fibres (or samples having rodlike geometry) and, although the technique suffers somewhat from not having a sound theoretical basis, it is of particular usefulness in instances where an orientation index or parameter is desirable for relative comparisons. 

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Hj) Height of Burst (Sonic) Test. The purpose of this test is to det the height of burst of a fuze using sonic techniques. This technique requires the measurement of the time of arrival of sound at directional microphones precisely placed in a plane. A brief description of this test is given on p IIIB-20 Ref 39 Addnl info can be obtd from "Instrumentation Section, Technical Services Laboratory, Ammunition Development Division, Ammunition Engineering Directorate, Picatinny Arsenal, Dover, NJ 07801 H2) Hydraulic Ram and Vibrator Test. This test could be used to simulate impact shock on bombs or rockets assembled with fuzes that are launched from aircraft. It also could check the transportability of fuzes that experience this environment. This test is listed, but not described in Ref 39, p IIB-37... 

Perhaps the simplest solvent dispersion method is that developed by Batzri and Korn (1973). Phospholipids and other lipids to be a part of the liposomal membrane are first dissolved in ethanol. This ethanolic solution is then rapidly injected into an aqueous solution of 0.16 M KC1 using a Hamilton syringe, resulting in a maximum concentration of no more than 7.5% ethanol. Using this method, single bilayer liposomes of about 25-nm diameter can be created that are indistinguishable from those formed by mechanical sonication techniques. The main disadvantages of ethanolic injection are the limited solubility of some lipids in the solvent (about 40 mM for phosphatidyl choline) and the dilute nature of the resultant liposome suspension. However, for the preparation of small quantities of SUVs, this method may be one of the best available. 

Uncertainties arising from inadequacies of the sonication technique and the conversion factors are obviously minor as compared to the subjectivity involved in the counting... 

Hueter TF, Bolt RH. Sonics Techniques for the Use of Sound and Ultrasound in Engineering and Science. New York John Wiley and Sons, Inc., 1955. 

Finally, a-TK, prepared from ketones and HTIB by the sonication technique (92TL7647), have been utilized as precursors to oxallyl... 

Due to the low breaking load of the bundles, Instron tensile moduli were not sufficiently reliable. Modulus data were therefore obtained by the sonic technique, using a modified PPM-5 (H. H. Morgan Company) dynamic modulus tester (Murayama ). 

The measurement of orientation by sonic techniques has received relatively little attention. This method along with that of birefringence and dichroism measures only the second moment of the orientation distribution function. It does offer, however, some advantages, probably the most important being that it can be easily used for measuring the average orientation in fibers. 

We see if one orientation function can be determined such as the crystalline orientation function by X-ray diffraction, then by sonic techniques the amorphous orientation can be calculated by Eq. (58). Samuels (57, 58) has made such measurements and finds reasonable values for amorphous orientation. 

Morgan (45) has suggested the use of sonic techniques for predicting the upper limits to birefringence in orientation. He uses the relationship of DeVries (/5)... 

By simultaneously measuring / by the sonic technique and birefringence by one of the optical techniques one can plot A against /. If the two methods correlate then by extrapolation of / to unity one can predict what the upper limit should be to the birefringence. Fig. 19, taken from Morgan s paper, shows the results of such data for several polymeric... 

One advantage of the sonic technique is that it can be used as a quality control device. One can simultaneously measure the sonic parameters with drawing operations of fibers or in film orientation. It is specifically suitable where fibers are involved since the equations are more applicable to rodlike specimens and are independent of cross sectional area. This restriction still does not limit its application to monitoring changes in orientation in film manufacturing where width is not excessive. 

A microwave-assisted solvent extraction (MASE) method was optimized by Chee et al. to extract phthalate esters from marine sediments, soils, and results were compared with those obtained by the same authors using conventional Soxhlet and sonication techniques. The analysis was performed by GC-ECD or GC-MS. The overall optimal conditions for the extraction of phthalate esters by MASE included the use of 1 1 acetone or hexane at 115°C for 10 min. Recoveries for six individual phthalate esters (DMP, DEP, DAP, DBP, BBP, DEHP) ranged from 71% to 91%, and were better than those obtained with Soxhlet (66% to 90%) or sonication (65% to 89%). The authors stated that advantages of MASE extraction over sonication or Soxhlet are larger sample throughput, lower usage of hazardous solvents, and less laborious cleanup steps. 

