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Correlations between relaxation time spectrum and melt spinning behavior of polypropylene. II: Melt spinning simulation from relaxation time spectrum
Author(s) -
Fulchiron R.,
Michel A.,
Verney V.,
Roustant J. C.
Publication year - 1995
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.760350610
Subject(s) - materials science , relaxation (psychology) , isothermal process , spinning , polypropylene , stress relaxation , thermodynamics , composite material , physics , psychology , social psychology , creep
Using an integral nonlinear constitutive equation including the Log‐Normal relaxation spectrum, the fiber‐spinning behavior of commercial polypropylenes is studied. The relaxation spectrum is strongly related to the molecular weight distribution. Moreover, by means of a finite element analysis, simulated stress and velocity profiles are obtained either in isothermal or nonisothermal cases. In the isothermal case, broadening the relaxation spectrum leads to more pronounced curvature of the velocity profile. In the nonisothermal case, the critical draw ratio is sensitive to the mean relaxation time which depends on both average molecular weight and distribution breadth. It is shown that increasing the average relaxation time leads to a less rapid growth of the velocity. Furthermore, this effect is less pronounced when the relaxation spectrum is wider.