Publications

Publications


  • Evaluation of the role of carbon nanotubes on the electrical properties of poly(butylene terephthalate) nanocomposites for industrial applications 2019

    Dorigato, A.; Freitas, V.; Covas, J. A.; Paiva, M. C.; Brugnara, M.; Pegoretti, A., "Evaluation of the role of carbon nanotubes on the electrical properties of poly(butylene terephthalate) nanocomposites for industrial applications" in THE JOURNAL OF ELASTOMERS AND PLASTICS, v. 51, n. 1 (2019), p. 3-25. - DOI: 10.1177/0095244318768634

    In this article, innovative electrically conductive polymer nanocomposites based on poly(butylene terephthalate) (PBT) filled with carbon nanotubes (CNTs) at different concentrations, to be used in the automotive field, have been investigated. Field emission scanning electron microscopy (FESEM) analysis revealed how a good nanofiller dispersion was obtained, especially by using surface treated nanotubes and by processing these materials using a more restrictive screw configuration. Melt flow index measurements highlighted that the processability of these nanocomposites was reduced at elevated filler amounts, even if CNT surface treatment promoted a partial retention of the fluidity of the neat PBT. Thermal degradation stability was improved upon the addition of CNT, even at limited filler amounts. Differential scanning calorimetry measurements evidenced how the presence of CNT slightly increased both the crystallization temperature and the crystalline fraction of the materials. The additivation of CNTs promoted a stiffening effect at elevated CNT contents, associated to an evident embrittlement of the samples. Electrical resistivity measurements showed that the most interesting results (i.e. 2.6 × 101 Ω·cm) were obtained for nanocomposites with a total filler content of 3 wt%, processed using the more restrictive screw configuration. For these materials, it was possible to obtain a rapid surface heating through Joule effect at applied voltages of 12 V.

    2019 journal paper

  • Application of the thermal energy storage concept to novel epoxy–short carbon fiber composites 2019

    Dorigato, A.; Fredi, G.; Pegoretti, A., "Application of the thermal energy storage concept to novel epoxy–short carbon fiber composites" in JOURNAL OF APPLIED POLYMER SCIENCE, v. 136, n. 21 (2019), p. 47434. - URL: http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)1097-4628 . - DOI: 10.1002/app.47434

    For the first time, multifunctional epoxy-short carbon fiber reinforced composites suitable for thermal energy storage technology were developed. Paraffin microcapsules (MC) and short carbon fibers (CFs) were added at different relative amounts to an epoxy matrix, and the microstructural and thermomechanical properties of the resulting materials were investigated. Scanning electron microscopy images of the composites showed a uniform distribution of the capsules within the matrix, with a rather good interfacial adhesion, while the increase in the polymer viscosity at elevated CF and MC amounts caused an increase in the void content. Differential scanning calorimetry tests revealed that melting enthalpy values (up to 60 J/g) can be obtained at high MC concentrations. The mixing and thermal curing of the composites did not lead to breakage of the capsules and to the consequent leakage of the paraffin out of the epoxy matrix. The thermal stability of the prepared composites is not negatively affected by the MC addition, and the temperatures at which the thermal degradation process begins were far above the curing or service temperature of the composites. Flexural and impact tests highlighted that the presence of MC reduces the mechanical properties of the samples, while CF positively contributes to retaining the original stiffness and mechanical resistance.

    2019 journal paper

  • Shape memory epoxy nanocomposites with carbonaceous fillers and in-situ generated silver nanoparticles 2019

    Dorigato, Andrea; Pegoretti, Alessandro, "Shape memory epoxy nanocomposites with carbonaceous fillers and in-situ generated silver nanoparticles" in POLYMER ENGINEERING AND SCIENCE, v. 59, n. 4 (2019), p. 694-703. - URL: http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)1548-2634 . - DOI: 10.1002/pen.24985

    2019 journal paper

  • Polyethylene-based single polymer laminates: Synergistic effects of nanosilica and metal hydroxides 2019

    Dorigato, Andrea; Fredi, Giulia; Fambri, Luca; Lopez Cuesta, Jose Marie; Pegoretti, Alessandro, "Polyethylene-based single polymer laminates: Synergistic effects of nanosilica and metal hydroxides" in JOURNAL OF REINFORCED PLASTICS AND COMPOSITES, v. 38, n. 2 (2019), p. 62-73. - URL: http://jrp.sagepub.com/content/by/year . - DOI: 10.1177/0731684418802974

