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Thanks to greater attention to the environment and the depletion of non-renewable resources, the sustainability and the circular economy have become crucial topics. The current trend of pavement engineering is to reduce the use of standard bitumen by replacing it with more sustainable materials such as industrial residues and by-products. In this regard, the present study aims to characterize innovative extended bitumen using recycled materials. Due to promising preliminary results as bitumen modifiers, the powdered rubber from end-of-life tires and the re-refined engine oil bottom (REOB) have been investigated as feasible components of bitumen extenders. Nevertheless, several variables strongly affect the performance of the resulting binder, which cannot be neglected. Hence, this research focuses on the rubber&ndash, REOB interaction in order to evaluate their optimum ratio, which may maximize the use and advantages of both recycled materials as suitable partial replacements for bitumen. Various rubber&ndash, REOB ratios were considered and investigated by means of low and high frequency nuclear magnetic resonance (NMR) spectrometers and scanning electron microscope (SEM).

Experimental organic–inorganic hybrid systems, based on silane functionalized difunctional and trifunctional epoxy resins and an alkoxysilane precursor mixture, containing small amounts of ammonium molybdate, are evaluated for potential use as adhesives cured at ambient temperatures. The precursor resin mixtures are found to exhibit a large increase in viscosity with a pseudoplastic behavior. Scanning electron microscopy (SEM) analysis shows the existence of siloxane domains with nanometric dimensions, except for the presence of microscopic molybdate particles. By monitoring the evolution of the glass transition temperature (Tg) during curing, varying the thickness of the specimens between 0.2 and 4.5 mm, it is found that the organic–inorganic hybrids display a significant increase in the final Tg over the parent unmodified epoxy resins, particularly in thin specimens and when ammonium molybdate is added. Small-angle X-ray scattering (SAXS) spectra show that the dimensions and typographic features of thick and thin specimens are similar, both containing an agglomeration of primary particles of 5–6 nm. POLYM. ENG. SCI., 2011. © 2010 Society of Plastics Engineers

BACKGROUND: the aim of this study was verify the possibility of using flowable composites in class V restorations and in class II cervical margin METHODS AND MATERIALS: the study was subdivided in two parts, in vivo and in vitro. The first contain 6 patients with a spot of flowable and microfilled resin on the vestibular surfaces of first superior molars. The in vitro part consists of 12 molar extracted in which was obtained class V restorations filled with flowable and microfilled. At 0 and 6 months impressions were taken for each tooth with Impregum Penta Soft and replicas were obtained with epoxy resin. The replicas were analyzed with profilometer and S.E.M. microscope. The statistic results were analyzed by the Paired Samples T Test and the Indipendent Samples T Test. RESULTS: each material, flowable and microfilled, looks modified at the microscopic and profilometric analysis even if the flowable surface modifications was more apparent. CONCLUSIONS: flowable resins can be used in class II and V cervical margins if non exposed to mechanical stresses.

Aim To evaluate the wear of new rotary instruments produced via electro discharge machining and to test their fatigue resistance. Methodology Twenty-one HyFlex EDM (Coltene/Whaledent, Switzerland) files were used for laboratory instrumentation of curved root canals of extracted teeth. Superficial characteristics were analyzed pre- and postoperatively by scanning electron microscopy (SEM) (JSM-5200, JEOL, Tokyo, Japan) at same points and with same angulations to identify the wear features. Number of fractures, microcracks blunt/disruption of cutting edge and tip deformations were reported. Twenty HyFlex EDM and 20 HyFlex CM (Coltene/Whaledent, Switzerland) were subjected to cyclic fatigue test in a 70° artificial metal canal. Results were statistically analyzed using Mann–Whitney tests. Results No fractures were registered during laboratory canal instrumentation. No wear and no degradation of the 25.12 and 25.08 files were reported. Slight plastic deformations were only observed in three 10.05 files. The cyclic fatigue test revealed a significant increase of fatigue resistance of EDM files compared to CM (p = 0.0001). Conclusions The typical irregular surface of HyFlex EDM remained unaffected after multiple uses, confirming a high wear resistance. The new manufacturing process of electrical discharge machining had a substantial impact on fatigue lifetime of EDM files when compared with HyFlex CM. Within limitations of the present in vitro results, EDM files appeared suitable in shaping severely curved canals.