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 ScienceVCH, New York (1997)

Legacy Lecture of Fall 2000This lecture was contributed by the MS-I class of Fall 2000.

Left to RightNhan 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

Not just one polystyrene

Physical Property

Test Condition

Unit Grade VEF

EF

HM

HR

HM-HR

Viscosity Number

? mL/g 74 96 119 96 119

Heat Distortion Temp B

0.45 MPa oC 80 82 84 98 98

Heat Distortion Temp B

1.8 MPa oC 70 72 76 86 86

Vicat Temp A

10 N oC 88 88 92 106 106

Vicat Temp B

50 N oC 84 84 89 101 101

Young's Modulus

1 mm/min MPa 3150 3200 3150 3200 3250

Creep Modulus

1000 h MPa ? 2300 2830 2700 2850

Tensile strength

5 mm/min MPa 46 50 56 50 63

Fracture elongation

5 mm/min % 1.5 2 2 2 3

Impact strength

-30 to + 23 oC kJ/m2 6 9 11 10 13

Notched Impact Strength

-30 to + 23 oC kJ/m2 2 2 2 2 2

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 relyingon 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?

Back to the BeginningEarly 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.

Compression Molding

Redrawn by Nikhil Gupta and Yichuan Xu from Billmeyer Fig. 17-1

Platen

Mold Plunger

Guide Pins

Mold Cavity

Platen

Hydraulic Plunger

Heat and Cooling

Heat and Cooling

Hydraulic Pressure

Compound to be molded

Injection Molding

Hydraulic Pressure

Nozzle

Redrawn by Ziqiang Lu and Andrea Dupre from Billmeyer Fig. 17-2

Feed hopper,contains polymer pellets

Blow Molding—e.g. milk bottle

Extruded Parison-Mold Open

Mold Closed and Bottle Blown

Finished Bottle Removed from Mold

Plastic

Redrawn by Thomas Morgan from Billmeyer Fig.17-3

Four-roll calender Wad of plastic

To conditioningequipment

Based on Billmeyer Fig. 17-4 (references Winding 1961)

A Plastics Extruder—e.g. tubing

Feed hopper

HeatersCores for

cooling water

Die

Screw

Drive shaft

Redrawn from Billmeyer 17-5 by Xiaoming Liang

Fiber Drawing

Drive roll

Heater (Optional)

Drawn yarn to bobbin

Undrawn pretwisted yarn

Control rolls

Snubbing pin

Skewed idler roll1

2

(2 > 1)

Stretching Zone

Redrawn by Nadia Edwin from Billmeyer 18-5 (Riley 1956)

Mel

t S

pinn

er

Redrawn by Lee Madsen From Billmeyer 18-4, citing Riley 1956

Bobbin

Extruded Fiber Coolsand Solidifies Here

Metered Extrusion(controlled flow)

Melting Zone

Polymer Chips/Beads

Pump

Filter and Spinneret

Air Diffuser

Heating Grid

Pool

Lubrication by oil disk and trough

Packaging

Bobbin drive

Yarn driver

Feed rolls

Moisture Conditioning Steam Chamber

Feed

Filtered polymer solution

Metered extrusion Pump

Filter and spinneret

Solidif ication by solvent evaporation

Heated chamber

Lubrication

Air inlet

Feed roll and guide

Yarn driving

Balloon guide

Packaging

Ring and traveler

Bobbin transverse

Spindle

Dry Spinning

Dry

Spi

nnin

g of

Fib

ers

from

a S

olut

ion

Wet Spinning (e.g. Kevlar)

Cotton

Dry Spun Acetate

Need tenacity vs. ElongationPlot—a Student Project like

Billmeyer 18-1

Fiber properties for textile useChemical Physical Biological Fabric Qualities Stability to: Acid Base Bleach Solvents Heat Sunlight Aging

Mechanical Tenacity Elongation Stiffness Flex cycles Abrasion

resistance Work recovery Tensile recovery

Toxicological Dematological Resistance:

Bacteria Molds Insects

Appearance Drape Hand Luster (Kawabata machine can measure)

Flammability Thermal Melting Point Softening Point Tg Tdecompose

Permeability Can protect

against biotoxins?

Comfort Warmth Water sorption Moisture

retention Wicking

Ease of drying Electrical Surface

resistivity (static)

Sensors Can detect

pathogens?

Stability Shape Shrinkage Felting Pilling Crease

resistance or retention

Wetability

Adapted from Billmeyer Table 18-1.