Rheometer elongational

In another elongational rheometer (221), the specimen is suspended on the end of a flexible tape, which is wound onto a wheel turned by a servo-controUed torque motor. This design is the basis for the Gottfert Rheostrain instmment, with which strain rates of 5 x 10 to 2 ate possible. 

Eig. 34. Diagram of the Rheometric Melt Elongational Rheometer (RME) for elongational viscosity measurements on polymer melts. 

Elongated fullerenes, 12 232 Elongation, of olefin fibers, 11 226 Elongational rheometer, 21 740 Elongation at break, 10 177 19 743 Elongation viscosity, of olefin fibers, 11 233, 234... 

J. Meissner and J. Hostettler, A New Elongational Rheometer for Polymer Melts and Other Highly Viscoelastic Liquids, Rheol. Acta, 33 1-21 (1994). 

Meissner J and Hosttler J (1994) A new elongational rheometer for polymer melts and other highly viscoelastic fluids. Rheol Acta 33 1-21. 

Schweizer T (2000) The uniaxial elongational rheometer RME - six years of experience. Rheol Acta 39 428-43. 

The advantages of various types of shear and elongation rheometers are discussed in Table 3.12 (shear) and Table 3.13 (elongation). 

Table 3.13. Advantages and limitations of various types of elongational rheometers ...

Analysis with Scanning Probe Microscopy U.S. 5,543,594, Nuclear Magnetic Resonance Imaging Rheometer U.S. 6,220,083, Elongational Rheometer and On-Line Process Controller U.S. 5,520,042, Apparatus and Method for the Simultaneous Measurements of... 

Prigogine, Trappeniers, and Mathot pressure-volume-temperature measurements lead zirconate titanate quaternary ammonium salts quasi-two-parameter theory rigid amorphous fraction Rheometrics extensional rheometer Rheometrics elongational rheometer for melts room temperature small-angle neutron scattering small-amplitude oscillatory shear flow small-angle x-ray scattering side-chain LCP... 

Therefore, measurements of the rate of thread self-thinning dal(adt) reveal the value of the effective viscosity of liquid /i. The results of such experiments with dilute polymer solution jets and threads [118-120] revealed the values of the effective viscosity that are larger than the solvent viscosity or the shear viscosity of the same solution by 3-4 orders of magnitude. For example, for dilute 0.02 wt% aqueous solution of poly(oxy ethylene) WSR-301, the elongational viscosity was found to be fi i = 7 Pa s, whereas its shear viscosity was = 3 x 10 Pa s. This approach resulted in the development of a new type of an elongational rheometer for dilute polymer solutions [118-122]. 

Schiimmer, P. Tebel, K. H. A new elongational rheometer for polymer solutions. J. Non-Newtonian Fluid Mech. 12, 331-347 (1983). 

An elongational rheometer developed in [26] based on this principle revealed that the initial longitudinal stress created by the electric stretching of a polymeric jet as it transforms from the modified Taylor cone to a thin jet, is of the order of 10-100 kPa. These values are one or two orders of magnitude larger than those measured for the uncharged viscoelastic jets. The rheometer also allows evaluatimi of the modulus of elasticity and relaxation time of concentrated polymer solutions and melts. 

A wide range of instruments have been developed as elongational rheometers. The earliest instrument of this type was by Ballman [Bll] and involved inserting a vertical specimen and stretching it at an accelerating crosshead speed. The stretch rate is... 

Figure 5.24 Schematic showing an elongational rheometer that enables one to condnct controlled elongational flow experimenL giving rise to constant elongation rate.

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