Publications

Publications


  • Multifunctional glass fiber/polyamide composites with thermal energy storage/release capability 2018

    Fredi, G.; Dorigato, A.; Pegoretti, A., "Multifunctional glass fiber/polyamide composites with thermal energy storage/release capability" in EXPRESS POLYMER LETTERS, v. 12, n. 4 (2018), p. 349-364. - URL: http://www.expresspolymlett.com/ . - DOI: 10.3144/expresspolymlett.2018.30

    Thermoplastic composite laminates with thermal energy storage (TES) capability were prepared by combining aglass fabric, a polyamide 12 (PA12) matrix and two different phase change materials (PCMs), i.e. a paraffinic wax microencapsulatedin melamine-formaldehyde shells and a paraffin shape stabilized with carbon nanotubes. The melt flow index ofthe PA12/PCM blends decreased with the PCM concentration, especially in the systems with shape stabilized wax. Differentialscanning calorimetry showed that, for the matrices with microcapsules, the values of enthalpy were approximatelythe 70% of the theoretical values, which was attributed to the fracture of some microcapsules. Nevertheless, most of the energystorage capability was preserved. On the other hand, much lower relative enthalpy values were measured on the compositeswith shape stabilized wax, due to a considerable paraffin leakage or degradation. The subsequent characterization ofthe glass fabric laminates highlighted that the fiber and void volume fractions were comparable for all the laminates exceptfor that with the higher amount of shape stabilized wax, where the high viscosity of the matrix led to a low fiber volumefraction and higher void content. The mechanical properties of the laminates were only slightly impaired by PCM addition,while a more sensible drop of the elastic modulus, of the stress at break and of the interlaminar shear strength could be observedin the shape stabilized wax systems.

    2018 journal paper

  • Ultrathin wood laminae-polyvinyl alcohol biodegradable composites 2018

    Dorigato, Andrea; Negri, Martino; Pegoretti, Alessandro, "Ultrathin wood laminae-polyvinyl alcohol biodegradable composites" in POLYMER COMPOSITES, v. 39, n. 4 (2018), p. 1116-1124. - URL: http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)1548-0569 . - DOI: 10.1002/pc.24040

    Novel polyvinyl alcohol (PVOH) based biodegradablecomposites were prepared by a hand lay-up processusing ultrathin beech laminae cut by a specializedplaner machine, and the resulting materials werethermo-mechanically characterized. Density measuredshowed how the adopted procedure led to laminateshaving a high porosity degree (about 50% by volume)and an elevated wood concentration (about 80% byweight). In fact, because the wood fibers were perfectlycut (not pressed and abraded), wood porositywas partially filled by the PVOH resin, as documentedby field emission scanning electron microscope(FESEM) micrographs. The occlusion of wood porosityby the PVOH matrix resulted to be beneficial for thetensile mechanical properties of the composites. Infact, quasi-static tensile tests and DMTA analysisrevealed how the stiffness (E, E0) and strength (rb) valuesof the composites both along longitudinal andtransversal directions were considerably higher thanthose of the constituents. On the other hand, the valuesof the specific energy adsorbed under impact conditionsby the composites samples were rather low,if compared to the neat matrix.

    2018 journal paper

  • 3D printable thermoplastic polyurethane blends with thermal energy storage/release capabilities 2018

    Rigotti, D.; Dorigato, A.; Pegoretti, A., "3D printable thermoplastic polyurethane blends with thermal energy storage/release capabilities" in MATERIALS TODAY COMMUNICATIONS, v. 15, (2018), p. 228-235. - URL: http://www.journals.elsevier.com/materials-today-communications/ . - DOI: 10.1016/j.mtcomm.2018.03.009

    The aim of this work was to develope novel 3D printable thermoplastic polyurethane (TPU) blends with thermalenergy storage (TES) capabilities. The target are potential applications for winter sport equipment. Differentamounts of an encapsulated paraffin were added to a TPU matrix, and the resulting blends were then used toproduce 3D printed samples. FESEM observation evidenced a homogeneous distribution of the capsules in thepolymer matrix and a good adhesion between the layers in the 3D printed parts. DSC tests indicated that aneffective energy storage/release capability was obtained in the 3D printed parts, with melting enthalpy values upto 70 J/g. The hard shells of the microcapsules, made of melamine formaldehyde resin, induced an increase ofthe stiffness, of the creep stability and of the Shore A hardness of the material, accompanied by a decrease of theelongation at break.

