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In this paper gelatin beads reinforced with natural hemp hurd have been produced as pH sensitive devices for the release of eugenol, as green pesticide. The composites beads, with a mean diameter of about 1 mm, were obtained by polymer droplet gelation in sunflower oil. Thermal properties were evaluated showing no noticeable difference after the introduction of hemp hurd. Barrier properties demonstrated an improvement of hydrophobization. The introduction of 5% w/w of hemp hurd led to a reduction of sorption coefficient of about 85% compared to unloaded gelatin beads. Besides, the diffusion coefficient decreased, introducing 5% w/w of hemp hurd, from 8.91 × 10−7 to 0.77 × 10−7cm2/s. Swelling and dissolution phenomena of gelatin beads were studied as function of pH. The swelling of gelatin beads raised as pH increased up to 2.3 g/g, 9.1 g/g and 27.33 g/g at pH 3, 7 and 12, respectively. The dissolution rate changed from 0.034 at pH 3 to 0.077 h−1at pH 12. Release kinetics of eugenol at different pH conditions were studied. The released eugenol after 24 h is 98%, 91%, 81 and 63% w/w (pH 3), 87%, 62%, 37 and 32 wt% (pH 7) and 81%, 68%, 60 and 52 wt% (pH 12) for unloaded gelatin beads and gelatin beads with 1%, 3 and 5% of hemp hurd, respectively. The eugenol release behavior was demonstrated to be highly sensitive to the pH release medium, which allows to tune such devices as green pesticide release systems in soils with different level of acidity/basicity.

This paper reports the possibility of functionalizing hemp fibers (HF) through a mechano-chemical treatment assisted by an easily scalable top-down technology. The mechanical action was able to remove non-cellulosic material and to cause exposure of the cellulose microfibrils. Its influence on structure, morphology, and properties of hemp fibers has been analyzed by means of the scanning electron microscopy, X-Ray, FTIR and Raman spectroscopy. The milling process induced a change in crystalline content of hemp fibers, which decreased after a treatment time of 30 min. The crystallinity index and cellulose chain arrangement influence the thermal stability of hemp fibers. In order to compare the improved properties of mechanochemically treated HF respect to the HF modified with conventional alkalization, they were introduced, as green reinforcement, into a pectin matrix. Thermal and mechanical properties demonstrated the effectiveness of milling treatment in improving the considered physical properties of the pectin matrix.

The paper reports the preparation of a novel material composed of pectin chemically modified with polycaprolactone (PCL). PCL was firstly functionalized through radical grafting of maleic anhydride and glycidyl methacrylate in the molten state and then used as grafting agent onto pectins from apple, using a solvent free process. The obtained material was submitted to melt process on laboratory scale and films obtained. Structural, thermal, mechanical, and barrier properties to water vapor were evaluated and compared with pure pectin and modified PCL’s films. The used strategy allowed to overcome the processability problems of a natural polymer, like pectin, that undergoes degradation with the temperature and is not processable without additives and plasticizers. The proposed green process represents a good opportunity to manufacture waste materials from fruits to obtain flexible and fully biodegradable polymers for food packaging applications, as interesting alternative to not biodegradable traditional thermoplastics.

Curcumin extracted from the rhizome of Curcuma Longa has been used in therapeutic preparations for centuries in different parts of the world. However, its bioactivity is limited by chemical instability, water insolubility, low bioavailability, and extensive metabolism. In this study, the coaxial electrospinning technique was used to produce both poly (ε-caprolactone) (PCL)–curcumin and core–shell nanofibers composed of PCL and curcumin in the core and poly (lactic acid) (PLA) in the shell. Morphology and physical properties, as well as the release of curcumin were studied and compared with neat PCL, showing the formation of randomly oriented, defect-free cylindrical fibers with a narrow distribution of the dimensions. The antibacterial and antibiofilm potential, including the capacity to interfere with the quorum-sensing mechanism, was evaluated on Pseudomonas aeruginosa PAO1, and Streptococcus mutans, two opportunistic pathogenic bacteria frequently associated with infections. The reported results demonstrated the ability of the Curcumin-loading membranes to inhibit both PAO1 and S. mutans biofilm growth and activity, thus representing a promising solution for the prevention of biofilm-associated infections. Moreover, the high biocompatibility and the ability to control the oxidative stress of damaged tissue, make the synthesized membranes useful as scaffolds in tissue engineering regeneration, helping to accelerate the healing process.

The study reports on the preparation and characterization of an active packaging based on pouches composed of a coupled system nylon/polyethylene (PE). The PE layer was filled with and active nano-hybrid of layered double hydroxide (LDH) on which it was anchored salicylate, as antimicrobial molecule. The release of the salicylate anchored to the LDH was compared to the release of the molecule free dispersed into the PE and resulted much slower. It was evaluated the efficiency of the active packaging to inhibit Pseudomonas aeruginosa, Escherichia coli, Listeria monocytogenes, Salmonella typhimurium, and Campylobacter. Global migration tests on the PE active layer, using ethanol (50% v/v) as food simulant, demonstrated the possibility of such active nanocomposite to be used for food contact being the migration limits in compliance with those imposed from the EU regulation. Fresh milk was packed into the active pouches and pouches with unfilled PE layer, as control. The pH reduction as function of the time, due to the production of lactic acid, resulted much slower in the active packaging. Total bacterial count (TBC) was evaluated on the milk, either packed into the active packaging or the control, up to 50 days of storage at 4 °C. Shelf life of the milk was evaluated using the Gompertz model. It was demonstrated an increasing of the shelf life of milk packaged in active pouches from 6 days up to 10 days.

