Poly(ethyl methacrylate-co-hydroxyethyl acrylate) random co-polymers: Dielectric and dynamic-mechanical characterization

Abstract

The conformational mobility in poly(ethyl methacrylate-co-hydrxyethyl acrylate) co-polymers was studied by dielectric relaxation spectroscopy, thermally stimulated depolarization currents and dynamic-mechanical experiments. The relaxation strength and the shape of the dielectric relaxation spectra of the homopolymer and co-polymer networks were analyzed using the Havriliak-Negami equation. The dependence of the relaxation strength on co-polymer composition and temperature was analyzed taking into account the merging of the main and the secondary relaxation processes. The shape of the e 00 versus frequency plots led to the conclusion that the distribution of relaxation times was broader in the co-polymers with intermediate composition than in the homopolymers, a feature that can be explained by the inhomogeneity produced at molecular scale by the sequence distribution of the monomeric units along the chain. Master curves were built both for the elastic modulus and the mechanical loss tangent, and the temperature dependence of the relaxation times was deduced from the shift factors. The fit to the Vogel equation permitted the calculation of the strength parameter, which is higher in the co-polymers that the simple average of the values of the homopolymers, a feature that can be related to the broadness of the distribution of relaxation times.

Computing thermomechanical properties of dry homopolymers used as raw materials for formulation of biomedical hydrogels

“…We can assume that this assumption holds for HEA at temperature well below the glass transition temperature. The storage modulus of HEA crosslinked with 1%weight of ethylene glycol dimethacrylate was indeed evaluated from dynamic mechanical analysis at 3000 MPa at 240 K (T g (HEA) = 300 K) [39], in agreement with the group contribution predicted value. However, the result for polyacrylamide seems abnormally high even for 0 GPa.…”

Physical properties of epoxy resin/titanium dioxide nanocomposites

“…The nanofiller agglomeration did not considerably affect the mechanical performance of the composites at cryogenic temperatures. Upon increasing the temperature, G ′ variation showed a step‐like decrease, which is associated with the glass transition [44]. At higher temperatures, the onset of the rubbery plateau corresponds to the position of the tanδ peak maximum and is also in good agreement with T end according to the DSC thermograms (Table 1).…”

Tailoring the swelling and glass‐transition temperature of acrylonitrile/hydroxyethyl acrylate copolymers

“…A few studies have been reported on the copolymerization of hydroxyethyl acrylate (HEA) with various comonomers, such as styrene, butyl acrylate, and ethyl methacrylate. [7][8][9][10][11] On the other hand, a great deal of work has been done to develop an important industrial engineering plastic called polyacrylonitrile (PAN) copolymers. For example, the emulsion polymerization of AN and methyl acrylate with an acid stabilizer was largely studied by McGrath and coworkers.…”

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ABSTRACT: Novel polyacrylonitrile (PAN)-co-poly(hydroxyethyl acrylate) (PHEA) copolymers at three different compositions (8,12, and 16 mol % PHEA) and their homopolymers were synthesized systematically by emulsion polymerization. Their chemical structures and compositions were elucidated by Fourier transform infrared, 1 H-NMR, and 13 C-NMR spectroscopy.

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