1,721,039 research outputs found
Integrated ternary bionanocomposites with superior mechanical performance via the synergistic role of graphene and plasma treated carbon nanotubes
Full text linkHerein, we prepared an integrated ternary bionanocomposite based on polylactic acid (PLA) as a host polymer and two different forms of carbon fillers, i.e. graphene nanoplatelets (GNPs) and carbon nanotubes (CNTs), used simultaneously at extremely low concentrations, relying on the synergistic effect of CNT and graphene nanoreinforcement and a novel, multi-step procedure to achieve a high level dispersion. The results indicated that this multi-step approach allows stiffness increments up to +66%, with simultaneous enhancement of tensile strength (up to +44%), and elongation at break (up to +36%) with respect to neat PLA, by adding an extremely low content (0.5 wt%) of a hybrid combination of CNTs and GNPs. The development of a multistep strategy to achieve molecular level dispersion of multifunctional nanoparticles integrated in a fully renewable polymer matrix allows the premise of industrial-scale production of advanced bionanocomposites with outstanding properties at extremely low loadings
VALORIZATION OF ANCHOVY FISHBONE WASTES FOR THE PREPARATION OF BIOPOLYMERIC BASED GREEN COMPOSITES FOR FOOD PACKAGING APPLICATIONS
Full text linkWet electrospinning-aided self-assembly of multifunctional GO-CNT@PCL core-shell nanocomposites with spider leg bioinspired hierarchical architectures
Full text linkWe report a fast route enabling the multiscale design of nanohybrid structures comprising a 3D fibrous network of polycaprolactone (PCL) wrapped by graphene oxide (GO) sheets onto which carbon nanotube (CNT) brushes are anchored. The method relies on electrospinning PCL solutions onto a suspension of GO and CNTs in ethanol. Self-assembly is due to electrostatic wrapping of GO sheets around PCL fibers and 7C-7C stacking between GO and CNTs. Hierarchical architecture and nanopatterned surface allow gathering the starting properties of PCL, GO and CNTs into lightweight (99% porosity) yet robust (1575% stiffness improvement), amphiphilic monoliths that can remove methylene blue and/or methyl orange from stagnant water with ca.100% efficiency
Modelling the structure-property relationships of high performance PBAT-based biocomposites with natural fibers obtained from Chamaerops humilis dwarf palm
No full textTwo fibrous fillers were achieved from stalks and leaves of Chamaerops humilis dwarf palm and tested as reinforcing agents for poly(butylene adipate co-terephthalate) (PBAT)-based composites. The influence of filler type and content on the morphomechanical properties of the green composites was assessed. The outcomes of tensile tests pointed out that both fillers are strong candidates to overcome the two main limiting aspects of PBAT, that is, the lack of both stiffness and cost-effectiveness, while preserving its stretchability and environmental sustainability. The remarkable stiffness increments (up to 300%), combined with fair retention of stretchability (33%) and doubled resistance, led to the fabrication of biocomposites with toughness values as high as 20-25 MJ/m(3). These results could be ascribed to the combination of several factors, including the formation of an extensive and robust interphasic region. This latter, ascribed to the chemical affinity between aromatic parts of fillers and matrix, presented different features in the two types of fillers, thus endowing resulting biocomposites with a broad array of mechanical performance, which can be predicted by introducing opportune modifications to Halpin-Tsai model which allow considering the crucial role of interphase
Lignocellulosic fillers and graphene nanoplatelets as hybrid reinforcement for polylactic acid: Effect on mechanical properties and degradability
Full text linkThis work investigates the effect of adding relatively low amounts of graphene nanoplatelets (GNP) to a biocomposite based on polylactic acid (PLA) and a lignocellulosic filler achieved by grinding Posidonia Oceanica leaves (Posidonia flour, PF). The ternary composites were prepared by melt extrusion and characterized from a morphological and mechanical point of view. Furthermore, hydrolytic degradation tests were performed under acidic, neutral and alkaline environment up to 900 h. Density measurements enabled to assess the degree of intraphase, i.e. the capability of polymer macromolecules to enter the voids of PF and a modified Halpin-Tsai model was presented and used to fit experimental data obtained from tensile tests. The results demonstrate that the hybrid reinforcement constituted by GNP and PF allows improving mechanical properties (up to 155%) and speeding up the degradation kinetics with respect to neat PLA and composites loaded with GNP only. In particular, the relatively fast degradation kinetics observed at pH = 7 and especially at pH = 10 make these hybrid composites very promising in the perspective of marine disposal
Innovative ready to use carrier-bacteria devices for bioremediation of oil contaminated water
Full text linkBioremediation, that uses microorganisms to remove environmental pollutants, is the best way of restoring
the environment due to its low cost and sustainability. Immobilization of microorganisms capable of
degrading specific contaminants significantly promotes bioremediation processes. An innovative ready to
use bioremediation system to clean up oil-contaminated water was developed immobilizing highly
performant marine and soil HC degrading bacteria, on biodegradable oil-absorbing carriers. Two soil
Actinobacteria (Gordonia sp. SoCg, Nocardia sp. SoB) and two marine Gammaproteobacteria (Alcanivorax
sp. SK2, Oleibacter sp.5), were immobilized on biopolymeric membranes prepared by electrospinning
(polylactic acid, PLA and polycaprolactone, PCL). These carriers are characterized by high uptake capacity,
oil retention, buoyancy, durability, reusability and recoverability of the oil absorbed. The morphology of the
carriers and microbial adhesion and proliferation were evaluated using scanning electron microscopy (SEM).
