Understanding the Critical Parameters of the PAMS Mandrel Fabrication Process

In this paper, we describe the reasoning that leads us to focus on the so-called curing process where a solid poly(a-methylstyrene) (PAMS) shell is formed from the initial solution phase. We demonstrate the existence of a percolation zone at about 55 wt% PAMS, beyond which the roundness of the shell can be expected to be irreversible. Using a simple model and a few supporting experiments to account for the rate of mass transfer of the fluorobenzene solvent phase, we show that curing rate is determined almost entirely by just a short exposure, to the sweeping gas, of the shells that graze the free surface of the curing bath as they move around in it. We propose here that specific control of the curing conditions at percolation would enable rounder mandrels.