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Notes: Summary— A case of naevus syringocystadenomatosus papilliferus of the left side of the scalp is reported in a severely mentally retarded female, aged 45, who has also an ipsilateral, extensive hyperostosis of the skull, atrophy of the cerebral hemisphere, coloboma of upper eyelid, with an adjacent dermoid growth. There is an area of cortical calcification in the post parietal region. She also suffers from rosacea, right sided hemiparesis, epilepsy and uvula bifida.

Notes: Molecular simulation of single chain in the vicinity of nanoparticle in comparison withpure system is presented. According to the Rouse theory, chains were considered as a sequence ofbeads connected together by harmonic springs. The motion of atoms was supported by thermal energyand retarded by the resistance of surrounding. New atom position, in given time, was determined bythe Smoluchowski equation, that consists of two terms: first one includes the influence of theinter-atomic collisions, the sterical obstacles and the strong intermolecular interactions in frictioncoefficient, second one express the energy field aggregated from potentials of all atoms. Sinusoidalshear stress was applied to the chain. The output of the model was energy as a function of time. Theenergy course was also sinusoidal but shifted according to the deformation. The amplitudes and phaseshifts were analyzed for the chains under different conditions .The chains were subjected to the modelfirst as the standalone objects. Then, barrier was defined and chains placed in the vicinity of it. Thebarrier acted as a volume excluded hindrance. This type of chain molecular dynamics could be used asa stand-alone model or it could be suitable component for complex models, for example networkmodel of polymer nanocomposite

Notes: This paper describes the viscoelastic properties of network model. In the firstapproximation, nanocomposite was modeled as a 3D tetrafunctional network consideringentanglements to act as the physical x-links. Nano-sized non-deformable domains of defined shapeand size were introduced into the network. The chains in the vicinity of the inclusions wereconsidered immobilized. Hence, the semicrystalline polymer was considered a three-phase systemcontaining flexible matrix bulk phase, immobilized chains near the inclusion surface and rigidcrystalline domains. The crystallites were characterized by their Young's modulus and their tractionproperties were calculated using the Hooke's law. Unlike the model, the real polymer has viscoelasticdeformation properties. The components which could cause viscoelastic properties were introducedand their impact on viscoelastic properties of whole network was investigated. The components werefor example the reptation motion of chain in entanglements or chain, whose motion was retarded byimpact of surroundings. The model enabled to investigate the influence of each component, as well asthe influence of distribution of each component. The types of nods, whose influence was investigatedin this contribution, were fast knot, free entanglement, one-way entanglement and energy barrier

Notes: Abstract In this paper we report on the morphogenesis of dental resins formed by a thermally initiated radical cross-linking copolymerization of model dental resins. These systems were considered reasonable model simplifications of the actual resins used in commercial filling composites, veneers, etc. Effect of bis-GMA content varying from 0 to 100% on the degree of conversion and morphology of the cured resin was investigated. Dynamic scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), dynamic mechanical thermal analysis (DMTA) and high temperature solvent extraction experiments were performed in order to determine the nature and location of unreacted unsaturations in relation to bis-GMA concentration. The interval of cure temperatures, ranging from 23 to 250°C, may seem irrelevant from the clinical point of view but is instrumental for an understanding of the processes involved. Single glass transition temperature (Tg) found in DMTA experiments showed that the copolymerization process between bis-GMA and TEGDMA is random in nature, however, the overall cure reaction is inhomogeneous and this inhomogeneity is increasing with increasing bis-GMA molar fraction. Heterogeneous character of the cure was reflected into the network morphogenesis characterized by microgellation preceded by cyclization and, following connection of microgels. These cure kinetics resulted in a heterogeneous morphology of the cured resin. Moreover, it was shown that the cure kinetics controls to a great extent the degree of conversion of the reactive vinylidene C=C bonds in a fully cured resin. A decrease in bis-GMA concentration in the resin mixture led to a higher degree of conversion, however, even a neat TEGDMA homopolymer did not exhibit C=C conversion greater than 65–70% under the cure conditions used. Leaching out tests, consisting of an extraction of unreacted monomer from a finely ground cured resin in boiling cyclohexanone at 160°C over a period of 5 d, revealed total weight loss of the order of 3.2–5.6 wt % regardless of the total conversion. No uncured monomer was detected in the extract solution using FTIR spectroscopy, however, the method used is not sensitive to the presence of oligomers. It was concluded that the remaining unreacted double bonds are the inevitable result of the diffusion controled heterogeneous cure reaction. The low rate of diffusion in the resin beyond its gel point is controlled by high monomer rigidity, low mobility and radius of gyration of the monomers. The unreacted C=C bonds exist in the form of pendant, side groups chemically attached to the network. In addition, a hypothesis has been proposed that for concentrations of rigid bis-GMA monomers above 50 wt %, preferably only one methacrylate group of its molecule has reacted on the time span of the experiment performed and has been incorporated in the cured network. Hence, a substantial part of unsaturation exists in the solid polymer in the form of pendant groups formed by mechanically ineffective bis-GMA monomers. The results are in good qualitative agreement with computer simulations based on the kinetic gelation model. © 2000 Kluwer Academic Publishers

