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The creation of tools by additive manufacturing is becoming increasingly convenient for CFRP one-off and small batch production. Screw extrusion additive manufacturing of thermoplastic polymers has boosted the development of large format manufacturing solutions. Interlayer adhesion and anisotropic properties of a 3D printed part are indisputably key aspects of tool manufacturing process. In this study, thermal and mechanical properties of large format 40% carbon fiber reinforced polyamide 6 3D printed tools were determined. Moreover, the influence on part performance of two main printing parameters, deposition temperature and extruding pressure, was analyzed with respect to polymer melt rheology. The printed material revealed a highly anisotropic thermal and mechanical behavior associated with the alignment of the high carbon fiber content. The optimal process window was identified in terms of substrate deposition temperature. Along the print direction, no major impact on tensile and flexural mechanical properties was detected, while the injection molding values were exceeded by approximately 10%. The layer adhesion was estimated by measuring the stress at break on transversely Z-oriented specimens. Higher deposition temperatures and pressures, combined with lower viscosity, promote wetting and bond formation between layers, ultimately leading to more consistent performances. The best results in the transverse direction were achieved between 140 and 160 °C, reaching roughly a fifth of the longitudinal values. A significant drop in performance was detected below 120 °C, which was identified as the minimum process temperature. A post-process annealing heat treatment was also investigated, no beneficial outcomes were reported. [ABSTRACT FROM AUTHOR]

This work presents an investigation on the morphology, mechanical, viscoelastic and transport properties of acrylonitrile–butadiene–styrene (ABS) nanocomposites reinforced with nanosilica (NS) and multiwalled carbon nanotubes (MWCNTs). The nanofillers content was varied from 1 to 5 wt%. Morphological and mechanical investigations revealed a better dispersion and effective stress transfer in carboxyl-treated MWCNT composites with respect to silane-treated NS. The highest values of tensile strength and Young's modulus were reached for 5 wt% of MWCNT. Theoretical modelling of elastic modulus of the composites with carbon nanotubes (CNT) was in good agreement with experimental data. On the other hand, in the case of composites with NS an interfacial modulus of 2.5 GPa was assumed in the model to approach the experimental data. The highest value of storage modulus was reported at a MWCNT content of 5 wt% followed by 3 wt% which discloses the stiffening effect of long curly CNTs in comparison with NS. The damping behaviour indicated a lowering and broadening of tan δ peak induced by CNT. The storage modulus and damping behaviour of the nanocomposites were analysed using theoretical models in which aspect ratio, stiffening effect, adhesion and entanglement phenomena were included. The lowest solvent diffusivity and permeability was exhibited by composite with MWCNT at 5 wt% owing to the tortuosity, higher adhesion and aspect ratio of the filler and revealed a decrement in permeability by 62% with regard to neat ABS. [ABSTRACT FROM AUTHOR]

In this work, polyurethane (PU) insulating panels containing different amounts of a microencapsulated paraffin with a nominal melting temperature of 24 °C, used as phase change material (PCM), were produced. The resulting panels behaved as multifunctional materials able to thermally insulate and simultaneously storing/releasing thermal energy near room temperature. The panels were characterized from a microstructural, thermal and mechanical point of view. Viscosity measurements highlighted an increase in the viscosity values of the PU liquid precursors due to the addition of the capsules, and this could lead to some difficulties during the production stages, especially in the mixing and foaming phases. From optical microscopy micrographs and density measurements, it was observed that the introduction of paraffin tended to destroy the cellular structure of PU foams, and for PCM contents above 30 mass/% the foams were characterized by an open-cell morphology. SEM observations showed that PCM was preferentially distributed in the cell walls intersection, and a rather limited interfacial adhesion between capsules and PU could be detected. Thermogravimetric analysis evidenced that the introduction of the PCM tended to increase the degradation resistance of the foams, while from differential scanning calorimetry tests it was possible to conclude that PCM addition was able to impart good thermal energy storage properties to the foams, with specific melting enthalpy values of 70 J g−1 for a microcapsules concentration of 50 mass/%. As expected, thermal conductivity (λ) of the foams increased with PCM amount, but this enhancement was not directly related to the higher λ of the PCM itself, but rather than to the cell opening effect promoted by the PCM introduction. The microcapsules addition progressively increased the stiffness of the foams, reducing the failure properties both under quasi-static and impact conditions. Moreover, the mechanical properties were strongly affected by the testing temperature (i.e. the physical state of the wax contained in the microcapsules). [ABSTRACT FROM AUTHOR]