    2018 journal paper

  • Multifunctional epoxy/carbon fiber laminates for thermal energy storage and release 2018

    Fredi, Giulia; Dorigato, Andrea; Fambri, Luca; Pegoretti, Alessandro, "Multifunctional epoxy/carbon fiber laminates for thermal energy storage and release" in COMPOSITES SCIENCE AND TECHNOLOGY, v. 158, (2018), p. 101-111. - URL: http://www.journals.elsevier.com/composites-science-and-technology/ . - DOI: 10.1016/j.compscitech.2018.02.005

    This work is focused on the preparation and characterization of novel multifunctional structural compositeswith thermal energy storage (TES) capability. Structural laminates were obtained by combiningan epoxy resin, a paraffinic phase change material (PCM) stabilized with carbon nanotubes (CNTs), andreinforcing carbon fibers. The stabilized paraffin kept its ability to melt and crystallize in the laminates,and the melting enthalpy of the composites was proportional to the paraffin weight fraction with amaximum value of 47.4 J/cm3. This thermal response was preserved even after fifty consecutive heatingcoolingcycles. Moreover, the thermal conductivity of the laminates through thickness direction resultedto increase proportionally to the content of CNT-stabilized PCM. The capability of the developed TESlaminates to contribute to the thermal energy management was also proven by monitoring their coolingrates through thermal imaging. The flexural modulus was only slightly affected by the presence of thePCM, while a decrease of flexural strength, strain at break and interlaminar shear strength was detected.Optical microscopy highlighted that this could be attributed to the preferential location of the PCM in theinterlaminar region. The obtained results demonstrated the feasibility of the concept of multifunctionalstructural TES composites.

    2018 journal paper

  • Evaluation of the shape memory behavior of a poly(cyclooctene) based nanocomposite device 2018

    Dorigato, A.; Pegoretti, A., "Evaluation of the shape memory behavior of a poly(cyclooctene) based nanocomposite device" in POLYMER ENGINEERING AND SCIENCE, v. 58, n. 3 (2018), p. 430-437. - URL: http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)1548-2634 . - DOI: 10.1002/pen.24590

    The objective of the present work is to investigate theelectro-activated shape memory behavior of a polycyclooctene(PCO) based nanocomposite device. At thisaim, carbon black (CB) and exfoliated graphite nanoplatelets(xGnP) were melt compounded with a PCO matrixcrosslinked with a dicumylperoxide content of 2 wt% anda total filler amount of 4 wt%. Electrical resistivity measurementson bulk materials evidenced a noticeabledecrease of the electrical resistivity upon CB addition,while no synergistic effects were detected mixing CB andxGnP. Nanocomposite with a CB amount of 4 wt%revealed also a noticeable heating capability throughJoule effect for voltage levels higher than 100 V. The subsequentcharacterization of an electro active shape memorydevice based on this composition demonstrated howit is possible to prepare a shape memory nanocompositematerial able to completely recover its original shape after100 s with a voltage of 90 V. The retention of the shapememory behavior after several (50) programming cycleswas also demonstrated.

    2018 journal paper

  • Electrically conductive nanocomposites for fused deposition modelling 2017

    Dorigato, A; Moretti, V.; Dul, S.; Unterberger, S.H.; Pegoretti, A., "Electrically conductive nanocomposites for fused deposition modelling" in SYNTHETIC METALS, v. 226, (2017), p. 7-14. - URL: http://www.journals.elsevier.com/synthetic-metals/ . - DOI: 10.1016/j.synthmet.2017.01.009

