(Color online) Three dimensional AFM image of inflated bubbles. The scan area is . The image is of a PVAc film at a thickness of , a pressure of , and at a temperature of .
(Color online) Schematic drawing of the experimental setup showing the AFM, the pressure cell, heating elements, and pressurizing unit.
(Color online) Three dimensional AFM image of a coated unpressurized template after annealing at . The film is thick and is scanned at a temperature of . Capillary forces have drawn the film into the hole to a depth of approximately .
Schematic of the areas scored on the template and of the scoring process. The score marks are made by lightly drawing a single edged razor blade over the template. The edges of the score mark are used in determining the film thickness.
A scan line over the edge of the score mark (filled triangles). An identical data set (open circles) has been offset such that the level of the template surface aligns with the film surface. The offset amount thus gives the film thickness.
(Color online) (a) Schematic of the assembled pressure cell showing the position of the template and electromagnet. (b) Photograph of the assembled pressure cell with the thermocouple attached. (c) The assembled pressure cell attached to the AFM.
Centerline profile plots of a bubble at three widely separated times. Open circle, filled circle, and open square at , and , respectively.
(Color online) (a) Schematic showing tip convolution with the uncovered hole. (b) Schematic showing how tip convolution prevents the acquisition of the bubble shape at the edge of the bubble and how, as the bubble grows, more of the bubble towards the hole edge is imaged.
The centerline profile plots from Fig. 7 with the extraneous points removed. Open circle, filled circle, and open square at , , and , respectively.
Fits to the bubble height data (filled circles) assuming clamped plate (short dashed), simply supported plate (dot dashed), and membrane (solid) deformations.
Membrane fit (long dashed line) to the bubble data (open circles), extrapolated to the hole wall. The solid line is a membrane fit to the data with extrapolation to the known zero level of the film using Eq. (9). The two fits allow an estimation of the error in the strain.
The effect of the force setpoint (FSP) on the bubble shape in contact mode. A setting of (filled circles) gives a nonsymmetric bubble profile. Decreasing the force (, open triangles) gives a more symmetrical bubble and larger bubble. Increasing the force (, open circles) causes the AFM tip to push the membrane into the hole.
The effect of the force setpoint on the bubble shape in tapping mode. A range of force setpoint (FSP) from shows no change in the bubble shape, showing that tapping mode does not distort the bubble.
The centerline profile plots for a thick polystyrene (PS) film at and a pressure of . Filled circle, open triangle, and filled square are at , , and , respectively.
Radius of curvature and strain as a function of time for a thick polystyrene (PS) film at a pressure of and at temperatures of (filled circle), (open circle), and (filled triangle). The solid lines in the strain data are best fits to the strain using the model given in Eqs. (5) and (6), from which the material properties can be determined.
The calculated stress for the data in Fig. 15 plotted vs log time. Also shown is the fit to the stress data using Eqs. (11a)–(11d). The inset shows the linear increase in stress for the first .
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