Paper Number
VP80 

Session
Pre-recorded Flash Presentations (virtual)

Title
Determination of the molecular weight distribution of ultra-high molecular weight polyethylene from solution rheology

Presentation Date and Time
All Week (Asynchronous) Any Time

Track / Room
Pre-recorded Presentation / Virtual

Authors (Click on name to view author profile)

  1. Ianniello, Vincenzo (University of Naples Federico II, Department of Chemical, Materials and ProductioN Engineering)
  2. Costanzo, Salvatore (University of Naples Federico II, Chemical, Materials and Industrial Production Engineering)
  3. Pasquino, Rossana (University of Naples Federico II, Chemical, Materials and Industrial Production Engineering)
  4. Ianniruberto, Giovanni (Federico II University, Department of Chemical, Materials and Production Engineering)
  5. Tervoort, Theo (ETH Zurich, Department of Materials)
  6. Grizzuti, Nino (University of Naples Federico II, Chemical, Materials and Industrial Production Engineering)

Author and Affiliation Lines (in printed abstract book)
Vincenzo Ianniello1, Salvatore Costanzo1, Rossana Pasquino1, Giovanni Ianniruberto1, Theo Tervoort2 and Nino Grizzuti1
1Department of Chemical, Materials and ProductioN Engineering, University of Naples Federico II, Napoli, Italia 80125, Italy; 2Department of Materials, ETH Zurich, Zurich, Zurich 8093, Switzerland

Speaker / Presenter 
Ianniello, Vincenzo

Keywords
experimental methods; theoretical methods; computational methods; applied rheology; polymer solutions; rheology methods

Text of Abstract
The rheological determination of material properties of polymers (molecular weight distribution, degree of branching, etc) is not always easy to pursue. In particular, when dealing with Ultra-High Molecular Weight (UHMW) polymers, the rheological measurements can be affected by experimental limitations (shear fracture, torque overload, temperature investigation range, loading problems). Diluting the polymer melt into an appropriate solvent [1] may overcome, or at least limit, these experimental issues. In this perspective, rheology can be used as a tool to relate the macroscopic viscoelastic response of polymer systems to their molecular architecture. The aim of this work is to determine the Molecular Weight Distribution (MWD) of a UHMW Polyethylene (UHMWPE) by extrapolating it from the linear viscoelastic response of UHMWPE solutions in a suitable solvent, namely, Low Molecular Weight Polyethylene (LMWPE). The pure melt is dissolved in a LMWPE and the rheological measurements are performed in a concentrated regime. Once we verified the scaling laws of the main rheological parameters (plateau modulus, relaxation time, zero-shear viscosity) as function of concentration, we are able to extrapolate the linear viscoelastic response of the pure melt. The analysis of rheological results is performed by using the time-dependent diffusion/double reptation model introduced by van Ruymbeke [2]. This model allows to determine the molecular wight distribution of the melt starting from the linear rheological behaviour of a melt or solution [3]. The MWD results of the model are compared from those obtained independently on the UHMWPE melt. References [1] A. Brem et al., Macrolecules, 53, 5957-5970, 2020; [2] E. van Ruymbeke et al., Journal of Non-Newtonian Fluid Mechanic, 105, 153–175, 2002; [3] K. Chaudhuri and A.K. Lele, Journal of Rheology, 64, 1-12, 2020. Acknowledgement This work forms part of the research programme of DPI, project #834