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In this study, a novel extraction method has been employed to obtain highly efficient cellulose nanocrystals (CNCs) and cellulose nanofibers (CNFs) from waste hemp fibers with maximum potential. By...

Bio-based composites made of poly(L-lactic acid) (PLLA) and β-cyclodextrin/d-limonene inclusion complex (CD-Lim) were prepared by melt extrusion. Encapsulation of volatile d-limonene molecules within β-cyclodextrin cages was proven to be a successful strategy to prevent evaporation during high-temperature processing. However, small amounts of limonene were released upon processing, resulting in the plasticization of the polymeric matrix. Morphological analysis revealed good dispersion of the filler, which acted as a nucleating agent, favoring the growth of PLLA crystals. The composites′ lowered glass transition temperature upon the addition of CD-Lim was also proved by thermomechanical analysis (DMA). Moreover, DMA revealed constant stiffness of modified materials at room temperature, which is crucial in PLLA-based formulations.

In this study, chitosan based microbeads containing Ungeremine, an antimicrobial alkaloid particularly active against Penicillium roqueforti, a filamentous fungus responsible of the bakery products deterioration, were prepared by external gelation by using sodium tripolyphosphate (TPP) as crosslinking agent. The stability of the beads, as well as the loading efficiency of the bioactive molecule, were assessed at different pH and TPP concentrations resulting particularly enhanced at low pH. All the microbeads evidenced antimicrobial activity against Penicillium roqueforti. The release kinetics of Ungeremine was tailored by opportunely modulating pH and TPP concentrations. Morphological analysis evidenced the improvement of the structural crosslinking density of microbeads including Ungeremine and spectroscopic analysis emphasized the active participation of Ungeremine to the crosslinking process occurring between chitosan and TPP. Finally, thermogravimetric analysis confirmed the increasing of free volume in three-dimensional networks and their liability to thermal degradation.

This manuscript describes antifungal, structural, thermal and morphological properties of a novel, eco-friendly bioplastic film, based on poly(butylenesuccinate) and cavoxin, a chalcone phytopathogenic metabolite, isolated from cultures by the fungus Phoma cava and included inside the biodegradable polymeric matrix. The antagonistic activity of the film explored against two fungal food contaminants Penicilliumroqueforti and Aspergillusniger, highlighted that cavoxin was fungicide at MIC concentrations. The chemico-physical analysis were performed on films before and after antifungal activity. Thermal analysis evidenced both the higher thermal stability of poly(butylenesuccinate) and cavoxin blend and the sharp nucleating action of cavoxin on the polymer. Infrared spectroscopy highlighted the presence of physical interaction between the polar groups of the blend components, whereas gel permeation chromatography highlighted that the hydrolytic effect of cavoxin on poly(butylenesuccinate) was responsible for the diffusion and releasing of the biomolecule from the matrix and UV–Vis spectroscopy provided quantitative information of release kinetics. Finally, morphological analysis confirmed both the polymeric surface hydrolysis exerted by cavoxin, and the adhesion of fungal spores on films after contact occurred during the antifungal assay.

Background The organic extracts (OEs) of Dittrichia viscosa, a ruderal plant common in the Mediterranean regions, proved to have herbicidal properties. In order to improve OE effectiveness and to develop novel eco-friendly bioherbicidal products, different amounts of OE were included in poly(butylene succinate)- and polycaprolactone-based films (PBS and PCL, respectively). Particular attention was given to the study of interactions between the polymers and OEs, with a deep spotlight concerning the influence of OEs on structural, morphological and thermal properties of both polymers, in order to assess the OE releasing kinetics from the matrices and its tuned herbicidal action against seeds. Results The bioassays carried out on Lepidium sativum and Phelipanche ramosa seeds evidenced a more controlled and effective OE release by PBS than PCL, and a longer lasting efficacy by the polymers with a higher OE content. The chemical-physical analyses were performed on films before and after biological assays. The thermogravimetric analysis confirmed that OE was a thermal stabilizer of the polymer; the presence of OE and polymer separated degradative kinetics suggested that only a partial and functional miscibility between polymers and OE occurred. The morphological analysis confirmed the good OE dispersion between PBS and PCL molecular chains. Infrared spectroscopy highlighted the enhanced hydrolysed structure of the doped polymers after the bioassays. These outcomes well matched the quantitative information outlined by release kinetics. Discussion The use of biodegradable polymers allows the effectiveness and tuning of the release of the formulated bioactive compounds to be improved. The easy-to-obtain and easy-to-formulate OE could become a suitable and environmentally friendly instrument in weed management programmes.

