Description

Paints & coatings

The minimum film forming temperature of a paint or coating is the lowest temperature at which it will uniformly coalesce when laid on a substrate as a thin film. The standard test for determining this temperature involves using an MFFT, as specified by such standards as ASTM D 2354 and ISO 2115. The design of the Rhopoint instrument is based directly on these standards.

Adhesives

The MFFT of one-pack adhesives can be found in a similar way to paints and coatings. With two-pack adhesives, a strip of aluminium foil can be laid on the platen, to ease cleaning, before applying the adhesive. Two-pack adhesives do not show an MFFT, but the minimum cure temperature can be found by scraping the sample with a spatula.

Running

The desired temperature program is selected and the instrument allowed to reach thermal equilibrium. Tracks of wet test material are applied using a cube applicator, or spreader. Once the material has dried or cured the result is visually apparent.

Standard features

Standard model (MFFT-90) has ten temperature programs:

Find out more about MFFT in our article ‘What is MFFT?’

The MFFT Method

A dull, nickel-plated copper platen is cooled at one end electronically and warmed at the other end, while air or nitrogen is caused to flow over the surface as a uniform blanket. The air flow is from cold end to hot end.

To achieve the required uniformity, the air or gas is delivered via a very carefully designed sintered metal distribution block. The design is such that freezing does not take place at the inlet. For use with air, a drying system is incorporated into the housing together with a flow controller. The air dryer contains indicator crystals which are clearly visible in their transparent container. The complete air conditioning system is accessible at the side of the instrument.

Water at normal mains pressure removes the excess heat from the coolers. In environments where the ambient water temperature is high, Rhopoint offer a chiller / recirculating unit to reduce this temperature. Quick release couplings are provided. Water is normally drawn from a laboratory tap and the outlet is run to drain by gravity. Alarms, both audible and visible, protect the cooling water supply.

Temperature sensors are mounted at intervals under the surface of the platen, these are used to control the temperature of the platen in accordance with the chosen program. They are also used to indicate platen temperatures down the length of the bar. A hinged viewing cover over the platen provides thermal insulation while allowing visual inspection of the determination as it progresses.

The use of this instrument may involve hazardous materials and operational procedures. It is the responsibility of the user of this instrument to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.