    An acrylonitrile-butadiene-styrene (ABS) matrix was melt compounded with various amounts (from 1 to8 wt%) of multi-walled carbon nanotubes (MWCNT) predispersed in an ABS carrier. The resultingmaterials were then i) compression molded (CM) to obtain plaques or ii) extruded infilaments used tofeed a fused deposition modelling (FDM) machine. 3D printed samples were obtained under threedifferent orientations.The nanofiller addition within the ABS matrix caused a remarkable increase of both stiffness and stressat yield of the bulk samples, accompanied by a strong reduction of the elongation at break. Themechanical properties of 3D printed samples resulted to be strongly dependent on the printingorientation. The addition of CNTs was very effective in improving the electrical conductivity with respectto neat ABS even at the smallestfiller content. The FDM process determined a partial loss in the electricalconductivity of ABS nanocomposites, with a marked dependency on the printing orientation. For CNTamounts higher than 4 wt%, CM samples manifested a rapid heating by Joule effect, while the process wasless efficient in the printed samples. CNT addition has high impact on thermal properties, resulting in adecrease of specific heat and a increase of thermal diffusivity and conductivity. Like observed for electricconductivity FDM also influences properties of thermal diffusivity and conductivity, resulted by apossible orientation of CNT.

    2017 journal paper

  • Novel polyamide 12 based nanocomposites for industrial applications 2017

    Dorigato, A; Brugnara, M.; Pegoretti, A., "Novel polyamide 12 based nanocomposites for industrial applications" in JOURNAL OF POLYMER RESEARCH, v. 24, n. 6 (2017). - DOI: 10.1007/s10965-017-1257-9

    In this paper novel electro-active polyamide12 (PA12) based nanocomposites were prepared thoughmelt compounding by adding different kinds of carbonaceousnanofillers. The thermo-electrical properties ofthe bulk samples were then compared with those of thecorresponding fibers. FESEM images highlighted an homogenousdispersion of carbon black (CB) and carbonnanofibers (CNF) within the matrix, while exfoliatedgraphite nanoplatelets (xGnP) based nanocompositesshowed an aggregated morphology. A slight increaseof the glass transition and of the crystallization temperaturewas evidenced by DSC tests, while thermogravimetricanalysis showed an improvement of the thermaldegradation resistance. Nanofiller addition promotedsubstantial increments of the elastic modulus coupledwith an electrical resistivity drop up to 103 Ω cm, withinteresting synergistic effects for nanocomposites filledwith both CB and CNF. FESEM micrographs on thefibers demonstrated how the drawing process promotedthe breakage of CB aggregates and their alignmentalong the drawing direction, leading to an increase ofboth the elastic and failure properties with respect to theneat fibers. On the other hand, nanofiller orientation ledto an electrical resistivity enhancement of two orders ofmagnitude with respect to the corresponding bulkmaterials, and a CB amount of 10 wt% was thus requiredto observe a sensible fiber heating upon voltageapplication.

    2017 journal paper

  • Wax confinement with carbon nanotubes for phase changing epoxy blends 2017

    Fredi, Giulia; Dorigato, Andrea; Fambri, Luca; Pegoretti, Alessandro, "Wax confinement with carbon nanotubes for phase changing epoxy blends" in POLYMERS, v. 9, n. 9 (2017), p. 405. - URL: http://www.mdpi.com/2073-4360/9/9/405/pdf . - DOI: 10.3390/polym9090405

    A paraffin wax was shape stabilized with 10 wt % of carbon nanotubes (CNTs) anddispersed in various concentrations in an epoxy resin to develop a novel blend with thermal energystorage capabilities. Thermogravimetric analysis showed that CNTs improve the thermal stability ofparaffin, while differential scanning calorimetry showed that the paraffin kept its ability to melt andcrystallize, with enthalpy values almost proportional to the paraffin fraction. In contrast, a noticeableloss of enthalpy was observed for epoxy/wax blends without CNTs, which was mainly attributedto the partial exudation of paraffin out of the epoxy matrix during the curing phase. Dynamicmechanical thermal analysis contributed to elucidate the effects of the melting of the paraffin phaseon the viscoelastic properties of the epoxy blends. Flexural elastic modulus and strength of the blendsdecreased with the wax/CNT content according to a rule of mixtures, while flexural strain at breakvalues deviate positively from it. These results show the potentialities of the investigated epoxyblends for the development of multifunctional structural composites.

