Papers by giorgio ramorino
Journal of material cycles and waste management, Apr 4, 2024
The amount of rubber scraps derived from rubber goods production consists of about 20-30% of the ... more The amount of rubber scraps derived from rubber goods production consists of about 20-30% of the processed material, so it is necessary to enhance this material by developing new recycling techniques as well as a new market for recycled rubber products. In the present research, nitrile-butadiene rubber (NBR) scraps are reprocessed via a calendering process acting with a mechanical devulcanization. Compounds were prepared with 20%, 80%, and 100% recycled rubber content and characterized. The experimental results highlighted that the compound prepared with 20% recycled rubber content via calendering and compression molding processes shows comparable mechanical properties to that of virgin NBR. The tensile properties are the most penalized by the increasing content of recycled material (100% recycled shows -25% and -50% stress and strain at break, respectively). Other properties remain comparable to the standard material up to 80% recycled material: 60 ± 5 Shore A, compression elastic modulus 8 MPa, compression set 20%. FTIR analysis revealed no changes in chemical structure from the recycling process. The results demonstrate that simple mechanical devulcanization can effectively reprocess industrial rubber waste while largely maintaining useful properties. This provides a potential pathway to enhance sustainability in rubber production through the valorization of process scraps.
In the last two decades, gelatin-based hydrogels have been widely used as tissue engineering scaf... more In the last two decades, gelatin-based hydrogels have been widely used as tissue engineering scaffolds due to their excellent biocompatibility, biodegradability, easy processability, transparency, non-toxicity, and reasonable structural similarity to the natural extracellular matrix (ECM). However, intrinsic low mechanical properties of gelatin are not structurally and mechanically suitable to support cell growth and proliferation. That’s why various crosslinking strategies including physical, chemical, enzymatic and combination of them as well as networking patterns including double network, interpenetrating network and nano reinforcing mechanism have been utilized to enhance the structural stability and mechanical integrity of gelatin. In this review, the advances in modulating the mechanical properties of gelatin-based hydrogels for the design and development of structurally stable scaffolds for tissue engineering are discussed. The optimized crosslinking parameters with the adeq...
Journal of Zhejiang University-SCIENCE B
Results in Engineering
Reinforcement of polymers by the addition of particles filler is a complex phenomenon that depend... more Reinforcement of polymers by the addition of particles filler is a complex phenomenon that depends mainly on the hydrodynamic effect and a complex interplay between polymer, filler, and interfacial region. Mineral fillers are usually adopted as low-cost extenders due to their lower cost. In this study, the influence of a waste material such as electric arc furnace steel slag is assessed as filler for Nitrile-Butadiene Rubber following experimental procedures and analytical calculations adopted for traditional fillers. It was found that the slag content affects the static and the dynamic properties by increasing the material's capability to storage and dissipate energy. In addition to an important contribution of the hydrodynamic effect, the presence of an increasing immobilized rubber fraction around the slag particles (quantified by a differential scanning calorimetry analysis) plays a central role. The slag stiffens the NBR composite; the increase of static tensile and dynamic shear storage moduli was found to be consistent with the Halpin-Tsai and Guth-Gold prevision models respectively. Moreover, the non-linear dynamic behavior was found to be well-fitted by the Kraus equation models. The reinforcing ability of the slag particles as filler was confirmed by the negative slope of the Kraus plot on swelling data.
Journal of Polymer Research
Environmental stress cracking is a serious problem for polyethylene because it can cause failure ... more Environmental stress cracking is a serious problem for polyethylene because it can cause failure without any visible warning due to the slow crack growth accelerated by aggressive agents. Tie molecules and entanglements are the main macromolecular characteristic increasing environmental stress cracking resistance, thus in this work mechanical and thermal properties governed by those macromolecular characteristics are determined by performing simple tests executable in the industrial laboratories for quality control on recycled high-density polyethylene. The mutual relation between the determined properties confirms their dependence on the investigated macromolecular characteristics and allows to predict in a comparative way the expected environmental stress cracking. The mechanical properties related to the environmental stress cracking resistance are the strain hardening modulus and the natural draw ratio. The strain hardening modulus is an intrinsic property that measure the disen...
