Abstract
A cantilever deflection technique was used to monitor stress in sim during drying of cellulose acetate coatings. Porosity was introduced in some coatings using dry-cast phase separation. Stress and weight loss profiles for dense coatings, a coating that contained small (∼1 μm) pores, and a coating that contained small (∼1 μm) pores and macrovoids (∼200 μm) are compared. In-plane tensile stress after drying ranged from 30 MPa (dense coatings) to 5 MPa (macrovoid-containing coating). The stress profiles for dense coatings feature a period of rapidly and then slowly increasing stress due to constrained shrinkage. For a coating that formed small pores, drying and stress development are delayed, stress rises and then drops a small amount due to capillary pressure relief. The stress profiles for the small pore and macrovoid-containing coatings are similar, except for a stress plateau at early stages of drying, which may be caused by macrovoid growth.
Original language | English (US) |
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Pages (from-to) | 2267-2277 |
Number of pages | 11 |
Journal | Polymer |
Volume | 43 |
Issue number | 8 |
DOIs | |
State | Published - Feb 18 2002 |
Keywords
- Coating stress
- Dry-phase separation
- Porosity