2. It is desired to bond together two sheets of a solid material, each of thickness b=0.77cm. This is done by using a thin layer of thermoplastic material, which fuses and forms a good bond at 160C. The two plates are inserted in a press as shown in the figure, with both platens of the press maintained at a constant temperature of 220C. How long will the sheets have to be held in the press if they are initially at 20C ? The solid sheets have a thermal diffusivity of 4.2103cm2/sec