    This work aims to investigate the fire performance of novel polyethylene-based single polymer composites. Fumed silicananoparticles and magnesium hydroxide microfiller were added at an optimized concentration to a linear low-densitypolyethylene matrix, which was then reinforced with ultra-high molecular weight polyethylene fibers. Through theoptimization of the production process, it was possible to limit the porosity inside the single polymer composites,thus retaining the pristine mechanical properties of the fibers. The addition of SiO2 and magnesium hydroxide determinedan increase in the elastic modulus in both the longitudinal and transversal direction, but it concurrently led to areduction in ductility, especially in the transversal direction. The fillers were proved to bring interesting improvements ofthe thermal degradation resistance and of the flame behaviour. Thermogravimetric analysis tests highlighted an increasein the onset degradation temperature and in the temperature associated to the maximum degradation rate. Moreover,both the oxidation onset temperature and limiting oxygen index were considerably improved. Cone calorimetry testsevidenced that filled single polymer composites were characterized by lower peak heat release rate and total heatreleased with respect to neat single polymer composites.

    2019 journal paper

  • Thermo-electrical behaviour of cyclic olefin copolymer/exfoliated graphite nanoplatelets nanocomposites foamed through supercritical carbon dioxide 2019

    Dorigato, A.; Biani, A.; Bonani, W.; Pegoretti, A., "Thermo-electrical behaviour of cyclic olefin copolymer/exfoliated graphite nanoplatelets nanocomposites foamed through supercritical carbon dioxide" in JOURNAL OF CELLULAR PLASTICS, v. 55, n. 3 (2019), p. 263-282. - DOI: 10.1177/0021955X19839733

    2019 journal paper

  • Thermo-mechanical and adhesive properties of polymeric films based on ZnAl-hydrotalcite composites for active wound dressings 2019

    Perioli, Luana; Dorigato, Andrea; Pagano, Cinzia; Leoni, Matteo; Pegoretti, Alessandro, "Thermo-mechanical and adhesive properties of polymeric films based on ZnAl-hydrotalcite composites for active wound dressings" in POLYMER ENGINEERING AND SCIENCE, v. 59, n. S1 (2019), p. E112-E119. - URL: http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)1548-2634 . - DOI: 10.1002/pen.24877

    Composite films based on sodium carboxymethyl cellulose(Na-CMC) loaded with a ZnAl(OH)2CO3yH2O hydrotalcite(ZnAl-HTlc), were developed and characterized. Thecomposites were mechanically more stable than thematrix alone: the noticeable enhancement of elastic modulus,creep resistance and failure properties, all proportionalto the filler content, came at the expenses of acertain embrittlement. The filler tended to aggregate inthe composites and the size of the aggregates increasedwith ZnAl-HTlc amount. Contact angle measurementshighlighted how ZnAl-HTlc introduction in the polymericmatrix could strongly modify the wettability conditions ofthe films increasing their hydrophilicity. Bioadhesion testsshowed that the adhesion behavior of the compositesdecreased as ZnAl-HTlc amount increases, testifying theinfluence of the filler on the ability of the film to bind skinsurface. Therefore, the developed films may find applicationas active wound dressings since ZnAl-HTlc can beeasily intercalated with an active pharmaceutical ingredientto be progressively released on the wound.

    2019 journal paper

  • Novel electroactive polyamide 12 based nanocomposites filled with reduced graphene oxide 2019

    Dorigato, A.; Pegoretti, A., "Novel electroactive polyamide 12 based nanocomposites filled with reduced graphene oxide" in POLYMER ENGINEERING AND SCIENCE, v. 59, n. 1 (2019), p. 198-205. - URL: http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)1548-2634 . - DOI: 10.1002/pen.24889

