ISO 1133 Melt Flow Rate (MFR) & Melt Volume-Flow Rate (MVR) Testing

ISO 1133 is a standard that specifies a method for measuring the melt flow rate (MFR) and melt volume rate (MVR) of thermoplastics. These values are important indicators of a material's viscosity, which is a measure of its ability to flow under certain conditions.

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ISO 1133 Melt Flow Rate (MFR) & Melt Volume-Flow Rate (MVR) Testing

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Overview
Scope, Applications, and Benefits
Test Process
Specifications
Instrumentation
Results and Deliverables

Overview

ISO 1133 is a standardised procedure that can be used to test the melting and flowing behaviour of thermoplastics at particular temperature and loading conditions. The test can be used to determine either the Melt Flow Rate (MFR), which is the mass of the polymer that is being melted and flowed per unit time, or the Melt Volume-Flow Rate (MVR), which is the volume being flowed per unit time.

This is an important test as it can be used to determine how easily thermoplastics can be processed, predict how they will perform in the future, and ensure that they behave consistently during the process.

Scope, Applications, and Benefits

Scope

ISO 1133 is a test method that checks the behaviour of thermoplastic materials when they are melted, especially if they are in granular, pellet, or powder form. It will help you understand how easily the thermoplastic can be processed by checking the flow characteristics of the thermoplastic when melted.

Key determinations:

– Melt Flow Rate (MFR): the mass of thermoplastic that passes through a die in a given time
– Melt Volume Flow Rate (MVR): the volume of thermoplastic that passes through a die in a given time

Applications

Quality control of polymer production
Monitoring batch-to-batch consistency
Evaluation of extrusion and injection moulding behaviour
Design and optimisation of polymer processing conditions
Comparison of polymer grades and material selection
Research and development of thermoplastic formulations
Identification of material degradation during processing

Benefits

Ensures consistent processability of polymers
Provides standardised flow property data
Supports material selection for specific applications
Detects changes in molecular weight or degradation
Facilitates comparison across polymer grades and suppliers
Enhances quality control and product reliability
Provides reproducible and repeatable testing method

Test Process

Sample Preparation

Polymer pellets, granules, or powder are dried if required and preheated in the melt plastometer barrel.

Loading & Heating

The sample is loaded into the barrel and heated to the specified temperature until equilibrium is reached.

Extrusion Under Load

A standard load is applied to force the molten polymer through a die.

Measurement & Calculation

The mass or volume of extruded polymer is measured to determine MFR (g/10 min) or MVR (cm³/10 min).

Technical Specifications

Parameter	Details
Applicable Materials	Thermoplastics (granules, pellets, powders)
Temperature Range	Defined by polymer type (typically 190–300°C for common thermoplastics)
Load Range	Defined by polymer type (e.g., 2.16 kg, 5 kg, 10 kg standard weights)
Output Units	MFR: g/10 min; MVR: cm³/10 min
Die Diameter	Typically 2.095 mm, with specified length
Piston Diameter	Standardized for flow consistency

Instrumentation Used for Testing

Melt flow indexer/melt plastometer
Precision die and piston assembly
Analytical balance for weighing extrudate
Timer
Thermostatically controlled heating barrel
Calibration weights and verification standards
Data recording and analysis software

Results and Deliverables

Melt Flow Rate (MFR) values (g/10 min)
Melt Volume-Flow Rate (MVR) values (cm³/10 min)
Assessment of polymer processability
Comparison with material specifications or prior batches
Reports
Process optimisation recommendations

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Frequently Asked Questions

Melt Flow Rate (MFR) is defined as the amount of molten plastic that can be extruded through a standard die in 10 minutes, under specified temperature and pressure conditions. MFR is measured in grams per 10 minutes and is a measure of the flowability of a plastic material.

Melt Volume Flow Rate (MVR) is a measure of the volume of molten plastic extruded through the die in 10 minutes, under the same temperature and pressure conditions. MVR is measured in cubic centimetres per 10 minutes.

ISO 1133 provides plastic material producers with a method for determining the processability of a thermoplastic material. ISO 1133 is commonly used in plastic material quality control, plastic material comparison, and plastic process optimisation for extrusion, injection molding, and other plastic process applications.

Typically a few grams of polymer pellets or powder are sufficient for the test, depending on the instrument and the specific test conditions.

A typical ISO 1133 test generally takes 10–20 minutes, including sample preheating, extrusion, and measurement time.