Purpose
The Wallace Rapid Plastimeter measures the plasticity or viscosity of unvulcanised rubbers. The test is simple, clean and quick. The instrument is used in conjunction with the Wallace -MRPRA Ageing Chamber ( Cat. Ref. O14) to determine the Plasticity Retention Index ( PRI) of raw natural rubbers.

The variable temperature model ( P14/ VT) characterises the flow behaviour of synthetic rubber compounds as, unlike the other models, its platen temperatures can be varied between 60° C and 180° C. For some applications the P14/ VT offers a quick, low cost alternative to a Mooney Viscosity test.

The instrument is supplied in four versions and each version comes complete with specimen cutter. The instrument is shipped with 10mm dia top platen installed and alternative top platens of 7.3 and 14mm diameter are supplied as accessories. The platens are easily interchangeable.

Principle
A modified parallel plate compression principle is used with automatically timed " conditioning" and " load" periods. A sample is compressed between two circular platens which are maintained at a temperature of 100° C. The sample is conditioned for 15 seconds at a thickness of 1mm. A compressive force of 100N is then applied for 15 secs. The final thickness of the test piece expressed in units of 0.01mm, is the plasticity number.

Test Procedure
The sample is prepared using the specimen cutter provided and it is then enclosed between two pieces of tissue paper, as defined by international standards, before being placed between the platens. The tissue paper prevents the material sticking to the platens or sliding between them.

The automatic test sequence is started when the operating handle is rotated.

The reduction in thickness of the sample is displayed digitally, which freezes, to show the plasticity number at the end of 15 sees.

Features
The P14 Rapid Plastimeter offers greatly enhanced operator access and is available in four different versions. A major feature on all versions is powered zero calibration eliminating the need for tedious manual setting. Aluminium castings are used throughout the design for rigidity and stability. All versions comply with National and International standards.

Rapid Plastimeter - Basic model, P14/ 1
* Fully automatic operation
* Built in diagnostics
* LED platen Temperature Indicator

Rapid Plastimeter - Printer Model, P14/ 2
* Compact printer with high speed print capability
* Single/ Median mode of operation
* 24 Character column print output
* Date and time recorder
* Traceability of aborted tests
* Alternative language settings
* Additional diagnostic features
* Platen Temperature print out

Rapid Plastimeter - Data Terminal and Printer Model, P14/ 3
* Data input terminal and display
* Compact printer with high speed print capability
* 24 Character column print printer
* Date and time recorder
* Continuous Platen temperature display
* Variable load durations
* Sample and operator identification with automatically increasing suffix
* Traceability of aborted tests
* Alternative language settings
* Calibration and service reminder
* PRI evaluation

Rapid Plastimeter - P14/ VT
Same specification as the P14/ 3, plus:
* Variable platen temperature 60° C - 180° C

General
The Plastimeter can be supplied to operate on any normal single phase AC electricity supply.

Three sizes of upper platen anvils are supplied: 7.3 mm, 10 mm and 14 mm diameter. These permit the instrument to operate satisfactorily over a wide plasticity range. The lower platen is suitable for all sizes. Changing the upper platen is a simple operation taking only a few minutes.

Specifications

Plastimeter dimensions : 306mm ( w) x 353mm ( d) x 306mm ( w)

Specimen cutter dimensions : 380mm ( d) x 80mm ( w)

Weight of Plastimeter : 34kg

Platen sizes : 10mm, 7.3 and 14mm Diameter

Standards : BS 903: Pt A59 : section A59.1 : 1997 ISO 2007: 1991

Platen temperature P14/ 1, 2, 3 : 100° C

Platen temperature P14/ VT : 60° C - 180° C

Test time : 15 secs preload, 15 secs compression

Compressive force : 100N

Plasticity Retention Index ( PRI)

PRI is a measure of the resistance of raw natural rubber to oxidation. The oxidation effect is assessed by measuring the plasticity before ageing ( P0) and after ageing for 30mins in the Wallace - MRPRA ageing oven at 140° C ( P30)

Plasticity Retention Index ( PRI)