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We investigated the stress−strain behavior of PMMA films under compressed CO2 and N2. The elongation at break increased and the stress decreased with increasing CO2 pressure at pressures above 3 MPa, indicating that the tensile property changed from brittle to ductile under compressed CO2. In contrast, the material property became more brittle under compressed CO2 at pressures below 2 MPa and under compressed N2. By depressurizing the compressed gas and excluding the hydrostatic pressure, the property of the gas‐absorbed specimen changed from brittle to ductile. These results suggest that deformability by molecular orientation is enhanced by the plasticizing effect caused by a large amount of absorbed gas while it is suppressed by the effect of hydrostatic pressure caused by a small amount of absorbed gas. Conversely, the elastic modulus decreased under both compressed CO2 and N2, but the decrease under CO2 was much larger than that under N2, suggesting that distortion in the elastic region is dominated by the plasticization effect. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43431.

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We investigated the stress-strain behavior of low molecular weight polycarbonate for optical disc grade (OD-PC) under carbon dioxide (CO 2 ) at various pressures, and compared the results with that under ambient pressure at various temperatures. Elongation at break decreased sharply with increased CO 2 pressure at around 2 MPa, while the elastic modulus decreased gradually up to 6 MPa. These results indicate that the tensile property changed from ductile to brittle with increased CO 2 pressure, although the molecular motion is accelerated due to the plasticization effect of CO 2 . Such ductile-to-brittle transition is similar to that observed under elevated temperatures caused by chain disentanglement due to accelerated molecular motion. Although the changes of tensile properties were similar, the craze structure obtained by the brittle behavior was different, i.e., a filamented-craze structure was obtained under high-pressure CO 2 , while a lace-like one was obtained under elevated temperatures. POLYM. ENG. SCI., 58:683-690, 2018.

This report demonstrates the use of scanning tunneling microscopy and atomic force microscopy to obtain surface roughness parameters for semiconductor materials. Correlation between figures of merit and physical properties such as bondability and reflectivity has been demonstrated. Eutectic bond strength for silicon die attachment is shown to be inversely proportional to the roughness of the backside of the silicon die. Reflectivity of aluminum metallization has been shown to decrease with increasing roughness. We also illustrate that in some metal systems the surface structure is independent of the grain size as determined by planar transmission electron micrographs. Our work relies heavily on generating numerical data, which can be used to understand critical relationships and develop processing solutions.