    2017 journal paper

  • Phase changing nanocomposites for low temperature thermal energy storage and release 2017

    Dorigato, A; Canclini, P.; Unterberger, S.H.; Pegoretti, A., "Phase changing nanocomposites for low temperature thermal energy storage and release" in EXPRESS POLYMER LETTERS, v. 11, n. 9 (2017), p. 738-752. - URL: http://www.expresspolymlett.com/letolt.php?file=EPL-0008111&mi=c . - DOI: 10.3144/expresspolymlett.2017.71

    The aim of this paper is to develop new elastomeric phase change materials (PCM) for the thermal energystorage/release below room temperature. In particular, poly(cyclooctene) (PCO)/paraffin blends filled with various concentrationsof carbon nanotubes (CNTs), were prepared by a melt compounding process. The microstructural, thermo-mechanicaland electrical properties of the resulting materials were investigated.The microstructure of these materials was characterized by the presence of paraffin domains inside the PCO, and CNTs werelocated only inside the paraffin domains in forms of aggregated clusters. DSC tests evidenced the existence of two distinctcrystallization peaks at –10 and at 6 °C, respectively associated to the paraffin and the PCO phases, indicating that both thepolymeric constituents are thermally active below room temperature. Moreover, CNT addition did not substantially alterthe melting/crystallization properties of the material. Noticeable improvements of the mechanical properties and of the electricalconductivity with respect to the neat PCO/paraffin blend could be obtained upon CNT addition, and also thermal conductivity/diffusivity values were considerably enhanced above the percolation threshold. Finite element modeling demonstratedthe efficacy of the prepared nanocomposites for applications in the thermal range from –30 to 6 °C.

    2017 journal paper

  • Effects of carbonaceous nanofillers on the mechanical and electrical properties of crosslinked poly(cyclooctene) 2017

    Dorigato, A; Pegoretti, A., "Effects of carbonaceous nanofillers on the mechanical and electrical properties of crosslinked poly(cyclooctene)" in POLYMER ENGINEERING AND SCIENCE, v. 57, n. 5 (2017), p. 537-543. - URL: http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)1548-2634 . - DOI: 10.1002/pen.24449

    In this work the mechanical and electrical behavior of poly(cyclooctene) (PCO)-based nanocomposites were investigated.At this aim, different amounts (0.5–4 wt%) ofcarbon black (CB), carbon nanofibers (NF) and exfoliatedgraphite nanoplatelets (xGnP) were melt compoundedwith a PCO matrix and crosslinked with dicumylperoxide(DCP). The progressive increase of the DCP concentrationled to an evident decrease of both the melting temperatureand the crystallization temperature, and also the relativecrystallinity was strongly reduced. Microstructuralobservations on nanocomposites materials with a DCPamount of 2 wt% evidenced how CB nanocompositeswere characterized by a good nanofiller dispersion withinthe matrix, while NF and xGnP nanofilled samples presenteda more aggregated morphology. The introductionof CB and xGnP determined an enhancement of the elasticmodulus of the material, without impairing the ultimateproperties of the pristine matrix. Electrical resistivitymeasurements evidenced how the prepared compositescan be interesting as electro-active materials for CB concentrationshigher than 2 wt%.

    2017 journal paper

  • Effects of the extrusion processes on the rheological, chemical, and coloration properties of a copper phthalocyanine-based masterbatch 2017

    Buccella, M; Dorigato, A; Rizzola, F; Caldara, M; Fambri, L, "Effects of the extrusion processes on the rheological, chemical, and coloration properties of a copper phthalocyanine-based masterbatch" in THE JOURNAL OF ELASTOMERS AND PLASTICS, v. 2017, (2017), p. 1-17. - URL: http://journals.sagepub.com.ezp.biblio.unitn.it/doi/pdf/10.1177/0095244317718597 . - DOI: 10.1177/0095244317718597

    The production process of a monodispersed blue masterbatch for the coloration of thecarpet filaments, constituted by a polyamide 6 (PA6) resin and a copper blue phthalocyaninepigment, was investigated and optimized. It was found that a compoundingprocess based on three extrusions without any subsequent filtration was the best way toachieve a fine pigment dispersion within the PA6 matrix, with a filter pressure valuereduction of 50% and a relative color strength increase of about 10% with respect to thestandard production process (i.e. a single extrusion). Rheological tests, viscosity measurementsand end groups analyses were used to determine the thermal stability of theprepared compounds. It was found that the triple extrusion promoted thermo-oxidativereactions. This innovative process setup can reduce the production waste, increasing theproductivity and the quality of the final product without compromising the rheologicalproperties of the monodispersed masterbatches.

