overview

1. Flow-induced crystallization of polypropyleneSTW progress, 21th of september 2011Tim van Erp, Gerrit Peters

2. overview • non-isothermal, multi-phase crystallization • effects of cooling rate • effects of pressure • flow-induced (non-isothermal, multi-phase) crystallization • experimental part • modeling part; discussion on parameters processing structure properties

3. PVT apparatus A = Outer pistonB = Inner rotating piston C = SampleD = Teflon sealing ring E = Cooling channelsF = Cooling channelsG = Thermocouples

4. processing protocol: FIC experiments Annealing 10 min @ 250°C Compressed air cooling @ ~1°C/s Isobaric mode Pressures: 100 – 500 – 900 – 1200 bar Short term shearing of ts = 1s Shear rates: 3 - 10 – 30 – 100 – 180 s-1 ∆T = Tm(p) – Tshear = 30 - 60°C

5. analysis PVT data normalizedspecific volume dimensionlesstransition temperature

6. analysis PVT data Deborah number (‘strength of flow’) WLF Temperature shift Pressure shift normalizedspecific volume dimensionlesstransition temperature Shear temperature

7. results ∆T = 30°C

8. results ∆T = 60°C

9. dimensionless transition temperature dimensionlesstransition temperature

10. flow regimes under non-isothermal conditions from spherulitic morphology to oriented structures

11. flow regimes under non-isothermal conditions saturation in crystallization temperature

12. overview • non-isothermal, multi-phase crystallization • effects of cooling rate • effects of pressure • flow-induced (non-isothermal, multi-phase) crystallization • experimental part • modeling part • quiescent crystallization • flow-inducedcrystallization

13. quiescent crystallization space filling Schneider rate equations Avrami equation nucleation density individualgrowth rate ‘number’ ‘radius’ ‘surface’ ‘undisturbed volume’ ‘real volume’

14. modeling flow effects on crystallization

15. flow-induced crystallization model total nucleation density (flow-induced) nucleation rate shish length (L) growth rate equations Avrami equation for ‘length’ ‘surface’ ‘undisturbed volume’ ‘real volume’

16. flow-induced crystallization model total nucleation density (flow-induced) nucleation rate shish length (L) growth rate equations Avrami equation for ‘length’ ‘surface’ ‘undisturbed volume’ ‘real volume’ experiment model

17. flow-induced crystallization model total nucleation density (flow-induced) nucleation rate shish length (L) growth rate equations Avrami equation very laborious and inaccurate work F. Custódio, PhD Thesis, 2008

18. FIC regimes total nucleation density (flow-induced) nucleation rate shish length (L) growth Avrami equation

19. prediction of FIC regimes Mismatch between experimental results and model in oriented regime

20. parameters gn and gl plane equation scaling parameter aT, aPrheological shift factors gn and gl arbitrary function of T and p?

21. critical stretch shish length (L) growth

22. critical stretch new definition for critical stretch criterium?

23. critical stretch new definition for critical stretch criterium?

24. prediction of FIC regimes Good agreement between experimental results and model

25. conclusions • characterization of flow enhanced (point-like) nucleation regime over wide range of processing conditions • characterization of FIC of oriented structures regime over wide range of processing conditions • extended dilatometry (PVT) proven to be a powerfull tool in characterizing flow induced crystallization