This study is focused on the 3D printing by fused filament fabrication (FFF) process of short carbon-fiber-reinforced polyamide (PA) composites. In particular, the effect of short carbon fiber (CF) on the mechanical, electrical and piezoresistivity properties of 3D-printed polyamide (PA) composite parts has been analyzed. In comparison with neat PA, the results revealed that the carbon fibers effectively improved all assessed mechanical properties of PA/CF composites. In particular, in XY build orientation, PA/CF 3D-printed composites exhibited a tensile strength of 96 MPa and a tensile modulus of 7.9 GPa, with an increment of + 34 and + 147%, respectively, when compared to the neat PA. Interlayer strength of 3D-printed PA and PA/CF composites reaches similar values, in the range 26-28 MPa. The impact strength of 3D-printed XY parts was reduced by the presence of CF. However, the fracture toughness of PA/CF composite 3D-printed parts was slightly higher in comparison with that of neat PA. Electrical resistivity of PA/CF 3D-printed parts is gradually decreasing from 1.7 × 104 to 0.7 × 104 Ω cm in the temperature range from − 16 to 100 °C. The piezoresistivity tests revealed that an exponential resistance change occurs for both compression-molded and 3D-printed PA/CF samples once strained in tension. A gauge factor of 3D-printed parts of about 65 ± 5 was determined from cyclic strains in the elastic region. [ABSTRACT FROM AUTHOR]

The environmental problems associated with global warming are urging the development of novel systems to manage and reduce the energy consumption. An attractive route to improve the energy efficiency of civil buildings is to store the thermal energy thanks, during heating, to the phase transition of a phase-change material (as paraffin) from the solid to the liquid state and vice versa. The stored energy can be then released under cooling. Herein, we developed a novel material (nanofelt) constituted by Si3N4 nanobelts able to absorb huge amounts of liquid paraffin in the molten state and to act as an efficient shape stabilizer. The nanofelt manufacturing technology is very simple and easy to be scaled-up. The effect of the Si3N4 nanofelts density and microstructure on the paraffin sorption and leakage and on the thermal properties of the resulting composite structures is investigated. It is shown that the produced Si3N4/paraffin composites are able to retain enormous fractions of paraffin (up to 70 wt%) after 44 day of desorption test on absorbent paper towel. The thermal energy storage efficiency measured through calorimetric tests is as high as 77.4% in heating and 80.1% in cooling. [ABSTRACT FROM AUTHOR]

In this work the effects of testing temperature and drawing orientation on the fracture behaviour of biobased and biodegradable thermoplastic starch based films, currently applied in the food packaging field, were investigated. At this aim, the Essential Work of Fracture (EWF) approach was applied on samples tested at 0 °C, 25 °C and 50 °C both in machine (MD) and in cross (CD) directions. The specific essential work of fracture (we) values strongly decreased with the testing temperature, and we values of CD samples were systematically higher than those of the corresponding MD samples. Considering that photograms of the CD samples taken during the EWF tests highlighted that the yielding zone became progressively opaque as an effect of the strain induced crystallization, it was hypothesized that in CD specimens part of the tensile energy applied during the straining process was utilized for the orientation of the macromolecules along the strain direction, rather than for the propagation of the crack in the ligament zone. Tensile tests under quasi-static conditions on dumbbell specimens highlighted that, regardless to the drawing direction, the stiffness and the resistance at yield and at break decreased with the temperature, while the strain at break was considerably enhanced. Moreover, because of the strong anisotropy induced by the molecular orientation in the drawing direction, MD tested samples had higher elastic modulus, yield resistance, and stress at break compared to CD samples. [ABSTRACT FROM AUTHOR]

Dynamic-mechanical analysis (DMA) was performed to investigate the viscoelastic response of multifunctional laminates for thermal energy storage (TES). The laminates were constituted by a microencapsulated paraffinic phase change material (PCM), a carbon fiber fabric, and an innovative reactive acrylic resin (Elium®). In the Elium®/PCM systems, the PCM fraction affected neither the glass transition temperature ( T g ) of the resin, found at 100–120 ∘C, nor the activation energy of the glass transition, determined with multifrequency scans from the position of the tan δ peaks. On the other hand, the low-temperature (0–40 ∘C) transition detected on the neat resin was hidden by the PCM melting, evidenced by a step in E ′ and peaks in E ″ and tan δ . In the laminates, the amplitude of the E ′ step and the intensity of the tan δ peak associated to the PCM melting presented a linear correlation with the PCM content and the melting enthalpy. Cyclic heating/cooling DMA tests showed that the decrease in E ′ due to PCM melting was almost completely recovered (90–95%) upon crystallization. The difference between the tan δ peak positions on heating and on cooling decreased from 30 to 12 ∘C when the heating/cooling rate changes from 3 to 1 ∘C/min. Multifrequency tests highlighted that the activation energy of the glass transition of the laminates was lower than that of the matrices, and it did not follow a trend with the PCM fraction. Interestingly, also the E ″ and tan δ peaks related to PCM melting depended on the testing frequency, and their asymmetric shape could be interpreted by considering a progressive melting of the PCM in the microcapsules during heating. [ABSTRACT FROM AUTHOR]

