Crazing in Two and Three Dimensions. 1. Two-Dimensional Crazing

Krupenkin, T. N.; Fredrickson, Glenn H.

doi:10.1021/ma981014g

Cited by 32 publications

(55 citation statements)

References 44 publications

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“…13 That is, for identical stress states, PS films with thickness greater than 150 nm show a craze microstructure that is similar to that of the bulk. In contrast, for PS films below 150 nm, the craze microstructure, described as a perforated sheet with craze fibril diameters of up to 100 nm, 13,14,26 is markedly different compared to the bulk. The volume fraction (φ) of the craze material in thin films is significantly greater (φ ) 0.33-0.5) in comparison to thick films (φ ) 0.15-0.25, as measured by transmission electron microscopy).…”

Section: Background: Crazes In Thin Polymer Filmsmentioning

confidence: 92%

High-Throughput Craze Studies in Gradient Thin Films Using Ductile Copper Grids

2004

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Polymer materials are being developed and used for numerous photonic and electronic applications where the polymer is expected to maintain its dielectric properties in confined geometries. In these applications, the initiation or growth of mechanically induced defects, such as crazes, cracks, or shear bands, can significantly alter the intended function of the polymer. In this paper, we introduce a high throughput methodology to facilitate the investigation of craze growth in confined films. Specifically, we extend the previous research conducted on the effects of film thickness on crazing of polystyrene into unexplored thickness regimes of films less than 100 nm. We combine novel techniques of gradient thin film preparation, the established methodology of the copper grid strain test, the automated features of atomic force microscopy, and batch image processing to provide increased throughput and standardization in our quantitative measurements. We demonstrate that the mechanisms of craze widening and micronecking are quantitatively continuous to film thicknesses as thin as 50 nm.

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Section: Background: Crazes In Thin Polymer Filmsmentioning

confidence: 92%

High-Throughput Craze Studies in Gradient Thin Films Using Ductile Copper Grids

2004

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“…For thin film polymers, a craze can be described as a localized defor mation zone (analogous to a necking zone during ductile yielding) with a superimposed fibril structure. 50 Crazes are load bearing as their surfaces are bridged by nanometer-sized fibrils [ Fig. 2(A,B)].…”

Section: Crazing and Craze Growthmentioning

confidence: 99%

Aspects of fatigue failure mechanisms in polymer fuel cell membranes

Kusoglu

Santare

Karlsson

2011

J Polym Sci B Polym Phys

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The swelling‐driven fatigue behavior of polymer fuel cell membranes during relative humidity (RH) cycling is investigated. In particular, swelling‐induced membrane stresses are obtained from a numerical model simulating fuel cell RH cycle tests, and compared to the lifetimes obtained experimentally from tests conducted in the absence of electrochemical effects. A strong correlation between the lifetimes of the membranes in the actual tests and model results is obtained. In general, higher RH (or swelling) amplitude results in larger stress amplitudes and shorter lifetime, that is, fewer cycles to failure. Tensile stresses are needed for forming local cavities in the membrane, which may eventually lead to craze formation. Cavitation is less likely to occur in compressed membrane at high humidities. The stress–lifetime plots for polymer fuel cell membranes exhibit similar features to those observed for other polymers. The crazing criterion for polymers suggests that craze initiation during RH cycling is more likely to occur in the low compression regions, such as under the channels, which is in agreement with experimental observations. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 49: 1506–1517, 2011

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“…The SDZ is a thinning or neck that forms in the film. The SDZ appears qualitatively different from a craze observed in bulk systems because the constraint in the normal direction of a film is relaxed [10,11,[13][14][15]. The extension ratio, , is an important property of a craze or SDZ and is the ratio of the width of the material that went into forming the deformation to the width of the deformed region after an applied strain.…”

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confidence: 99%