A fluorescence method was adapted to measure moisture-uptake kinetics in films of poly(methyl methacrylate), and data were interpreted in the context of a Fickian diffusion model. The films, 2-60 m thick, were supported on acid-etched microscope slides. They were compared with several freestanding slabs about 1 mm thick. The moisture diffusion in the slabs was Fickian with a diffusivity of 3.2 ϫ 10 Ϫ9 cm 2 /s. The apparent Fickian diffusivity in the films decreased substantially with decreasing film thickness; however, a careful examination revealed that the initial moisture uptake was governed by a thicknessindependent diffusivity for a wide range of film thicknesses.This suggested that the appearance of non-Fickian behavior originated within about a micrometer of the buried interface, possibly as a result of water accumulation beneath the film or slight thickness variations. Moisture uptake in the thickest films was more rapid than in the slabs, most likely because of residual thermal stresses.

As a part of the IMI-NFG's series of low-cost experiments in glass science [1,2] we have developed a simple home-built apparatus for measuring the thermal conductivity of glassy materials, from polymers to oxide glasses, in the range of 0.1 to 1.5 W/ °C. Our apparatus is inexpensive, relatively easy to construct and accurate enough for students to use for quantitative measurements of their own glass or polymer samples. Standard materials are used to demonstrate good correlation with literature values. We also measured the thermal conductivity of a silica filled epoxy and showed a linear increase with fill fraction to 20%. This simple, lowcost method can provide students and researchers with a much broader access to this important property.