In this work, α−costic acid (α-CA), a metabolite coming from a perennial autochthon shrub Dittrichia viscose, was used as natural additive of polylactic acid (PLA), a biodegradable thermoplastic polymer, in order to modulate its chemico-physical properties, for the achievement of a wholly biobased packaging system. It’s the first time that α−costic acid is exploited for this appealing and novel application. The investigations performed on PLA/α-CA films, evidenced strong physical interaction occurring between the polymer and α-CA, as confirmed by NMR and FTIR-ATR analyses; SEM micrographs showed a good embedding of α-CA particles inside PLA polymer matrix; GPC analysis highlighted a slight hydrolysis of polymer matrix clearly evidenced in mechanical properties. DSC analysis underlined the significant decreasing of Tg, associated with the increase of PLA chain mobility. TGA thermograms evidenced one broad degradation profile of PLA/α-CA system, accounting for the weighty physical interaction occurring between the polar groups of both polymer and plasticizer. Finally, PLA surface wettability notably enhanced by the inclusion of α-CA polar groups. In conclusion, α-CA can be considered as a promising plasticizer of PLA and a worthy modifier of its overall properties.

In this study, chitosan (C) tripolyphosphate (T) sub-micro particles containing ungeremine (CTUn), an alkaloid particularly active against Penicillium roqueforti, a fungus responsible of the bakery products deterioration, were prepared through external gelation crosslinking process. The particles were included in a thermoplastic starch based polymer Mater-Bi (MBi), and MBi/CTUn bioactive biocomposites were obtained. The films showed bioactivity against P. roqueforti. In particular, the bioassays were performed on films with different concentration of CTUn and at different pH values. CTUn particles influenced MBi crystallization (DSC analysis) and promoted thermal degradation of MBi starch component (TGA). Morphological analysis confirmed even distribution of sub-micro particles into the polymeric matrix. Water permeability slightly increased, as expected, whereas oxygen permeability decreased. Tensile tests showed CTUN sub-microparticles improved rigidity and tensile strength of the films at the expense of ductility. Finally, MBi/CTUn biocomposites evidenced interesting performances potentially exploitable in bioactive bakery based food packaging materials.

In this paper, lemon and fennel wastes were recovered and used as secondary-raw polysaccharide sources. These polysaccharides were exploited as natural plasticizers of sodium alginate (A) based films, in order to improve sodium alginate performances, limited by its fragility, extending its potential application in a cost effective and eco-friendly way. Different green processes, such as maceration (MAC), ultrasound assisted extraction (UAE) and microwave assisted extraction (MAE), were carried out for obtaining high yield of lemon and fennel polysaccharides (LP and FP). Actually, HPAE-PAD and TLC analyses evidenced the presence of xyslose, galactose, glucose and rhamnose monomers and galacturonic acid, typical of polysaccharides like pectin and xyloglucan chains. These findings were confirmed by NMR and FTIR spectroscopic analyses. Moreovers, gel filtration chromatography assessed the high molecular weight of recovered polysaccharides, particularly of FP waste fraction. The extracted polysaccharides were used as eco-friendly and cost-effective plasticizers of sodium alginate films (AFP and ALP). DSC analysis evidenced a significant decreasing of glass transition temperature of the polymer, tensile tests showed an enlightened rising of elongation at break and TGA analysis showed a faster degradation kinetics of AFP and ALP films, as expected in a plasticized system.