Reinforced polymers have gained a significant interest in the research community in recent years due to their enhanced performance as compared to their parent polymers. Nanosized reinforcement-based polymer composites have shown a considerable enhancement in performance as compared to micro-/macro-sized fillers. But achieving a high degree of filler alignment in nanocomposites via conventional manufacturing techniques continues to be a challenging task. Additive manufacturing (AM) is a possible solution to this challenge and has undergone a significant development in recent years. AM is an efficient technique to fabricate nanocomposites in complex shapes which uses a layer-by-layer method to fabricate materials and thereby eliminates the need for multi-step processing and the use of fasteners/joints to fabricate complex structures. Due to a wide range of properties and the existence of carbon in a variety of forms, carbon filler-based polymer matrix composites are suitable for applications in several technical sectors. AM of carbon-based structures and fiber-reinforced polymer composites enables the production of highly customized parts with a high degree of filler alignment. AM techniques which are generally employed for the fabrication of carbon-based fillers/fiber-reinforced polymer composites are fused deposition modeling, stereolithography, direct ink writing and selective laser sintering. Although AM techniques are efficient, some critical issues such as voids and defects between interlayers, the low adhesion strength between filaments, part curling and insufficient curing of layers need to be addressed to utilize its full potential. [ABSTRACT FROM AUTHOR]

In this paper, different amounts of both devulcanized rubber (DR) and non-devulcanized rubber (NDR) were melt compounded and compression moulded with a brittle thermoplastic matrix such as polystyrene (PS). Scanning electron microscopy observations of the prepared blends showed that the PS/rubber interfacial adhesion, although rather limited, was improved in the case of DR, and that DR domains within the PS matrix had a lower size than NDR particles. Thermogravimetric analysis highlighted that the onset degradation temperature decreased upon the addition of rubber, and the maximum mass loss rate temperature increased. Differential scanning calorimetry tests showed that the glass transition temperature slightly decreased upon addition of DR and NDR. This increase also enhanced the maximum service temperature determined by measuring the Vicat grade. The surface hardness, the tensile modulus and stress at break were negatively affected when recycled rubber was added, because of the limited compatibility between PS and rubber particles and the relatively large size of the rubber domains. A notable increase in material ductility, with an enhancement of the tensile strain at break and of the impact resistance, was detected at elevated rubber amounts. Quite interestingly, mechanical properties of the blends with DR were systematically higher than those of the corresponding blends with NDR. [ABSTRACT FROM AUTHOR]

The following is the correct author list: G. Barera SP 1,2 sp , S. Dul SP 3 sp , A. Pegoretti SP 1 sp SP 1 sp Department of Industrial Engineering, University of Trento, Via Sommarive 9, 38123, Trento, Italy SP 2 sp CMS S.p.A., Via A. Locatelli 123, 24019, Zogno, BG, Italy SP 3 sp Empa, Swiss Federal Laboratories for Materials Science and Technology, Lerchenfeldstrasse 5, 9014 St. Gallen, Switzerland The article has been updated to correct the error. B Correction to b B : b B JMEPEG b https://doi.org/10.1007/s11665-023-08238-0 In this article as originally published, Sithiprumnea Dul was omitted from the author list. [Extracted from the article]

In this study, manganese recycled from cathodes of spent Zn–MnO2 batteries was used for the sol–gel synthesis of a manganese oxide pseudocapacitor with high specific capacitance. The recycled material is a mixture of α-MnO2, Mn3O4, and ZnMn2O4, according to X-ray diffraction, energy dispersive X-ray, Raman spectra, and chemical analysis. Manganese oxide has smaller particle size when synthesized at 700 °C for 3 h (M1) than when synthesized at 700 °C for 12 h (M2), as evidenced by scanning electron microscopy and transmission energy microscopy. The specific capacitances of M1 and M2 after 1000 cyclic voltammetry cycles at 50 mV s−1 are 350 F g−1 and 125 F g−1, respectively. After 500 galvanostatic cycles at 1.0 A g−1, M1 and M2 exhibit specific capacitances of 275 F g−1 and 150 F g−1, respectively. Electrochemical impedance spectra revealed that M1 has lower charge transfer resistance and diffusion resistance than M2. [ABSTRACT FROM AUTHOR]