This paper concerns the facile preparation of alginate beads encapsulating layered double hydroxide (LDH) intercalated with diclofenac sodium as drug delivery systems. To better evaluate the effect of LDH carrier, alginate beads loaded with free diclofenac were also prepared. Composites hydrogel beads were ionotropically crosslinked in CaCl2 solution at 4 °C. Thermal and barrier properties were evaluated and correlated with the presence of the inorganic phase. Swelling behavior was investigated over time. Release kinetics of diclofenac at different pH and temperatures were evaluated. The diclofenac release behavior appeared to be affected by the presence of LDH, the pH of release medium and the temperature allowing for fabricating a sustainable composite characterized by a triggered drug release rate. Finally, empirical relationships correlating the drug diffusion as a function of temperature and pH were extrapolated.

In this paper it is reported the preparation of a food packaging based on isotactic polypropylene (PP) coated with layered double hydroxide (LDH) hosting sorbate as active molecule. The active nano-hybrid (LDH-sorbate) was dispersed into a food grade resin and used as coating. The release of the sorbate anchored to the LDH was compared to the release of the molecule free dispersed into the food grade resin and resulted much slower. It was evaluated the efficiency of the active packaging to inhibit Salmonella enterica subsp. arizonae, Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Campylobacter jejuni, and the global migration using two food simulant (i.e. poly (2,6-diphenyl-p-phenylene oxide) and vegetable oil). Experimental data, in compliance with the migration limits of the European Union regulation, demonstrated the suitability of the prepared material for food contact. White bread was packed into the active PP film and untreated PP, as control. Organoleptic characteristics, moisture analysis, peroxide evolution and mold count showed that the bread packaged in the active film retained its starting characteristics up to 12 days of storage at ambient temperature.

The wettability of hemp fibers, to be applied in fiber-reinforced foams, can be improved with several chemical treatments. In this paper, a innovative treatment with sodium ascorbate was evaluated. Untreated and treated fibers have been characterized using FTIR spectroscopy and TGA measurements. Furthermore, the feasibility of treated fibers was evaluated preparing diatomite-based fiber-reinforced foams. These materials were finally characterized by mechanical compressive strength and thermal properties (thermal conductivity). The fiber-reinforced foams have been produced using a diatomite natural source as a matrix. A suitable amount of Si powder and vegetable surfactant were used as chemical and physical foaming agents while a polysilicate solution was used as reactive crosslinker. The foams highlight low density, around 350 kg/m3, and low thermal conductivity (0.06 W/mK).

Solvent-free syntheses provide an alternative path that reduces the use of hazardous substances. In this work, a sustainable synthesis of nanometric layered double hydroxide particles grafted over halloysite nanotubes (HNT@LDH) is reported using a mechanochemical technique. Samples loaded with different LDH percentage (100%, 50%, 40%, 30%, 20%, 10% with respect to the HNT content) were prepared and characterized. Spectroscopic and morphological characterizations allowed to select the sample with 20% by weight of LDH as the best composite (HNT@LDH20), wherein no LDH phase segregation was observed and the nanosheets were homogeneously grafted throughout the surface of the halloysite nanotubes. The combination of cationic and anionic clays in one filler enables the preparation of a composite which can be easily dispersed in a polymer and release active molecules. To this end, salicylate ions were incorporated into the layered double hydroxide nanoflakes of HNT@LDH20 and three intercalation strategies, comprising both solvent-free and traditional intercalating routes, were tested. Results of salicylate release tests indicate that the intercalating route used affects the amount of species hosted, the strength of the salicylate-LDH interactions and the drug release time, thus offering the possibility of selecting the most suitable method of drug incorporation to tune the salicylate content depending on a specific aim.

The photo-oxidative studies of ethylene vinyl acetate copolymer (EVA) matrix, filled with Layered Double Hydroxide (LDH) modified with methacrylic anion (MA), were herein reported, together with gas permeation tests. The formulation of nano-hybrid LDHs was characterized using X-ray diffractometry (XRD) and thermogravimetric analysis (TGA), demonstrating the partial intercalation of the 30% of MA anion between the LDH’s galleries. The as-modified filler was introduced into an EVA matrix by mechanical milling, producing free-standing films subjected to accelerated aging. Fourier transform infrared spectroscopy (FT-IR) results suggested that the nanohybrid presence determined a stabilizing effect up to 45 days of UV irradiation, especially if compared to the EVA/LDH references for all formulated EVA hybrid nanocomposites. Conversely, the presence of nanohybrid in the matrix did not significantly change the thermal stability of EVA samples. The dispersion of modified MA-LDH in the EVA matrix produces defect-free samples in the whole range of investigated loadings. The samples show a slight decrease in gas permeability, coupled with a substantial stabilization of the original CO2/O2 selectivity, which also proves the integrity of the films after 30 days of UV irradiation.

