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Preparation and thermal characterization of graft copolymer obtained by radiation grafting of individual and binary monomer systems
Author(s) -
Osman Massarat B. S.,
Hegazy El Sayed A.,
Mostafa Abo ElKhair B.,
AbdelMaksoud Afaf M.
Publication year - 1995
Publication title -
polymer international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.592
H-Index - 105
eISSN - 1097-0126
pISSN - 0959-8103
DOI - 10.1002/pi.1995.210360108
Subject(s) - comonomer , materials science , copolymer , polymer chemistry , differential scanning calorimetry , grafting , monomer , glass transition , recrystallization (geology) , chemical engineering , polypropylene , polymer , composite material , thermodynamics , paleontology , physics , biology , engineering
Graft copolymers were obtained by radiation‐induced grafting of vinyl acetate (VAc) and N ‐vinylpyrrolidone (NVP) individually and in binary mixture on to polypropylene (PP) films. The effect of some grafting conditions on the grafting yield was determined. The addition of Cu 2 Cl 2 as inhibitor to the reaction medium inhibited the homopolymerization of the comonomer. The grafting process was remarkably enhanced by using dioxan as a diluent compared with other solvents used. The addition of some inorganic salts has a great influence on the individual grafting of both monomers. The gel percent in the graft copolymer was determined; it increased as the grafting yield increased. The swelling behaviour and electrical conductivity for the grafted films slightly increased by grafting. The changes in thermal parameters such as glass transition ( T g ), melting ( T m ) and recrystallization ( T rc ) temperatures and heats of melting (Δ H m ) and recrystallization (Δ H rc ) of the graft copolymers were also followed by differential scanning calorimetry (DSC). These thermal parameters of PP were varied by grafting with VAc and NVP and depend on the graft yield, which reflects the change in its crystalline domains and formation of crosslinks in the graft chains. The heat of recrystallization of the graft copolymer by cooling from the molten state decreases by grafting which is a good indication of crosslink formation, since crosslinking decreases the crystallizability of the polymer matrix.