Novel poly(3-hydroxybutyrate-co-3-hydroxyhexanoate)(PHBH)/fibrillated nanocellulose biodegradable composites for additive manufacturing were produced and characterized. Fibrillated nanocellulose (NCF) was isolated with high energy ultrasonication and dispersed via solution mixing in the polymer matrix. Composite filaments having a nanofiller concentration of 0.5 wt%, 1 wt% and 3 wt% were then extruded, characterized and used in fused deposition modeling (FDM). Neat PHBH powder was then manually added to prepare a solid mixture at different fibrillated nanocellulose concentrations (from 0.5 to 3 wt%), to be then used to feed an extruder. SEM observations on filaments and 3D printed samples evidenced the good dispersion of fibrillated nanocellulose inside the matrix with the presence of agglomerates at higher NCF contents. The beneficial effects of the fibrillated nanocellulose in terms of stress at break and of elongation at break showed a maximum at a fibrillated nanocellulose content of 0.5 wt%. Moreover, the presence of fibrillated nanocellulose did not affect the thermal degradation behaviour of the materials, and also the glass transition and the melting temperatures were not influenced by NCF addition. [ABSTRACT FROM AUTHOR]

In this study, a co-precipitation method was used for the synthesis of undoped ferrites (Fe2O3/Fe3O4-R) and nickel-doped ferrites from nickel reagents (NiFe2O4-R) and from nickel recycled from spent Ni-MH batteries (NiFe2O4-B). Ferrite structure and composition were confirmed by X-ray diffraction and inductively coupled plasma optical emission spectrometry. Energy dispersive X-ray analysis showed the presence of iron, oxygen, and nickel in the surface composition of the nickel-doped ferrites. Scanning electron microscopy showed agglomerated particles of different sizes and shapes. Transmission electron microscopy revealed spherical particles of 50 nm. NiFe2O4-B is a multifunctional material that can be used as a catalyst and pseudocapacitor. The catalytic properties of NiFe2O4-B were analyzed by measuring the decolorization of methylene blue (MB) in a photo-Fenton process under solar radiation. Pseudocapacitive properties, analyzed by cyclic voltammetry, showed that NiFe2O4-B composites exhibit favorable characteristics for application as electrochemical pseudocapacitors. [ABSTRACT FROM AUTHOR]

Cobalt recycled from spent Li-ion batteries has been used in the catalysis of azo dye. Metallic cobalt with a compact hexagonal structure was recycled by electrodeposition after leaching a solution of Li-ion battery cathode and applying a potential of − 1.1 V, with charge density = 15 C cm−2 and pH = 2.7. This cobalt, with H2O2 0.27 mol L−1, was used for degradation of azo dye. H2O2 transformed Co in situ into Co3O4 with a spinel-type structure. Co3O4 was confirmed by Raman spectrum bands in the region of 450 and 700 cm−1. The kinetics of the degradation reactions are of first order. Discoloration efficiency of 85% was reached after 210 min under UV radiation. Formation of Co3O4 in situ is an innovative and efficient method to solve two problems: Li-ion battery recycling and azo dye discolorization. [ABSTRACT FROM AUTHOR]

The use of electrochemical quartz crystal microbalance (EQCM) and inductively coupled plasma optical emission spectrometry (ICP-OES) as well as potentiodynamic and potentiostatic methods has revealed the electrodeposition mechanism from simulated solutions containing Ni, Co, Zn, and Mn, and a leached solution from cathodes of spent Ni-MH batteries. For simulated solutions, electrodeposition occurs via direct reduction, involving two electrons. Zn addition in the solution containing Ni and Co leads to a change in the electrodeposition potential for more negative values. Mn addition in the bath containing Ni, Co, and Zn does not change the electrodeposition process. The electrodeposition from the leached solution occurs in parallel with the hydrogen and oxygen reduction, with the passage of 4 mol of electrons. The MM/ z ratios calculated using ICP-OES are very similar to those obtained by EQCM measurements, revealing the appropriateness of the mechanisms proposed in this work. [ABSTRACT FROM AUTHOR]

