Static and Dynamic Measurements

Dynamic Mechanical Measurements Comlnned with Other Physical 

Considerable information about molecular motions and grosser structural features can be obtained from other physical measurements on polymeric systems which are subjected to sinusoidally varying deformations. This subject is beyond the scope of this book, but reference may be made to dynamic investigations of birefringence, - infrared absorption, - light scattering, X-ray scattering, 2 - 21 dielectric constant, 22 and piezoelectricity, 23.i24 j,g studies 

Saunders and A. G. Ward, Proc. 2nd Inter. Congr. Rheol., Oxford, 1953, p. 284. 

Oberst, in Kunststoffe. edited by Nitscbe and K. Wolf, Volume 2, Springer-Verlag, Berlin, 1961, p. 148. 

Philippoff, in Physical Acoustics, edited by W. P. Mason, Volume 11B, Academic Press, New York, I965,p. I. 

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In this chapter, we overview basic techniques for making nanoscale adhesion and mechanical property measurements. Both quasi-static and dynamic measurements are addressed. In Section 2 of this chapter, we overview basic AFM instrumentation and techniques, while depth-sensing nanoindentation is overviewed in Section 3. Section 4 addresses recent advances in instrumentation and techniques... 

See also Electroanalytical techniques Electroanalytical cells, 9 567 Electroanalytical techniques, 9 567-590 active, 9 568-581 economic aspects, 9 588 passive, 9 581-586 static and dynamic measurements, 9 586-588... 

There seems to be some debate over the limit between static and dynamic measurements related to the question of the frequency of image registration (frames per second) at which a true real time observation is done. Obviously this judgement—if it is necessary at all— has to be made with reference to the rate of change at the surface. No attempt is made in this text to enter this discussion. Consequently, no attempt is made in this text to enter into this debate video STM will not be separated from other real time STM . 

The numerical value of the glass-transition temperature depends on the rate of measurement (see Section 10.1.2). The techniques are therefore subdivided into static and dynamic measurements. The static methods include determinations of heat capacities (including differential thermal analysis), volume change, and, as a consequence of the Lorentz-Lorenz volume-refractive index relationship, the change in refractive index as a function of temperature. Dynamic methods are represented by techniques such as broad-line nuclear magnetic resonance, mechanical loss, and dielectric-loss measurements. Static and dynamic glass transition temperatures can be interconverted. The probability p of segmental mobility increases as the free volume fraction / Lp increases (see also Section 5.5.1). For /wlf = of necessity, p = 0. For / Lp oo, it follows that p = 1. The functionality is consequently... 

In the last two decades, thanks to the advance of stable laser, ultrafast electronics, and personal computer, LLS (especially dynamic LLS) has evolved from a very special instrument for physicists and physical chemists to a routine analytical tool in polymer laboratories or even to a daily quality-control device in production lines. Commercially available research-grade LLS instruments (eg, ALV, Germany, and Brookhaven, U.S.A.) are capable of making static and dynamic measurements simultaneously for studies of colloidal particles in suspensions or macromolecules in solutions as well as in gels and viscous media. 

Good for both static and dynamic measurements They are also available as micro- and nanosensors Good for high precision dynamic force measurements Compact, has wide dynamic range, and high Good for small force measurements... 

Wang, Y, Cui, Y. Yun, B. [2006]. A fiber bragg grating sensor system for simultaneously static and dynamic measurements with a wavelength-swept fiber laser, IEEE Photonics Technology Letters Vol. 18(No. 14) 1539-1541. 

Characterization of the viscoelastic properties of polymers are classified into two categories static and dynamic measurements. The static mechanical tests involve creep, stress relaxation, and stress-strain measurements. In a creep test, a constant stress is applied to the specimen, and its deformation is measured as a function of time. In a stress relaxation test, the specimen is deformed a fixed amount, and the change in the stress is measured as a function of time. The stress-strain measurement is carried out by stretching the sample at constant tensile speed and then recording the load and deformation simultaneously. 

Egelhaf, S. and Schurtenberger, P., A Fiber-optics-based light scattering instrument for time-resolved simultaneous static and dynamic measurements. Rev. ScL Instrum., 67, 540-545 (1996). 

U. Delabre, C. Richard, J, Meunier, and A. M. Cazabat, Line tension of nematic pancakes at the air-water interface static and dynamic measurements, Eur. Phys. Lett., 83, 66004 (2008] U. Delabre, C. Richard, G. Gu6na, J. Meunier, and A. M. Cazabat, Nematic pancakes revisited, Langmuir, 24, 3998 (2008]. 

There has been considerable interest in the mechanisms of the a — /3 transition, and this has been modeled for static and dynamic measurements [58-60], X-ray diffraction patterns and infrared (IR) and Raman spectra show specific changes through this a—>/3 transition [42-44,61-63], The stress and strain dependence of the molar fraction of the / -form, X, increases drastically above the critical stress / the fraction is almost linearly proportional to the strain the transition is reversible the stress-strain curve has a plateau of the critical stress /, i.e., the curve is divided into three regions the elastic deformation of the a-phase (0-4% strain), the a — /3 transition (plateau region 4-12% strain), and the elastic deformation of the /3-phase (> 12% strain). These experimental results indicate that this stress-induced phase transition is a thermodynamic first-order transition. 

Figure 5.5. A multiangle PCS instrument. (Reprinted with permission from Egelhaaf, S. U., Schurtenberger, P., A Fiber-Optics-Based Light Scattering Instrument for Time-Resolved Simultaneous Static and Dynamic Measurements, Rev. Sci. Instrum., 1996, 67, 540-545. Copyright 1996, American Institute of Physics.)...

The major difference between the static and dynamic measurement is the strain amplitude (Fjaer et al., 2008) ... 

Combining static and dynamic measuring techniques provides a possibility for continuously monitoring physical stock levels on a real-time basis. By reconciling recorded changes in stock levels against actually metered movements, the system can detect and immediately identify any product losses. 

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