Blueberries are popular among consumers for their high nutritional value but are highly perishable due to the microbial decay. The use of active packaging that is able to interact with the food through releasing or absorbing substances can be a valid approach to preserve the quality and increase the fruit’s shelf-life. In this paper, an active packaging based on polyethylene (PE) filled with a nano-carrier of salicylate was prepared and characterized. Fresh blueberries were packaged in passive modified atmosphere packaging (pMA) for 13 days at 8 °C. The combination of the active filler in bulk and pMA showed a significant inhibition of mold development and a reduction of the respiration rate of fruits. Moreover, the release of salicylate on blueberries did not alter the fruits’ sensory traits and preserved the firmness and the nutritional quality. Finally, the combination of active packaging and pMA resulted a valid solution to extend blueberries’ shelf-life up to 13 days.

Recently two-dimensional nanomaterials, such as graphene and molybdenum disulfide (MoS2), have received much attention as adsorbent materials for the effective removal of organic contaminants. MoS2 is attracting attention, not only for its chemical-physical properties, but also for its wide availability in nature as a constituent of molybdenite. The aim of this investigation was to assess the effects of different MoS2 concentrations (5 × 10−1, 5 × 10−2 and 5 × 10−3 mg/ml) on the embryonated eggs of Gallus gallus domesticus, according to Beck method. We evaluated the toxic effect of the MoS2 powder purchased at Sigma-Aldrich indicated as “received” and MoS2 powder treated via mechanical milling indicated as “ball mille”. Subsequently, the embryos were sacrificed at different times of embryonic development (11th, 15th and 19th day after incubation) in order to evaluate their embryotoxic and teratogenic effects. The alterations of the embryonic development were studied by morphological and immunohistochemical analysis of the tissues. The results obtained have shown the toxicity of both powders of MoS2 with a high percentage of deaths and growth delays. Moreover, the immunohistochemical analysis performed on several tissue sections showed a strong positivity to the anti-metallothionein1 antibody only for the erythrocytes.

In this paper, the use of hemp fibers modified with graphite oxide for the removal of methylene blue (MB) from aqueous solutions was investigated. Parameters such as contact time, pH, temperature, initial concentration of dye and ionic strength were varied and their effects on the adsorption recovery were evaluated. The adsorption process attained the equilibrium within 30 min while the adsorption capacity was found to increase with increasing contact time. The experimental data were fitted through a pseudo-second order model. Maximum adsorption capacity slightly increases with temperature changing from 54 mg/g to 58 mg/g at pH = 7.5, from 37 mg/g to 45 mg/g at pH = 3 and from 44 mg/g to 49 mg/g at pH = 12, by increasing the temperature from 20 °C to 80 °C indicating that the process is slightly endothermic (ΔH = 3.43 kJ/mol). The thermodynamic parameters were even calculated demonstrating that the process is spontaneous (ΔG ≈ −4.4 J/mol K and ΔS = 3.16 J/mol K)). Finally, a mathematical algorithm was applied to forecast the response surface model. A second order model was chosen to fit the experimental data and the statistical effect of the process parameters were estimated. A numerical optimization was even performed to individuate the optimal set of process parameters (pH = 9.25, T = 53.8 °C and C0 = 13.2 mg/L) which maximizes the removal capacity. A possible adsorption mechanism was even presented. So, it was proved the efficiency of the adsorption of a novel, inexpensive and sustainable composite material obtained from agro-waste resources by performing reusability cycles.

This research aims for designing and fabricating green and sustainable systems for an efficient removal of methylene blue from aqueous solutions. The hybrid beads, obtained by using ionotropic gelation technique and calcium chloride as cross-linking agent, are composed of sodium alginate matrix, hemp hurd as agro-waste resource and halloysite nanoclay (HNTs). The produced composite beads were characterized morphologically by using SEM and EDX techniques. The batch adsorption studies were performed up to 24 hours using methylene blue (MB) as model hazardous dye in order to investigate the effect of HNTs content (0-35% wt) and pH (2, 7 and 12) on the adsorption capacity. In neutral conditions, a maximum adsorption capacity of 32 mg/g was obtained for sample with 0% of HNTs while it increases up to 41, 43 and 50 mg/g for 5, 20 and 35%wt, respectively. Moreover, swelling/deswelling behavior and point of zero charge (PZC) analysis were even investigated since they are known to affect the adsorption process. A slight increase in PZC can be observed by adding clay nanotubes from 7.42 (0% wt HNTs) up to 7.98 (35% wt HNTs). The experimental data were fitted through first order model, pseudo-second order model and intraparticle diffusion model, demonstrating that the adsorption phenomenon is well described by second order process as well as that the process is mainly characterized by boundary diffusion and intraparticle diffusion. Finally, diffusion of dye was evaluated as function of HNTs content and H+ concentration appearing to decrease from pH=2 up to pH=7 and then to increase in alkaline medium (pH=12). Diffusion coefficient and recovery % trends were modeled through design of experiment methodology.

Layered double hydroxides (LDHs) constitute a large family of anionic inorganic clays having interesting and sometimes unexplored characteristics. They are natural, cheap, and simple to be produced, with a high degree of purity. In addition, they can be easily modified by means of organic molecules, and organic modification is an inevitable step for the intercalation of polymer macromolecules into the layers of LDH. The obtained hybrids can be used to prepare polymeric nanocomposites with new properties. The layered structure of LDHs enables the intercalation of polymer macromolecules, and hence the formation of polymer nanocomposites with peculiar functionalities for targeted applications. With appropriate host molecules, nanohybrid LDH molecules can be used as functional fillers able to protect packaged food from bacteria spoilage and pollutant environment. This chapter reviews the state of the art of LDH-active hybrids (i.e., antimicrobials, oxygen scavengers, etc.), with particular attention to their potential use in food-packaging applications. The incorporation process into polymer matrices (either biodegradable or not), the structure of these nanocomposites and the resulting properties (thermal, mechanical, and barrier) are also described. Possible trends and future perspectives are finally proposed and discussed.