In this paper novel electro-active polyamide 12 (PA12) based nanocomposites were prepared though melt compounding by adding different kinds of carbonaceous nanofillers. The thermo-electrical properties of the bulk samples were then compared with those of the corresponding fibers. FESEM images highlighted an homogenous dispersion of carbon black (CB) and carbon nanofibers (CNF) within the matrix, while exfoliated graphite nanoplatelets (xGnP) based nanocomposites showed an aggregated morphology. A slight increase of the glass transition and of the crystallization temperature was evidenced by DSC tests, while thermogravimetric analysis showed an improvement of the thermal degradation resistance. Nanofiller addition promoted substantial increments of the elastic modulus coupled with an electrical resistivity drop up to 10 Ωˑcm, with interesting synergistic effects for nanocomposites filled with both CB and CNF. FESEM micrographs on the fibers demonstrated how the drawing process promoted the breakage of CB aggregates and their alignment along the drawing direction, leading to an increase of both the elastic and failure properties with respect to the neat fibers. On the other hand, nanofiller orientation led to an electrical resistivity enhancement of two orders of magnitude with respect to the corresponding bulk materials, and a CB amount of 10 wt% was thus required to observe a sensible fiber heating upon voltage application. [ABSTRACT FROM AUTHOR]

Objective: The objective of this work is to perform a systematic review and meta-analysis of all randomized controlled trials comparing a single intravenous dose of palonosetron (PAL) 0.25 mg with other 5-HT(3)R in patients receiving moderately or highly emetogenic (MoHE) chemotherapy.Methods: Several databases were searched, including MEDLINE, EMBASE, LILACS, and CENTRAL. The primary endpoints were the incidence of acute and delayed nausea and vomiting. The side effects of each treatment were analyzed. A subgroup analysis was performed to evaluate the influence of the use of corticosteroids. The results are expressed as risk ratio (RR) and the correspondent 95% confidence interval (CI).Results: Five studies were included, with 2057 patients. PAL was compared with ondansetron, granisetron, and dolasetron. Patients in PAL group had less nausea, both acute (RR = 0.86; CI 95% = 0.76 to 0.96; p = 0.007) and delayed (RR = 0.82; CI95% = 0.75 to 0.89; p < 0.00001). They also had less acute vomiting (RR = 0.76; CI 95% = 0.66 to 0.88; p = 0.0002) and delayed vomiting (RR = 0.76; CI95% = 0.68 to 0.85; p < 0.00001). There were no statistical differences in side effects like headache (RR = 0.84; CI 95% = 0.61 to 1.17; p = 0.30), dizziness (RR = 0.40; CI 95% = 0.13 to 1.27; p = 0.12), constipation (RR = 1.29; CI 95% = 0.77 to 2.17; p = 0.33) or diarrhea (RR = 0.67; CI 95% = 0.24 to 1.85; p = 0.44). Patients receiving PAL presented less nausea and vomiting regardless of the use of corticoids. We found no statistical heterogeneity in the global analysis.Conclusion: PAL was more effective than the other 5-HT(3)R in preventing acute and delayed CINV in patients receiving MoHE treatments, regardless of the use of concomitant corticosteroids. [ABSTRACT FROM AUTHOR]

A cyclic olefin copolymer (COC) matrix was melt compounded with various amounts of fumed silica nanoparticles (1, 3 and 5 vol%) and the resulting materials were foamed through supercritical carbon dioxide. Foams were produced at four different foaming pressures (90, 110, 130, and 150 bar), keeping all other processing parameters constant. The main physical properties of both bulk and foamed samples were investigated in order to assess the role of both nanofiller content and foaming pressure. It was observed that the density values of the foamed materials decreased as the foaming pressure increased and that the presence of nanofillers leads to slightly denser materials. Both scanning and transmission electron microscopy evidenced the presence of filler aggregates on the bulk composites. These aggregates resulted to be elongated along the cell wall direction upon foaming. Dynamic mechanical thermal analysis, quasi-static tensile tests, and creep tests evidenced a positive effect played by nanosilica in improving the stiffness, the strength, and the creep stability of the polymer matrix for all foaming pressures. The application of a theoretical model for closed-cell foams highlighted how the stiffening effect provided by the nanosilica networking is mostly effective at elevated filler amounts and reduced foaming pressure values. [ABSTRACT FROM AUTHOR]

