RH7 & RH10 Capillary Rheometer (毛细管流变仪) - Features

主要性能和长处

Rosand Twin Bore Principle
Malvern was the first manufacturer to introduce the twin bore measurement principle in a commercially available rheometer (流变仪) unit. Simultaneous measurements can therefore be made on both long and short dies to determine the inlet pressure drop at the die, and therefore absolute viscosity, using the Bagley method. More commonly, Rosand 'zero length' dies are used to directly measure the inlet pressure drop and measure the extensional viscosity using the Cogswell (钝齿膨胀) method. The twin bore technique gives obvious experimental advantages including improved throughput since both experiments are preheated simultaneously. Alternatively, the software can be configured to run a two material test, thus measuring the apparent viscosity of two different materials simultaneously.

Rigid 'H' frame design
The 'H' frame design principle gives a vertical frame stiffness well in excess of that achievable with cantilever or 'C' frame designs. The frame design is effectively rigid at loads many times in excess of the 100kN measurement limit. This is an important consideration in transient tests such as PVT, which rely upon compliance free measurement for accurate volume determination.
Bi-Modal speed control.

Malvern has developed a bespoke Bi-Modal digital speed control technology to control the latest generation of capillary rheometers (毛细管流变仪). The technology uses different speed control algorithms suited to high and low speed operation in order to optimize performance. This gives the rheometer (流变仪) units an impressive dynamic range in speed control. In practice, the lower limit is determined only by long experimental times at low shear rates (切割率) but a dynamic range in speed of in excess of 200:000:1 is available if required. This greatly enhances the system's flexibility and means that a greater range of shear rates (切割率) can be covered using a particular die.

Integral fume chamber with extraction
For operator safety, the RH7 and RH10 are equipped with a safety interlocked fume chamber with fan extraction of the gases to a vent at the back of the rheometer (流变仪) unit. An extractor fan is also situated below the rheometer (流变仪) barrel.

Floor standing design
The floor standing design affords the Rheometers (流变仪) with an open architecture below the barrel and heater assembly. This space can be used to accommodate other experimental options such as die swell measurement, a slot die, haul-off (melt strength) and a haul-off (post-extrusion) oven.