    Novel electroactive nanocomposites were prepared by addingto a polyamide 12 (PA12) matrix different amounts (from1 to 8 wt%) of reduced graphene oxide (rGO), and thethermo-electrical behavior of the prepared bulk materialswas compared with that of the corresponding fibers. FESEMmicrographs on bulk materials highlighted an evident aggregationof the rGO lamellae, proportional to the filler concentration.The presence of rGO stacks was responsible of aheavy embrittlement of the samples, with a strong reductionof the elongation at break, and of the limited electrical conductivityof the samples (about 105 Xcm with a rGO amountof 4 wt%). Moreover, nanofiller addition determined animprovement of the thermal degradation resistance, associatedto a slight drop of the glass transition temperature(about 78C with a nanofiller concentration of 4 wt%) and ofthe crystallinity degree (up to 9% for an rGO loading of 4wt%). The extrusion process adopted to prepare nanocompositefibers caused a partial breakage of rGO aggregatesand their progressive alignment along the drawing direction,determining thus an electrical resistivity increase withrespect to the bulk samples. Therefore, the surface heatingof the prepared fibers through Joule effect was possible onlyat elevated rGO amounts (i.e., 8 wt%).

    2019 journal paper

  • Effect of expandable and expanded graphites on the thermo-mechanical properties of polyamide 11 2019

    Oulmou, F.; Benhamida, A.; Dorigato, A.; Sola, A.; Messori, M.; Pegoretti, A., "Effect of expandable and expanded graphites on the thermo-mechanical properties of polyamide 11" in THE JOURNAL OF ELASTOMERS AND PLASTICS, v. 51, n. 2 (2019), p. 175-190. - DOI: 10.1177/0095244318781956

    The preparation and thermo-mechanical characterization of composites based onpolyamide 11 (PA11) filled with various amounts of both expandable and expandedgraphites are presented. Investigation conducted using X-ray diffraction (XRD), scanningelectron microscopy and surface area analyses indicated how graphite expanded underthe selected processing conditions. The XRD analysis on PA11/graphite compositesrevealed no change in the crystal form of the PA11, while the presence of diffractionpeaks associated to the graphite-stacked lamellae can be still detected. All the investigatedcomposites showed an improvement of the thermal stability and mechanicalproperties (elastic and storage moduli).

    2019 journal paper

  • Discontinuous carbon fiber/polyamide composites with microencapsulated paraffin for thermal energy storage 2019

    Fredi, Giulia; Dorigato, Andrea; Unterberger, Seraphin; Artuso, Nicolò; Pegoretti, Alessandro, "Discontinuous carbon fiber/polyamide composites with microencapsulated paraffin for thermal energy storage" in JOURNAL OF APPLIED POLYMER SCIENCE, v. 136, n. 16 (2019), p. 47408. - URL: http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)1097-4628 . - DOI: 10.1002/app.47408

    This work focuses on the development of multifunctional thermoplastic composites with thermal energy storage capability. A polyamide 12 (PA12) matrix was filled with a phase change material (PCM), constituted by paraffin microcapsules (Tmelt = 43 °C), and reinforced with carbon fibers (CFs) of two different lengths (chopped/CF “long”[CFL] and milled/CF “short” [CFS]). DSC tests showed that the melting/crystallization enthalpy values increase with the PCM weight fraction up to 60 J/g. The enthalpy was 41–94% of the expected value and decreased with an increase in the fiber content, because the capsules were damaged by the increasing viscosity and shear stresses during compounding. Long CFs increased the elastic modulus (+316%), tensile strength (+26%), and thermal conductivity (+54%) with respect to neat PA12. Thermal imaging tests evidenced a slower cooling for the samples containing PCM, and once again the CFS-containing samples outperformed those with CFL, due to the higher effective PCM content.

    2019 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

  • Combined effect of fumed silica and metal hydroxides as fire retardants in PE single-polymer composites 2018

    Fredi, Giulia; De Col, A; Dorigato, A; Lopez-Cuesta, J-M; Fambri, L; Pegoretti, A, "Combined effect of fumed silica and metal hydroxides as fire retardants in PE single-polymer composites" in AIP Conference Proceedings, Melville, NY, USA: American Institute of Physics Inc., 2018, p. 020021-1-020021-4. - (AIP CONFERENCE PROCEEDINGS). - ISBN: 9780735416970. Proceedings of: 9th International Conference on Times of Polymers and Composites: From Aerospace to Nanotechnology, Ischia, Naples; Italy, 17–21 June, 2018. - URL: http://scitation.aip.org/content/aip/proceeding/aipcp . - DOI: 10.1063/1.5045883

    This work aimed to study the combined effect of metal hydroxides and fumed silica in enhancing the fire-retardant properties of a polyethylene single-polymer composite. The LLDPE matrix was blended with fumed silica and aluminum or magnesium hydroxides in different weight fractions. The obtained matrices were characterized to select that with the best combination of processability, mechanical and thermal properties, and fire resistance, to produce a single-polymer composite (SPC). The current research is focusing on the selection of the processing parameters for the production of the SPC, and on the characterization of the obtained laminates.

