Poly(4-vinylpyridine), 4VP, resins cross-linked with oligo(ethylene glycol dimethacrylates) were used for chelating resins. Sorption for some metal ions by complexation in acetate buffer (pH 3-6) was investigated mainly by using the 4VP resins cross-linked with hydrophilic tetraethylene glycol dimethacrylate (4VP-4EG) and that cross-linked with hydrophobic divinylbenzene (4VP-DVB). The differen...

The use of epoxy resins in metal structures for adhesive reasons is getting wider. Epoxy resins possess enhanced mechanical, chemical and physical properties, i.e. increased shear and compression strength, resistance in solvents, as well as at high temperatures. Tensile tests were carried out with standard aluminium tension specimens glued with epoxy resins. The thickness of the glue and the ac...

Composites resins are the most popular restorative materials providing very good esthetics and long period of good clinical performance. Depth of cure of composite resins is crucial in determining the maximal increment thickness when restoring tooth cavities. In restorations with conventional composite resins the thickness of each increment has been defined as up to 2 mm. Bulk fill composite re...

this study investigates the effect of different types of subtitle on incidental vocabulary learning among iranian efl learners. to this end, 60 high school students in behbahan were selected after taking a proficiency test. the test was administered to ensure participants' homogeneity. participants were randomly assigned to three experimental groups, namely, bimodal group (a), standard gro...

Correspondence to: Lincoln I. Nojima Universidade do Brasil UFRJ Faculdade de Odontologia Programa de Pós-graduação em Odontologia Av. Professor Rodolpho Paulo Rocco, 325 Ilha do Fundão Rio de Janeiro RJ Brasil CEP: 21941-617 Phone: 2590-2727 / Fax: 21-2590-9771 E-mail: [email protected] Abstract Aim: To assess the flexural strength of orthodontic acrylic resins from two different manufacturer...

Polyphenolic resol resins were obtained from an ethanolic extraction of green plantain peels (Musa paradisiaca) grown in Colombia. A synthesis was then performed by polycondensation in an alkaline pH solution in order to perform research on phenolic resin production with high mechanical performance. The polymers were characterized by DSC and TGA analyses and the resins showed a melting point of...

Phenol formaldehyde (PF) resins are widely used as wood adhesives in the industrial production of exterior-grade plywood panels, oriented strand board panels and particleboards due to their superior performance including high bonding strength, heat resistance, excellent water resistance and chemical stability1. However, phenol, one raw material for the synthesis of PF resins, is a petroleum-bas...

For the development of a cost-effective melamine-modified urea formaldehyde resin (MUF), the study evaluated the effects of reaction pH and melamine content on resin properties and bond performance of the MUF resin adhesive systems. Eight resins, each with three replicates, were prepared in a factorial experiment that included two formulation variables: two reaction pHs (i.e., 4.5 and 8.0) and ...

The polymerization shrinkage of composite resins may affect negatively the clinical outcome of the restoration. Extensive research has been carried out to develop new formulations of composite resins in order to provide good handling characteristics and some dimensional stability during polymerization. The purpose of this study was to analyze, in vitro, the magnitude of the volumetric polymeriz...

A single-pass test was used to study the surface failure of commercial and experimental restorative resins and composites. The surface failure observed for unfilled diacrylate resins was more severe than that seen for an unfilled acrylic resin. Addition of nonsilanated filler to the diacrylate resins increased the resistance to penetration but did not dramatically change the mode of surface fai...