Polymer Processing

1. Polymer Processing • References • Billmeyer* Ch. 17, 18 • Elias** Ch. 14 • *Textbook of Polymer Science 2nd Ed. • Wiley-Interscience, New York (1962,1971) • **An Introduction to Polymer Science • VCH, New York (1997)

2. Legacy Lecture of Fall 2000 This lecture was contributed by the MS-I class of Fall 2000. Left to Right Nhan Thai, Lee Madsen, Lu Ziqiang, Zu Yichuan, Nikhil Gupta Simon Mwongela, Andrea Dupre, Mariah McMasters, Vera Verdree, Angela Davis Nadia Edwin, Thomas Morgan, Amy Morara, Xiaoming Liang Missing: Justin Mecomber

3. Not just one polystyrene Selected PS grades from BASF. VEF=very easy flow; HM=high molar mass; HR = heat resistant. Taken from Elias, Ch. 14. Processing engineers select grades using data such as these, perhaps relying on such numbers more than the molecular data such as M or Rg that chemists are used to. Note how completely unmolecular! What molecular properties do you suppose correspond to EF, HR or HM?

4. Back to the Beginning Early in the course, we tried several ways to categorize polymers, such as condensation vs. addition, etc. From a processing point of view, the main classes are: Thermoplastic: the resin is heated to make a viscous liquid and then processed into a usable object without much additional chemistry. Example: polyethylene, polystyrene. Thermoset: upon heating, further reaction occurs to make molecules “set up” into a useful product. Chemistry occurs, so these are sometimes called “reactive polymers”. The resin may be provided as either small molecules or “prepregs”—partially polymerized stuff. Example: polyurethanes, phenol-formaldehyde, melamine-formaldehyde, epoxy glue.

5. Compound to be molded Platen Heat and Cooling Heat and Cooling Mold Plunger Guide Pins Mold Cavity Platen Hydraulic Pressure Hydraulic Plunger Compression Molding Redrawn by Nikhil Gupta and Yichuan Xu from Billmeyer Fig. 17-1

6. Nozzle Hydraulic Pressure Injection Molding Feed hopper, contains polymer pellets Redrawn by Ziqiang Lu and Andrea Dupre from Billmeyer Fig. 17-2

7. Plastic Extruded Parison- Mold Open Mold Closed and Bottle Blown Finished Bottle Removed from Mold Blow Molding—e.g. milk bottle Redrawn by Thomas Morgan from Billmeyer Fig.17-3

8. Wad of plastic To conditioning equipment Four-roll calender Based on Billmeyer Fig. 17-4 (references Winding 1961)

9. Drive shaft Feed hopper Cores for cooling water Heaters Die Screw A Plastics Extruder—e.g. tubing Redrawn from Billmeyer 17-5 by Xiaoming Liang

10. Heater (Optional) Stretching Zone Drive roll 2 Snubbing pin Control rolls (2 > 1) Drawn yarn to bobbin 1 Skewed idler roll Undrawn pretwisted yarn Fiber Drawing Redrawn by Nadia Edwin from Billmeyer 18-5 (Riley 1956)

11. Polymer Chips/Beads Melting Zone Heating Grid Pool Metered Extrusion (controlled flow) Pump Filter and Spinneret Air Diffuser Extruded Fiber Cools and Solidifies Here Moisture Conditioning Steam Chamber Lubrication by oil disk and trough Feed rolls Packaging Bobbin Yarn driver Bobbin drive Melt Spinner Redrawn by Lee Madsen From Billmeyer 18-4, citing Riley 1956

12. Dry Spinning of Fibers from a Solution

13. Wet Spinning (e.g. Kevlar)

14. Cotton

15. Dry Spun Acetate

16. Need tenacity vs. ElongationPlot—a Student Project like Billmeyer 18-1

17. Fiber properties for textile use Adapted from Billmeyer Table 18-1.