Numerical Investigation of Die Swell Behavior in EPDM Rubber Extrusion: Effects of Compound Formulation and Processing Conditions.
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| Title: | Numerical Investigation of Die Swell Behavior in EPDM Rubber Extrusion: Effects of Compound Formulation and Processing Conditions. |
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| Authors: | Sun, Yancai1,2,3,4 (AUTHOR), Wang, Haoran2,5 (AUTHOR), Jiang, Jingtao3,6 (AUTHOR), Wang, Kongshuo4,7 (AUTHOR), Bai, Wenjuan1,5 (AUTHOR), Chu, Dianming1,4,6 (AUTHOR), Jian, Ranran1,7 (AUTHOR), Hou, Peiwu1,8 (AUTHOR), He, Yan1,8 (AUTHOR) heyan@qust.edu.cn, Deng, Wenzhong2,3 (AUTHOR) |
| Source: | Polymers (20734360). May2026, Vol. 18 Issue 9, p1122. 22p. |
| Subjects: | Extrusion process, Viscoelasticity, Rubber chemistry, Ethylene-propylene rubber, Applied sciences |
| Abstract: | Die swell is the dominant source of dimensional deviation in rubber profile extrusion. Because it is driven by recoverable elastic strain, a purely viscous baseline flow field cannot reproduce its speed dependence; a viscoelastic correction is required. This study presents, to the best of our knowledge, the first controlled comparison of a Carreau–Arrhenius baseline flow field against a fractional-order viscoelastic correction for carbon-black-filled EPDM across an industrial speed window. The viscoelastic correction (PyCFD-FMM) is a post-processing fractional-order viscoelastic swell correction built on the shared non-isothermal Polyflow Carreau–Arrhenius flow field, derived from a six-mode fractional Maxwell model parameterized from dynamic mechanical analysis via the Laun rule and closed through the Tanner recoverable-strain theory. Three carbon-black-filled EPDM compounds (Shore A 60–80) were extruded at four screw speeds (15–30 rpm) under instrumented conditions. Experimentally, swell ratios of 1.12–1.15 increase monotonically with screw speed (Fisher-combined p = 0.007 ; measurement repeatability CV ≤ 0.27 % across n = 4 replicates per condition). The purely viscous baseline output gives a decreasing apparent swell–speed trend—opposite to experiment—whereas PyCFD-FMM recovers the correct increasing trend for all compounds. Under single-anchor hold-out evaluation at 20/25/30 rpm, the non-anchor MAPE decreases from 0.99% for the baseline flow-field output to 0.30% (PyCFD-FMM); an anchor-sensitivity check over all four rpm choices keeps the compound-averaged non-anchor MAPE within 0.27–0.39% and preserves the correct slope sign in every case. Swell decomposition into geometric baseline and net correction factor ( B PyCFD = B geom × f corr ) confirms that the viscous baseline flow field captures flow-geometry effects but carries no elastic memory. Within the tested window, the viscoelastic correction meets a dual-gate criterion—correct slope sign and reduced non-anchor MAPE—which the purely viscous baseline cannot satisfy by construction. [ABSTRACT FROM AUTHOR] |
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| Database: | Engineering Source |
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