The paper reports the formulation of an active packaging based on PET coated with a Layered Double Hydroxide (LDH) hosting 2-acetoxybenzoic anion (salicylate) as antimicrobial molecule. The release of the molecule anchored to the LDH, compared to the molecule free dispersed into the coating, appeared much slower. Permeability of carbon dioxide and oxygen through the packaging at different temperatures was evaluated, as well as the capability of the active material to inhibit Pseudomonas, Listeria and Lactobacillus. Table grape was stored in thermal stress conditions (i.e. 10 °C) into the active packaging and the total mesophilic aerobic count and yeasts and moulds population was evaluated up to 14 days of storage. The experimental results were used for a theoretical prediction of shelf life of the packed grapes and compared with the same fruit packed into untreated material. Global and specific migration of salicylic acid from the active packaging demonstrated, in compliance with the migration limits of the EU regulation, the suitability of the considered material for food contact.

Layered double hydroxide (LDH) nanofillers were considered as hosts of p-hydroxybenzoate as an antimicrobial molecule for active coating. A food grade resin with LDH-p-hydroxybenzoate and two different types of food grade zeolites was used to prepare active coatings for Polyethylene terephthalate (PET) trays. The release kinetics of the active molecule were followed using UV spectrophotometry and the experimental results were analyzed with the Gallagher&ndash, Corrigan model. The thermal properties of the coating mixtures and the PET coating were analyzed and found to be dependent on the coating&rsquo, s composition. On the basis of CO2 transmission rate and off-odors tests, the best coating composition was selected. Global migration in ethanol (10% v/v), acetic acid (3% w/v), and vegetable oil, and specific migration of p-hydroxybenzoic acid revealed the suitability of the material for food contact. Antimicrobial tests on the packaging demonstrated a good inhibition against Salmonella spp. and Campylobacter jejuni. Red meat was packed into the selected active materials and results were compared to uncoated PET packaging. Color tests (browning of the meat) and analysis of Enterobacteriaceae spp. and total viable count evolution up to 10 days of storage demonstrated the capability of the considered active packaging in prolonging the shelf life of red meat.

Antimicrobial packaging systems are recognized as effective approaches to prolong food shelf life. In this context, Bio-based PA11 loaded with a food-grade zeolite were prepared using ball milling technology in the dry state. Zeolite was filled with sodium salicylate, as an antimicrobial agent, and incorporated into the polymer matrix (~50 wt % of salicylate) at different loadings (up to 10 wt %). Structural characterization and an analysis of the physical properties (thermal, barrier, mechanical) were conducted on the composites&rsquo, films and compared with the unfilled PA11. The successful entrapment of the antimicrobial molecule into the zeolite&rsquo, s cavities was demonstrated by the thermal degradation analysis, showing a delay in the molecule&rsquo, s degradation. Morphological organization, evaluated using SEM analysis, indicated the homogeneous distribution of the filler within the polymer matrix. The filler improves the thermal stability of PA11 and mechanical properties, also enhancing its barrier properties against CO2 and O2. The elongated form of the zeolite particles, evaluated through SEM analysis, was used to model the permeability data. The controlled release of salicylate, evaluated as a function of time and found to depend on the filler loading, was analyzed using the Gallagher‒Corrigan model.

The paper is focused on a deep analysis of transport properties of natural hemp fibers (HF) functionalized through a mechano-chemical treatment assisted by high energy ball milling. The effect of milling time on fibers’ morphology was investigated by means of the scanning electron microscopy and FTIR spectroscopy. The results show that the mechanical effect induced a reduction of the mean diameter of hemp fibers and, simultaneously, the achievement of a close packing of cellulose chains. The barrier properties appeared to be dependent either on the packing of cellulose or the water cluster formation. Fick’s law solution in cylindrical coordinates was used to simulate experimental sorption kinetics and to extrapolate the diffusion parameters. The change of diffusion with equilibrium moisture content was described through an empirical relationship. Sorption isotherms were explained on the basis of Park model which accounts for a dual mode sorption at low activities as well as the water clustering phenomenon occurring at high activities. The mean cluster size (MCS) of water molecules was estimated through the application of Zimm Lundberg theory. Finally, the spreading pressure calculation allowed to estimate the driving force of diffusion inside the systems.

Layered double hydroxide (LDH) modified with different organic molecules were obtained via co-precipitation method. The prepared inorganic-organic hybrids were dispersed at 3 wt% in a low density polyethylene (LDPE) matrix by high energy ball milling (HEBM). Films were obtained and structural organization and thermal, mechanical and oxygen barrier properties investigated. In order to evaluate a possible application in food packaging field, overall migration tests were also conducted on selected composites. They were used acetic acid 3% and ethanol 10%, to simulate foods with acidic and hydrophilic character in non-swelling conditions, and alcoholic foods and dairy products under more swelling conditions, respectively.