Nonlinear viscoelastic creep was studied on polypropylene/fumed silica nanocomposites. The free-volume theory of nonlinear viscoelastic creep was successfully applied to obtain generalized creep master curves using a tensile compliance vs. internal time superposition in the region of nonlinear viscoelasticity. Concurrently, a time-temperature superposition approach was also adopted for the construction of creep master curves. A good agreement between the time-strain and the time-temperature superposition approaches was assessed by comparing the master curves obtained from the two data reduction methods. Both approaches evidenced a remarkable stabilizing effect induced by the nanoparticles that was observed especially for higher creep stresses and at increased temperatures and, considering the correspondent superposition principle, at long loading times. At the same time, both storage and loss moduli measured through dynamic mechanical analyses, were enhanced in all nanocomposites. Activation energy values obtained from the analysis of dynamic multi-frequency tests were in good accordance with those referred to creep tests. [ABSTRACT FROM AUTHOR]

Microcrystalline cellulose (MCC) powder was selected as a natural reinforcement for a commercial acrylic adhesive widely used in the field of art protection and restoration (Paraloid B72). In particular, various amounts (from 5 to 30 wt%) of MCC were melt compounded with Paraloid B72 to prepare new thermoplastic polymer composites for the cultural heritage conservation field. Scanning electron microscopy showed that MCC flakes are uniformly dispersed within the matrix at all the tested compositions, without preferential orientation. Thermogravimetric analysis evidenced an increase of thermal stability due to the MCC introduction, even at low filler amounts, while DSC measurements demonstrated that the glass transition temperature progressively increases with the MCC content. Interestingly, DMTA analysis revealed a stabilizing effect on the material produced by microcellulose addition, with an increase of the storage modulus and a decrease of the thermal expansion coefficient, in proportion to the filler loading. Moreover, MCC addition determined an increase of the elastic modulus and creep stability with respect to the neat resin, and an enhancement of fracture toughness ( K). [ABSTRACT FROM AUTHOR]

A linear low density polyethylene matrix was melt compounded with a given amount (2 vol.%) of both untreated (hydrophilic) and surface treated (hydrophobic) fumed silica nanoparticles with the aim to investigate the influence of the time under processing conditions on the microstructure and thermo-mechanical properties of the resulting materials. Crosslinking reactions induced by thermal processing caused a remarkable increase of the melt viscosity, as revealed by the melt flow index values of both neat matrix and nanocomposites. Thermal oxidation of the matrix was slightly reduced by the introduction of fumed silica nanoparticles, especially for long compounding times. Differential scanning calorimetry evidenced how silica nanoparticles had a nucleating effect on the matrix, while both the melting temperature and the relative crystallinity were decreased by the compounding process. Nanosilica addition promoted a general improvement of the tensile properties, that progressively decreased with the processing time. [ABSTRACT FROM AUTHOR]

The paper analyzes how the structure of social networks affects innovation diffusion and competition under different information regimes. Diffusion is modeled as the result of idiosyncratic adoption thresholds, local network effects and information diffusion (broadcasting and demonstration effect from previous adopters). A high social cohesion decreases the probability of one innovation cornering the market. Nonetheless, with imperfect information, in small-world networks the higher speed of diffusion produced by the low average distance increases this probability. A low social cohesion also increases the probability of falling into traps of under-adoption. However, such probability is significantly lower with imperfect information, because such regime is characterized by higher levels of market concentrations and this reduces the frictions due to the coexistence of non-compatible product innovations. [ABSTRACT FROM AUTHOR]

Various kinds of fumed silica nanoparticles, different in terms of specific surface area and surface functionalization, were melt compounded with a poly(lactic acid) biodegradable matrix, with the aim to investigate the thermo-mechanical and optical properties of the resulting materials. Untreated nanoparticles at elevated surface area resulted to be effective in increasing elastic modulus, because of the extended filler-matrix interaction, while the finer dispersion of silica aggregates at the nanoscale obtained with surface treated nanoparticles led to noticeable improvements of the tensile properties at yield and at break, both under quasi-static and impact conditions. Also the fracture toughness and the creep stability were substantially enhanced by nanosilica addition, without impairing the original optical transparency of the matrix. [ABSTRACT FROM AUTHOR]