Citrus pomace derived from the industrial processing of juice and essential oils mostly consists of pectin, cellulose, hemicellulose, and simple sugars. In this work, citrus pomace waste from an agricultural company in South Italy was used as source of pectin. The extraction conditions of the polysaccharide were optimized using a suitable combination of time and a concentration of a mild organic solvent, such as acetic acid, thus recovering high Mw pectin and bioactive molecules (flavonoids and polyphenols). The pectin was structurally (GPC, FTIR), morphologically (SEM), thermally (TGA/DTG), and mechanically characterized, while bioactive molecules were separated and the total phenolic content (TPC) and total flavonoids content (TFC) were evaluated. With the aim to develop novel biocomposite-based materials, the pectin extracted from citrus waste was reinforced with different amounts of lignocellulose fractions also recovered from citrus waste after polysaccharide extraction, according to a “zero waste” circular economy approach. The prepared biocomposites were morphologically and mechanically characterized to be used as biodegradable mulching systems for crop protection. Thus, the citrus waste biomass was recovered, fractionated into its main raw materials, and these were recombined to develop novel upgraded biocomposites for mulching applications, by means of a cost-effective and eco-sustainable approach.

Cardoon seed oil (CO), derived from the nonedible Cynara cardunculus plant, growing in marginal and contaminated soils of Mediterranean regions, was successfully epoxidized (ECO) in a fed-batch modality. The cost-effective and environmentally friendly oils have been used as bioplasticizers of poly(lactic acid) (PLA), to improve the overall properties and broaden its industrial applications as a biodegradable packaging material. Hence, physical blends and films of PLA, containing 3% by weight of CO and ECO, were prepared by melt extrusion and compression molding, and the effect of the both bioplasticizers on structural, thermal, and mechanical properties of the obtained films was investigated. Cardoon oils induced the decreasing of glass transition temperature due to PLA free volume enhancement. This effect was particularly marked in PLA–ECO film. Thermal stability of PLA was meaningfully improved upon addition of the oils, and the mechanical properties made evident the increase of PLA ductility, particularly enhanced in the PLA–ECO system, where the polymeric matrix and the oil showed stronger physical interaction and improved phase compatibility, as also revealed by spectroscopic and morphological analyses. Therefore, the plasticization action exerted by very low concentrations of epoxidized cardoon oil efficiently overcomes PLA drawbacks, thus encouraging the feasibility of its use as a bioplastic for packaging material.

The aim of this study was the development of novel polysaccharide based films intended to be used as edible food packaging material. The films were prepared by solution casting method using highly methoxylated pectin (PEC) and poly(ethylene glycol) (PEG) of various molecular weights (400, 600 and 1000 gmol(-1)) in different ratios (5:1, 3:1 and 1:1). The film formation was supported by hydrogen bonding between PEC and PEG, which was evidenced by means of ATR-FTIR and NMR analysis. TGA revealed that generally PEG behaves like a pro-degrading agent for pectin, except in the case of PEC/PEG film with a ratio of 1:1. Furthermore, DSC thermograms indicated that PEG1000 exists as a separate phase in the pectin matrix while the formulations with PEG400 and PEG600 showed mainly amorphous morphology. The addition of PEG enhanced the plasticization of PEC films, as evidenced by progressive decreasing of the glass transition temperature values (T-g). The tensile test measurements showed that increasing concentration of PEG produced weaker and more flexibile films. Due to the increased molecular mobility, the pectin phase became more permeable to water vapor as the PEG concentration increased. The obtained results showed that the combination of both polymers resulted in interesting bio -inspired edible films with the potential to compete with commercially used synthetic package materials. This is the peer-reviewed version of the article: Šešlija, S., Nešić, A., Ružić, J., Kalagasidis Krušić, M., Veličković, S. J., Avolio, R., Santagata, G.,& Malinconico, M. (2018). Edible blend films of pectin and poly(ethylene glycol): Preparation and physico-chemical evaluation. Food HydrocolloidsElsevier Sci Ltd, Oxford., 77, 494-501. [https://doi.org/10.1016/j.foodhyd.2017.10.027] The published version: [https://cer.ihtm.bg.ac.rs/handle/123456789/2473]

