Understanding the interrelation between stress response and microstructural evolution in polymers during deformation is key for engineering premium products from a bottom-up approach. We use a suite of in-situ probes to investigate different aspects of structure development during uniaxial deformation in semicrystalline polymers and polymer melts. In particular, small-angle neutron scattering (SANS) is a very powerful tool, as it provides information about single chain conformation as well as orientation and alignment induced by external fields such as shear flow or elongation. In this talk, I will present an example of the use of in-situ time-resolved SANS measurements during uniaxial deformation of polymer melts subjected to startup and cessation of uniaxial extensional flow. The fast relaxation of the melts constitutes a challenge for time-resolved measurements. I will discuss the approach we use to overcome such challenges, which include the use of state-of-the-art protocols for stroboscopic SANS data collection in combination with commercial rheometers. Our measurements allowed us to correlate chain alignment and extensional rheology of a series of bimodal polystyrene blends, which led to the development of a stress-SANS rule in extension.

Polymer chain stretching during uniaxial deformation: An <i>in-situ</i>, time-resolved SANS study in polymer melts

253rd National Meeting (2017)

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Polymer chain stretching during uniaxial deformation: An in-situ, time-resolved SANS study in polymer melts