High-density polyethylene-based nanocomposites were prepared through a melt compounding process by using surface functionalized fumed silica nanoparticles in various amounts, in order to investigate their capability to improve both mechanical properties and resistance to thermal degradation. The fine dispersion of silica aggregates led to noticeable improvements of both the elastic modulus and of the stress at yield proportionally to the filler content, while the tensile properties at break were not impaired even at elevated filler content. Thermogravimetric analysis showed that the selected nanoparticles were extremely effective both in increasing the decomposition temperature and in decreasing the mass loss rate, even at relatively low filler loadings. The formation of a char enriched layer, limiting the diffusion of the oxygen through the nanofilled samples, was responsible of noticeable improvements of the limiting oxygen index, especially at elevated silica loadings. In contrast with commonly reported literature results, cone calorimeter tests also revealed the efficacy of functionalized nanoparticles in delaying the time to ignition and in decreasing the heat release rate values. Therefore, the addition of functionalized fumed silica nanoparticles could represent an effective way to enhance the flammability properties of polyolefin matrices even at low filler concentrations. [ABSTRACT FROM AUTHOR]

High density polyethylene was melt compounded with various untreated (hydrophilic) or surface treated (hydrophobic) fumed silica nanoparticles, having different surface areas. The thermo-mechanical properties of the resulting nanocomposites have been thoroughly investigated. Field emission scanning electron microscopy revealed that nanofiller aggregation was more pronounced as the silica surface area increased, while nanofiller dispersion improved with a proper filler functionalization. The homogeneous distribution of fumed silica aggregates at low filler content allowed us to reach remarkable improvements of thermal stability, evidenced by an increase of the degradation temperature and a decrease of the mass loss rate with respect to neat matrix, especially when surface treated nanoparticles were utilized. Interestingly, the stabilizing effect produced by fumed silica nanoparticles was accompanied by noticeable enhancements of the ultimate tensile mechanical properties, both under quasi-static and impact conditions. Concurrently, a progressive enhancement of both elastic modulus and tensile stress at yield with the filler amount, was observed. [ABSTRACT FROM AUTHOR]

An alternative route for the production of graphene-polymer nanocomposites is proposed. First graphene oxide lamellae are homogenously dispersed in a polyvinyl alcohol matrix. In a second step, mild thermal treatments are carried out on composites in order to promote a thermal reduction of the graphene oxide into reduced graphene oxide. The occurrence of an in situ reduction of graphene oxide is confirmed by various experimental techniques, such as differential scanning calorimetry, thermogravimetric analysis and electrical resistivity measurements. [ABSTRACT FROM AUTHOR]

The microstructure and thermomechanical behaviour of a novel fully biodegradable polyvinyl alcohol (PVOH)-based single-polymer composite (SPC) is presented. Three kinds of PVOH stapled fibres, having different melting temperatures and tensile mechanical properties, were considered as a reinforcement, whilst plasticized PVOH granules were selected as a continuous matrix. Calorimetric tests on the constituents showed significantly different melting temperatures between the matrix and the fibres, thus evidencing adequate processing windows for the preparation of SPCs. On the other hand, scanning electron microscopy on the cryofractured surfaces of melt-mixed and compression-moulded SPCs experimentally proved that the morphological integrity of the reinforcement was maintained only when high melting temperature fibres were utilized. Quasi-static mechanical tensile tests highlighted the capability of the selected PVOH fibres to remarkably increase the elastic modulus, the stress at yield and the Vicat softening temperature of the PVOH matrix. Moreover, dynamic storage modulus and glass transition temperature of SPC increased with respect to the neat PVOH over the whole range of considered temperatures, whilst short-term creep stability was strongly improved, proportionally to the fibre content. The application of a time-temperature superposition principle to creep data confirmed the effectiveness of these fibres in increasing the long-term creep stability of the resulting materials. [ABSTRACT FROM AUTHOR]

Both untreated and calcined fumed alumina nanoparticles were dispersed into an epoxy-based adhesive at various percentages. The glass transition temperature of the nanofilled adhesives increased up to an optimal filler loading and then decreased, probably due to concurrent and contrasting effects of chain blocking and reduction of the crosslinking degree. Tensile modulus, stress at break, and fracture toughness of bulk adhesive were positively affected by the presence of untreated alumina nanoparticles at an optimal filler content. Mechanical tests on single-lap aluminum bonded joints indicated that untreated alumina nanoparticles markedly improved both the shear strength and fatigue life of the bonded joints. In particular, the shear strength increased by about 60% for an optimal filler content of 1 vol.%, and an adhesive failure mechanism was evidenced for all the tested specimens. Concurrently, a relevant decrease of the equilibrium contact angle with water was observed for nanofilled bulk adhesives. In summary, alumina nanoparticles can effectively improve the mechanical performances of epoxy structural adhesives, both by increasing their mechanical properties and by enhancing the interfacial wettability with an aluminum substrate. [ABSTRACT FROM AUTHOR]