Biodegradable polymer films based on polybutylene succinate (PBS) and polybutylene adipate terephthalate (PBAT) blends with varying weight ratios were prepared by extrusion and chill roll calendering. The films were characterized by infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), mechanical tensile tests, scanning electron microscopy (SEM), and rheology. In the blends with higher content of PBAT, PBS crystallization was inhibited. As for mechanical performance, increasing the PBS content in PBAT an increase in the stiffness and a decrease in the ductility of the blends is detected. Finally, rheological measurements evidence an increase in the viscosity of the blends with increasing the PBAT content.

In this paper, physico-chemical, mechanical and antimicrobial properties of hydrogels based on alginate/N-succinylchitosan blends crosslinked by calcium or zinc ions containing cellulose microfibers were investigated and discussed. With respect to plain alginate hydrogels, the addition of N-succinylchitosan significantly improved properties such as swelling degree and stability in saline solution. The water vapour transmission rate confirmed that all the hydrogels were able to assure a moist wound environment. Morphological analysis showed a good embedding of fibres within the zinc crosslinked hydrogels. In addition, zinc-crosslinked hydrogels evidenced antimicrobial activity against two common skin pathogenic bacteria, Staphylococcus aureus and Escherichia coli. Cytotoxicity assays proved that the amount of zinc released is slightly over the toxic level. Overall, the characteristics of the zinc-crosslinked hydrogels showed their potential interest as materials for wound dressing.

In this work, biodegradable films based on poly (lactic acid) (PLA) and corn thermoplastic starch (TPS), additivated with epoxidized cardoon oil plasticizer (ECO) at 3% by weight with respect to PLA mass fraction, were prepared by melt extrusion process and compression molding. The effect of ECO on structural, thermal, mechanical, barrier, and spectral optical properties of the films was investigated. Spectroscopic analysis evidenced the development of physical interaction between oil and polymers, mainly PLA. In addition, no oil migration occurrence was detected after six months of film preparation, as evidenced by oil mass evaluation by precipitation as well as by 1H-NMR methods, thus highlighting the good inclusion of oil inside the polymeric network. The plasticizing action of the oil induced a lean improvement of the interfacial adhesion between hydrophobic PLA and hydrophilic TPS, particularly accentuated in PLA80_ECO composition, as evidenced by morphological analysis of blend fracture surfaces. TGA data underlined that, differently from TPS-based films, PLA-based systems followed one degradative thermal profile suggesting a slight compatibilization effect of epoxidized oil in these films. The shifting of Tg values, by differential scanning calorimetry (DSC) analysis, indicated a weak miscibility at molecular level. Generally, in the investigated blends, the phase separation between PLA and TPS polymers was responsible for the mechanical properties failing, in particular, the tensile strength evidenced a negative deviation from the rule of mixtures, particularly marked in TPS-based blends, where no physical entanglements occurred between the polymers since their immiscibility even in presence of ECO. The epoxidized oil strongly improved the barrier properties (water vapor permeability (WVP) and oxygen permeability (O2P)) of all the films, likely developing a physical barrier to water and oxygen diffusion and solubilization. With respect to neat PLA, PL80 and PL80_ECO films evidenced the improvement of surface wettability, due to the presence of polar groups both in TPS (hydroxyl residues) and in epoxidized oil (oxirane rings). Finally, following to the conditioning in climatic chamber at T = 25 &deg, C and RH = 50%, PLA80 film became opaque due to TPS water absorption, causing a light transmittance decreasing, as evidenced by spectral optical analysis.

