The purposes of this study were to determine the weight fraction of filler in thirty-nine resin-based materials including flowable and packable composites, and to examine the morphology of the filler particles. The percentages of inorganic fillers by weight were determined by Thermogravimetric Analysis and by ashing in air technique at 900 degrees C. The size and shape of the filler particles were examined using scanning electron microscopy (SEM) after dissolution of the organic matrix. The weight fraction of inorganic fillers ranged between 41.6 and 84.6%. Wide variations were found among materials of the same category. Values found in the present study were sometimes different from those given by the manufacturers. The SEM photomicrographs showed various shapes, and sizes of inorganic fillers. Compared with universal hybrid restorative materials, flowable composites have lower filler loading and packable resin composites did not show higher values as claimed by some manufacturers. Various factors may explain the observed discrepancies between the manufacturer's data and our results. The silane treatment as well as the incorporation of organic material as part of the fillers of the composite could be responsible for those differences.

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SynopsisGelation and melting of aqueous gelatin were investigated by differential scanning calorimetry. This phenomenon can be analyzed as a conventional crystallization process assuming predetermined primary nucleation and unidirectional growth. The results were interpreted in terms of the fringed micelle model. Calculated values of the diameter of the renatured collagen fibril were found in excellent agreement with those determined previously by electron microscopy.

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This paper is focused on the quantitative characterization of cavitation developing in unfilled and nano‐CaCO3 filled high density polyethylene (HDPE) subjected to tensile test. In particular, a methodology to reveal the voids, take into account their localization, and evaluate their characteristics (density and shape), is presented. For this, post‐mortem investigations coupling a cryosectioning method and a pressure‐controlled scanning electron microscope (PC‐SEM) were conducted. In the two materials, whatever the active cavitation mechanism (crazing in neat HDPE or debonding in CaCO3/HDPE system), it was shown that the cavity density and the cavity height/width ratio (shape factor) increase with the deformation state. These two parameters are also influenced by the macroscopic stress triaxiality generated by the necking process. Indeed, when the intensity of the triaxiality is high, the cavity density and the cavity shape factor significantly increase from the skin to the core of the specimen. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers