Abstract A new oleic acid derivative plasticizer, epoxidized trimethylolpropane trioleate (EPO), has been synthesized and its application in PVC formulations compared with di(2-ethylhexyl) 1,2-cyclohexanoate (DOCH/DEHCH), a commercial phthalate-free plasticizer of petrochemical origin. EPO and their blends with DOCH were added to PVC resin (50 PHR) and the plasticized PVC has been characterized by thermal and mechanical measurements. EPO demonstrated good compatibility with the PVC resin improving the thermal stability and elongation at break. Due to EPO high molar mass, a slight increase in the glass transition temperature and hardness was observed as the content of EPO in the plasticizer blend increased. The results indicate that EPO is a potential plasticizer for PVC when pure and, by replacing 50% of DOCH, the PVC compound shows similar properties to pure DOCH, but better elongation at break and thermal stability.

Abstract Methacrylamides monomers for dental applications were synthesized using a one-step procedure starting from methacrylic anhydride and the respective diamine: N,N’-(propane-1,3-diyl)-bis(N-ethyl-2-methylacrylamide) (1), N,N’-(butane-1,4-diyl)-bis(2-methacrylamide) (2), N,N’-(octane-1,8-diyl-)bis(2-methylacrylamide) (3) and N,N’-(1,4-phenylene)-bis(2-methylacrylamide) (4). The structures were confirmed by 1H NMR, 13C NMR, FTIR-ATR and UHPLC-QTOF-MS. Thermal polymerization kinetics was investigated by modulated DSC for monomers (2), (3) and (4) using heating rates of 1, 2, 3 and 5 °C min-1. All IR spectra showed the C=C axial deformation at 1610 cm-1, in 1H NMR spectra the olefinic hydrogens were observed at 5.3 an 5.8 ppm and in 13C NMR, the vinylic carbons at 120 and 140 ppm. The exact m/z values were: 267.2068, 225.1595, 281.2222 and 245.1283 for monomers (1), (2), (3) and (4), respectively. The activation energy was: -182.7; -165.8 and -156.7 kJ mol-1 for monomers (2), (3) and (4), respectively. Monomers are promising candidates for use as hydrolytic stable adhesive systems for dental applications.

Abstract The effects of disinfection by microwave irradiation and immersion in peracetic acid on the physical-mechanical properties of a microwave-activated acrylic resin were evaluated. Specimens of acrylic resin were divided into a control group (specimens not disinfected) and 2 test groups subjected to one disinfection method: microwave irradiation at 850 W for 1 minute or immersion in 50 mL of 0.2% peracetic acid for 5 minutes. Specimens were submitted to Knoop hardness, flexural strength, flexural modulus, Izod impact, water sorption and solubility, glass transition temperature, and degree of conversion tests. Microwave disinfection significantly increased the mean Knoop hardness, Izod impact strength, water sorption, water solubility and glass transition temperature, whereas the flexural properties remained unaffected. Microwave disinfection increased the degree of conversion. Peracetic acid disinfection showed no changes in any properties. Both disinfection techniques did not adversely affect the evaluated properties.

Abstract This study evaluated the three-year lifespan of the bond to dentin of experimental self-etch adhesives containing benzodioxole derivatives – 1,3-benzodioxole (BDO) and piperonyl alcohol (PA) – as co-initiator alternative to amines. Adhesive resins were formulated using Bis-GMA, TEGDMA, HEMA, camphorquinone and different co-initiators: BDO, PA or ethyl 4-dimethylamino benzoate (EDAB – amine). An experimental self-etch primer was used to complete the two-step, self-etch adhesive system. Clearfil SE Bond (CSE) was used as commercial reference. Bond strength to human dentin was assessed by microtensile bond strength (µTBS) test, and failure mode was classified. Morphology of the dentin bonding interface was assessed via scanning electron microscopy (SEM). Irrespective of the dental adhesives evaluated, µTBS was higher after 24 hours compared with that after 1.5 and 3 years (p ≤ 0.001). However, adhesives with BDO and PA as co-initiators showed significantly higher bond strength than the bonding resin with EDAB (p ≤ 0.002), independent of the time evaluated. The commercial adhesive CSE showed similar bond strength compared with the other groups (p ≥ 0.05). Mixed failures were mainly observed after 24 hours, while adhesive failures were more frequently observed after 1.5 and 3 years. No notable differences in homogeneity and continuity along the bonded interfaces were detected among the materials in the SEM analysis. In conclusion, benzodioxole derivatives are feasible alternative co-initiators to tertiary amine in camphorquinone-based self-etching dental adhesive formulations.

RESUMO Objetivo: Analisar se corantes e fibras de nylon influenciam nas propriedades de uma resina acrílica ativada por energia de micro-ondas. Métodos: Espécimes retangulares e em forma de disco foram confeccionados em resina acrílica rosa médio com e sem fibras de nylon e incolor sem fibras. Para obter os espécimes retangulares, foi utilizada uma matriz de aço inoxidável com as seguintes dimensões: 64 X 10 X 3 (± 0,5mm) e para obter os espécimes em forma de disco, foi utilizada uma matriz com 50mm (± 0,5mm) de diâmetro e 0,5mm (±0,05mm) de espessura. Os mesmos foram randomizados para formar os grupos controle (acrílico incolor sem fibras) e experimentais (rosa médio com e sem fibras), sendo cada grupo composto por dez (10) espécimes retangulares e cinco (5) em forma de disco. Foram os mesmos então submetidos a seis (6) ensaios (resistência ao impacto izod, n=10; dureza knoop, n=10; temperatura de transição vítrea, n=3; sorção e solubilidade, n=5; grau de conversão, n=1; resistência à flexão e módulo de flexão, n=10). Todas as variáveis foram submetidas à análise de variância seguida pelo teste de comparações múltiplas de Tukey, com nível de significância de 5%. Resultados: O grau de conversão foi de 88% para os 3 grupos de resinas e os resultados não mostraram diferença estatisticamente significativa entre os mesmos para cada variável (p>0,05). Conclusão: Os resultados mostraram que o corante e a presença de fibras de nylon em resina acrílica não afetaram as propriedades analisadas nesse estudo.