In this study, pectin based films including different amounts of sodium alginate were prepared by casting method. All the films, with and without polyglycerol as plasticizer, were crosslinked with zinc ions in order to extend their potential functionality. The development of junction points, occurring during the crosslinking process with zinc ions, induced the increasing of free volume with following changing in chemico-physical properties of films. The inclusion of alginate in pectin based formulations improved the strength of zinc ions crosslinking network, whereas the addition of polyglycerol significantly improved mechanical performance. Finally, zinc-crosslinked films evidenced antimicrobial activity against the most common exploited pathogens: Staphylococcus Aureus, Escherichia Coli and Candida Albicans. These results suggest that zinc-crosslinked based films can be exploitable as novel bio-active biomaterials for protection and disinfection of medical devices. (C) 2016 Elsevier Ltd. All rights reserved.

Agricultural activities need plastics for many applications such as films for soil mulching and pots for plants transplanting. The use of plastic products, made of fossil raw materials, such as polystyrene, polyethylene, and polypropylene results in huge quantities of plastic wastes to be disposed of. In the past two decades, the growing environmental awareness strongly encouraged researchers and industries toward the use of biodegradable polymers for solving the plastic waste problem. Researchers have made strong efforts to identify new biopolymers coming from renewable sources as valid ecosustainable alternatives to petroleum based plastic commodities. The main research results and current applications concerning the biodegradable plastics in agriculture, such as thermo-extruded Mater-Bi and sprayable water-born polysaccharides based coatings, are described in this chapter. A lineup of biopolymers coming from raw and renewable sources, such as polysaccharides, are reported; the intrinsic chemico-physical properties of polysaccharides, responsible for the realization of dry water stable hydrogels, suitable for the formation of both soil mulching coatings and transplanting biopots, are investigated. A description of the natural additives, fillers and cellulosic fibers included in the polymeric matrices, able to enhance the mechanical performance of coatings and pots is provided, together with the outputs in the specific applications.

In this study, we used natural polysaccharides (pectin, alginate and chitosan) as binders to generate pellets for crayfish feeding. Pellets were produced by cold extrusion in order to preserve nutrients from degradation and reduce energy consumption. Thereafter, pellets were submitted to a coating procedure, with the aim of improving pellet stability in water. Pellet water stability was analyzed by monitoring the diameter of the released particles in water over progressive time intervals up to 24 h, employing a Low Angle Laser Light Scattering Technique. Alginate containing pellets released particles with a smaller diameter than chitosan and pectin containing pellets, indicating that alginate containing pellets disaggregated more and therefore were less stable in water than the other pellet types. The effects of the different polysaccharide containing pellets were evaluated on crayfish feeding response employing juvenile Cherax albidus . The feeding experiment was carried out for 12 weeks, at the end of which growth parameters and the activity of amylase, lipases and proteases in the gastric juice, hepatopancreas and intestine were recorded. Crayfish fed pectin containing pellets exhibited a significant weight gain. Digestive enzyme activities did not statistically show significant differences in the digestive tract except for amylase that was significantly higher in the intestine of animals fed pectin containing pellets. Our data indicate that pectin and chitosan pellets showed the best water stability performances, moreover pectin pellets brought about the highest body weight gain and affected the amylase profile in the intestine of juvenile Cherax albidus .

