Preparação de catalisadores para reações de esterificação do ácido oleico baseados em matrizes polímericas sulfonadas POLI(1- FENILETILENO) (PS) e POLI(1-CLOROETILENO) (PVC)

Chemical modification of polymer matrices is an alternative way to change its surface properties. The introduction of sulfonic acid groups in polymer matrices alter properties such as adhesion, wettability, biocampatibility, catalytic activity, among others. This paper describes the preparation of polymeric solid acid based on the chemical modification of poly (1-fenietileno) (PS) and Poly (1-chloroethylene) (PVC) by the introduction of sulfonic acid groups and the application of these polymers as catalysts in the esterification reaction of oleic acid with methanol. The modified materials were characterized by Infrared Spectroscopy, Elemental Analysis and titration acid-base of the acid groups. All techniques confirmed the chemical changes and the presence of sulfur associated with sulfonic acid groups or sulfates. The modified polymers excellent performance in the esterification reaction of oleic acid with methanol a degree of conversion higher than 90% for all investigated polymers (modified PS and PVC (5% w / w)), with a mass ratio of oleic acid: methanol 1:10 to 100 ° C. The best performance was observed for the modified PVC catalyst (PVCS) which showed low degree of swelling during the reactions is recovered by filtration different from that observed for polystyrene sulfonate (PSS). Given these facts, the PVCS was employed as a catalyst in the esterification reaction of oleic acid in different times and different temperatures to obtain the kinetic parameters of the reaction. Experimental data show a great fit for pseudo-homogeneous model of second order and activation energy value of 41.12 kJ mol -1, below that found in the literature for the uncatalyzed reaction, 68.65 kJ mol -1 .The PVCS exhibits good catalytic activity for 3 times of reuse, with a slight decrease in the third cycle, but with a conversion of about 78%. The results show that solid polymeric acid has good chemical stability for the application in esterification reaction of commercial importance with possible application in the biodiesel production. The advantages in use of this system are the increased reaction rate at about 150 times, at these test conditions, the replacement of sulfuric acid as a catalyst for this being the most corrosive and the possibility of reuse of the polymer for several cycles.

Inter-relação entre lesão cervical não cariosa e comprometimento periodontal: diagnóstico, tratamento e previsibilidade - estudo clínico prospectivo e laboratorial

The coexistence of gingival recession (GR) with root coverage indication and non-carious cervical lesions (LCNC) generates the need for a protocol that respects and promotes health of dental and periodontal tissues and allows treatment predictability. The main objectives of this theses were: (1) verify, through clinical evaluations, the connective tissue graft for root coverage on direct and indirect restorations made of ceramic resin; (2) analyze the influence of the battery level of the LED curing unit in the composite resin characteristics; (3) assess the influence of restorative materials, composite resin and ceramics, on the viability of gingival fibroblasts from primary culture. Nine patients with good oral hygiene and occlusal stability diagnosed with LCNCs the anterior teeth including premolars associated with gingival recession (class I and II of Miller) and only gingival recession were selected. After initial clinical examination, occlusal adjustment was performed and the patients had their teeth randomized allocated on direct composite resin restoration of LCNC, polishing and GR treatment with connective tissue graft and advanced coronally flap CR group (n = 15); and indirect ceramic restoration of the LCNC's and GR treatment (CTG+CAF) Group C (n = 15). The GR presented teeth with no clinically formed LCNCs cavity were treated using (CTG+CAF) being the control group (n = 15). Sorption and solubility tests, analysis of the degree of conversion and diametral tensile strength were performed in composite resin samples (n = 10) photoactivated by 100, 50 and 10% battery charge LED unit. The viability of fibroblasts on composite resin, ceramics and dentin disks (n = 3) was examined. Clinical follow-up was performed for three months. The data obtained at different stages were tabulated and subjected to analysis for detection of normal distribution and homogeneity. The results showed that: the LED unit with 10% battery affects the characteristics of the composite resin; restorative materials present biocompatibility with gingival fibroblasts; and the association of surgical and restorative treatment of teeth affected by NCCL and GR presents successful results at 3-month follow-up.