Mastering Thermal Profiles for Recycled Plastics > 자유게시판

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Tailoring barrel thermal settings for recycled polymers demands careful consideration due to their frequent contamination, تولید کننده کامپاند پلیمری chain scission, and variable feedstock quality

Start with a detailed assessment of the material’s prior thermal exposure

Recycled polymers may have been exposed to multiple processing cycles, which can lower their molecular weight and alter their melting behavior

Consequently, these materials typically exhibit reduced melting points and heightened susceptibility to thermal breakdown

Begin by conducting a thorough material characterization

Employ DSC and MFI analyses to map out the thermal transition points and flow behavior

These results form the foundation for your thermal profile

Never apply virgin resin settings directly—they risk burning, yellowing, or uneven extrusion

Design a progressive heat ramp from inlet to discharge

Keep the feed zone minimally heated—only enough to avoid clogging without initiating early softening

The compression zone should rise steadily to ensure complete melting without excessive shear heat

Hold the final zone just under the polymer’s critical decomposition point

Monitor the melt temperature at the die or nozzle using a reliable sensor

This real-time feedback is critical because recycled materials can vary batch to batch

If the melt temperature is too high, reduce the barrel settings in the rear zones and lower screw speed to reduce shear heating

If the melt is too cool, increase the front zone temperatures slightly and consider increasing screw RPM to generate more shear, but only if the material can tolerate it

It’s also important to minimize residence time

Recycled polymers are more sensitive to prolonged heat exposure, so optimize cycle times and avoid unnecessary holding periods

Clean the barrel and screw regularly to remove degraded material that can act as a nucleation point for further degradation

If feasible, mix in 5–15% virgin resin to stabilize processing

It smooths out inconsistencies and lessens reliance on extreme settings

Run pilot trials and record the impact of every thermal adjustment on finish, hue, and strength

Over time, you’ll build a reliable profile tailored to your specific recycled stream