Page 328 - 00. Complete Version - Progress Report IPEN 2014-2016

328 Materials and Nanotechnology | Progress Report

Figure 52. Nanocarriers.

In addition to that, we are developing a tech- processes already developed and applied to-
nique for the capping of inorganic nanoparti- ward rubber recycling, the viability of these
cles of biomedical and clinical relevance with processes presents many challenges, either
crosslinked proteins, without the need of tox- technical or referring to material quality. The
ic reagents and solvents, to improve the bio- major effect of high energy photon, as gam-
availability, provide site specific delivery and ma rays in butyl and halogenated butyl rub-
possibly reduce allergenic reactions (Figure 52). bers is the generation of free radicals, along
changes in mechanical properties. The ad-
Recovering/recycling of butyl and dition of halogen atoms in the butyl rubber
halobutyl rubbers compounds promotes a molecular rearrangement on the
by ionizing radiation dehydrohalogenation of halobutyl rubber to

form a double bond in secondary and tertia-
Polymeric materials (plastics and rubbers) at- ry carbon in bromobutyl and chlorobutyl rub-
tain a continuously and increasing proportion bers, respectively, which facilitates the forma-
of litter discarded in landfills; their impact in tion of cross-links when exposed to radiation
environment are more and more concerning. high energy. It was developed a controlled deg-
The implementation of new technologies to- radation process (de-vulcanization) in butyl
ward polymeric residues reduction, acceptable and halobutyl rubbers (chlorine and bromine),
under environmental viewpoint and at an ef- in order to characterize their availability for
fective cost, proved to be a great problem, due changing their properties. The rubber devul-
to inhering complexities for polymers re-use. canized induced by high energy degradation
Ionizing radiation is capable to change struc- was tested for reuse in the original formula-
ture and properties of polymeric materials; it tion of the mixture of rubber and can replace
is an expectation for problem solving of poly- some parts of the pistine in the manufacture
meric residues management. Butyl and halobu- of final products. Butyl and halobutyl rubbers
tyl rubbers are used in a comprehensive scale, compounds were subjected to gamma radia-
in a great variety of applications such as tires tion, in air, at 5 kGy, 15 kGy, 25 kGy, 50 kGy, 100
spare-parts and various artifacts. Rubbers are kGy, 150 kGy and 200 kGy, in a gamma radi-
provided with a very low natural decomposi- ator, Co60. Mechanical essays of tension and
tion, due to their chemical structure weather elongation at break showed chain-scission at
resistant and to enzymatic degradation and doses up to 25 kGy; for doses higher than 50
microorganisms. Rubber recovering is diffi- kGy, it was observed an intense degradation.
cult by its insolubility due to very crosslinked Especially butyl rubber, halogenated rubbers
structures. Besides, this tridimensional struc- are a little more radiation resistant. Irradiat-
ture shows a lot of problems for material re- ed butyl, bromobutyl and chlorobutyl rubber
covering and reprocessing. In spite of various compounds and sheared at 25 kGy doses pre-

Instituto de Pesquisas Energéticas e Nucleares