    2017 journal paper

  • Fatigue behaviour of biocomposites 2017

    Pegoretti, A; Dorigato, A., "Fatigue behaviour of biocomposites" in Luigi Ambrosio (edited by), Biomedical Composites - Second Edition, Duxford, UK: Elsevier/Woodhead Publishing Ltd, 2017, p. 431-478. - ISBN: 978-0-08-100752-5

    2017 chapter

  • POLYETHYLENE WAX/EPDM BLENDS AS SHAPE-STABILIZED PHASE CHANGE MATERIALS FOR THERMAL ENERGY STORAGE 2017

    Dorigato, A.; Ciampolillo, M.V.; Cataldi, A.; Bersani, M.; Pegoretti, A., "POLYETHYLENE WAX/EPDM BLENDS AS SHAPE-STABILIZED PHASE CHANGE MATERIALS FOR THERMAL ENERGY STORAGE" in RUBBER CHEMISTRY AND TECHNOLOGY, v. 90, n. 3 (2017), p. 575-584. - DOI: 10.5254/rct.82.83719

    2017 journal paper

  • Cyclic olefin copolymer–silica nanocomposites foams 2016

    Pegoretti, Alessandro; Dorigato, Andrea; Biani, Andrea; Slouf, Miroslav, "Cyclic olefin copolymer–silica nanocomposites foams" in JOURNAL OF MATERIALS SCIENCE, v. 51, n. 8 (2016), p. 3907-3916. - URL: http://link.springer.com/journal/10853 . - DOI: 10.1007/s10853-015-9710-9

    A cyclic olefin copolymer (COC) matrix wasmelt compounded with various amounts of fumed silicananoparticles (1, 3 and 5 vol%) and the resulting materialswere foamed through supercritical carbon dioxide. Foamswere produced at four different foaming pressures (90, 110,130, and 150 bar), keeping all other processing parametersconstant. The main physical properties of both bulk andfoamed samples were investigated in order to assess therole of both nanofiller content and foaming pressure. It wasobserved that the density values of the foamed materialsdecreased as the foaming pressure increased and that thepresence of nanofillers leads to slightly denser materials.Both scanning and transmission electron microscopy evidencedthe presence of filler aggregates on the bulk composites.These aggregates resulted to be elongated along thecell wall direction upon foaming. Dynamic mechanicalthermal analysis, quasi-static tensile tests, and creep testsevidenced a positive effect played by nanosilica inimproving the stiffness, the strength, and the creep stabilityof the polymer matrix for all foaming pressures. Theapplication of a theoretical model for closed-cell foamshighlighted how the stiffening effect provided by thenanosilica networking is mostly effective at elevated filleramounts and reduced foaming pressure values.

    2016 journal paper

  • Mechanical behaviour of cyclic olefin copolymer/exfoliated graphite nanoplatelets nanocomposites foamed by supercritical carbon dioxide 2016

    Biani, A.; Dorigato, Andrea; Bonani, Walter; Slouf, Miroslav; Pegoretti, Alessandro, "Mechanical behaviour of cyclic olefin copolymer/exfoliated graphite nanoplatelets nanocomposites foamed by supercritical carbon dioxide" in EXPRESS POLYMER LETTERS, v. 10, n. 12 (2016), p. 977-989. - URL: http://www.expresspolymlett.com/letolt.php?file=EPL-0007313&mi=c . - DOI: 10.3144/expresspolymlett.2016.91

