A diffusional interphase in layered polyesters

• Published in: Journal of applied polymer science Vol. 59; no. 2; pp. 263 - 267
• Main Authors: Shah, Chirag B., Rockett, Thomas J.
• Format: Journal Article
• Language: English
• Published: New York Wiley Subscription Services, Inc., A Wiley Company 10.01.1996; Wiley
• Subjects: Applied sciences; Exact sciences and technology; Forms of application and semi-finished materials; Laminates; Polymer industry, paints, wood; Technology of polymers; Laminate; Alkyd resin; Experimental study; Property processing relationship; Thickness; Structure processing relationship; Interface structure; Interface properties; Optical properties; Morphology; Birefringence; Unsaturated polymer; Phthalate polymer
• ISSN: 0021-8995; 1097-4628
• DOI: 10.1002/(SICI)1097-4628(19960110)59:2<263::AID-APP10>3.0.CO;2-Y

The properties of the birefringent interphase in the laminates of unsaturated polyester resin were characterized using polarized microscopy and a birefringence compensation technique. The thickness of the interphase was found to depend on the casting conditions, and values ranging from 0.004 to 0.25 mm were observed. The location and dependence of the thickness on the curing conditions suggested that the interphase formed due to the diffusion of constituents from the liquid resin of the second layer into the previously cured layer. The index of refraction of the interphase was higher than that of the polyester above and below it. There was a sharp front marking a boundary of the interphase from the rest of the resin. These observations indicated characteristics of non‐Fickian interfacial diffusion. Qualitative estimation of the birefringence in the interphase by interference colors indicated the first‐order optical retardation. The birefringence was hypothesized to be due to residual stresses resulting from the fabrication procedure. The birefringence was quantified using a Berek compensator to measure the stresses. The approximate stress values were found to be in the range of 10–40 MPa. © 1996 John Wiley & Sons, Inc.