# Heat transfer problem

1. Oct 20, 2005

### David McKnight

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

2. Oct 20, 2005

### Tom Mattson

Staff Emeritus
According to the Physics Forums Guidelines (which you agreed to), you have to show how you started this problem.

3. Oct 21, 2005

### David McKnight

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 ā 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 Iām not sure where ā should it be added to the (kT) formula?