    2018 conference paper

  • Synergistic effects of carbon black and carbon nanotubes on the electrical resistivity of poly(butylene-terephthalate) nanocomposites 2018

    Dorigato, Andrea; Brugnara, Marco; Pegoretti, Alessandro, "Synergistic effects of carbon black and carbon nanotubes on the electrical resistivity of poly(butylene-terephthalate) nanocomposites" in ADVANCES IN POLYMER TECHNOLOGY, v. 37, n. 6 (2018), p. 1744-1754. - URL: https://onlinelibrary.wiley.com/doi/abs/10.1002/adv.21833 . - DOI: 10.1002/adv.21833

    In this study, novel electrically conductive polymeric nanocomposites based on polybutylene terephthalate (PBT) filled with commercial carbon black (CB) and carbon nanotubes (CNTs) at different relative ratios have been investigated. Field emission scanning electron microscope (FESEM) analysis revealed how a good nanofiller dispersion was obtained both by introducing CB and CNT. Melt flow index measurements highlighted that the processability of the nanocomposites was heavily compromised at elevated filler amounts, and the viscosity percolation threshold was established at 3 wt% for CNTs and between 6 and 10 wt% for CB nanocomposites. Differential scanning calorimetry (DSC) measurements evidenced how the presenceof CNT slightly increased the glass transition temperature of the materials, and an increase of 12°C of the crystallization temperature was obtained with a CNT amount of 6 wt%. Also the crystalline fraction was increased upon CNT addition. Electrical resistivity measurements evidenced that the most interesting results were obtained for nanocomposites with a total filler content of 6 wt% and a CNT/CB relative amount equal to 2:1. The synergistic effect obtained with the combination of both nanofillers allowed the achievement of a rapid surface heating through Joule effect even at applied voltages of 2 V.

    2018 journal paper

  • Influence of the Processing Parameters on the Dispersion and Coloration Behavior of a Halogenated Copper Phthalocyanine-Based Masterbatch 2018

    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. 2018, 37, n. 3 (2018), p. 21721.1-21721.8. - URL: https://onlinelibrary.wiley.com/doi/full/10.1002/adv.21721 . - DOI: 10.1002/adv.21721

    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: https://onlinelibrary.wiley.com/doi/abs/10.1002/pen.24590 . - DOI: 10.1002/pen.24590

    The objective of the present work is to investigate the electro-activated shape memory behavior of a polycyclooctene (PCO) based nanocomposite device. At this aim, carbon black (CB) and exfoliated graphite nanoplatelets (xGnP) were melt compounded with a PCO matrix crosslinked with a dicumylperoxide content of 2 wt% and a total filler amount of 4 wt%. Electrical resistivity measurements on bulk materials evidenced a noticeable decrease of the electrical resistivity upon CB addition, while no synergistic effects were detected mixing CB and xGnP. Nanocomposite with a CB amount of 4 wt% revealed also a noticeable heating capability through Joule effect for voltage levels higher than 100 V. The subsequent characterization of an electro active shape memory device based on this composition demonstrated how it is possible to prepare a shape memory nanocomposite material able to completely recover its original shape after 100 s with a voltage of 90 V. The retention of the shape memory behavior after several (50) programming cycles was also demonstrated. © 2017 Society of Plastics Engineers

    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: https://www.sciencedirect.com/science/article/pii/S0266353817325939 . - DOI: 10.1016/j.compscitech.2018.02.005

    This work is focused on the preparation and characterization of novel multifunctional structural composites with thermal energy storage (TES) capability. Structural laminates were obtained by combining an epoxy resin, a paraffinic phase change material (PCM) stabilized with carbon nanotubes (CNTs), and reinforcing 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 a maximum value of 47.4 J/cm3. This thermal response was preserved even after fifty consecutive heatingcooling cycles. Moreover, the thermal conductivity of the laminates through thickness direction resulted to increase proportionally to the content of CNT-stabilized PCM. The capability of the developed TES laminates to contribute to the thermal energy management was also proven by monitoring their cooling rates through thermal imaging. The flexural modulus was only slightly affected by the presence of the PCM, 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 the interlaminar region. The obtained results demonstrated the feasibility of the concept of multifunctional structural TES composites. ©2018 Elsevier Ltd. All rights reserved.