Novel active coatings from renewable sources were developed using a pectin matrix and a modified layered double hydroxyde (LDH), as filler. The active molecule, ionically bonded to the LDH, was sodium salicylate. The hybrid filler loading was 5 wt% of LDH-salicylate, with a total content of active molecule into the composites of 1.6 wt%. The degree of plasticization of the composites varied in the range 4–16 vol % of glycerol. Morphological, thermal and barrier properties of the composites were analyzed. The x-ray analysis showed a complete delamination of the hybrid filler at any glycerol loading. The thermal degradation behavior and mechanical properties resulted strictly influenced by the glycerol content. Barrier properties (sorption, diffusion and permeability) to water vapor indicated that composite plasticized with 4 vol% of glycerol showed the best improvement of barrier properties. This suggested that the interaction pectin-active filler-degree of glycerol plays a significant role in determining the transport phenomena. Fresh apricots were coated with the active composite plasticized with 4 vol % of glycerol, demonstrating the efficiency of this formulation in extending the preservation of such fruits.

A novel antimicrobial packaging system, as active coating on a commercial Poly(ethylene terephthalate) (PET) film, was formulated and tested in vitro against the spoilage bacteria of Mozzarella cheese. It is based on layered double hydroxide (LDHs) intercalated with salicylate and carbonate anions dispersed in a solvent-based heat seal. The population of spoilage microorganisms (total coliforms, Pseudomonas, fungi), along with the functional microbiota of Mozzarella cheese (lactic acid bacteria) was characterized. Microbial shelf life was evaluated at 18 °C, to simulate thermal abuse. Experimental results show an increase in the microbial shelf life of the packaged Mozzarella cheese of about 20 days, confirming that the investigated active coating may exert an inhibitory effect on the microorganisms responsible for spoilage phenomena, without affecting the functional microbiota of the product.

The aim of this study was the assessment of high energy ball milling technique to develop poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) nanocomposites containing bacterial cellulose nanowhiskers (BCNW). Crystallization behaviour of PHBV/BCNW nanocomposites was studied under non-isothermal and isothermal conditions using differential scanning calorimetry. The changes in PHBV crystalline structure were also studied using X-ray diffraction. The results confirmed that BCNW acted as nucleating agents and, hence, favored the crystallization of the PHBV. The oxygen permeability of the nanocomposites was reduced by ~22 % when compared to that of the neat PHBV. This work provides a new insight into the development of polyhydroxyalkanoate composites by means of the high energy ball milling technique., J. Ambrosio-Martín would like to thank the Spanish Ministry of Economy and Competitiveness for the FPI grant BES-2010-038203. M. J. Fabra is recipient of a “Juan de la Cierva” contract from the Spanish Ministry of Economy and Competitiveness. The authors acknowledge financial support from the MINECO (MAT2012-38947-C02-01 project) and from the FP7 ECOBIOCAP project.

Membranes based on poly(&epsilon, caprolactone)/poly(3-hydroxybutyrate) blends (PCL/PHB at 50 wt%) were obtained by electrospinning and curcumin encapsulated at 1 wt% as active agent, as drug delivery systems for biomedical applications. PCL and PHB were also separately electrospinned and loaded with 1 wt% of curcumin. The processing parameters of PHB were drastically different from PCL and the blend PCL/PHB, in fact, the temperature used was 40 &deg, C, and the distance injector&ndash, collector was 28 cm. Different conditions were used for PCL: lower temperature (i.e., 25 &deg, C) and shorter distance injector&ndash, collector (i.e., 18 cm). The blend was processed in the same conditions of PCL. The fibers obtained with PHB showed diameters in the order of magnitude of micron (i.e., &asymp, 3.45 &micro, m), while the PCL mats is composed of fiber of nanometric dimensions (i.e., &asymp, 340 nm). PCL/PHB blend allowed to obtain nanometric fibers (i.e., &asymp, 520 nm). Same trend of results was obtained for the fibers&rsquo, porosity. The morphology, thermal, mechanical and barrier properties (sorption and diffusion) through water vapor were evaluated on all the electrospun fibers, as well as the release behavior of curcumin, and correlated to the processing parameter and the fibers&rsquo, morphologies.

Two-dimensional (2D) nanomaterials have received much attention in recent years, because of their unusual properties associated with their ultra-thin thickness and 2D morphology. Besides graphene, a new 2D material, molybdenum disulfide (MoS2), has attracted immense interest in various applications. On the other hand, ball-milling process provides an original strategy to modify materials at the nanometer scale. This methodology represents a smart solution for the fabrication of MoS2 nanopowders extremely-efficient in adsorbing water contaminants in aqueous solution. This work reports a comprehensive morphological, structural, and physicochemical investigation of MoS2 nanopowders treated with dry ball-milling. The adsorption performances of the produced nanopowders were tested using methylene blue (MB) dye and phenol in aqueous solution. The adsorption capacity as a function of ball-milling time was deeply studied and explained. Importantly, the ball-milled MoS2 nanopowders can be easily and efficiently regenerated without compromising their adsorption capacity, so to be reusable for dye adsorption. The eventual toxic effects of the prepared materials on microcrustacean Artemia salina were also studied. The present results demonstrate that ball-milling of MoS2 offers a valid method for large-scale production of extremely efficient adsorbent for the decontamination of wastewaters from several pollutants.

