Abstract
The mechanism of mass transport and associated crystallization in polycarbonate (PC) were studied. Based on Harmon's model for case I (or Fickian), case II (or swelling), and anomalous transport, the data of the initial period of mass uptake were analyzed. Due to the initially small dimensional variation of the PC and the initially small amount of crystallization, the influence of crystallinity on the mass transport can be ignored. The diffusivity in case I and the velocity in case II both followed the Arrhenius relationship. Case II dominated the transport process as the activation energy of case II is lower than that of case I. This finding was further verified by measuring the movement of diffusion fronts with a carefully selected observation coordinate. A distinct transport front was identified from the measurements of optical microscope and the microhardness. This investigation addresses more complicated microstructures of PC during mass transport. © 2004 American Institute of Physics.