[EN] The use of a modified poly(Epsilon-caprolactone) (gPCL) to enhance polymer miscibility in films based on ther-moplastic starch (S) and poly(Epsilon-caprolactone) is reported. PCL was functionalized by grafting with maleicanyhdride (MA) and/or glycidyl methacrylate (GMA) by reactive blending in a batch mixer. gPCL basedmaterials were analysed in terms of their grafting degree, structural and thermal properties. Blends basedon starch and PCL (wt. ratio 80:20) with including gPCL (0, 2.5 and 5 wt.%), as a compatibilizer, wereobtained by extrusion and compression moulding, and their structural, thermal, mechanical and bar-rier properties were investigated. Blends containing gPCL evidenced better interfacial adhesion betweenstarch and PCL domains, as deduced from both structural (XRD, FTIR, SEM) and bulk properties (DSC, TGA).Moreover, grafted PCL-based compatibilizers greatly improved functional properties of S-PCL blend films,as pointed out from mechanical performance and higher barrier properties, valuable to meet the foodpackaging requirements., The authors gratefully acknowledge the project MAREA, "Materiali Avanzati per la Ricerca ed il comparto Agroalimentare"-in the frame of National Operative Program (PON 2007-2013) and Ministerio de Economia y Competitividad (Spain) throughout the project AGL2013-42989 for their research financial support. They would like to thank the laboratory of electron microscopy "LaMEST" CNR, in the person of Maria Cristina Del Barone for the kind technical assistance in performing SEM analysis. R. Rodrigo Ortega-Toro thanks the Conselleria de Educacio de la Comunitat Valenciana for the Santiago Grisolia grant (GRISOLIA 2012/001) and to Short-Term Scientific Missions (STSM) from European Cooperation in Science and Technology (COST).

Structural, morphological and thermal properties of films based on poly(butylene succinate) (PBS) and inclusion complex (IC) of beta-cyclodextrins (beta-CD) and D-limonene were studied, in order to prepare novel bio-active food packaging materials. Formation of the inclusion complex was proved by infrared spectroscopy, nuclear magnetic resonance, and X-ray diffraction. The IC contains 7 wt% of D-limonene, as quantified by precipitation, as well as by C-13 NMR and by thermogravimetry. Inclusion within beta-CD cavity stabilizes D-limonene against evaporation, which allows melt compounding with PBS. Infrared spectroscopy of compression molded composite films, evidenced both the D-limonene encapsulation inside beta-CD cages, and the occurrence of interactions between hydroxyl groups of beta-CD-lim complex and the carbonyl groups of PBS units. Optical micrographs showed a phase separated morphology, with homogeneous distribution of the IC within the PBS matrix, probably due to interactions between the polar groups of the composite components. DSC analysis highlighted the anti-nucleating action of beta-CD-lim complex towards PBS, evidenced by a significant delay in crystallization kinetics of PBS. (C) 2016 Elsevier Ltd. All rights reserved.

In this paper we propose an in situ forming ionically cross-linked alginate (Alg) hydrogel delivering a Tea Tree Oil microemulsion (MeTTO) and potentially useful as an advanced dressing for infected wounds. Alg hydrogels were prepared by a spray-by-spray deposition method with the aim to minimize the discomforts during application. From pseudoternary phase diagrams, it was found that proper combination of TTO, water, polysorbate 80 and ethanol gave stable spherical MeTTO with good antimicrobial activity. On this basis, MeTTO at 20% TTO was selected for further inclusion in an Alg hydrogel prepared by alternating sprays of Alg/MeTTO and calcium chloride solutions. Homogeneous dispersion of MeTTO inside cross-linked Alg was assessed by different macroscopic and microscopic methods demonstrating the superior propensity of MeTTO to be integrated in the water-based hydrogel as compared to TTO. Antimicrobial effect of Alg/MeTTO hydrogels on Escherichia Coli strains was remarkable, highlighting the potential of the system as bioactive wound dressing.

