The aim of the study was to develop and evaluate the in vitro performance of a new and simplified formulation of photocuring resin to be used as dental sealant. Two experimental dental sealants (CYTED1 and CYTED2) were formulated and their kinetic of polymerisation and physico-chemical properties were studied and compared to those of two commercially available sealants (Helioseal, Delton-FS). Rates of photoinitiated polymerisation (Rp), as well as the conversions and the quantum yields of polymerisation ( p ) were calculated. Flexural strength, Youngs modulus, microhardness, microleakage, water sorption, and solubility were also tested. ANOVA, Student-Newman-Keuls, Pearson correlation and Kruskal-Wallis tests were used (p < 0.05). The highest Rp and p were obtained for the sealant CYTED2, Rp and p were similar for CYTEDl and Helioseal, and the lowest for Delton. Water sorption values were similar for Helioseal and CYTED2 being higher for CYTED1 and lower for Delton. No differences were found for solubility and microleakage values. Mechanical properties were better for Delton and no differences were found within the rest of the sealants. At short irradiation times (30 s), the maximum effectiveness of the photoinitiating system was obtained by the experimental CYTED2.
In this work, 4,4ʹ-hexafluoroisopropiliden anhydride diftalic (6FDA) and 4,4ʹ-hexafluoropropiliden bis(p-phenilenoxi) dianiline (6FPA) polyimides were synthesized by two step polycondensation. The polyimides were utilized in the dense membrane formation by casting solution method. The membranes were cross–linked by immersion in a 1,5-pentadiamine in methanol solution prepared at different concentrations. The fraction of insoluble mass indicates the cross-linking degree, which varies from 0 to 1. In the other hand, the fractional free volume (FFV) calculated from Bondi theory decreases as the cross-linking degree increases in the membrane. The membranes were tested in the permeation of pure H2, CO2, N2 and CH4 gases. The results exhibited that permeability of the cross-linked membranes increases compared to the uncross-linked membrane. In the other hand, gas permselectivity data where located in the Robeson´s diagram being near to upper limit for the H2/CO2 pair of gases. The membranes are good candidates to carry out the low molecular weight’s gas separation.
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