Análise comparativa entre o grau de molhabilidade dos polímeros reciclados PVC e PET tratados por imersão ou deposição de filmes orgânicos em plasmas fluorados

Abstract

The goal of this work was to study the wettability of the recycled polyvinylchloride (PVC) and polyethylene terephthalate (PET) surface, in which was used the technique of Plasma immersion (PI), by means of ionic bombardment using the gas Sulfur Hexafluoride (SF6) with total pressures down to 100 torr. The substrates were confined in a low vacuum reactor, and gas was excited by a radiofrequency discharge source, RF: (13.56 MHz) applied to the lower electrode (sample holder), coupled to a match in box. The surface wettability result of these polymers via "contact angle, ϴ", were compared with parallel studies in the literature. In this case, the technique of Infrared Absorption Spectroscopy (FTIR) was applied in order to analyze the possible physico-chemical changes in the surface of the polymers in the presence of an organic film of Isopropanol, SF 6 , whose values of ϴ were lower than the untreated material, even in the fluorinated atmosphere.Therefore, the parameters pressure, time or discharge power of RF were varied, In all cases, moderate to high fluorine is considered, with contact angles close to 120º are inferior to a similar treatment in literature, in which it was applied, a cooling prototype of the sampled electrode throughout the process; condition that resulted in PVC, ϴ ~ 156º (surface with higher degree of fluorine); and PET in turn reached ϴ ~ 140 °.

Surface functionalization of polyvinyl chloride by plasma immersion techniques

“…According to the data of Table 2, wettability after treatment depends on the plasma configuration. Plasma immersion using nitrogen decreases contact angles [5] , while plasma immersion using fluorine increases them [6] , independent of the plasma technique. Owing to the plasma action, the breaking of covalent chemical bonds, such as C-H or C-O and their subsequent recombination may lead to the formation of C-F bonds after the fluoride treatment by PI [5,6,9] which explains the increased hydrophobic character of the polymers undergoing this treatment.…”

“…Table 2 shows the values of contact angles, immediately after the treatment and after 30 days (ageing). Also, the optical transmittance of visible light (at 550 nm) was investigated for PVC after the different plasma treatments: PI cathode, PI anode and PIII, at low and high applied rf power using fluorine or nitrogen plasma [6][7][8][9] . PVC is a slightly hydrophobic polymer with a water contact angle of around 76° [ 6,9] .…”

“…For treatment by PI, the increasing power supplied to the SF6 plasma enhances ion bombardment. Thus, a greater number of fragmented species impinging on the surface offers a greater number of active sites for binding C-F, which justifies the higher θ values after fluorination [5][6][7][8][9] . In the reactor there are also the effects of ionic bombardment for all PI configurations [9] .…”

“…Twenty four substrates of blue PVC (2.5 cm × 1.5 cm, and 1 cm of thickness) were used. Eight substrates were treated in three different rf plasma immersion modes, as indicated in previous literature [6][7][8][9] , and summarized as follows:…”

“…To our best knowledge, different PI electrical configurations for the surface functionalization of PVC have not been previously reported. Other results concerning hydrophobic/hydrophilic surface treatments of PET [5] and PVC [6] in low-pressure plasmas have been reported. In those treatments, plasma immersion techniques (PI) and Plasma Immersion Ion Implantation (PIII) were employed, to modify surface wetting, roughness and optical transmission.…”