Processing Machinery
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Improper Selection of Processing Temperature Window for Polypropylene
Problem Phenomenon
The barrel or die head temperature is set unreasonably, resulting in poor plasticization quality, degradation, or incomplete melting of the material.
The selection of the temperature window directly affects the melt quality and the final product performance.
Cause Analysis
(1) The temperature is set too low, the melt viscosity is high, and plasticization is insufficient
(2) The temperature is set too high, and the material thermally degrades and the molecular weight decreases
(3) The temperature distribution of each section is unreasonable, with the feeding section temperature too high or the plasticizing section temperature too low
(4) Material grade differences and MFR changes are not considered
(5) Environmental temperature changes are not adjusted in time
Solution
(1) Reasonably set the temperature range according to the characteristics of polypropylene: 200-280°C
(2) The barrel temperature gradually rises from the feeding section to the homogenizing section, but does not exceed the upper limit temperature
(3) Regularly calibrate the actual barrel temperature with a thermometer or infrared temperature gun
(4) Fine-tune the temperature as needed after testing the MFR of each batch of raw material
(5) Establish standardized process parameter cards to reduce differences in manual operation
Key Takeaway
The selection of the temperature window is the basis of processing, and it needs to be set reasonably according to material characteristics and actual operating experience.
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