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Formation of thermally induced craze and prevention by using infrared radiation annealing method
Author(s) -
Kim Seong Yun,
Kim Sung Ho,
Pak Seong Yeol,
Youn Jae Ryoun
Publication year - 2012
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.36351
Subject(s) - crazing , materials science , residual stress , annealing (glass) , composite material , infrared , polymer , stress (linguistics) , thermal , optics , thermodynamics , linguistics , philosophy , physics
It is important to study the residual stress distribution and craze formation of transparent overmolded polymeric parts, because the overmolding can cause stress concentration near the interface region and the craze can be generated by the concentrated stress. Thermally induced crazing of an electric appliances product overmolded by using a transparent polymer is discussed in this study. Craze criterion was determined to be 20 MPa at the temperature higher than 60°C by using mechanical characteristic analysis of the polymeric material. Crazes were observed in the product annealed at over 60°C due to thermal residual stresses generated by the temperature difference between the surface and inside of the part upon surface heating. However, they were not observed in the product annealed by infrared radiation (IR) at over 60°C due to simultaneous heating throughout the thickness of the product. The numerical residual stress results were in good agreement with the experimental results, indicating that overmolding process, thermoviscoelastic stress development of the polymeric part, and IR annealing process were considered properly in the three‐dimensional numerical analysis. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012