Notes: Clinical implementation of fibre-reinforced composites (FRCs) for treatment of misaligned teeth requires a stability of the material under stress in a moist environment. The performance of the material is strongly dependent on its resistance to hydrolytic deterioration of the components. Of particular concern are the quality and durability of the interfaces between the fibres and the matrix. Scanning electron microscopy (SEM) was utilized to evaluate qualitatively the effect of water immersion on the interfaces between constituents in a variety of E-glass fibre-reinforced thermoplastics. A particular series of organosilane-coated fibres embedded in polycarbonate (PC) were chosen for further quantitative study of the residual shear strength of the interfaces using an embedded-single-fibre test. Annealed PC and maleated polypropylene (MPP) reinforced with bare E-glass fibres have an appropriate combination of mechanical properties and environmental stability for potential orthodontic applications. The usual sizing agents used for commercial E-glass fibres interfere with the bonding of the fibres to the matrix and the usual silane treatments used to promote bonding could lead to problems of hydrolytic stability under extreme conditions of stress and moisture.

Notes: The effect of a deterioration of matrix and matrix-fibre interface, caused by moisture, on the flexural properties (modulus, strength and ultimate strain) of unidirectional E-glass fibre-reinforced thermoplastics [polycarbonate, poly(ethyleneterephthalate glycol) and nylon 12] was investigated. Specimens of span/thickness ratio varying from 15 to 30, prepared from pultruded thermoplastic prepregs, were tested in directions parallel to and perpendicular to the fibre orientation as moulded and after immersion in water at 85°C for 100 h. No significant reduction in longitudinal properties, controlled by fibre behaviour, resulted from exposure to water. A significant reduction in transverse properties, controlled by the matrix and interface behaviour, was observed. Polycarbonate/bare E-glass fibre composite annealed at 275°C for 1 h before immersion in water exhibited a superior resistance to moisture attack. This phenomenon is attributed to the “transcrystalline” interphase near the fibre surface and good wetting of fibres by the matrix. Resistance against moisture favours this material for further clinical application as an orthodontic wire.

Notes: Abstract The effects of filler particle shape on the Young's and shear moduli of PP/CaCO3 and PP/Mg(OH)2 composites were studied in the concentration interval up to 50 vol/vol % filler. Calcium carbonate had irregular, approximately spherical particles and magnesium hydroxide had particles either in the form of hexagonal plates or micro-needles. The analysis based on the classical models together with structural observations enabled explanation of the composition dependences of elastic moduli of the blends studied. It was found that immobilization of PP matrix on the filler surface prominently influenced the values ofG′ andE′ moduli of PP/CaCO3 and PP/Mg(OH)2 composites. The presence of the strongly immobilized PP with increasing geometrical anisotropy of the filler particles enabled a hyperstructure creation in the composites PP/Mg(OH)2.

Notes: Abstract Fillers suppressed the temperature dependence of storage modulus and caused the flattening of the temperature dependence of the loss modulus in the glass transition region of polypropylene (PP). The glass transition temperature (T β) of PP did not change with filler content (v f). This indicates that none of the fillers affect the mobility of PP in the bulk. A new loss maximum appeared at 50 °C forv f〉0.2. This maximum became more prominent when increasing either the filler content or filler specific surface area. Interparticle interactions, leading to the space network of weakly bonded particles, affected PP mobility indirectly. The enhanced interfacial adhesion led to a further decrease of PP mobility nearT β and to the increase of the new loss maximum at 50 °C.