Reference no: EM132787708

A certain grade of polyethylene in the molten state obeys the following equations of state linking pressure P (in Pa), specific volume v (in m3/kg), and absolute temperature T in K. (10-3 + 3.2 × 105)(103 - 0.822) = 290 In the solid state, at 20°C the density is 970 kg/m3.

1) Find the free linear shrinkage of a block of polyethylene on cooling uniformly from 130°C to 20°C.

2) If it is injection moulded, find the packing pressure required in a moulding which is sealed with the melt at 130°C, to ensure that the linear mould shrinkage on cooling to 20°C does not exceed 2% (Assume uniform, i.e. slow, cooling)