    2018 journal paper

  • 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 a glass 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

  • Novel phase change materials using thermoplastic composites 2018

    Dorigato, A; Fredi, G; Pegoretti, A, "Novel phase change materials using thermoplastic composites" in AIP Conference Proceedings, Melville, NY, USA: American Institute of Physics Inc., 2018, p. 020044-1-020044-4. - (AIP CONFERENCE PROCEEDINGS). - ISBN: 9780735416970. Proceedings of: 9th International Conference on Times of Polymers and Composites: From Aerospace to Nanotechnology, Ischia, Naples; Italy, 17-21 June 2018. - URL: http://scitation.aip.org/content/aip/proceeding/aipcp . - DOI: 10.1063/1.5045906

    In this work a Polyamide 12 (PA12) matrix was melt compounded with different amounts of discontinuous carbon fibers with different length and encapsulated paraffin, in order to develop novel thermoplastic composites with thermal energy storage/release capability. The microstructural, thermal and mechanical properties of the resulting materials were investigated. SEM images demonstrated how a rather good fiber matrix adhesion was obtained both by using long and short carbon fibers, while the microcapsules seem to be partially damaged by melt compounding operations and present also an interfacial debonding. DSC tests revealed how the melting enthalpy increased with the capsules amount, but the thermal energy storage/release capability of the composites was limited by the partial breakage of the microcapsules and the consequent molten paraffin leakage within the material. The introduction of microcapsules in the PA12 matrix determined an evident decrease of the elastic modulus, of the stress at yield and of the deformation at break, even when carbon fiber reinforcement was present, probably because of the limited interfacial adhesion between PA12 matrix and the microcapsules.

    2018 conference 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

  • Thermoplastic Polyurethane Blends With Thermal Energy Storage/Release Capability 2018

    Dorigato, A; Rigotti, D; Pegoretti, A, "Thermoplastic Polyurethane Blends With Thermal Energy Storage/Release Capability" in FRONTIERS IN MATERIALS, v. 2018, n. 5 (2018), p. 1-10. - URL: https://www.frontiersin.org/articles/10.3389/fmats.2018.00058/full . - DOI: 10.3389/fmats.2018.00058

    In this work innovative thermal energy storage materials were developed by encapsulating a paraffin having a melting temperature of 6 degrees C (M6D) in a thermoplastic polyurethane (TPU), and the most important physical properties of the resulting samples were investigated from a thermo-mechanical point of view. Field emission scanning electron microscope (FESEM) micrographs demonstrated a homogeneous microcapsules distribution and good interfacial adhesion with the TPU matrix even at elevated M6D concentrations. With a capsule concentration of 60 wt% it was possible to obtain elevated melting enthalpy values (up to 95 J/g), retaining the energy storage/release properties even after 50 thermal cycles. The hardness and the dimensional stability of the TPU matrix above its glass transition temperature were strongly increased upon M6D addition, but this stiffening effect was associated to a certain embrittlement. The investigated blends could be applied for winter sport application for low temperature thermal energy storage/release materials.

    2018 journal paper

  • Ultrathin Wood Laminae - Thermoplastic Starch Biodegradable Composites 2018

    Dorigato, Andrea; Negri, Martino; Pegoretti, Alessandro, "Ultrathin Wood Laminae - Thermoplastic Starch Biodegradable Composites" in JOURNAL OF RENEWABLE MATERIALS, v. 6, n. 5 (2018), p. 493-503. - DOI: 10.7569/JRM.2017.634177

    Novel fully biodegradable thermoplastic composite laminates reinforced with ultrathin wood laminae were prepared through a hot-pressing process by using two different thermoplastic starch (TPS) matrices. The microstructure and physical properties of the resulting unidirectional and bidirectional laminates were studied. The investigated materials presented a complex microstructure, in which the porosity of the wood laminae was almost entirely occluded by the polymer matrix. The mechanical behavior of the laminates was strongly affected by the obtained microstructure, and matrix penetration in wood pores led to biodegradable composites with elastic modulus and tensile strength higher than those of their constituents. Finally, thermal welding and thermoformability tests proved how these materials possess features typical of thermoplastic materials.

