Abstract
Effects of surface topology and energy on the stick-slip transition were studied in capillary flow of highly entangled polyethylene (PE) melts. Surface roughness was shown to increase the critical stress of the stick-slip transition because of the increased resistance to interfacial disentanglement. Lowering the surface energy of a smooth die wall by treatment with a fluorocarbon completely eliminates the stick-slip transition and produces massive interfacial slip at PE/wall boundary down to a stress level of 0.05 MPa. On the other hand, considerable roughness on the same low energy surface can produce a stick hydrodynamic boundary condition and restore the stick-slip transition despite the weak PE/wall interfacial interactions. Additionally, a slip-slip transition was found in the die with a nearly non-adsorbing wall that appears to involve a secondary chain-debonding process.
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Wang, SQ., Drda, P.A. Stick-slip transition in capillary flow of linear polyethylene: 3. Surface conditions. Rheola Acta 36, 128–134 (1997). https://doi.org/10.1007/BF00366818
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DOI: https://doi.org/10.1007/BF00366818