Extrusion of PolyethyleneJared StradleyCHEN 4903December 4, 2006

Extruders

Overview Project objectives Theory Experimental setup and procedures Results Conclusions and Recommendations References Wrap up Q & A

Project objectives Characterize the flow of

polyethylene in cylindrical die Estimate the maximum flow rate

through a 1” diameter pipe die

Theory Basically, it’s flow through a pipe or

an annulus

Theory cont. Major equations

Pipe flow:

LRPPQ c

8)( 421

drdV

LPPr

2)( 21

More theory Annular flow:

/1ln11

8)( 22

44

21

LRPP

Q

Experimental setup

Experimental procedures Ran polyethylene at 155, 160 and

165 °C at 3, 5, 10 and 15 rpm Collected samples of each run Ran polypropylene at 200, 205 and

210 °C at 3, 5, 10 and 15 rpm Also collected samples Calculated Q, and dv/dr

ResultsShear Stress vs. Velocity Gradient for Polyethylene (pipe flow)

0.0E+00

5.0E+05

1.0E+06

1.5E+06

2.0E+06

2.5E+06

3.0E+06

0 2000 4000 6000 8000 10000 12000

dv/dr (1/s)

τ (Pa

)

155 °C160 °C165 °C

Results cont. Bingham plastic:

o drdV

Results cont.Pressure Drop vs. Velocity for Polyethylene (annulus)

0.00E+00

5.00E+05

1.00E+06

1.50E+06

2.00E+06

2.50E+06

3.00E+06

0.000 5.000 10.000 15.000 20.000 25.000 30.000 35.000 40.000

Velocity (cm/s)

Pres

sure

dro

p (P

a)

155 °C

160 °C

165 °C

Some more resultsPressure drop vs. rpm for polypropylene (pipe flow)

2.00E+06

2.50E+06

3.00E+06

3.50E+06

4.00E+06

4.50E+06

5.00E+06

0 2 4 6 8 10 12 14 16 18

rpm

Pres

sure

dro

p(Pa

)

200 °C

205 °C

210 °C

Maximum pressure drop: 6.40 MPa

Final result

Pressure Drop vs. Velocity for Polyethylene (annulus)

y = 115926x - 318281y = 109967x - 235980

0.00E+00

5.00E+05

1.00E+06

1.50E+06

2.00E+06

2.50E+06

3.00E+06

0.000 5.000 10.000 15.000 20.000 25.000 30.000 35.000 40.000

Velocity (cm/s)

Pres

sure

dro

p (P

a) 155 °C160 °C165 °C

Maximum velocity possible: 59.180 + 4.127 cm/s (95% CI)

Conclusion Polyethylene can be extruded at a

velocity of 59.180 + 4.127 cm/s through a 1” cylindrical pipe die

(95% CI) This result holds for temperatures

between 155 and 165 °C This value compares well with the

industrial flow rate of 0.5 m/s

Recommendations Run both Polyethylene and

Polypropylene at more temperatures Run both at higher rpm Take samples on same day

References Bird, R. B., W. E. Stewart, E. N. Lightfoot.

Transport Phenomena. New York: John Wiley & Sons, 1960.

Ring, T. A. Fundamentals of Ceramic Powder Processing and Synthesis. San Diego: Academic Press, 1996.

de Nevers, N. Fluid Mechanics for Chemical Engineers. New York: McGraw-Hill, 2005.

www.chemfinder.com www.nicodemus.org www.search.com

Wrap up Project objectives Theory Experimental setup and procedures Results Conclusions and Recommendations References

Questions?