Melt Flow Index 

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DMA ke bare mein batao plz mam

Watch our video on DMA.

When we talk about viscosity we need to know if we are talking about solid or melt or solution viscosity because different factors like crystallinity, molecular weight or molecular interaction can influence viscosity. If we are talking about solid viscosity then crystalline will have higher viscosity at given temperature but for other two it will depend upon molecular weight. For two semi-crystalline polymer, viscosity at given temperature will depend on their crystal form/crystal stability like PE melt at 135 C whereas PP melt at 165 C so at 200C, PP will have higher viscosity than PE. For amorphous polymer, viscosity will depend on molecular weight of the polymer. Polymer selection should depends on the performance requirement of the application rather than viscosity, once polymer is selected the MFI value is chosen to achieve desired processibility and performance.

@@PolymerWorld Thanks mam for your valuable guidance.

During MFI measurement pressure is applied to pack the material in the barrel. At that time any air or moisture trapped in the material escapes. So drying does not have much effect on the MFI value unless the polymer is hygroscopic in nature.

In pure form, MFI indicate molecular weight so a polymer sample with lower MFI usually have higher molecular weight.

@@PolymerWorld tqsm