A New Approach to Capillary Extrusion Rheometry

Abstract

Abstract. A capillary extrusion rheometer has been developed which circumvents many of the problems of traditional hypodermic principle rheometers. The capillary is enclosed in a hollow plunger driven at a series of fixed rates into a barrel containing the test sample. Drawbacks observed with traditional viscometers have been obviated, for example, entrapment of air between the sample and the plunger leading to gas compression effects, gross motion of the fluid in the barrel leading to fluid structure breakdown and difficulties in determining plunger/barrel friction contributions. With strict temperature control, it has been shown that absolute values for fluid flow properties could be determined on small samples quickly and easily with an accuracy of ±0.5%.

Study of the accelerated oxidation of low and high erucic rapeseed oil

“…Accuracy was + 0.5%. Details of the design and operation of this instrument have been published (6).…”

“…Appioximately 20 ml of oxidized oil was placed in the small barrel of the rheometer (6) and the temperature adjusted to 20 + 0.1 C. The viscosity was calculated from triplicate measurements. For some of the more oxidized oils the measurements were made over a range of shear rates to determine the non-Newtonian character of the fluid flow.…”

Measurement of Flow Properties of Fluid Foods ‐ Developments, Limitations, and Interpretation of Phenomena

“…Furthermore, while pressure gauges are appropriate for highly viscous materials, e.g., high polymers, in general they are not sensitive enough for the low pressure drops encountered with most foods. Recent attempts t o replace pressure gauges include the use of manometers and pressure transducers (Escardino et al 1972; Ambros and Zitny 1974;and Scheve et al 1974), as well as the force measuring system of a Universal Testing Machine (Blake and Moran 1975).…”

Measurement of Flow Ability of Butter by Capillary Rheometry

“…An appropriate method to study the large deformation behavior of materials is capillary rheometry. Basically developed for polymer melts, it has been extensively used in the food industry for different products such as mechanically deboned poultry meat (Mayfield et al 1978), mozzarella cheese (Smith et al 1980), safflower, soybean, rapseed and castor oils (Blake and Moran 1975) and butter (Kawanari et al 1981).…”