Rientra nell’ambito dei macchinari radiologici digitali dentali extraorali, in cui cioè sia la so... more Rientra nell’ambito dei macchinari radiologici digitali dentali extraorali, in cui cioè sia la sorgente dei raggi X sia il sensore dei raggi X sono collocati al di fuori del cavo orale del paziente sotto indagine. In particolare, la presente invenzione riguarda un dispositivo per l’immobilizzazione del capo del paziente nel corso dell’acquisizione radiografica. Tale dispositivo è conosciuto nell’arte col nome di craniostato
Journal of the Mechanical Behavior of Biomedical Materials, 2022
This study focuses on the variations in the brain tissue dynamic behaviour pointing out new insig... more This study focuses on the variations in the brain tissue dynamic behaviour pointing out new insight into the material nonlinear viscoelasticity. Shear dynamic response curves are obtained in different working conditions in terms of strain sweep and superimposed static compression offsets (SCO) applied in orthogonal direction to the shear. The strain sweep mode is used to study the storage and loss moduli dependence on the amplitude of the applied strain. It is found that the material exhibits linear viscoelastic behaviour up to about 0.1% strain amplitude. Above this critical threshold, the storage modulus G' decreases rapidly with increasing dynamic strain amplitude and this effect is gradually intensified as the SCO are increased. In addition, it is observed that the loss factor (G''/G') increases by increasing the SCO applied to the specimens. The dynamic strain amplitude results of the storage modulus reveal that the elastic component of the brain tissue's stiffness (G') evaluated at low strain strongly increases with increasing static superimposed compression strain while the loss factor in the same strain range appears to be SCO independent. Finally, dynamic stiffness recovery after a large strain deformation is considered. The reduction in low amplitude dynamic modulus and subsequent recovery kinetics due to a perturbation is found to be independent of the level of the SCO. The same assessments were carried out on 5 consecutive strain sweep cycle loading. It has been noticed that at the last cycle, the dissipation peak is reduced, and the non-linearity of the curve begins earlier. This could be explained by the effects of cerebral edema on cells and their surrounding environment.
Symbiosis Users Network -SUN Proceedings of the fourth SUN Conference, 2020
Italy with an annual production of 20 million tons is the leading producer of electric arc furnac... more Italy with an annual production of 20 million tons is the leading producer of electric arc furnace (EAF) steel in Europe. The geographical distribution of EAF steel producers is concentrated in Lombardy, therefore the macro sector of metallurgical industry is related to that of vulcanized rubber as it is located in the same geographical area. The aim of this work is to assess the influence of EAF slag as filler for nitrile butadiene rubber (NBR) in order to promote an alternative use of EAF slag by preventing its disposal. The processability characteristics of filled NBR are determined by the rheometric curves; the first results show that the presence of slag in NBR accelerates the crosslinking kinetics. The mechanical characterization, consisting of hardness and compression test and compression set, shows a stiffening of the material that could affect positively the gasket behavior in sealing system assembled both in load or in displacement control.
Minerals, 2021
The European steel industry produces about 70 million tons/year of steel by the electric arc furn... more The European steel industry produces about 70 million tons/year of steel by the electric arc furnace (EAF). The slag consists of about 15% by weight of the produced steel, thus from the perspective of the circular economy, it has a high potential as a co-product. This research aims to assess an innovative reuse of EAF slag as filler in different polymer matrixes: thermoplastic (polypropylene), thermosetting (epoxy resin), elastomeric (nitrile butadiene rubber), and recycled end of life rubber tire. A comparison between neat polymer and polymer filled with a certain amount of EAF slag has been carried out by tensile (or flexural), compression, and hardness tests. Experimental results show that slag as a filler increases the composites’ hardness and elastic modulus at the expense of toughness. For a safe reuse of the slag, the leaching of hazardous elements must comply with current legislation. It was found that, although the used EAF slag releases small amounts of Cr, Mo, and V, inco...
Materials Science and Engineering: C, 2021
Selection of feasible hybrid-hydrogels for best chondrogenic differentiation of human mesenchymal... more Selection of feasible hybrid-hydrogels for best chondrogenic differentiation of human mesenchymal stromal cells (hMSCs) represents an important challenge in cartilage regeneration. In this study, three-dimensional hybrid hydrogels obtained by chemical crosslinking of poly (ethylene glycol) diglycidyl ether (PEGDGE), gelatin (G) without or with chitosan (Ch) or dextran (Dx) polysaccharides were developed. The hydrogels, namely G-PEG, G-PEG-Ch and G-PEG-Dx, were prepared with an innovative, versatile and cell-friendly technique that involves two preparation steps specifically chosen to increase the degree of crosslinking and the physical-mechanical stability of the product: a first homogeneous phase reaction followed by directional freezing, freeze-drying and postcuring. Chondrogenic differentiation of human bone marrow mesenchymal stromal cells (hBM-MSC) was tested on these hydrogels to ascertain whether the presence of different polysaccharides could favor the formation of the native cartilage structure. We demonstrated that the hydrogels exhibited an open pore porous morphology with high interconnectivity and the incorporation of Ch and Dx into the G-PEG common backbone determined a slightly reduced stiffness compared to that of G-PEG hydrogels. We demonstrated that G-PEG-Dx showed a significant increase of its anisotropic characteristic and G-PEG-Ch exhibited higher and faster stress relaxation behavior than the other hydrogels. These characteristics were associated to absence of chondrogenic differentiation on G-PEG-Dx scaffold and good chondrogenic differentiation on G-PEG and G-PEG-Ch. Furthermore, G-PEG-Ch induced the minor collagen proteins and the formation of collagen fibrils with a diameter like native cartilage. This study demonstrated that both anisotropic and stress relaxation characteristics of the hybrid hydrogels were important features directly influencing the chondrogenic differentiation potentiality of hBM-MSC.