This paper reports the preparation of green pesticides based on nano-hybrids composed of a Layered Double Hydroxide (LDH) with cinnamate anion. The dispersion into a pectin matrix was obtained using high energy ball milling in wet conditions. Structure and physical properties of the fillers and the composites films were evaluated. Controlled release of cinnamate was followed using UV spectrophotometry and the release kinetics were found to be dependent on the filler loading. The experimental results were analyzed by the Gallagher-Corrigan model. Antimicrobial activity was evaluated on different bacterial strains, as well as plant pathogens belonging to the genus Phytophthora using modified agar diffusion, broth microdilution and dual culture methods, respectively. Experimental results suggested the possibility to use the analyzed composites as green protective coatings for crops’ protection.

This paper reports the surface treatment of layered double hydroxide (LDH) by using ionic liquid (IL) composed of phosphonium cation combined with 2-ethylhexanoate (EHT) counter anion as surfactant agent. Then, different amounts (1, 3, 5 and 7 wt %) of thermally stable organically modified LDH (up to 350 °C) denoted LDH-EHT were incorporated into polycaprolactone (PCL) matrix by mechanical milling. The influence of LDH-EHT loading has been investigated on the physical properties, such as the thermal and barrier properties, as well as the morphologies of the resulting nanocomposites. Thus, intercalated or microcomposite morphologies were obtained depending on the LDH-EHT loading, leading to significant reduction of the diffusion coefficient respect to water vapor. The modulation of barrier properties, using low functionalized filler amount, is a very important aspect for materials in packaging applications.

This chapter reviews hydrolytic degradation and biodegradation of poly(lactic acid) (PLA). Hydrolytic degradation, which induces morphological and compositional changes, is considered the most important step in biodegradation. The main factors influencing hydrolytic degradation (temperature, pH, sample morphology, and molecular weight) are considered and analyzed. An overview of biodegradation under composting conditions is also given. The chapter also analyses the possibilities of modulating degradation and biodegradation rates according to the expected lifetime of objects made of PLA. This can be considered frontier research in this field.

Halloysite nanotubes (HNTs) were loaded with lsozyme, as antimicrobial molecule, at a HNTs/lysozyme ratio of 1:1. Such a nano-hybrid was incorporated into a poly (ε-caprolactone) (PCL) matrix at 10 wt % and films were obtained. The nano-composites were submitted to a cold drawn process at three different draw ratios, λ = 3, 4, and 5, where λ is l(final length)/l0(initial length). Morphology, physical, and barrier properties of the starting nanocomposite and drawn samples were studied, and correlated to the release of the lysozyme molecule. It was demonstrated that with a simple mechanical treatment it is possible to obtain controlled release systems for specific active packaging requirements.

Phosphonium ionic liquid (IL) combined with 2-ethylhexanoate counter anion has been used as interfacial agent of layered double hydroxide (LDH). First, the intercalation of hexanoate anion between the LDH layers was confirmed by thermogravimetric analysis (TGA) and X-ray diffraction (XRD). Then, this thermally stable organophilic LDH was introduced at different amount (1, 3 and 5 wt%) into pectin matrix leading to an increase of the thermal stability of the resulting nanocomposites (+35–40 °C). In addition, the good distribution of the modified LDH led to an increase of the mechanical performances through the elastic moduli (+60%) as well as a significant increase of the water barrier properties of two orders of magnitude for the pectin containing 5 wt% of LDH-Ionic Liquid.

Composites based on Poly(ethylene terephthalate) (PET) and Halloysite nanotubes (HNTs) were prepared through high energy ball milling (HEBM) at ambient temperature and with no solvents. A wide range of HNTs loading was used (i.e. 1–7 wt%) and films produced. Morphological organization and physical (thermal, degradation, mechanical) properties were analyzed and correlated to HNTs content. HNTs were also filled with an antimicrobial model molecule, sodium benzoate, to test the effectiveness of such nano-containers as filler for polymers to be used in active packaging, enlightening very good perspectives in this field.

The synthesis of star-like A(B)n copolymers based on the hydrophilic poly(ethylene glycol) monomethyl ether (m-PEG, block A) and the hydrophobic poly(methyl methacrylate) (PMMA, blocks B) is reported. We obtained copolymers made of one m-PEG chain and 2 or 4 PMMA blocks using a combined “arm first”—“core first” approach. Such structures were called tree-shaped copolymers where the m-PEG was considered as the trunk and PMMA arms as the branches. Star-like copolymers (B)nA-A(B)n built by two tree-shaped fragments with a poly(propylene oxide) (PPO) as the central junction, were also synthesized according to a previously reported procedure. The latter were called star-shaped structures and the synthesis was performed to obtain architectures different from the tree-shaped one but characterized by a similar length of the PMMA arms. Microstructural analysis was carried out through 1H-NMR and GPC, and the thermal and transport properties (sorption and diffusion) to liquid water were investigated and correlated to...

