Mechanism of Post-Radiation-Chemical Graft Polymerization of Styrene in Polyethylene

Abstract

Structural and morphological features of graft polystyrene (PS) and polyethylene (PE) copolymers produced by post-radiation chemical polymerization have been investigated by methods of X-ray microanalysis, electron microscopy, DSC and wetting angles measurement. The studied samples differed in the degree of graft, iron(II) sulphate content, sizes of PE films and distribution of graft polymer over the polyolefin cross section. It is shown that in all cases sample surfaces are enriched with PS. As the content of graft PS increases, its concentration increases both in the volume and on the surface of the samples. The distinctive feature of the post-radiation graft polymerization is the stepped curves of graft polymer distribution along the matrix cross section. A probable reason for such evolution of the distribution profiles is related to both the distribution of peroxide groups throughout the sample thickness and to the change in the monomer and iron(II) salt diffusion coefficients in the graft polyolefin layer. According to the results of electron microscope investigations and copolymer wettability during graft polymerization, a heterogeneous system is formed both in the sample volume and in the surface layer. It is shown that the melting point, glass transition temperature and degree of crystallinity of the copolymer decreases with the increasing proportion of graft PS. It is suggested that during graft polymerization a process of PE crystallite decomposition (melting) and enrichment of the amorphous phase of graft polymer by fragments of PE macromolecules occurs spontaneously. The driving force of this process is the osmotic pressure exerted by the phase network of crystallites on the growing phase of the graft PS.

Spectra of Internal Friction in Polyethylene

“…Distinctive feature of obtained experimental results is decrease of intensity of dissipative losses background (internal friction background) at increase of investigation temperature. In previous studies [15,[20][21][22][23], on the contrary, there is a sharp increase of internal friction background at temperatures above the β k -process temperature.…”

“…At the same time, along with the study of fracture processes of these materials, the analysis of the phase state of the systems and their supramolecular structure, local dissipative processes (including relaxation processes) are also studied. It is established [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] that these processes are associated with the manifestation of the mobility of various structural elements. Therefore, the smallest structural changes lead to significant changes in the parameters of these local dissipative processes and characteristics of the whole system under study.…”

Gamma radiation-induced grafting of poly(butyl acrylate) onto ethylene vinyl acetate copolymer for improved crude oil flowability

“…Graft copolymerization serves as an exceptionally versatile means of functionalization, enabling the incorporation of functional groups into diverse polymer types through the direct polymerization of monomers onto the polymer backbone 77 , 78 . When grafting polymerization is applied to the EVA copolymer backbone using BuA monomer, two primary approaches are employed, as illustrated in (Fig.…”

Epoxyorganosilane Finishing Compositions for Fibrous Fillers of Thermosetting and Thermoplastic Binders

“…In order to study the compatibility of components in the entire concentration range, we used the method of optical interferometry. All of the measurements were performed on an ODA–2 diffusiometer (IPCE RAS, Moscow, Russia) [ 13 , 45 , 46 ]. A helium–neon laser (λ = 632.8 nm) was used as a source of monochromatic light with a parallel beam.…”