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Determination of the Residence Time of the Melt Polymer in the Extruder

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Determination of the Residence Time of the Melt Polymer in the Extruder

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    1. Determination of the Residence Time of the Melt Polymer in the Extruder

    2. Extruder Plastic film Plastic sheet Plastic tube Plastic rod Biscuits Pasta Breakfast cereal Snack Confectionery Pet food

    3. Blown Film Extrusion Line Extruder Blown film tower Winder

    4. Extruder Feed system Screw & Barrel Die Air ring

    5. Screw and Barrel

    6. Blown Film Tower Bubble guide Collapsing frame Top nip Idler rollers

    7. Winder Lay flat tube Slit both sides Slit one side

    8. Residence time & its distribution Quantitative analysis of the flow in the extrusion process Residence time is the time resins are in exposed to heat in the extruder Residence time is an average value

    9. Concept Introduction of a marker into the extruder along with the resin. The concentration of the marker in the plastics is monitored as a function of time

    10. Choice of Markers Similar flow properties as the resin Easily detected Safe to use Economical

    11. Example of marker TiO2 Carbon black Radioactive traces Glass microsphere Fillers Dyes Functionalized tracers

    12. Methods Step Input Continuous feed of the marker when the process is at steady state conditions Pulse Input Introduce small amount of the marker into the extruder system

    13. Application Understanding the effect of the processing equipments Characterize purging and mixing Determine expected exposure time

    14. Procedure: Extruder Warm up (1 hour) main power switch: on Open the cooling water Operating the extruder Plug in the three power cords Open the air supply valve (from the ceiling above the machine) Press run on the GDP 333 blowing motor Turn the take up roll on (Red-yellow knob) Turn the winder on by pulling start and run switch up)

    15. Procedure: Extruder Check that the screw speed is 0 (if not adjust to zero) Press “start” and “cold start” Slowly increase the speed of the screw by the gradual speed knob Feed LDPE resin through the hopper It takes about 5 minute for the extrudate to come out from the die

    16. Procedure: Extruder Drag the extrudate up to the top nip Pass it through idle rolls to the winder

    17. Procedure: Extruder Adjust the blow up ratio by introducing the air by slowly turning the air valve. After the desired size is obtained, close the valve

    18. Procedure: RT & RTD

    19. Procedure: RT & RTD When the mark reaches the winder, start the timer Mark the film every one minute until the color disappear (Now, it’s time to turn on the UV spec.)

    20. Procedure: Shut down Purge with LDPE resin to clean Follow the Shut down procedure in the lab manual except #3. It should be changed to “3. Turn off the screw speed by turning the gradual speed knob to 0 rpm. Then, push stop button”

    21. Procedure: C-black concentration C-black concentration is determined using the light absorption of the film High concentration ? high light absorption Low concentration ? low light absorption

    22. Results

    23. Calculation Residence time average Standard deviation Tmax = Tavg + 3?

    24. Report includes Twag, ?, and Tmax Residence time distribution with the mark shows Twag and Tmax Factors affecting residence time and residence time distribution

    25. Lab 5: Final Report Introduction, discussion, and conclusion Tabulated summary of the result Identification of unknown sample Justification of your identification from each results Which result did not agree with identification? What is the reason you discard that result?

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