How long to melt plastic through composite material?

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SUMMARY

The discussion focuses on calculating the time required to melt polyethylene plastic through a composite material consisting of paper and aluminum. The composite layers are 0.005 inches of paper and 0.0003 inches of aluminum, while the polyethylene has a melting point of 325°F. The relevant equations include the heat transfer equation dQ/dt = kTA dT/dx and the thermal conductivity relationship 1/kT = 1/kPaper + 1/kAlu. The power supplied to the system is 1500 W, and the heat source temperature is set at 350°F, necessitating the calculation of the temperature gradient to determine the time to melt the plastic.

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  • Familiarity with differential calculus and its application in physics.
  • Knowledge of thermal conductivity for different materials, particularly paper and aluminum.
  • Basic concepts of heat capacity and its role in phase change processes.
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  • Study the derivation and application of the heat transfer equation dQ/dt = kTA dT/dx.
  • Learn how to calculate thermal conductivity for composite materials.
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David McKnight
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How could I calculate how much time would be required to melt a plastic through a composite material?

Composite is .005 inches paper and .0003 inches of Aluminum
Plastic is .001 inches polyethlene with melting point of 325 F

Assume heat source is uniform across area of composite
 
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According to the Physics Forums Guidelines (which you agreed to), you have to show how you started this problem.
 
What I've done so far is research and realized my ability of working with differential calculus is lacking. But I do believe that the equations needed are:

dQ/dt = kTA dT/dx

1/kT=1/kPaper +1/ kAlu (so I can figure this out)

A = 2pi 4 inches (1/8 inches)

dQ/dt = the power supplied to the paper side which 1500 W – but I need to solve for dt (not sure how to re-arrange diff calc formula)

dT/dx = (350-73) F to 25 F (So heat source is set at 350 F and the melt point of plastic is 325 F)

I believe I need to consider the heat capacity of the plastic but I’m not sure where – should it be added to the (kT) formula?
 

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