Processing Machinery
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LLDPE shear rigidity
Problem Phenomenon
After increasing screw speed, melt viscosity does not decrease noticeably, output improvement is limited and torque increases
Cause Analysis
LLDPE's short-chain branch structure lacks long-chain branch entanglement, with weak shear-thinning ability; it shows "rigidity during shear", with limited viscosity decrease under high shear and increased motor torque and wear
Solution
①Design screw and motor power according to LLDPE rheological properties; ②match high-viscosity grades with high-power extruders; ③avoid relying on high speed to increase output; after adjustment, continuously sample to verify the effect, and resume mass production only after confirming stability
Key Takeaway
LLDPE's shear rigidity is the core constraint of equipment selection; old equipment with insufficient power is inevitably limited when processing LLDPE; after confirming effectiveness, fix the parameters and practices into the work instruction to prevent recurrence
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