ISSN 1070-4272, Russian Journal of Applied Chemistry, 2006, Vol. 79, No. 9, pp. 1526!1531. + Pleiades Publishing, Inc., 2006.
Original Russian Text + O.A. Ermolovich, A.V. Makarevich, 2006, published in Zhurnal Prikladnoi Khimii, 2006, Vol. 79, No. 9, pp. 1542!1547.
AND POLYMERIC MATERIALS
Effect of Compatibilizer Additives on the Technological
and Performance Characteristics of Biodegradable Materials
Based on Starch-Filled Polyethylene
O. A. Ermolovich and A. V. Makarevich
Belyi Institute of Mechanics of Metal!Polymer Systems, National Academy of Sciences of Belarus,
Received June 16, 2005; in final form, January 2006
Abstract-The deformation and strength characteristics, as well as rheological properties and biodegradability
of film materials prepared by hot pressing and slot extrusion methods from polyethylene3plasticized starch3
compatibilizer blends were examined. Polyethylene with grafted itaconic acid served as compatibilizer.
The formulation and technological parameters of preparation of biodegradable film materials were optimized
to meet the technical performance criteria.
The need to solve the problem of contamination of
the environment with industrial and domestic plastic
waste (packaging and agricultural films, containers,
disposables, etc.) stimulated, in particular, the devel-
opment of biodegradable polymeric materials (BPMs).
Waste BPM products are capable of degradation when
exposed to natural factors (soil and atmospheric mi-
croorganisms, ultraviolet radiation) and water-soluble
chemical reagents .
A large group of BPMs is based on biopolymers
belonging to polysaccharides, as well as on their com-
posites with synthetic thermoplastics. Polysaccharides
are isolated from renewable plant (corn, potato, and
rice starchs, cellulose) and animal (chitin, chitosan)
raw materials [4, 5]. An important place in the BPM
group of interest is occupied by composites based on
starch (St) and polyethylene (PE).
Nonpolar PE is thermodynamically incompatible
with polysaccharides whose macromolecules contain
polar groups . This is responsible for the fact that
an increase in the St content deteriorates the process
parameters, above all, the fluidity of PE/St melts, as
well as the physicomechanical characteristics of the
products thereof. At the same time, the St concentra-
tion in a blend with PE should be fairly high to make
the composite biodegradable. The development of
BPMs combining high biodegradability with good
deformation and strength characteristics still remains
an important problem in materials science and poly-
mer composite technology.
One way to solve this problem is to use starch-
filled composites of functionalized PE, with polar
functional groups grafted to its macromolecules, as
the polymeric binder. Today, reactive extrusion of
polymers is actively introduced into industry . For
example, PE is chemically modified by grafting polar
vinyl monomers (maleic anhydride, itaconic acid, etc.)
to the PE macromolecules occurring in the viscous-
flow state . The macromolecules of modified PE
contain carboxy groups and exhibit enhanced thermo-
dynamic compatibility with the polar polysaccharide
filler, which intensifies the interphase interactions.
The mechanism of the latter is virtually not under-
stood; this is a multifactor physicochemical process
affecting the structural organization and properties
of composites . Chemical reactions between the
carboxy groups grafted to the PE macromolecules and
the hydroxy groups of St and the plasticizer [typically,
glycerol (Gl)] can proceed via formation of ester and
hydrogen bonds (the energy parameters of the latter
are determined, in particular, by the proton-donating
and proton-accepting powers, as well as by the con-
centration of the reacting groups).
Full replacement of PE by expensive functionalized
PE in BPM like PE/plasticized starch (PSt) is eco-
nomically unfavorable. In this study we suggested
compatibilization of the PE/PSt blend by introducing
functionalized PE as the third component of the blend
(compatibilizer). Polymeric compatibilizers are reac-
tive copolymers or chemically modified polymers