ISO 1133-1 Determination of Melt Mass Flow Rate (MFR) and Melt Volume Flow Rate (MVR) of Thermoplastics

The standard "ISO 1133-1 Plastics - Determination of melt mass flow rate (MFR) and melt volume flow rate (MVR) of thermoplastics - Part 1: Standard method" developed by the International Organization for Standardization (ISO) describes two procedures for determining the melt mass flow rate (MFR) and melt volume flow rate (MVR) of thermoplastic materials under specified temperature and load conditions. Procedure A is a mass measurement method. Procedure B is a displacement measurement method.

Normally, test conditions for measuring melt flow rate are specified in the materials standard, with reference to this standard. The test conditions normally used for thermoplastics are included in the standard's annex (Annex A).

Melt volume flow rate (MVR) is particularly useful when comparing materials with different filler contents and filled versus unfilled thermoplastics. Melt mass flow rate (MFR) can be determined from melt volume flow rate (MVR) measurements, and vice versa, if the melt density at the test temperature is known.

This standard is also likely to be valid for thermoplastics where the rheological behavior is affected during measurement by phenomena such as hydrolysis (chain rupture), condensation and crosslinking, but only if the effect is to a limited extent and only if repeatability and reproducibility are within an acceptable range.

This standard is not suitable for materials whose rheological behavior is significantly affected during testing. In such cases, ISO 1133-2 applies.

The cutting rates used in these methods are much lower than those used under normal processing conditions, and therefore, the data obtained for various thermoplastics using these methods may not always correlate with their behavior during processing. Both methods are primarily used for quality control.

For the purposes of this standard, the following terms and definitions apply:

• Melt mass flow rate is the rate at which molten resin is extruded through a die of specified length and diameter under specified conditions of temperature, load, and piston position in the cylinder of an extrusion plastometer. The rate is determined by the mass extruded over a specified time. The mass flow rate is expressed in grams per 10 minutes.
• Melt volume flow rate is the rate at which molten resin is extruded through a die of specified length and diameter under specified conditions of temperature, load, and piston position in the cylinder of an extrusion plastometer. The rate is determined by the volume extruded over a specified time. The melt volume flow rate is expressed in cubic centimeters per 10 minutes.
• The load is the combined force exerted by the mass of the piston and any additional weight or weights specified by the test conditions. The load is expressed in kilograms as the mass exerted by it.
• A preformed compressed load is a test sample prepared as a compressed load of polymer sample. To ensure rapid insertion of the sample into the cylinder bore and void-free extrudate, it may be necessary to preform samples, initially in powder or flake form, into a compressed load.
• The time-temperature history is the history of the temperature and time to which the sample was exposed during testing, including sample preparation.
• The standard mold is the mold with a nominal length of 8.000 mm and a nominal hole diameter of 2.095 mm.
• A half-size mold is a mold with a nominal length of 4.000 mm and a nominal hole diameter of 1.050 mm.
• Moisture-sensitive plastics are plastics with rheological properties that are sensitive to moisture content. They undergo hydrolysis when absorbed water is absorbed and heated above their glass transition temperature (for amorphous plastics) or melting point (for semicrystalline plastics), resulting in a decrease in molar mass and, consequently, a decrease in melt viscosity and an increase in melt mass flow rate (MFR) and melt volume flow rate (MVR).

Melt mass flow rate (MFR) and melt volume flow rate (MVR) are determined by extruding molten material from a plastometer cylinder through a die of specified length and diameter under predetermined temperature and load conditions.

For measuring MFR (procedure A), timed segments of extrudate are weighed and used to calculate the extrusion rate in grams per 10 minutes. For measuring MVR (procedure B), the distance the piston moves in a specified time, or the time it takes the piston to move a specified distance, is recorded and used to calculate the extrusion rate in cubic centimeters per 10 minutes. If the melt density of the material at the test temperature is known, MVR can be converted to MFR and vice versa. The melt density is required at the test temperature and pressure. In practice, the pressure is low, and values ​​obtained at the test temperature and ambient pressure are sufficient.

The ISO 1133-1 standard is essential because it provides a uniform and reliable method for determining the melt mass flow rate (MFR) and melt volume flow rate (MVR) of thermoplastic materials. These measurements are critical for quality control, material comparison, and processing behavior in the plastics industry.

This standard is considered important for the following reasons:

• Industry-wide standardization: Without a consistent method such as the ISO 1133-1 standard, different laboratories or manufacturers may obtain different results for the same material, making comparisons unreliable.
• Processability assessment: MFR and MVR are indicators of a polymer's viscosity and flow behavior when melted, which help predict how it will perform during processing methods such as injection molding or extrusion.
• Material specification and consistency: Manufacturers use melt mass flow rate (MFR) and melt volume flow rate (MVR) to ensure each batch of plastic has the consistent flow properties necessary to maintain product quality.
• Regulatory and contractual compliance: Many product standards and customer specifications refer to ISO 1133-1 to define acceptable flow rate ranges for materials.
• Design and simulation: Engineers rely on accurate MFR/MVR data to model flow behavior in tools and dies, which impacts product design and performance.

Meanwhile, the ISO 1133-1 standard is suitable for everyday use in most applications. In contrast, the ISO 1133-2 standard is important when dealing with materials that may degrade, crosslink, or otherwise change under test conditions.

Our organization, which has been supporting businesses across all sectors for years through a wide range of testing, measurement, analysis, and evaluation activities, boasts a strong team of employees who closely follow global developments in science and technology and are constantly improving themselves. In this context, we also provide testing services in accordance with ISO 1133-1 Plastics - Determination of melt mass flow rate (MFR) and melt volume flow rate (MVR) of thermoplastics - Part 1: Standard method.