A lignin-rich residue (LRR) obtained as a by-product from the fermentative bioethanol production process, and commercial alkali lignin (AL), were used as fillers for the preparation of bio-based blends and composites with poly(3-hydrobutyrate) (PHB). Chemical characterization of LRR demonstrated that the filler contained sugar residues. Rheological and thermal characterization of the blends demonstrated that LRR did not affect thermal stability of PHB, while AL had a strong pro-degrading effect. Addition of suitable amounts of LRR dramatically affected the rheological behavior of the polymer melt, suggesting that the additive can modify polymer processability. LRR was also a heterogeneous nucleating agent, potentially able to control the physical aging of PHB. Lower resilience and elongation at break values were found for the biocomposites, due to the poor interfacial adhesion between filler and matrix. Biodegradation behavior of the composites was qualitatively assessed by analyzing the surface of soil buried films. Significant surface degradation was observed for PHB, while the process was retarded at high filler concentration, as LRR inhibited hydrolytic and biotic polymer degradation. The reported results demonstrated the feasibility of the conversion of an agro-industrial by-product into a bio-resource in an environmentally friendly and cost-effective way. © 2014 Elsevier B.V.

The use of plastic mulching films in horticulture causes the serious drawback of huge amount of wastes to be disposed of at the end of their lifetime. Several pre-competitive research products based on raw materials coming from renewable sources were recently developed to be used as biodegradable materials for soil mulching. Biodegradable materials are designed in order both to retain their mechanical and physical properties during their using time and to degrade at the end of their lifetime. These materials can be integrated directly in the soil in order to biodegrade because the bacterial flora transforms them in carbon dioxide or methane, water and biomass. The innovative materials can be obtained using natural polymers, such as starch, cellulose, chitosan, alginate and glucomannan. Biodegradable extruded mulching films were performed by means of thermo-plasticizing process. Spray mulch coatings were realized directly in field, by spraying water solutions based on natural polysaccharides, thus covering the cultivated soil with a protective thin geo-membrane. In this paper an overview on the formulation development, processing understanding, field performance, mechanical and radiometric properties of these innovative materials for soil mulching is presented. In field the biodegradable mulching films showed suitable mechanical properties if compared to the low density polyethylene films. The radiometric properties and their effect on the temperature condition and on weed control in the mulched soil were evaluated too. At the end of their lifetime the biodegradable materials were shattered and buried into the soil together with plants.

A polyphenol-containing extract from winery bio-waste (EP) has been used as an additive for a starch-based polymer (Mater-Bi). EP was used to tailor Mater-Bi properties, thus avoiding the use of synthetic polymer additives. It was found that EP was able to efficiently modulate the processing, mechanical, thermal and biodegradation properties. The observed decrease in melt viscosity showed that EP could improve productivity in polymer processing. Owing to the plasticizing activity of the additive, larger values of elongation at break were found. Moreover, the Mater-Bi crosslinking, which occurs upon thermal aging, was delayed in the presence of EP. Finally, the bio-disintegration rate of doped Mater-Bi decreased, thus suggesting that EP acted as an antimicrobial agent by interfering with the bio-digestion of the polymer films.

Films of pure sodium alginate and films containing sodium alginate with hydroxyethylcellulose and/or polyglycerol were prepared in order to study their effect on the physical properties. In addition, the films, with different composition, were ionically crosslinked with calcium ions by soaking the films in a solution of calcium chloride. The films containing hydroxyethylcellulose are homogeneous with good mechanical properties. The addition of hydroxyethylcellulose and polyglycerol modifies in a noticeable way some thermal and mechanical parameters, but also the amount of water absorbed in terms of bound water and free water. (C) 2010 Elsevier Ltd. All rights reserved.

A study of the interaction among sodium alginates of different molecular compositions, water and glycerol was carried out, in order to weigh up the influence of different polymeric microstructures on the chemical-physical properties of films obtained by water soluble blends of sodium alginates and increasing amounts of glycerol. Thermal, mechanical and morphological analyses performed on the films confirmed the existence of specific interactions between sodium alginates and glycerol; it was as well demonstrated that only at specific mass ratio between the single polymers and glycerol it is possible to obtain the correct plasticizing effect induced by glycerol.