What is the purpose of melt flow index?
The melt flow index (MFI) or melt flow rate (MFR) is a measure for the ease of flow of melted plastics. It is often used in the plastic industry for quality control of thermoplastics.
Why is powder flowability important?
To achieve better manufacturing efficiency and product quality in powder processing industries, a predictable powder flow is of greater importance to avoid capacity shortfall and production interruption that involve costly loss of production time.
What material property significantly affects the melt flow rate?
Flow rate in a polymer is related inversely to viscosity. High-viscosity materials flow with greater resistance and therefore more slowly under any particular set of conditions than low-viscosity materials do. Therefore, higher-MW polymers have lower MFR values and lower-MW polymers have higher MFR.
What is the main properties of thermoplastics?
Characteristics of Thermoplastic Thermoplastics are generally high molecular weight polymers. The chains in the polymer are associated with the intermolecular forces. The intermolecular force acting between the chains becomes weak on increasing temperature and yields a liquid with high viscosity.
What are the properties of thermoplastic?
Thermoplastic material characteristics
- Crystallinity. The crystallinity of a material identifies the state of the polymer at processing temperatures, and can range from amorphous to crystalline states.
- Mold and melt temperature.
- Thermal properties.
- Viscosity.
- pvT data.
- Shrinkage.
- Optical properties.
- Composite materials.
What is MVR in plastics?
The Melt Flow Rate is a measure of the ease of flow of melted plastic and represents a typical index for Quality Control of thermoplastics. An alternative quantity is the volume flow expressed (SI units) in cm3/10min, called Melt Volume-Flow Rate or MVR.
What is flowability in powder metallurgy?
Powder metallurgy is a growing field with much potential. The powder with the best flowability (highly free flowing) scored best across all experiments and tests indicating all tests as significant. A well and free flowing powder is characterized by low values in cohesion, angle of repose, specific energy, etc.
What increases flowability of powder?
One common widely used way to improve powder flowability is adding some nanopowder fillers, such as nanosilica, glass oxide, fluoroplastics, or organic lubricants, such as metal stearate [84]. It is related to the cohesive force and compressibility of powders.
Why is understanding the flow properties of bulk materials important?
A thorough understanding of a bulk material’s flow properties and its flowability are crucial for identifying the cause of poor flow, powder flooding or rate limitations, segregation, or product non-uniformity.
What is flow stress – materials?
What is Flow Stress – Materials – Definition. Flow stresses occur when a mass of flowing fluid induces a dynamic pressure on a conduit wall. The force of the fluid striking the wall acts as the load.
How to determine the flow function of powder?
Figure 4 : Graphical determination of powder flow function From the 3 different yield locus, 3 couples (Major consolidation stress sigma1 ; Cohesive strength fc) can be calculated. A graph showing fc=f (sigma1) can then be drawn. This is the material flow function of the powder being tested (not to be confused with the flow factor ff).
How to test powder flow properties of shear cell?
1. Powder flow properties : Shear Cell Tester (Jenike Method) 2. Intermediary Methods : powder cohesive index 3. Shortcut Methods : angle of repose, Carr and Hausner Index 4. Electrostatics