    A cycloolefin copolymer matrix was melt mixed with exfoliated graphite nanoplatelets (xGnP) and the resultingnanocomposites were foamed by supercritical carbon dioxide. The density of the obtained foams decreased with the foamingpressure. Moreover, xGnP limited the cell growth during the expansion process thus reducing the cell diameter (from 1.08to 0.22 mm with an XGnP amount of 10 wt% at 150 bar) and increasing the cell density (from 12 to 45 cells/mm2 with ananofiller content of 10 wt% at 150 bar). Electron microscopy observations of foams evidenced exfoliation and orientationof the nanoplatelets along the cell walls. Quasi-static compressive tests and tensile creep tests on foams clearly indicatedthat xGnP improved the modulus (up to a factor of 10 for a xGnP content of 10 wt%) and the creep stability.

    2016 journal paper

  • Thermal and mechanical behavior of innovative melt-blown fabrics based on polyamide nanocomposites 2016

    Dorigato, Andrea; Brugnara, Marco; Giacomelli, Gianmarco; Fambri, Luca; Pegoretti, Alessandro, "Thermal and mechanical behavior of innovative melt-blown fabrics based on polyamide nanocomposites" in JOURNAL OF INDUSTRIAL TEXTILES, v. 45, n. 6 (2016), p. 1504-1515. - URL: http://jit.sagepub.com . - DOI: 10.1177/1528083714564633

    A commercial organo-modified clay (OMC) was added to a polyamide 6 (PA6) matrix atvarious concentrations during the polymerization stage or by melt compounding in atwin-screw extruder, and the resulting pellets were used for the production of depthfilters in the shape of cylindrical nonwoven webs through a melt-blown process. Theprocessability of the investigated materials was significantly affected by nanofiller introduction.Differential scanning calorimetry revealed that OMCs play a nucleating effecton the crystallization of the polyamide matrix, with a remarkable increase in the crystallizationtemperature on cooling from the melt. Consequently, a parameter related tothe filtering performances of the web, such as the pressure drop (P) evaluated oncylindrical filters, decreased with the increase in die-to-collector distance in a morepronounced way for nanocomposite nonwovens. This behavior was related to thesignificant decrease of the connecting points in the networks due to the rapid coolingof the filaments on the collecting mandrel. Compressive mechanical tests evidencedhow organoclay addition led to a remarkable increase of the rigidity of the web, whenthe data were compared at the same P value, irrespectively from the preparationtechnique.

    2016 journal paper

  • Influence of the Processing Parameters on the Dispersion and Coloration Behavior of a Halogenated Copper Phthalocyanine-Based Masterbatch 2016

    Buccella, Mauro; Dorigato, Andrea; Rizzola, Fabio; Caldara, Mauro; Fambri, Luca, "Influence of the Processing Parameters on the Dispersion and Coloration Behavior of a Halogenated Copper Phthalocyanine-Based Masterbatch" in ADVANCES IN POLYMER TECHNOLOGY, v. 2016, (2016), p. 1-8. - URL: http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)1098-2329 // http://onlinelibrary.wiley.com.ezp.biblio.unitn.it/doi/10.1002/adv.21721/epdf . - DOI: 10.1002/adv.21721

    A monodispersed green masterbatch was produced through an industrial extrusion process, by mixing a commer-cial Polyamide 6 matrix (PA6) with a halogenated copper phthalocyanine green pigment. The production process was investigatedand optimized in order to improve the pigment dispersion, reducing the clogging power and increasing the color strength of theresulting products. The compounding process based on three extrusions without filtration led to a filter pressure value (FPV)reduction of about 84% and a relative color strength (RCS) increase of about 50% with respect to the standard production process(i.e single extrusion). The thermal stability of the prepared compounds was evaluated by rheological test, viscosity measurements,and end group analysis, and it was found that a triple extrusion without filtration promoted thermo-oxidative matrix degradation.However, the same processing conditions led to a significant reduction of the production waste, increasing the productivity andthe quality of the final product.

