Segmental mobility and glass transition of poly(ethylene-vinyl acetate) copolymers: Is there a continuum in the dynamic glass transitions from PVAc to PE?. (12th October 2015)

• Record Type: Journal Article
• Authors: Puente, J.A.S.; Rijal, B.; Delbreilh, L.; Fatyeyeva, K.; Saiter, A.; Dargent, E.
• Is Part Of: Polymer. Volume 76(2015)
• Page Start: 213
• Page End: 219
• Publication Date: 2015-10-12
• Subjects: Amorphous phase -- Dynamic glass transition -- Poly(ethylene-vinyl acetate); Polymers -- Periodicals; Polymerization -- Periodicals; Polymères -- Périodiques; Polymérisation -- Périodiques; 547.7
• DOI: 10.1016/j.polymer.2015.09.007
• Languages: English
• ISSNs: 0032-3861

Abstract

Abstract: The segmental dynamics of amorphous poly(ethylene-vinyl acetate) copolymers (from PVAc to EVA50) were studied. In that sample set with similar backbone stiffness and different amount of dipoles, the dynamic glass transition was investigated by Modulated Temperature Differential Scanning Calorimetry and Broadband Dielectric Spectroscopy measurements. A decrease of the cooperativity length scale was obtained with the vinyl acetate (VAc) content decreasing. On the other hand, there was no modification of the temperature dependence of the relaxation time. Thus, the fragility value is quite constant whatever the VAc content. These results show that fragility and cooperativity have two different origins. An extrapolation to nonconstrained polyethylene amorphous phase was proposed and new glass transition temperature and fragility values were determined. Graphical abstract: Highlights: Amorphous phase mobility is studied for poly(ethylene-vinyl acetate) copolymers. Fragility is constant from PVAc to EVA50 while cooperativity length decreases. New extrapolated T g and fragility values are proposed for PE. Fragility and cooperativity are not governed by the same macromolecular properties.