1070-4272/02/7504-0629 $27.00 C 2002 MAIK [Nauka/Interperiodica]
Russian Journal of Applied Chemistry, Vol. 75, No. 4, 2002, pp. 629!635. Translated from Zhurnal Prikladnoi Khimii, Vol. 75, No. 4, 2002,
Original Russian Text Copyright + 2002 by Pesetskii, Makarenko.
AND POLYMERIC MATERIALS
Grafting of Glycidyl Methacrylate to Polypropylene
in an Extruder, Initiated with Organic Peroxides
S. S. Pesetskii and O. A. Makarenko
Belyi Institute of Mechanics of Metal!Polymer Systems, State Scientific Institution,
National Academy of Sciences of Belarus, Gomel, Belarus
Received January 8, 2002
Abstract-The efficiency of grafting of glycidyl methacrylate to polypropylene and the degree of de-
gradation of macromolecules, evaluated from the melt flow index, were studied in relation to the structure
of the peroxide initiator.
Reactive extrusion is widely used for production
of a wide set of polymeric products . In this proc-
ess, the starting polymers are usually polyolefins,
which is largely due to their availability, low cost, and
wide use in engineering, and also to the possibility of
controlling the physicochemical properties of the re-
sulting materials by chemical modification. In partic-
ular, reactive extrusion is used for chemical modifi-
cation of olefin polymers and copolymers and their
blends by grafting polar monomers to their macro-
molecules with the aim to enhance adhesion or to
prepare polymer3polymer systems [1, 2].
Chemical reactions in a polymer melt in an extrud-
er occur, as a rule, by the radical mechanism .
Most often, these reactions are initiated with organic
peroxides. Examples of such reactions are graftings to
polypropylene (PP) of acrylic acid and its derivatives
[4, 5], maleic anhydride , glycidyl methacrylate
(GMA) , and oxazoline .
Under conditions of fast processes characteristic of
reactive extrusion, the course of grafting and concom-
itant transformations are largely influenced not only
by the chemical activity of a peroxide initiator, but
also by its solubility in the main components of the
reaction mixture: a polymer and a monomer [21, 22].
The influence of the mutual solubility of the compo-
nents is particularly strong at poor mixing efficiency,
which is characteristic of, e.g., single-screw mixer3
The influence of the peroxide structure on the
kinetics of monomer grafting to PP was considered
in . All the peroxides used in  had asymmet-
ric structure and simultaneously were monomers con-
taining a carboxy group. Therefore, decomposition of
the peroxides was accompanied by their grafting to
the macromolecules. It was found that peroxides gen-
erating methyl radicals in decomposition afford higher
efficiency of grafting than peroxy acids generating
In this work, we considered the specific features of
GMA grafting to PP in the presence of peroxide initi-
ators that exhibit increased affinity for the polymer.
Previously , we showed for the example of graft-
ing of methylenebutanedioic acid to polyethylene that
such peroxides ensure the highest yield of the grafted
products. With peroxides exhibiting increased affinity
for the monomer, the grafting efficiency was lower.
In our study, we used PP of Kaplen brand [Moscow
Oil Refinery, 01030 grade, TU (Technical Specifica-
tions) 2211-015-00203521395, density 0.905 g cm
melting point (determined by differential scanning
calorimetry) 169oC] and organic monoperoxides (tert-
butyl peroxide, TBP; dicumyl peroxide, DCP, Org-
sintez Joint-Stock Company, Russia) and diperoxides
both ELF Atochem, France; di(tert-butylperoxyiso-
propyl)benzene (Perk-14, P-14), Aldrich; 2,2-di(tert-
(D-1); and 2,2-di(3-methyl-1-butyn-3-ylperoxy)-3,5,6-
trimethylbicyclo[2.2.1]heptane (D-2) }.
The structures and properties of these peroxides are
given in Table 1. The solubility parameters d of the