While it is not uncommon to hear the term extrusion plastometer used in a sales presentation, in most labs this equipment is more commonly known as a melt indexer or sometimes as a melt-flow indexer. This is the most commonly used pieces of equipment in many labs as it is used to test both the melt-flow or mass-flow rate of compounded or pure forms of thermoplastics.
The melt flow indexer allows for rapid testing of one point in a standard viscosity curve under specific, standard conditions. These exact conditions and standards are from the ISO 1133 and ASTM D1239 standards, which are widely used across all industries, although some applications may require one or the other standard to be used.
The importance of knowing the melt flow rate for a given sample is to be able to determine the average molecular weight. By knowing this it possible to determine how the material of the sample will respond given the physical properties that are found in polymers at the specific molecular weight and subsequent melt flow rate or MFR.
There are two commonly used measurement options for testing using an extrusion plastometer. Depending on the industry and the specific standards used, it will be essential to know if you will be using Method A or Method B. Method A allows for temperature control while the operator controls the measurement. With Method B there are more measurement points and is done automatically by the machine without the need for the operator to do anything but load the sample in the barrel.
Different companies will also offer additional components that can be added onto the basic extrusion plastometer to add to the functionality and testing options. These are often known as modular designs, building in the opportunity to add to the system at any time in the future as testing requirements expand.