The lamellar structure of montmorillonite (MMT) clays exhibits an interesting potential to improve the barrier properties of thermoplastic polyurethanes (TPU). However direct melt blending of an ester-based TPU and functional organoclays, despite showing good filler dispersion, did not allowed for improving neither barrier properties (i.e., sorption and diffusion to water vapor) not mechanical performances with respect to the unfilled TPU. Therefore, two alternative strategies involving poly(e-caprolactone) (PCL)/organoclay masterbatches were explored to investigate the possibility to prepare materials with improved mechanical and barrier properties. In the first strategy, a PCL/organoclay masterbatch with high inorganic content was obtained by melt-blending (coined “free PCL” masterbatch), whereas in the second strategy PCL-grafted organoclay nanohybrids, also with high inorganic content were synthesized by in situ intercalative grafting/ring-opening polymerization of e-caprolactone (CL). Purposely, ROP of CL was initiated from hydroxyl groups available onto the MMT surface actually organo-modified by alkylammonium cations bearing hydroxyl functions (coined “nanohybrid PCL” masterbatch). These highly-filled PCL masterbatches (with ca. 25 wt% in inorganics) were then added into the ester-based TPU to prepare nanoclay/polyurethane nanocomposites by melt-blending. The morphology and dispersion of the resulting materials were characterized by X-ray diffraction and transmission electron microscopy. Improved sorption and diffusion properties towards water vapor as well as mechanical properties were measured. Herein, these results are discussed as a function of both clay dispersion and matrix/organoclay interaction.

In this paper the barrier properties to water vapour of polylactic acid (PLA) films prepared with different thermal treatments were analyzed with the aim of correlating them to the morphology of the samples. The crystallization kinetics of the material was assessed during isothermal steps reached after cooling from the melt or heating from the solid. The temperature at which the maximum crystallization rate was attained was selected as the crystallization temperature for the samples analyzed for barrier properties. The structural and morphological organization was analyzed by means of X-ray diffraction analysis, differential thermal analysis (DSC) and optical analysis. Sorption and diffusion experiments were conducted either varying the temperature or the morphology of the samples. It was found that sorption was mainly dependent on the amount of the permeable non crystalline phase, while diffusion was also dependent on the morphological organization of the crystalline domains. Open image in new window

Novel biodegradable composites were prepared using PLA and a nano-hybrid composed of halloysite nanotubes (HNTs) filled with Lysozyme, as antimicrobial. The nano-hybrid was characterized from a structural point of view and the Lysozyme content evaluated by thermogravimetric analysis. Several composites were prepared using ball milling, in dry conditions at ambient temperature, varying the nano-hybrid loading (i.e. 3, 5, 10 wt%). The structural organization and physical properties (thermal, mechanical and barrier to water vapor) ware analyzed and correlated to the nano-hybrid content. Controlled Lysozyme release into saline solution was followed using UV spectrophotometry. The release kinetics was found to be dependent on HNTs-Lysozyme relative fractions. The experimental results were analyzed by a modified Gallagher-Corrigan model.

Novel hybrid materials, obtained by direct Catalytic Chemical Vapour Deposition (CCVD) growth of carbon nanotubes (CNT) over a clay mineral catalyst, were incorporated into Polylactic acid (PLA) through melt mixing. Nanocomposites in the form of films were exposed to UV irradiation at constant temperature (30 degrees C) and relative humidity (50%). Young's Modulus measurements show a strong mechanical degradation with the UV irradiation time. The decrease was higher in neat PLA compared with nanocomposites and was attributed to the extensive macromolecular chain scission due to the UV irradiation. From thermogravimetric characterization it was found that the degradation temperature decreases with the photoageing. The addition of the hybrid filler causes an initial decrease of this temperature (up to 3%) and a slight increase thereafter. A similar behaviour was found for the enthalpy relaxation during the morphological rearrangement which occurred in the glass transition process. Indeed, the electrical conductivity of the nanocomposites was found to monotonically increase with the UV irradiation time. (C) 2012 Elsevier B.V. All rights reserved.

Preparation and analysis of morphology, mechanical, and electrical properties of nanocomposites based on ethylene vinyl acetate (EVA) copolymer and commercial multiwalled carbon nanotubes (CNTs) was achieved. The used techniques for obtaining nanocomposites were the conventional melt-mixing and the in situ ethylene polymerization/coating reaction, as catalyzed directly from CNT surface, with different polyethylene content (i.e. 55.0% and 66.6%). Nanocomposites were also prepared using crude CNTs. The incorporation in the molten state of such polyethylene surface-coated CNTs, used as “masterbatch,” in EVA was demonstrated a good strategy for allowing the complete destructuring of the native bundle-like aggregates, leading to the preparation of polymer nanocomposites with largely improved properties, even at very low nanofiller content. Copyright © 2011 John Wiley & Sons, Ltd.

Multi walled carbon nanotubes have been incorporated into a linear low density polyethylene matrix through high energy ball milling technique at room temperature, without any chemical modification or physical treatment of the nanotubes. Highly oriented samples, with different draw ratios, were obtained by drawing at 80 °C the composite films. SEM and FTIR results on the drawn PE films demonstrate that the molecular chains in both crystalline and amorphous phases are well oriented along the drawing direction. The effect of different weight percent loadings of nanotubes and draw ratio on the morphology, thermal, mechanical and electrical properties of the composite fibers have been investigated.

Preparation and analysis of morphologic and electrical properties of high-performance multi-walled carbon nanotube/polyamide 6 nanocomposites was achieved. The MWNTs were surface-coated by in situ polymerization of ethylene as catalyzed directly from the nanotube surface previously treated by a highly active metallocene-based complex. The so-produced polyethylene-coated MWNTs were melt-mixed with the PA6 matrix. Pristine MWNTs were also dispersed in PA6. The in situ ethylene polymerization/coating reaction allowed the destructuring of the native bundle-like aggregates leading to the preparation of nanocomposites with improved properties even at very low nanofiller content.

