Modeling Stress and Failure in Shrinking Coatings

Lei, Herong; Francis, Lorraine F.; Scriven, L. E.

doi:10.1557/proc-653-z10.5.1

Cited by 3 publications

(5 citation statements)

References 7 publications

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“…Above this concentration, the sample became too fluid‐like, and no meaningful G data could be obtained with the existing tensile testing machine. The shear modulus would drop sharply and approached zero when the solution concentration reached its stress built‐up concentration ϕ

_{s}^{*}

15. For the polyimide solution, the stress built‐up concentration was found to be ϕ

_{s}^{*}

= 0.39.…”

Section: Resultsmentioning

confidence: 99%

“…Hence, parameters σ and ϕ can be determined from the deformation gradients $F_\parallel^{\rm e}$ and F ⟂ by Eq. 19 through a series of calculation 14, 15…”

Section: Theoreticalmentioning

confidence: 99%

“…This model is applicable to a purely elastic coating film, but it fails when plastic deformation is not negligible. Lei and coworkers14, 15 proposed a more realistic one‐dimensional model to predict the drying‐induced stress with both elastic and plastic deformations included. Later Lei et al16 extended the model from one‐ to two‐dimensional by including the boundary effects.…”

Section: Introductionmentioning

confidence: 99%

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Drying‐induced birefringence of polyimide optical films

Chen

Liu

et al. 2009

AIChE Journal

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Drying-induced birefringence of polyimide film was investigated. The polyimide solutions were coated and dried on two different types of substrates and then removed for optical measurements. The operating window, which was a region for stable and uniform film formation, was determined experimentally. The out-of-plane birefringence (OPBR) was found to increase with decreasing dry film thickness, and the increase became more significant for films less than 10 lm thick. The experimental OPBR results were compared with the predictions of two theoretical models. The results agreed reasonably well with the one-dimensional model of Lei et al. (J Appl Polym Sci. 2001;81:1000-1013. On the other hand, a simple viscoelastic model, which is an extension of the elastic model of Croll (J Appl Polym Sci. 1979;23:847-858), could provide clear physical insight, but its applicability was somewhat limited. The effects of several variables such as elasticity number, solidification concentration, yield stress, and mass transfer rate on OPBR were examined. V

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_{s}^{*}

15. For the polyimide solution, the stress built‐up concentration was found to be ϕ

_{s}^{*}

= 0.39.…”

Section: Resultsmentioning

confidence: 99%

“…Hence, parameters σ and ϕ can be determined from the deformation gradients $F_\parallel^{\rm e}$ and F ⟂ by Eq. 19 through a series of calculation 14, 15…”

Section: Theoreticalmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Drying‐induced birefringence of polyimide optical films

Chen

Liu

et al. 2009

AIChE Journal

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“…The volume fraction of solvent at solidification point / s can be obtained by extrapolating from the Young's modulus E versus the solvent content / ms plot at E ¼ 0 [51]. This plot must be determined experimentally.…”

Section: Modelsmentioning

confidence: 99%

Operating window for the peeling of polyimide film

Wang

Liu

et al. 2009

Polymer Engineering & Sci

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The peeling behavior of polyimide film coated on steel substrates was experimentally investigated and compared with existing models. An operating window for peeling, which is defined as a closed domain for steady and defect-free peeling, is presented in terms of peeling force versus residual solvent content. The window is bounded by two major defects: the film becomes too brittle for peeling at high peeling force, and stick-slip striation defect appears at low peeling force. There exists a critical residual solvent content below which the adhesion between the polyimide film and the substrate is too strong and then peeling is impossible. Existing models for predicting steady peeling and the onset of peeling defects have been modified and applied to setup the boundaries of the operating window. There also exists another operating window for drying of polyimide and is presented in the form of drying temperature versus film thickness.FIG. 12. The SEM images of stick-slip striation defects during peeling. (a) T ¼ 1208C, t ¼ 15 lm, v ch ¼ 10 mm/min, residual solvent content ¼ 11.9 wt% and (b) T ¼ 1808C, t ¼ 28 lm, v ch ¼ 2 mm/min, residual solvent content ¼ 7.3 wt%.

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“…16 and 26 are solved for the current viscoplastic deformation gradient by using the backward time difference scheme. Lei, 1999 was designed based on the above analysis for 2-D drying and stress development under plane-strain conditions. The flow chart of the program is shown in Figure 4.…”

Section: H Hmentioning

confidence: 99%