Page 22 - PR 2014 2016 03 Applications of Ionizing Radiations

64 Application of Ionizing Radiations | Progress Report

Creating Selective Membranes lation already in course in many countries limits
with Ionizing Irradiation the emission of volatile organic compounds
(VOC) in the atmosphere, affecting mainly the
Polymeric membranes were styrene grafted by paint manufacturers who are seeking for al-
several irradiation methods and the obtained ternatives by replacing the paint solvent for
material is chemically modified to become alu- those with high solids. Thus, the technology of
minum selective. For this purpose, polymeric curing polymer coatings by radiation is based
substrates like PVC (polyvinyl chloride) and PP on the interaction of the chemical system to
(polypropylene) were styrene grafted mutually the ultraviolet (UV) or electron beam (EB) inci-
by gamma and electron beam irradiation. The dent radiation, forming reactive species capa-
modification process included three basic reac- ble of inducing the polymerization reactions
tion paths: Friedel-Crafts acylation, 2-methyla- and cross-linking, resulting in formation of the
nisole coupling and a final oxidation to achieve cured product. In this technology, the solvents
aluminum selectivity. The obtained product used to reduce the viscosity of the formula-
was an aluminum selective material where tions are replaced with reactive monomers
original membrane characteristics (physical that remain in the cured product, providing
shape and mechanical resistance) were con- no VOC, and the film formation occurs at room
served even after this aggressive treatment. temperature. However, the cured products are
insoluble and infusible, increasing the degree of
complexity for reprocessing, recycling and / or
(bio) degradation. Thus, this project evaluated
coating films cured by UV / EB and its mixtures
with pro-degrading agents, on a polymer sub-
strate by means of its thermal, mechanical,
rheological and morphological characteristics.

Figure 33. Physical aspect of final product - aluminum selective
membrane. (1) Styrene grafted PP-1, with high yield of grafting (not
chemically modified). (2) Chemically modified PP-1 (low yield - first
step of modification). (3) Chemically modified PP-1 (high yields -
first step of modification and grafting). (4) Chemically modified PP-2
(high yield for the first modification and low yield of grafting).

Cure of inks, paints and varnishes
by UV/EB technology and
evaluation of its degradability

The search for environmentally friend materi-
als is becoming the major focus of research at
the twenty-first century, considering the high
level of pollution generated by the inadequate
disposal of materials, especially polymers, in the
environment. In addition, environmental legis- Figure 34. Preparation of coating film and UV curing.

Instituto de Pesquisas Energéticas e Nucleares