Melt Flow Rate

property

A measure of the ease of flow of molten thermoplastic polymer under standardized conditions, expressed as grams of material extruded per 10 minutes through a specified die.

In Simple Terms

Melt flow rate tells you how easily a plastic flows when melted. Higher numbers mean the plastic flows more easily, like thin honey versus thick molasses. This helps manufacturers choose the right resin grade for their production process.

Why It Matters

MFR is crucial for resin trading and processing decisions. It determines processability in injection molding and extrusion, affects cycle times and energy consumption, and serves as a quality control parameter for incoming material inspection.

Technical Details

Measured per ASTM D1238 or ISO 1133, MFR testing uses specific temperature and load conditions for each polymer type. The test forces molten polymer through a standardized capillary die, with results inversely related to molecular weight and melt viscosity. Different polymer grades require different test conditions.

Real-World Examples

Injection Molding Grade Selection

A parts manufacturer needs PP with MFR 12-25 g/10min for thin-wall containers, while thick automotive parts require PP with MFR 1-3 g/10min for better mechanical properties.

Quality Control in Resin Trading

A resin trader receives HDPE shipment specification of MFR 0.3 g/10min but testing shows 0.8 g/10min, indicating potential off-spec material requiring investigation or price adjustment.

Blown Film Processing

LLDPE film producers typically specify MFR 0.5-2.0 g/10min for optimal bubble stability and film properties, while higher MFR grades cause processing difficulties.