New rheometers & test instruments emerge at recent shows.

Viscosity testing equipment remains a featured category among the various new testing and measuring devices being introduced at recent trade shows and conferences. The following article offers a sampling of the viscosity testing equipment displayed. Several firms declined to reveal pricing information on these instruments.

RHEOMETERS OF ALL TYPES

A new sliding-plate rheometer designed to measure linear and nonlinear viscoelastic properties of polymer melts and other materials has been unveiled by Interlaken Technology Corp., Eden Prairie, Minn. The True Shear Rheometer is designed for the processor experiencing difficulties with polymer melts subjected to rapid transient/shearing deformation, such as the melt-forming operations of film blowing or blow molding. The new unit has a strain-rate performance range from 0.01 to 1000 |sec.sup.-1~, reportedly exceeding that of conventional rheometers.

The rheometer uses sliding-plate geometry, eliminating the instabilities associated with rotational flows. Shear stress is measured directly with a novel transducer developed at McGill University, Montreal. Sliding-plate fixtures and transducer are located in a forced convection oven to perform tests up to 570 F.

Seven new integrated test programs have been developed for the unit, which includes an IBM-compatible PC. The entire system is priced between $60,000 to $200,000, depending on the configuration.

A new rheometer designed to provide complete characterization of both melts and solids has been introduced by Bohlin Instruments Inc., Cranbury, N.J. The VOR Melt Rheometer VORM) features an oven capable of up to 1022 F, low-compliance torque, and a force transducer for steady and oscillatory measurements. The company says the control oven minimizes overshoots and offsets between oven setpoints and sample temperatures.

The unit offers software control packages specially tailored for polymer applications, including automatic data evaluation, such as ASTM D4473-85 for curing composites. The rheometer also offers a liquid nitrogen option and tools for torsional measurements on solid bars, which provide for characterization of solid-state polymer properties up to 1022 F.

Bohlin also is introducing its CS 50 Rheometer, a wider-range, extended-torque version of its Controlled Stress Rheometer. The wider torque range permits higher shear rates in viscometry as well as oscillation measurements of high modulus materials.

A new computer program designed to provide a method of predicting the effects of extended or long-term rheological behavior of a plastic material from a small sample and short-term tests is being launched by Bohlin. Designated "Time Temperature Superposition & Spectra Calculation," this software generates a statistical probability of long-term creep, relaxation and steady shear behavior gleaned from rheological data from a capillary rheometer or other rheological test device. Data are presented graphically in up to 12 probability curves and can be also viewed in a tabular form. The new program permits users to output data to a file or printer/plotter.

Cole-Parmer Instrument Co., Niles, Ill., has introduced new rotary viscometers that measure polymer viscosities within an accuracy of 1%.

Two models offer ranges of 10 cp to 1 million cp, or 40 cp to 8 million cp. The low-range instrument comes with four spindles; the high-range with six spindles.

Both units feature six-digit LCD displays and out-of-range indicators, data-logging output, spindle control, speed control with eight rpm settings, bubble level and height adjustment. Optional features include temperature-control module, helix drive, computer interface, low-centipoise adapter, and small-volume sample adapter.

OTHER NEW TESTING DEVICES

Autospect Inc., Ann Arbor, Mich., is introducing a new battery-powered version of its portable QMS-P (Quality Measuring System), designed for surface measurements of painted/coated automotive plastic surfaces. The QMS-P has a sensor head for high- and low-gloss surfaces and a portable processor unit for recording data. The system measures gloss, distinctness of reflected image, and orange peel. Color, metallics and part curvature do not affect measurement accuracy, the company says. The portable unit starts at around $30,000. The company also offers an automated, industrial measurement system that provides on-line SPC data.

Applied Test Systems, Inc., Butler, Pa., is offering a new modularized universal mechanical tester that controls compression, tensile, flexural and shear tests.

Designated Series 1400 UTM, the new unit is designed to run on IBM-compatible computers, and tests all types of materials to 60,000 lb. Software for the Series 1400 UTM provides real time full-color graphics, data storage for batch and specimen tests, and analysis and summary of test results. The company is offering both benchtop and floor models of the new unit.