    2016 journal paper

  • Coloration properties and chemo-rheological characterization of a dioxazine pigment-based monodispersed masterbatch 2015

    Buccella, M.; Dorigato, A.; Crugnola, F.; Caldara, M.; Fambri, L., "Coloration properties and chemo-rheological characterization of a dioxazine pigment-based monodispersed masterbatch" in JOURNAL OF APPLIED POLYMER SCIENCE, v. 132, n. 7 (2015), p. 1-7. - URL: http://onlinelibrary.wiley.com/doi/10.1002/app.41452/abstract . - DOI: 10.1002/app.41452

    A dioxazine-based color pigment was added to a commercial polyamide 6 (PA6) through an extrusion process, in order to prepare monoconcentrated violet masterbatches through different production set-up. A detailed characterization of the resulting materials was carried out in order to find the best processing parameters combination to optimize pigment dispersion and to reduce the clogging power. The preparation of masterbatches with repeated extrusions markedly reduced the filter pressure value and increased the Relative Color Strength, while filtration did not significantly influence pigment dispersion. Rheological measurements and end-groups analysis were conducted on the same materials with the aim to evaluate their thermal degradation resistance, and the thermal stability of the compounds was retained even upon three extrusions. Therefore, it can be concluded that a proper optimization of the process parameters could lead to an important reduction of the production waste, increasing the quality of the final product

    2015 journal paper

  • Innovative microcrystalline cellulose composites as lining adhesives for canvas 2015

    Cataldi, Annalisa; Dorigato, Andrea; Deflorian, Flavio; Pegoretti, Alessandro, "Innovative microcrystalline cellulose composites as lining adhesives for canvas" in POLYMER ENGINEERING AND SCIENCE, v. 55, n. 6 (2015), p. 1349-1354. - URL: http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)1548-2634 . - DOI: 10.1002/pen.24074

    Thin adhesive composite films were prepared by meltcompoundingand compression molding of a thermoplasticresin (ParaloidVR B72) widely used for art protectionand restoration with a microcrystalline cellulose powder(MCC). To simulate an oil painting restoration work,MCC-based composites were applied as lining adhesiveson two kinds of canvases (English linen and woven polyester).Interestingly, single–lap shear tests both in quasi-staticand creep conditions showed a remarkable stabilizingeffect provided by MCC addition. Post-mortem microstructuralanalysis of the overlap adhesive area proved howMCC introduction did not change the fracture behavior ofthe bonded joints. The visual assessment of transparencyand color measurements evidenced a chromatic variationof MCC-based films with a filler amount of 30 wt%, while,UV-vis analysis showed a decrease of relative transmittancein proportion to the MCC content. Additionally, rheologicaltests highlighted a viscosity increase for Paraloid B72 inboth dry and wet conditions (T523C and RH5of 55%) asthe MCC content increases.

    2015 journal paper

  • Liquid crystalline polymer nanocomposites reinforced with in-situ reduced graphene oxide 2015

    Pedrazzoli, D; Dorigato, A.; Conti, T.; Vanzetti, L.; Bersani, M.; Pegoretti, A., "Liquid crystalline polymer nanocomposites reinforced with in-situ reduced graphene oxide" in EXPRESS POLYMER LETTERS, v. 9, n. 8 (2015), p. 709-720. - URL: http://www.expresspolymlett.com/letolt.php?file=EPL-0005975&mi=c . - DOI: 10.3144/expresspolymlett.2015.66

    In this work liquid-crystalline polymer (LCP) nanocomposites reinforced with in-situ reduced graphene oxideare investigated. Graphene oxide (GO) was first synthesized by the Hummers method, and the kinetics of its thermal reductionwas assessed. GO layers were then homogeneously dispersed in a thermotropic liquid crystalline polymer matrix (Vectran®), and an in-situ thermal reduction of GO into reduced graphene oxide (rGO) was performed. Even at low rGOamount, the resulting nanocomposites exhibited an enhancement of both the mechanical properties and the thermal stability.Improvements of the creep stability and of the thermo-mechanical behavior were also observed upon nanofiller incorporation.Furthermore, in-situ thermal reduction of the insulating GO into the more electrically conductive rGO led to animportant surface resistivity decrease in the nanofilled samples.

