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The Melt Flow Index (MFI) is a measure of the ease of flow of the melt of a thermoplastic polymer. It is defined as the mass of polymer, in grams, flowing in ten minutes through a capillary of a specific diameter and length by a pressure applied via prescribed alternative gravimetric weights for alternative prescribed temperatures.
Polymer degradation is the reduction in the physical properties of a polymer, such as strength, ... malleability, melt flow index, appearance and colour. The changes ...
The melt flow rate (MFR) or melt flow index (MFI) is a measure of molecular weight of polypropylene. The measure helps to determine how easily the molten raw material will flow during processing. Polypropylene with higher MFR will fill the plastic mold more easily during the injection or blow-molding production process.
During a shearing process, such as extrusion, LLDPE remains more viscous and, therefore, harder to process than an LDPE of equivalent melt index. The lower shear sensitivity of LLDPE allows for a faster stress relaxation of the polymer chains during extrusion, and, therefore, the physical properties are susceptible to changes in blow-up ratios.
Pages in category "Polymer chemistry" The following 130 pages are in this category, out of 130 total. ... Melt flow index; Membrane osmometer; Methylaluminoxane;
The Melt Volume Flow Rate measures the time a predetermined volume of a thermoplastic polymer takes to pass through a capillary of predetermined diameter. Also the melt flow index, since it encompasses both the MFR and MVR, is not synonymous with the Melt Flow Rate.
Polymers are composed of long molecular chains which form irregular, entangled coils in the melt. Some polymers retain such a disordered structure upon freezing and readily convert into amorphous solids. In other polymers, the chains rearrange upon freezing and form partly ordered regions with a typical size of the order 1 micrometer. [3]
This action requires the polymer to be in a molten state where the melt viscosity and flow behavior have a drastic influence on the amount of diffusion and entanglement. [10] Therefore, the rheological weldability is best between materials with matching or very similar melting temperatures and melt viscosity. [ 2 ]