Paper Number
PO68 

Session
Poster Session

Title
Linear and non-linear rheology of PBT/PTHF segmented copolymers

Presentation Date and Time
October 11, 2017 (Wednesday) 6:30

Track / Room
Poster Session / Cripple Creek Ballroom

Authors (Click on name to view author profile)

1. De Almeida, André (INSA Lyon)
2. Baeza, Guilhem P. (INSA Lyon)
3. Vlassopoulos, Dimitris (FORTH-IESL)

Author and Affiliation Lines (in printed abstract book)
André De Almeida¹, Guilhem P. Baeza¹, and Dimitris Vlassopoulos^2
1INSA Lyon, villeurbanne, France; ²FORTH-IESL, HERAKLION, Greece

Speaker / Presenter 
De Almeida, André

Text of Abstract
Thermoplastic elastomers represent an important class of materials for the energy and the transport industries. While their molecular structure is reasonably well understood [1], a formidable challenge from the engineering point of view is the molecular understanding of their processing performance. In this work, we study the linear and non-linear rheology of segmented copolymer melts made of successive incompatible units of crystallizable polybutylene terephthalate (pBT) and poly-tetrahydrofuran (pTHF) [2] with varying pBT content (from 30 to 60% in weight). In particular, we examine the crystallization kinetics at different temperatures below their melting point by observing the time evolution of G’ and G’’ (as well as DSC thermograms) following quenching. Interestingly, while the general trend resembles the familiar Avrami S-shape, two steps of moduli growth are evidenced during the crystallization process, reflecting a change in the mechanism of crystal growth. By following the same quenching protocol during start-up experiments at different shear rates (performed by means of a cone-partionned-plate “CPP” setup), we observe an unusual strain hardening after a long period of steady stress. The latter scales roughly with strain and is attributed to induced structure of the pBT phase. Similar tests at different times (4min, 8min, 20min and 55min)) during the crystallization process support this scenario of structure formation.

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] Gabriëlse, W., M. Soliman, and K. Dijkstra, Microstructure and Phase Behavior of Block Copoly(ether ester) Thermoplastic Elastomers. Macromolecules, 2001. 34(6): p. 1685-1693.