ABSTRACT Objective: The aim of this study is to analyze if both color and nylon fibers have an influence on microwave-cured acrylic resin properties. Methods: Rectangular and disk-shaped specimens were prepared using acrylic resins; medium pink with and without nylon fibers and colorless without nylon fibers. To obtain the rectangular specimens, a stainless steel die was used with the following dimensions: 64 X 10 x 3 mm (± 0.5mm). To obtain disk-shaped specimens, a die 50mm (±0.5mm) in diameter and 0.5mm (±0.05mm) thick was employed. They were randomized to form groups: control (colorless acrylic) and experimental (medium pink, with and without nylon fibers), with each group consisting of ten (10) specimens rectangular in shape and five (5) disk-shaped. They were analyzed in six (6) assays (izod impact strength, n=10; Knoop hardness, n=10; glass transition temperature, n=3; water sorption and solubility, n=5; degree of monomer/polymer conversion, n=1; flexural strength and flexural modulus, n=10). All variables were subjected to the analysis of variance test followed by Tukey's multiple comparison test, at a 5% level of significance. Results: The analysis of the monomer/polymer degree of conversion did not reveal any difference between the three groups of resins (medium pink, with and without nylon fibers and colorless resin); it was approximately 88%. The results did not show significant differences between the groups for each variable (p>0.05). Conclusion: The results showed that color and presence of nylon fibers in acrylic resins did not affect the properties analyzed in this study.

Objetivo: Avaliar a eficácia dos métodos de desinfecção em microondas e imersão em ácido peracético em resina acrílica termopolimerizável, autopolimerizável e resina acrílica polimerizada por microondas, contaminadas com Candida albicans. Métodos: Cinco amostras foram preparadas para cada tipo de resina acrílica. Todas foram infectadas com Candida Albicans, incubadas a 37 ° C durante 24 h. O grupo submetido a energia de microondas foi irradiada com uma potência de 840W durante 1 minuto e o outro grupo foi submetido a desinfecção por imersão de ácido peracético a 0,2% durante 5 minutos. Resultados: Todas as amostras mostraram estar contaminadas depois do período de incubação. Depois dos diferentes processos de desinfecção, tanto a imersão em 0,2% de ácido peracético, como a irradiação de microondas foram eficazes na desinfecção dos 3 tipos de resinas acrílicas contaminados por Candida Albicans. Conclusão: Concluiu-se que a imersão em ácido peracético 0,2% durante 5 minutos e a irradiação de microondas com potência de 840W durante 1 minuto são métodos eficazes para a desinfecção de resina acrílica termopolimerizável, resina acrílica autopolimerizável e resina acrílica polimerizada por microondas, contaminados com Candida Albicans.

Objective: The objective of this study was to evaluate the effectiveness of disinfection methods in microwave and immersion in peracetic acid in heat-cured, self-cured and microwave-cured acrylic resin, contaminated with Candida albicans. Methods: Five specimens were prepared for each type of acrylic resin. All were infected with Candida Albicans, incubated at 37°C for 24 hours. The group which underwent microwave energy was irradiated with a power of 840W for 1 minute and the other group underwent disinfection by soaking of 0.2% peracetic acid for 5 minutes. Results: All samples proved to be contaminated after the incubation period. After the different processes of disinfection, both immersion in 0.2% peracetic acid as microwave irradiation were effective in disinfection of the 3 types of acrylic resins contaminated by Candida Albicans. Conclusion: Concluded that soaking in 0,2% peracetic acid for 5 minutes with microwave irradiation power 840W for 1 minute are effective methods for disinfecting heat-cured acrylic resin, self-cured acrylic resin and microwave-cured acrylic resin, contaminated with Candida Albicans.

Filmes base PELBD + PEBD contendo 5% de sorbato de potássio (SK) foram preparados por extrusão plana. Os filmes com e sem SK foram caracterizados por calorimetria exploratória diferencial (DSC) e fluorescência de Raios X por dispersão de comprimento de onda (WDXRF). O perfil de migração do SK foi acompanhado por FTIR/ATR e UV-Vis e sua influência na curva de selagem (hot tack) dos filmes foi determinada. A adição de SK não causou alteração nas propriedades térmicas do polietileno na concentração estudada, porém a migração do SK para a superfície do filme interferiu na curva de selabilidade, atuando como uma impureza, causando diminuição da força de selagem em faixa de temperaturas mais baixas.

Films produced with blends of linear low density polyethylene and low density polyethylene (LLDPE + LDPE) containing 5 wt % of potassium sorbate (KS) were prepared by flat film extrusion. These films were characterized by differential scanning calorimetry and wavelength dispersive X-ray fluorescence. The migration profile of KS was followed by Attenuated Total Reflection-Fourier Transform Infrared and Ultraviolet spectroscopies and its effect on the sealing curve was determined. The addition of 5% of KS showed no effect in the thermal properties of polyethylene. However, the sealing properties were slightly affected by KS migration, acting as an impurity in the sealed area, which needed a higher sealing force at lower temperatures.