Breaking Mechanisms

A dilute emulsion comprising oil drops dispersed in an aqueous solution was sheared between two glass slides under an optical microscope [149]. Original drops were deformed into long threads (Fig. 1.13a) that broke in numerous identical aligned and regularly spaced droplets (Fig. 1.13b). One can distinguish some very 

The breakup of a cylindrical thread at rest has been studied [142,145,151]. A varicosity of wavelength A, (Fig. 1.14) at the surface of a liquid cylinder immersed in another liquid will be amplified if its development causes a decrease of the interfacial area. Such a condition is satisfied if A is larger than 2jtrc, tc being the radius 

The Xm values can be found in [151] or in [145]. These tabulated values and the two following volume conservation relations allow a complete determination of the characteristic lengths of the instability  

The values of Xm are known only for stationary threads. The characteristic lengths are in good agreement with experimental observations [145] and were used in polymer melts in order to deduce the interfacial tension [152,153]. 

When a shear flow is applied, the situation becomes more complex because the stretching rate and the orientation of the thread are linked [148,154] and are 

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Alaond, s.U. and Bland, U.E. "The Effect of Break Mechanism on Gelling Agent Residue and Flow Impairment in 20/40 Mesh Sand," SPE paper 12485, 1984 Formation Damage Control Symposium, Bakersfield, February 13-14. 

Yu, M.-F. et al. (2000) Strength and breaking mechanism of multiwalled carbon nanotubes under tensile load. Science 287, 637-640. 

It was also shown [9] that when [TiCl4]/[CCl3C02H] was less than 6, the reaction curves were S-shaped, and that this phenomenon was most probably due to a slow buildup of the concentration of growing chains thereby a connection with the polymerisations co-catalysed by water was established. The detailed discussion of reaction mechanism [9] is of historical interest since it is one of the earliest expositions indicating the simultaneous occurrence of different chain breaking mechanisms. 

The second Higgs field acts in such a way that if the vacuum expectation value is zero, ( ) = 0, then the symmetry breaking mechanism effectively collapses to the Higgs mechanism of the standard SU(2) x U(l) electroweak theory. The result is a vector electromagnetic gauge theory 0(3)/> and a broken chiral SU(2) weak interaction theory. The mass of the vector boson sector is in the A(3) boson plus the W and Z° particles. 

In both cases it has been proposed that the pyruvoyl group forms a positively charged Schiff base with the substrate. The bond-breaking mechanisms are not obvious but some ideas have been proposed.281-2833 The ATP may arise from reaction with an intermediate acetyl phosphate.282 SeeEq. 15-61. 

Foam breaking Injection port provided for chemical breaking mechanical breaker optional, consists of a double disk rotated at high speed with its own drive... 

The relationship of structure to activity is discussed on the basis of measurements performed in the presence of 0.05 mole of antioxidant per kg. of polypropylene. The results obtained at lower concentrations (0.01 and 0.025 mole/kg.) showed some differences in details. On the other hand, almost identical relationships were found (45) in stabilizing polypropylene at higher antioxidant concentrations (0.1 mole/kg.). Analysis of those concentration relationships supports our assumption that the activity of pyrocatechol derivatives is influenced above all by reactions between the peroxidic bodies and antioxidants in the oxidation chain-breaking mechanism. 

Liquid jet instability is only one possible cause of thread fracture during melt spinning. The order breaking mechanism is cohesive fracture. The importance of this phenomenon has been stressed by Ziabicki and Takserman-Krozer (1964). 

Another possible chain-breaking mechanism is chain transfer to polymer [43,44]. Here, a new reactive center is formed on the polymer chain of the receiving molecule, usually along its chain rather than at either end ... 

Regardless of the chain-breaking mechanism, the propagation rate is... 

The radical chain lengths resulting from the various chain-breaking mechanisms can be summarized as follows ... 

In practice, several or all chain-breaking mechanisms may contribute. If so, the weight fraction can be taken as the weighted average of those derived for coupling and for chain transfer plus disproportionation (eqns 10.47 and 10.48). 

Cottrell, Graham, and Reid have shown that the pyrolyses of nitroethane and nitropropane probably do not proceed by a bond breaking mechanism. 

In contrast to the materials prepared by using PDMS oligomers, the PTMO-containing materials typically provide a much more enhanced strain-to-break mechanical response, as well as tensile strength, for an equivalent volume content (4, 7). An indication of this behavior is shown in Figure 8, which illustrates three examples of the stress-strain behavior of materials prepared with TEOS and functionalized PTMO(2000) at constant water and... 

Fig. 44. FibrUs life-time versus drawing velocity V. Symbols as in Fig. 39 the slope in toluene vapors is no longer — 1, indicating that the fibrils drawing and breaking mechanisms do not have the same activation volumes in toluene vapors. From Ref. by permission of the publishers, Butterworth and Co. Ltd.

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