A high capacity of adhesion and proliferation of bacterial cells was observed on membranes after 5 days. The
bioremediation efficiency of the carrier-bacteria systems was tested on crude oil by GC-FID analysis and
compared whit planktonic cells. The bacterial immobilization on PLA and PCL membranes was a
promoting factor for biodegradation, increasing hydrocarbon removal up to 20%, in respect to planktonic
cells. Biofilm-mediated bioremediation is a versatile tool to be developed for in situ and ex situ
bioremediation of aquatic systems. Several applications can be designed to exploit both the high oil uptake
capacity of the carriers, and the biodegradation potential of autochtonous microrganisms and/or of selected
microorganisms that are immobilized on the carriers before exposure to the contaminated site
An innovative route to prepare in situ graded crosslinked PVA graphene electrospun mats for drug release
Full text linkWe present a fast, one step method to obtain PVA/graphene/chlorhexidine nanofibrous membranes, with a crosslinking gradient along their cross-section. Briefly, polymeric solutions were electrospun onto a heated plate, enabling the in situ crosslinking of PVA macromolecules. Of course, the crosslinking degree of such structures was found to decrease upon the distance from the plate during deposition. The outcomes reveal the crucial role of graphene, capable of promoting heat transfer throughout the entire structure, thus leading to 70-80% crosslinking degrees and preventing delamination issues. Such membranes were compared to untreated and oven thermally treated ones, and a robust relationship between processing, structure and properties was outlined, with a special focus on the release behaviour of such materials, which proved to be tuneable from instantaneous/burst to sustained release (up to 500 hours) by adjusting formulation and preparation technique
Polymer-coated Nanolimes Dispersions for Reduction, Deacidification and Consolidation of Ancient Paper
Full text linkNanolimes have been widely explored as nanomaterial for cultural heritage preservation. In particular, they have shown interesting properties to contrast the ageing of manuscripts, books and artistic works, opening up the possibility to store such items in a good quality state for longer. In the present work we reported an innovative nanolime-based formulation for paper restoration, which includes in its composition a reducing agent and a fibers consolidator as well. To formulate an efficient product, we deeply investigated the cellulose oxidation process with a multi-technique approach. The here presented formulation consists in a hydroalcoholic ternary dispersion of nanolimes coated with hydroxypropyl methylcellulose (HPMC) and tert- butylamine borane complex (TBAB) as cellulose fibers consolidator and reducer, respectively. The effectiveness of the ternary mixture has been demonstrated on oxidized paper, whose chemical and mechanical properties were partially recovered after the treatment
Collapsibility of metastable sand by non-conventional oedometer tests
No full textThe stability of foundations soils could represent a clear and present threat for the conservation of even well preserved buildings, particularly for Architectural heritage conservation and land art heritage. A dramatic case is the presence of collapsible metastable sands as foundation soils, as it occurs in the sacral complex Valle dei Templi in Agrigento. This site listed by UNESCO, stands on a crest of a calcarenite cuesta, overlaying a layer of these sands. When the collapsible sand is dry, the structure is strong enough to bond the sand particles together. When the sand becomes wet, a de-structuration mechanism occurs and the soil’s strength is compromised. This paper has a twofold aim: (1) to gain a better understanding of the kind of bonding forces between the textural components of the collapsible metastable sand and (2) to identify a proper consolidant, that could combine the compatibility of inorganic systems and the performance of polymeric materials, paying attention to the environmental issues related to this site. Soaking tests have been performed by submerging sand samples in different solvents in order to verify the role of water menisci in mechanical stability of the sand highlighting a perfect stability using a non polar solvent. Sand samples have been consolidated by using poly ethylene glycol and nanosilica. Oedometer tests on consolidated and untreated samples have been used to verify the reduction of collapse potential induced by the treatment with the proposed mixtures
OPUNTIA FICUS INDICA/MATER-BI® BASED GREEN COMPOSITES FOR FERTILIZER CONTROLLED RELEASE DEVICES PRODUCTION
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