Dear sir.. everyone.
I have a fiendish problem.. The problem is the neck-in trouble of PP in T-die process. What is Melt elasticity or What is Melt strength?? Which one does make an impact on the trouble? In order to decrease the trouble, what should i do..? Please help me....
More heat, more time, more pressure.
Melt strength is the resistance of the melt to extension, while melt = elasticity is a measure of elastic recovery. Melt elasticity and melt = strength are directly related. The higher the melt elasticity, the = higher the melt strength. Melt strength are commonly increased by = molecular weight, crosslinking or long chain branching or by blending = with LLDPE copolymer.
To measure those melt properties one uses typically a Goettfert Rheotens = Tensile Tester. The Goettfert Rheotens measures the extensional = properties of polymer melts by drawing a vertical melt strand at a = constant extension rate. The force needed to elongate the strand is = measured and used to calculate other properties of interest, like melt = strength and melt elasticity.
For resolving your issue you could either try more die pressure, or to = switch to a Higher Melt Strength PP, unless you are using such already = ...
Rheotens Test
HMSPP - Hight Melt Strength PP
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