Sodium montmorillonite was incorporated into a poly(epsilon-caprolactone)-starch blend by means of a ball mill. The structural organization and physical (mechanical, thermal and barrier) properties were analyzed and correlated with the milling conditions. Scanning electron microscopy and X-ray characterization show that the milling process can improve the compatibilization between the PCL and the starch phases, while promotes the dispersion of clay minerals at nanometric level. The milling time strongly influences the mechanical and barrier properties. In particular, the best results in terms of elastic modulus and permeability coefficient were achieved with a complete delamination of the pristine clay structure. In summary, the milling process not only has demonstrated to be a promising compatibilization method for immiscible PCL-starch blends, but it can be also used to improve the dispersion of nanoparticles into the polymer blends. (C) 2008 Elsevier Ltd. All rights reserved.

Lignin powder, obtained from an abundant and low-cost source, straw, through a low-environmental-impact process, steam explosion, was used for the preparation of blends with a biodegradable polyester, poly(e-caprolactone) (PCL), with an innovative technique, high-energy ball milling. Lignin strongly stabilized PCL against UV radiation. The modulus of the blends increased with the addition of lignin; nevertheless, the elongation at breaking decreased. Through thermal characterization (differential scanning calorimetry and dynamic mechanical analysis), lignin and PCL were found to be immiscible. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

We have successfully synthesized poly(lactide), poly(glycolide), and poly(lactide- co -glycolide) copolymers in bulk by ring-opening homo- and copolymerization of glycolide and l -lactide, using sodium hydride as the environmentally friendly and nontoxic initiator. Random copolymers were obtained, and the microstructure was characterized by nuclear magnetic resonance ( 1 H and 13 C NMR) and matrix-assisted laser desorption ionization mass spectrometry (MALDI MS). The mechanism of reaction was elucidated by analysis of the polymer end groups. Homopolymer and copolymers films and their blends were obtained, and structure and physical properties analyzed. Thermal degradation analysis showed superior characteristics of copolymers with respect to the blends. Transport properties of water vapor were also evaluated and correlated to the copolymer composition.

Nanocomposites of polylactide (PLA) and functionalized graphene sheets (FGS) were obtained via melt compounding. Pre-incorporation of the FGS fillers into lactic acid oligomers (OLLA) by in situ melt polycondensation was performed with the aim of improving the FGS dispersion and distribution into the polymeric matrix. To evaluate the effect of the pre-incorporation step, a comparison with direct addition of the filler to the melt mixing process was carried out. Addition of OLLA and FGS led to enhanced better barrier properties. Specifically, reductions of up to 45% and 41% in oxygen and water vapor permeability were achieved, respectively. Mechanical and electrical properties of the PLA and its nanocomposites were also studied and correlated with both the addition of oligomers and the incorporation method., J. Ambrosio-Martın would like to thank the Spanish Ministry ofEconomy and Competitiveness for the FPI grant BES-2010–038203. M.J. Fabra is recipient of a “Juan de la Cierva” contractfrom the Spanish Ministry of Economy and Competitiveness. Theauthors acknowledge financial support from the MINECO(MAT2012–38947-C02-01 project) and from the FP7 ECOBIO-CAP project.

This work aims to evaluate the possibility to introduce natural nano-containers for active molecules, such as halloysite nanotubes (HNTs), into an environmentally friendly material: natural zein. Composites were prepared in a wide range of HNTs composition (i.e. 1–10 wt%) and structural and physical properties were analyzed. HNTs were also filled with an active molecule commonly used as preservative in food packaging, such as potassium sorbate (KS), and the diffusion of such molecule was evaluated. The zein thermal degradation resulted significantly improved with the filler content. Mechanical properties showed a reinforcement of zein matrix. HNTs were filled with potassium sorbate and dispersed into the zein matrix.

The present paper reports, for the first time, the successful fabrication of layered double hydroxide (Mg-Al LDH)-reinforced polycaprolactone (PCL) nanofibers by electrospinning. Either the LDH in carbonate form or an LDH organically modified with 12-hydroxydodecanoic acid (LDH-HA) were incorporated into PCL and electrospun using a voltage of 20 KV. The LDH-HA was prepared by an ionic exchange reaction from pristine LDH and encapsulated into PCL from acetone solutions at 15 wt %. The morphological analysis showed pure PCL fibers with an average diameter of 600 +/- 50 nm, and this dimension was maintained in the fibers with LDH, with the inorganic component residing outside the fibers and not exfoliated. At variance, the fibers with the LDH-HA showed a significantly lower average diameter in the range of 350 +/- 50 nm, indicating the improved electrospinnability of PCL. Moreover, the inorganic lamellae were exfoliated, as shown by X-rays and residing inside the nanofibers as demonstrated by energy dispersive X-ray spectroscopy analysis. The structural parameters, such as degradation temperature and crystallinity, were investigated for all the samples and correlated with the electrospinning process.

The effect of the electrical field on the conductivity of linear low-density polyethylene/carbon nanotubes/ (LLDPE/CNT) composites during temperature cycling has been investigated. Under applied voltage a positive resistivity temperature coefficient was observed during heating already at low (2–3 wt%) CNT content, followed by a large negative temperature coefficient during cooling whose value depends on the applied voltage. The resistivity values after thermal cycling were markedly lower, while they slightly increased in the absence of an electrical field. The effects of thermal cycling on structural and physical properties of the composites have been evaluated by X-ray diffraction and differential scanning calorimetry.