Alternative treatment for recurrent labial infection by herpes simplex virus (HSV) have been considered. The aim of this study was to evaluate the effectiveness of laser phototherapy in prevention and reduction of severity of labial manifestations of herpes labialis virus. Seventy-one patients, divided into experimental (n = 41) and control (n = 30) groups were followed up for 16 months. Patients in the control group were treated topically with aciclovir and patients in the experimental group were subjected to laser phototherapy (one session per week, 10 weeks): 780 nm, 60 mW, 3.0 J/cm(2) or 4.5 J/cm(2) on healthy (no HSV-1 infection) and affected (with HSV-1 infection) tissues. Patients in the experimental group presented a significant decrease in dimension of herpes labialis lesions (P = 0.013) and inflammatory edema (P = 0.031). The reduction in pain level (P = 0.051) and monthly recurrences (P = 0.076) did not reach statistical significance. This study represents an in vivo indication that this treatment should be further considered as an effective alternative to therapeutic regimens for herpes labialis lesions. [ABSTRACT FROM AUTHOR]

The effect of the deformation temperature on the energy stored in post-yield deformed poly(butylene terephthalate) PBT, was studied by means of DSC tests. Deformed specimens were rapidly cooled after unloading, in order to avoid the energy relaxation processes occurring before the DSC measurements. Cooling revealed to have a significant contribution on the whole stored energy, as shown by DSC tests conducted on undeformed PBT specimens conditioned at various temperatures. This work is aimed at separating the effects due to cooling and those ascribed to deformation on the energy storage and release processes, permitting to better understand previous findings on post-yield compressed PBT. [ABSTRACT FROM AUTHOR]

We apply a range of techniques (thermal methods, microscopy, X-ray diffraction, IR spectroscopy) to characterize a drug (atenolol), several excipients (PVP=polyvinylpyrrolidone, MGST=magnesium stearate, Avicel©) and drug-excipients mixtures either as prepared, annealed, and exposed to moisture. We compare the data of the mixtures with those computed from a weighted average of similarly treated pure compounds to find evidence of drug properties modified by the interaction with the excipient. We find that thermal response is by far the most sensitive indicator of interaction while IR is the least sensitive one. Avicel© has essentially no interaction with atenolol, while MGST modifies significantly only the thermal response of the drug in the MGST-rich mixtures. PVP interacts strongly with atenolol, and this interaction appears to be mediated by the substantial amount of hydration water the excipient brings in its mixtures with a water-free drug. [ABSTRACT FROM AUTHOR]

In this paper the creep crack propagation in a short glass fibre reinforced polypropylene composite has been investigated at various temperatures in the range from 32 to 60°C. Creep crack speed ( da/ dt) resulted initially decreasing till a minimum value, and then gradually increasing up to instability and fracture. Both initial and minimum crack speed values were found to strongly increase as test temperature increased. Moreover, isothermal curves of the applied stress intensity factor Kappl as a function of the crack speed ( da/ dt) were obtained at various temperatures. Portions of these curves in the stable crack acceleration region were hence shifted along the da/ dt, axis according to a time-temperature reduction scheme, thus allowing the construction of a creep crack propagation master curve. The shift factor values, aT for the creep crack propagation master curve appeared to be higher than those obtained, in the same temperature range, from dynamic mechanical measurements in a linear viscoelastic regime. [ABSTRACT FROM AUTHOR]

The effect of the critical volume fraction vcr of poly(styrene- co-acrylonitrile) (SAN) on the mechanical properties of its blends with rubber-toughened polypropylene (RTPP) containing about 12% grafted ethylene-propylene copolymer was studied. To encompass a wide spectrum of mechanical properties, blend components were selected which are characterized with rather different viscoelastic, tensile and ultimate properties. The SAN volume fraction in blends covers the interval 0∼0.30; concentration dependencies of measured mechanical properties indicate vcr = 0.13. Experimental data on storage modulus Eb′, loss modulus Eb″, tensile modulus Eb, yield Syb and tensile Sub strength are in plausible accord with their simultaneous prediction based on a predictive scheme which operates with a two-parameter equivalent box model and the data on the phase continuity of components obtained from modified equations of the percolation theory. Strain at break, tensile energy to break and total impact energy of blends show a conspicuous drop in the interval 0∼15 % of SAN where SAN forms a discontinuous component; further growth of the SAN fraction accounts for a reduction of the blend ultimate properties to the values typical of brittle polymers. [ABSTRACT FROM AUTHOR]