Rigid polyurethane foam (PUr) is a common residue from the footwear industry that seeks a sustainable disposal alternative. A flexible composite incorporating PUr that could be used in this same industry is an exciting solution. Poly (vinyl chloride) (PVC) and polyvinyl butyral (PVB) were tested as possible matrixes for flexible composites containing 20%, 35%, and 50% of PUr produced by two different processes, extrusion and injection molding. PVB/PUr and PVC/PUr were compared considering the morphology observed with scanning electron microscopy (SEM), density, degradation during processing, and dynamical mechanical properties. PVC was severely degraded when processed with PUr and showed a low adhesion to PUr particles resulting in decreased storage modules and increased glass transition temperature. PVB is a better matrix for PUr flexible composites since it showed no sign of degradation and formed a stronger interface with PUr particles resulting in PVB/PUr composites with higher storage modulus.

Abstract Objective: To discover the perceptions of pediatric patients, their parents and undergraduate Dentistry students of the use of the diode laser in frenectomy surgeries. Material and Methods: A qualitative study was conducted through semi-structured interviews, recorded and transcribed with subsequent content analysis. Twelve healthy children (5-8 years old) who needed a frenectomy were selected and invited, together with their parents, to undergo laser diode surgery. In addition, 28 undergraduate dentistry students were invited to attend the procedures. One week after performing the surgical procedures, the children (Group 1), their parents (Group 2) and the students who attended the procedures (Group 3) were individually interviewed for the thematic analysis. Results: The analysis of the conversations identified three emerging contents: positive thoughts on the use of diode laser; frustrations from the use of diode laser; and aspects related to professional training. Conclusion: The results pointed to the acceptance of surgical laser use in pediatric dentistry; however, the feelings of frustration indicate that its use requires guidance from the child and his/her parents, in addition to careful handling and specific training.

This study reports the preparation and characterization of composites with recycled poly(vinyl butyral) (PVB) and residue of rigid polyurethane foam (PUr), with PUr contents of 20, 35 and 50 wt %, using an extruder equipped with a Maillefer single screw and injection molding. The components of the composites were thermally characterized using differential scanning calorimetry (DSC) and thermogravimetry. The composites were evaluated by melt flow index (MFI), tensile and hardness mechanical tests and scanning electron microscopy (SEM). Tg determined by DSC of PVB sample (53 °C) indicated the presence of plasticizer (Tg of pure PVB is 70 °C). MFI of the composites indicated a viscosity increase with the PUr content and, as the shear rate was held constant during injection molding, higher viscosities promoted higher shear stresses in the composites, thereby causing breaking or tearing of the PUr particles. The SEM micrographs showed low adhesion between PVB and PUr and the presence of voids, both inherent in the rigid foam and in the interphase PVB-PUr. The SEM micrographs also showed that PVB/PUr (50/50) composite exhibited the smallest particle size and a more homogeneous and compact structure with fewer voids in the interface. The stiffness of the composites increases with addition of the PUr particles, as evidenced in the mechanical tests.