Page 62 - 00. Complete Version - Progress Report IPEN 2014-2016

62 Application of Ionizing Radiations | Progress Report

matrix. Indeed, there is a great technological ties only when compared to metal on a mac-
interest in the study of polymeric nanocom- roscopic scale, and they have been used in the
posites due to their excellent properties and medical field because of its remarkable antimi-
ability to control the characteristics of those crobial activity. Titanium dioxide nanoparticles
systems to reach application requirements. In obtained by the sol gel method were used as
this work, polystyrene (PS) crystal composite the coating catheters for subsequent impreg-
with 3 % of organically modified clay – Choc- nation of silver nanoparticles with ionizing ra-
olate – were irradiated with radiation doses of diation at 25 kGy. A Raman spectrometry was
300, 450 and 600 kGy in an electron accelera- used to identify the polymorph of titanium ox-
tor. The results demonstrated that irradiation ide, rutile. In trials with (ICP OES), amounts of
PS with clay presented a reduction in tensile titanium and silver coated catheters in titani-
strength compared with pure PS. Furthermore, um oxide and silver were evaluated. The com-
the Izod impact strength also had a reduction parative assessment conducted between the
in samples of PS with clay compared to pure catheters before and after irradiation by FTIR,
PS and TGA analysis indicate a tendency to Raman and DSC enabled the use of ionizing
decrease the thermal stability of the material radiation as an agent of sterilization and im-
after irradiation. In conclusion, the radiation pregnating of silver nanoparticles.
is acting in the clay incorporated in the poly-
mer and changing their properties. Mechanical and thermal comparison analyses
in polyamide 6 compounds with talc mineral
Effect of ionizing radiation in polyurethane filler and colloidal silicon dioxide (Aerosil)
catheters coatings with silver nanoparticles

In order to have sustainable development, it is
The present work aimed to study the use of ion- very desirable that the possibilities of obtain-
izing radiation for coating of silver nanopar- ing ecologically acceptable raw materials that
ticles on central polyurethane catheters (FIG. increase dimensional properties and reduce
1), providing reduction of infections associ- cost in the industrial sector are explored. In
ated with contamination of catheters intro- this sense, the possibility of replacing miner-
duced into the bloodstream (FIG. 2). Fourier al talc powder with the colloidal silicon diox-
transform infrared spectroscopy (FTIR) enabled ide (AEROSIL®) as a mineral filler in polyam-
the identification of functional groups in the ide 6 (PA 6) compounds was tested. Colloidal
structure of macromolecules, such as polyether silicon dioxide is an amorphous substance
urethane. A study of the thermal behavior of with low density that satisfies consumer de-
central venous catheters before and after irra- mands. In this study, both fillers – talc and col-
diation was performed in order to character- loidal silicon dioxide – used with PA 6 were
ize the polymeric material of these catheters. explored. Moreover, their density and prop-
The DSC and TG were employed to observe the erties in terms of thermogravimetric analy-
changes material properties before and after sis (TGA) were evaluated. Additional mechan-
degradation. The DSC curve at the constant ical tests such as tensile strength, elongation
heating and cooling rate allowed the charac- at break and impact resistance were also car-
terization of thermal properties, such as Tm ried out. The tests concluded both compounds
and Tg of copolymers, as well as highlighting (PA 6 with colloidal silicon dioxide and PA 6
the main thermal events. Silver nanoparticles with talc) demonstrated the same behavior.
have physical, chemical and biological proper- The results have demonstrated that colloidal

Instituto de Pesquisas Energéticas e Nucleares