    2015 journal paper

  • Reprocessing effects on polypropylene/silica nanocomposites 2014

    Dorigato A; Pegoretti A, "Reprocessing effects on polypropylene/silica nanocomposites" in JOURNAL OF APPLIED POLYMER SCIENCE, v. 131, n. 10 (2014), p. 40242_1-40242_7. - DOI: 10.1002/app.40242

    A polypropylene 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. Chain scission reactions induced by thermal processing caused a remarkable decrease of the melt viscosity, as revealed by the melt flow index values of both neat matrix and nanocomposites, but the degradative effect was significantly hindered by the presence of silica nanoparticles. It was observed that the size of nanofiller aggregates noticeably decreased as the compounding time increased, especially when hydrophobic silica nano filler was considered. While the melting temperature seemed to be unaffected by the processing time, a remarkable embrittlement of the samples was observed for prolonged compounding times.

    2014 journal paper

  • Effect of the water sorption on the mechanical response of microcrystalline cellulose based composites for art protection and restoration 2014

    Cataldi A; Dorigato A; Deflorian F; Pegoretti A, "Effect of the water sorption on the mechanical response of microcrystalline cellulose based composites for art protection and restoration" in JOURNAL OF APPLIED POLYMER SCIENCE, v. 131, n. 18 (2014), p. 40741-1-40741-6. - DOI: 10.1002/APP.40741

    Thermoplastic composites based on a commercial acrylic matrix widely used in the field of art protection and restoration (Paraloid B72) and various concentrations (up to 30 wt %) of microcrystalline cellulose powder (MCC) were prepared by melt-compounding and compression molding. The mechanical behavior of the resulting materials conditioned at a temperature of 23 degrees C and a relative humidity level of 55% was compared to that of the corresponding dried materials. Even though the moisture absorption of the filler was lower than the neat matrix, the maximum moisture content increased with the MCC amount, probably due to the preferential water diffusion path through the microvoids and/or the filler-matrix interface. Although the increase of moisture content for filled samples, DMTA analysis evidenced a stabilization upon MCC introduction, with an increase of the storage modulus and a decrease of the thermal expansion coefficient proportional to the filler loading. A similar trend was displayed by the corresponding dried materials. The tensile elastic modulus and the ultimate properties such as the stress at break and the tensile energy to break (TEB) of conditioned samples increased proportionally to the filler amount. On the contrary, the failure properties of dried composites were negatively affected by the presence of the microcellulose. It is worthwhile to report that a significant improvement of the creep stability was induced by MCC introduction both for dried and conditioned samples. (C) 2014 Wiley Periodicals, Inc.

    2014 journal paper

  • Thermo-mechanical properties of innovative microcrystalline cellulose filled composites for art protection and restoration 2014

    Cataldi A; Dorigato A; Deflorian F; Pegoretti A., "Thermo-mechanical properties of innovative microcrystalline cellulose filled composites for art protection and restoration" in JOURNAL OF MATERIALS SCIENCE, v. 49, n. 5 (2014), p. 2035-2044. - DOI: 10.1007/s10853-013-7892-6

    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 allthe 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 (KIC).

    2014 journal paper

  • Evaluation of color pigment dispersion in polyamide 6 matrix 2014

    L. Fambri; M. Buccella; A. Dorigato; M. Caldara, "Evaluation of color pigment dispersion in polyamide 6 matrix" in 27th International Symposium on Polymer Analysis and Characterization - Book of Abstracts, Les Diablerets (CH): ISPAC, 2014, p. 114-114. Proceedings of: 27th International Symposium on Polymer Analysis and Characterization, Les Diablerets (CH), 15-18 June, 2014. - URL: http://ispac-conferences.org/ispac-2014-Les-Diablerets.aspx

    2014 poster paper

  • Ethylene-producing bacteria that ripen fruit 2014

    Digiacomo, F; Girelli, G; Aor, B; Marchioretti, C; Pedrotti, M; Perli, T; Tonon, E; Valentini, V; Avi, Damiano; Ferrentino, G; Dorigato, Andrea; Jousson, Olivier; Mansy, Sheref Samir; Del Bianco, Cristina, "Ethylene-producing bacteria that ripen fruit" in ACS SYNTHETIC BIOLOGY, v. 3, (2014), p. 935-938. - DOI: 10.1021/sb5000077

    2014 journal paper