Sustainable Materials and Technologies, 2021
Biomaterials Science, 2020
This work provides a comprehensive view on how multiple mechanical cues of the substrate influenc... more This work provides a comprehensive view on how multiple mechanical cues of the substrate influence fundamental cellular processes, including spreading, proliferation, migration and differentiation, towards 3D tissue constructs.
Environmental Technology Reviews, 2020
ABSTRACT Nowadays sustainability is a key topic and waste should be considered a resource. For th... more ABSTRACT Nowadays sustainability is a key topic and waste should be considered a resource. For this reason, a large body of literature is being developed on the management of the large quantity of post-consumer tires with sustainable approaches. The ongoing research activity on tires is focused on providing eco-sustainable solutions aimed, on one hand, at reducing the amount of waste and, on the other hand, at optimizing and improving the technologies and methodologies to obtain ‘green’ products to be recycled on large scale. This review examines the solutions for the reuse of waste from post-consumer tires proposed in the literature during the last five years (2015–2019) with a focus on advantages, drawbacks and future research developments of each end-of-life tires (ELTs) recovery technology. The final aim is to provide a comparison of different fields of application for the recovery of post- consumer tires, particularly for those researchers who want to start an activity in this field. The results show that the most investigated field of application is the civil engineering area. However, it could be environmentally and socially useful to further investigate solutions suitable for recovery in sanitary applications such as water purification. Porous carbon, obtained from ELTs by pyrolysis and subsequent activation, can be successfully used as adsorbent to remove contaminants that could be harmful to the environment and human health. The latter application seems to be particularly advisable in less economically developed areas as it would represent a possible solution to the problem of environmental reclamation of water resources. GRAPHICAL ABSTRACT
Applied Sciences, 2020
This work reports and analyzes the mechanical properties of some composites obtained using stabil... more This work reports and analyzes the mechanical properties of some composites obtained using stabilized waste with epoxy resins E-227. For comparison, correspondent composite samples were realized using calcite as a filler. The recovered stabilized waste was obtained by means of a new method to stabilize municipal solid waste incineration (MSWI) fly ash (FA), based on the use of bottom ash (BA). The aim of this paper is to show that the stabilization process, which can be considered a zero—waste treatment, produces inert materials, that can be reused as a filler. The production of new filler was made on a pilot plant, designed to verify the transferability of the proposed stabilization technology. Mechanical analysis revealed that flexural modulus raises by increasing the filler content around 30% wt, independently of filler type, stabilized sample or calcium carbonate. Mechanical properties are lower in the samples with the high amount of filler due to the crowding effect. The morpho...
The fracture resistance of different rubbers containing various nanofillers, such as multiwall ca... more The fracture resistance of different rubbers containing various nanofillers, such as multiwall carbon nanotube (MWCNT), organoclay, silica and carbon black (CB), was determined by the J-integral making use of the single edge notched tensile loaded (SEN-T) single specimen approach. The elastomeric matrices were natural (NR), ethylene propylene diene (EPDM) and hydrogenated nitrile rubbers (HNBR). Moreover, the strain softening (Payne effect) of selected rubbers with 30 part per hundred rubber (phr) filler content was also investigated by dynamic mechanical thermal analysis (DMTA) in shear mode. DMTA results indicated that the Payne effect follows the ranking: MWCNT(fibrous)!>!organoclay(platy)!> silica(spherical). J-resistance (J R ) curves were constructed by plotting the J value as a function of the crack tip opening displacement (CTOD ! ), monitored during loading. CTOD ! = 0.1 mm was considered as crack initiation threshold and thus assigned to the critical value J Ic . J Ic increased with increasing filler loading, whereby MWCNT outperformed both silica and CB. On the other hand, J Ic did not change with filler loading for the NR/organoclay systems that was traced to straininduced crystallization effect in NR. The tearing modulus (T J ) also increased with increasing filler loading. The related increase strongly depended on both rubber and filler types. Nonetheless, the most prominent improvement in T J among the fillers studied was noticed for the fibrous MWCNT.
The development and understanding of self-healing mechanisms have been investigated in blends of ... more The development and understanding of self-healing mechanisms have been investigated in blends of ionomers (Poly (ethyelene-co-methacrylic acid), sodium & zinc ions)(EMNa & EMZn) containing both elastomers (Epoxidized natural rubbers (ENR) and cis-1, 4-Polyisoprene (PISP)) and crystalline component (Poly (vinly alcohol-co-ethylene)[PVAcE]) as secondary phases. All the blends were prepared by melt-blending and self-healing behavior was studied in ballistic puncture tests. Self-healing behavior of each material ...
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Papers by giorgio ramorino