Figure 4.9 Hydrolysis of maltoheptaose by a-amylase using sonication technique.

Figure 4.10 Hydrolysis of starch by alpha amylase using sonication technique.

Successfiil inq>lemeiitation of such an approach would considerably reduce both the time and cost of in situ biotreatment. Pretceating groundwaters with sonication techniques would form VOCs that could be removed effectively by either bioremediation technologies or a dual vapor extraction technique (developed by Stanford University under the VOC-Arid Program, now part of Plumes Focus Area). Sonication could also be coupled widi technologies aimed at mobilizing dense nonaqueous phase liquids (DNAPLs) in the subsur ce, such as surfactant floodii. ... 

Figure 7. Effect of different vapor stripping air injection rates of the removal of TCE from solution using sonication techniques (20 kHz, 35.8 W/cm ).

The sonic technique suffers from one of the same difficulties as the birefringence method in that only an average orientation of the total system is obtained. Thus, if one has a multicomponent system (e.g. semicrystalline, block copolymer. etc.X one cannot separate component orientation by this technique alone. It is noteworthy that the orientation measured by the sonic method can be correlated directly with birefringence data on the same material.This ease of correlation has been suggested to lead to values of the intrinsic birefringence by extrapolation of the sonic data to perfect orientation. 

In conclusion the usefulness of the sonic technique has found merit when applied to uniaxially deformed materials that can be fabricated to give rodlike geometry. It seems that its application to biaxially deformed material, however, hardly has desirability, particularly if one is attempting to determine planar orientation. 

In other work silica based helical and twisted nanoribbons of controlled chirality were synthesized by sol-gel processing in acidic conditions using organic self-assembly as a template (Fig. 19). The authors have demonstrated that nanohelices can be successfully fragmented into individualized chiral helical and twisted silica ribbons of several hundred nanometers by a sonication technique. It was found that the power of sonication and nature of the solvent are crucial parameters for achieving narrow size distribution of the fragmented helices, and the better the dispersion. In addition it was shown that freeze-drying of the helices clearly consolidated the Si-O-Si bonds. The sonication of helices in water or in ethanol directly after the transcription destroyed the local chiral structures, whereas the helices which were freeze-dried first and then dispersed in these solvents preserved their local chiral structure after sonication. 

Biobased epoxy nanocomposites can be reinforced with organo montmorillonite clay and carbon fibers obtained from poly(acryl-onitrile) (45). To get the organically modified clay into the glassy biobased epoxy networks, a sonication technique was used. In this way, clay nanoplatelets were obtained that were homogeneously dispersed and completely exfoliated in the matrix. 

Thermoset/CNT nanocomposites are processed [80, 81] in a similar way as PCN are prepared. Generally sonication is used to disperse CNT in the resin. Zhou and co-workers [82] incorporated 0-0.4 wt% of MWCNT in epoxy matrix by sonication technique and evaluated their mechanical properties. Improvement in property in all respects was observed up to 0.3 wt% of nanotube. Beyond this concentration the strength and elongation decrease though the modulus keeps increasing. As a result of addition of 0.3 wt% nanotube the tensile strength increases from 93.5 MPa to 121 MPa and % elongation increases from 4.0 wt% to 7.5 wt%. Schadler and coworkers [83] evaluated mechanical properties a MWCNT-epoxy nanocomposites... 

Among other techniques such as X-ray diffraction, birefringence, NMR spectroscopy, polarized fluorescence, Raman depolarization and sonic techniques the... 

Cl 171 evaluates this effect by using sonic techniques to measure modulus of elasticity, or by measuring cold modulus of rupture, before and after specified cyclic thermal treatment. 

In this paper we present a high pressure study of various lubricants, performed on a falling body viscometer in which the knowledge of the plunger position is continuously obtained by ultra-sonic techniques. 

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