Paper Number
SG22 

Session
Self-assembled Systems, Gels and Liquid Crystals

Title
Influence of thermal and deformation history on the viscoelastic properties of well-defined entangled segmented copolymers

Presentation Date and Time
February 14, 2017 (Tuesday) 2:20

Track / Room
Track 3 / White Ibis

Authors (Click on name to view author profile)

1. Baeza, Guilhem P. (Foundation for Research and Technology Hellas - FO.R.T.H, Institute of Electronic Structure and Laser)
2. Sharma, Ashwinikumar (Université catholique de Louvain, Bio and Soft Matter, Institute on Condensed Matter and Nano-)
3. Louhichi, Ameur (Foundation for Research and Technology - FORTH, Institute of Electronic Structure and Laser)
4. Fitié, Carel (DSM Ahead, DSM Engineering Plastics)
5. Goldansaz, Hadi (Université catholique de Louvain, Bio and Soft Matter, Institute on Condensed Matter and Nano-)
6. Vlassopoulos, Dimitris (Foundation for Research and Technology - FORTH, Institute of the Electronic Structure and Laser)
7. Van Ruymbeke, Evelyne (Université catholique de Louvain, Bio and Soft Matter, Inst. on Cond. Matter and Nano-science)

Author and Affiliation Lines (in printed abstract book)
Guilhem P. Baeza¹, Ashwinikumar Sharma², Ameur Louhichi¹, Carel Fitié³, Hadi Goldansaz², Dimitris Vlassopoulos¹, and Evelyne Van Ruymbeke^2
1Institute of the Electronic Structure and Laser, Foundation for Research and Technology - FORTH, Heraklion, Crete 70013, Greece; ²Bio and Soft Matter, Inst. on Cond. Matter and Nano-science, Université catholique de Louvain, Louvain-la-Neuve B-1348, Belgium; ³DSM Engineering Plastics, DSM Ahead, Geleen 6167RD, The Netherlands

Speaker / Presenter 
Baeza, Guilhem P.

Text of Abstract
We explore the role of chain rigidity in thermoplastic elastomers (TPE) consisting of segmented copolymers [1] based on soft poly-tetrahydrofuran (pTHF) blocs and more rigid crystallizable T4T units [2] (called “hard-segments” HS). By means of X-rays scattering techniques (SAXS and WAXS) as well as differential calorimetry (DSC), we first evidence that the ribbon-like crystallites made of HS become thicker (1 to 5 nm) and tend to spontaneously align at a 10-50 nm lengthscale when the HS content passes from 5 to 20%w in the material. Based on these results and statistical calculations, we discuss the impact of the chain rigidity on the rheology of the TPEs in a systematic way. First, small amplitude oscillation shear (SAOS) shows a strong increase of both the plateau modulus (from 1 to 30 MPa) and the melting point Tm (from 90 to 160°C) respectively for 5 and 20%HS. Then, cyclic strain amplitude sweeps performed around Tm evidence the crucial role of the chain segments mobility on the HS network building. While at T>Tm, the chains seem to associate under shear making the material stiffer, the crystallite network is irreversibly destroyed after one cycle at T<Tm and its modulus keeps on decreasing with further solicitations. More interestingly, at intermediate temperature (slightly below Tm), our experiments reveal that a structure can raise in the first few cycles before to collapse after a long solicitation. All the authors acknowledge the financial support of the European Initial Training Network “SUPOLEN”.

References: [1] Gaymans, R.J., Segmented copolymers with monodisperse crystallizable hard segments: Novel semi-crystalline materials. Progress in Polymer Science, 2011. 36(6): p. 713-748. [2] Vanhutten, P.F., R.M. Mangnus, and R.J. Gaymans, Segmented Copolymers with Polyesteramide Units of Uniform Length - Structure-Analysis. Polymer, 1993. 34(20): p. 4193-4202.