    2018 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

  • 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. 2017, 226, (2017), p. 7-14. - URL: https://www.sciencedirect.com/science/article/abs/pii/S0379677917300097 . - DOI: 10.1016/j.synthmet.2017.01.009

    An acrylonitrile-butadiene-styrene (ABS) matrix was melt compounded with various amounts (from 1 to 8 wt%) of multi-walled carbon nanotubes (MWCNT) predispersed in an ABS carrier. The resulting materials were then i) compression molded (CM) to obtain plaques or ii) extruded infilaments used to feed a fused deposition modelling (FDM) machine. 3D printed samples were obtained under three different orientations.The nanofiller addition within the ABS matrix caused a remarkable increase of both stiffness and stress at yield of the bulk samples, accompanied by a strong reduction of the elongation at break. The mechanical 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 respect to neat ABS even at the smallestfiller content. The FDM process determined a partial loss in the electrical conductivity of ABS nanocomposites, with a marked dependency on the printing orientation. For CNT amounts higher than 4 wt%, CM samples manifested a rapid heating by Joule effect, while the process was less efficient in the printed samples. CNT addition has high impact on thermal properties, resulting in a decrease of specific heat and a increase of thermal diffusivity and conductivity. Like observed for electric conductivity FDM also influences properties of thermal diffusivity and conductivity, resulted by a possible orientation of CNT. © 2017 Elsevier B.V. All rights reserved.

    2017 journal paper

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

    Dorigato, Andrea; Ciampolillo, M. V.; Cataldi, Annalisa; Bersani, M.; Pegoretti, Alessandro, "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

    Various amounts of a paraffinic wax were dispersed by melt mixing in an ethylene/propylene diene monomers (EPDM) rubber matrix. The resulting compounds were then vulcanized to obtain shape-stabilized rubbery phase change materials for thermal energy storage. The addition of the paraffinic wax induced a retardation in the vulcanization kinetics of the EPDM matrix. Calorimetric measurements evidenced how the homogenous distribution of the wax domains within the rubber, confirmed by electron microscopy observations, allowed for retaining the melting enthalpy of the neat paraffinic wax even at elevated concentration. The thermal energy storage and release capabilities of the investigated compounds were maintained even after various thermal cycles. The incorporation of polyethylene wax had a positive effect (increasing proportionally to its content) on the mechanical properties of the EPDM matrix, as documented from both the dynamical and the quasi-static tensile tests.

    2017 journal paper

  • Novel polyamide 12 based nanocomposites for industrial applications 2017

    Dorigato, Andrea; Brugnara, Marco; Pegoretti, Alessandro, "Novel polyamide 12 based nanocomposites for industrial applications" in JOURNAL OF POLYMER RESEARCH, v. 24, n. 6 (2017), p. 1-13. - URL: https://link.springer.com/article/10.1007/s10965-017-1257-9 . - DOI: 10.1007/s10965-017-1257-9

    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 103 Ω cm, 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.

    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. 2017, n. 9 (2017), p. 1-16. - 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) and dispersed in various concentrations in an epoxy resin to develop a novel blend with thermal energy storage capabilities. Thermogravimetric analysis showed that CNTs improve the thermal stability of paraffin, while differential scanning calorimetry showed that the paraffin kept its ability to melt and crystallize, with enthalpy values almost proportional to the paraffin fraction. In contrast, a noticeable loss of enthalpy was observed for epoxy/wax blends without CNTs, which was mainly attributed to the partial exudation of paraffin out of the epoxy matrix during the curing phase. Dynamic mechanical thermal analysis contributed to elucidate the effects of the melting of the paraffin phase on the viscoelastic properties of the epoxy blends. Flexural elastic modulus and strength of the blends decreased with the wax/CNT content according to a rule of mixtures, while flexural strain at break values deviate positively from it. These results show the potentialities of the investigated epoxy blends for the development of multifunctional structural composites.

    2017 journal paper