Abstract
In this short review we discuss experimental results on molecular motion in polymer melts, obtained by neutron spin echo spectroscopy (NSE). We show that in the short-time regime the assumption of entropic restoring forces (Rouse model) describes perfectly well the space and time dependence of self- and pair-correlation functions of one chain molecule. For longer times or stronger geometrical constraints we observe systematic deviations from the Rouse model revealing the presence of a well-defined intermediate dynamical length scale beyond which density fluctuations within a given chain are strongly reduced. Its value is found to be in excellent agreement with the entanglement distance obtained from rheological measurements. Measurements of the temperature dependence of the entanglement distance, the radius of gyration and the plateau modulus give first insight into the molecular origin of entanglement constraints. The data favour packing models and contradict the topological approach.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
