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The addition of nanoparticles could allow to upgrade the performances of biopolymers, making them fit to replace petroleum-based plastics. In order to maximize the sustainability benefits of bio-nanocomposites, it is fundamental to opportunely tune their bulk properties by acting on their nanostructure. In particular, in nanocomposite blends the final morphologies are highly dependent on the selective localization of the nanoparticles: mainly inside one of the polymeric phases and/or at the interface.In this work, nanocomposite PBS (polybutylene succinate)/PLA (polylactic acid) blown films were prepared with the aim of optimizing their mechanical and gas barrier properties by profiting from the multiple functions of nanofillers as reinforcements, compatibilizers and morphology-directors. PBS/PLA blends, at a constant polymers’ weight proportion (80/20), were prepared by twin-screw extrusion, adding a constant amount of a lamellar nanosilicate (Cloisite 30B), according to different mixing routes: (i) by first dispersing the nanofillers inside the PLA or PBS phase, followed by the compounding with the other resin; (ii) by direct mixing of all the three components.The nanocomposite systems showed a finer dispersion of the PLA phase compared to the neat PBS/PLA blend. While a good exfoliation degree of the nanosilicate was generally observed for all the hybrid samples, the different blending sequence of the nanofillers significantly affected their preferential localization. In particular, the barrier and mechanical performances of the hybrid film PBS/(PLA + C30B) were most positively affected by the selective localization of the nanoplatelets at PBS/PLA interface, since their compatibilizing action was effectively exploited. In fact, this latter sample exhibited an interesting increase (+ 29%) of the deformation at break and a significant improvement (+ 33%) of the oxygen barrier compared with the neat PBS/PLA blend.

Biodegradable polymers suffer from inherent performance limitations that severely limit their practical application. Their functionalization by coating technology is a promising strategy to significantly improve their physical properties for food packaging. In this study, we investigated the double coating technique to produce multifunctional, high barrier and heat-sealable biodegradable films. The systems consisted of a web layer, made of poly(lactide) (PLA) and poly(butylene-adipate-co-terephthalate) (PBAT), which was first coated with a poly(vinyl) alcohol based layer, providing high barrier, and then with a second layer of PLA + ethylene-bis-stereamide (EBS) wax (from 0 to 20%), to provide sealability and improve moisture resistance. The films were fully characterized in terms of chemical, thermal, morphological, surface and functional properties. The deposition of the PVOH coating alone, with a thickness of 5 μm, led to a decrease in the oxygen transmission rate from 2200 cm3/m2 d bar, for the neat substrate (thickness of 22 μm), to 8.14 cm3/m2 d bar (thickness of 27 μm). The deposition of the second PLA layer did not affect the barrier properties but provided heat sealability, with a maximum bonding strength equal to 6.53 N/25 mm. The EBS wax incorporation into the PLA slightly increased the surface hydrophobicity, since the water contact angle passed from 65.4°, for the neat polylactide layer, to 71° for the 20% wax concentration. With respect to the substrate, the double-coated films exhibited increased stiffness, with an elastic modulus ca. three times higher, and a reduced elongation at break, which, however still remained above 75%. Overall, the developed double-coated films exhibited performances comparable to those of the most common synthetic polymer films used in the packaging industry, underlining their suitability for the packaging of sensitive foods with high O2-barrier requirements.

The emission of off-odors from mechanically recycled plastics severely limits their re-introduction into the market for the production of new objects, for the same use or even for less demanding applications, thus hindering the implementation of an effective circular economy for plastics. The addition of adsorbing agents during the extrusion of polymers represents one of the most promising strategy to reduce the odorous emissions of plastics, due to its characteristics of cost-effectiveness, flexibility and low energy consumption. The novelty of this work lies in the assessment of zeolites as VOC adsorbents during the extrusion of recycled plastics. They appear more suitable than other types of adsorbents, due to their ability to capture and “hold” the adsorbed substances at the high temperatures of the extrusion process. Moreover, the effectiveness of this deodorization strategy was compared with the traditional degassing technique. Two types of mixed polyolefin wastes, coming from completely different collection and recycling processes, were tested: Fil-S (Film-Small), deriving from post-consumer flexible films of small size, and PW (pulper waste), which is the residual plastic waste obtained from the paper recycling process. The melt compounding of the recycled materials with two micrometric zeolites (zeolite 13X and Z310) resulted as more effective in the off-odors removal with respect to degassing. In particular, the highest reduction (−45%) of the Average Odor Intensity (AOI) was measured for both PW/Z310 and Fil-S/13X systems at 4 wt% of the zeolites’ amount, compared with the corresponding untreated recyclates. Finally, by combining degassing and melt compounding with zeolites, the best result was obtained for the composite Fil-S/13X, whose Average Odor Intensity resulted as quite close (+22%) to the one of the virgin LDPE.

At present, the use of benzimidazole drugs in veterinary medicine is strongly limited by both pharmacokinetics and formulative issues. In this research, the possibility of applying an innovative semi-solid extrusion 3D printing process in a co-axial configuration was speculated, with the aim of producing a new gastro-retentive dosage form loaded with ricobendazole. To obtain the drug delivery system (DDS), the ionotropic gelation of alginate in combination with a divalent cation during the extrusion was exploited. Two feeds were optimized in accordance with the printing requirements and the drug chemical properties: the crosslinking ink, i.e., a water ethanol mixture containing CaCl2 at two different ratios 0.05 M and 0.1 M, hydroxyethyl cellulose 2% w/v, Tween 85 0.1% v/v and Ricobendazole 5% w/v; and alginate ink, i.e., a sodium alginate solution at 6% w/v. The characterization of the dried DDS obtained from the extrusion of gels containing different amounts of calcium chloride showed a limited effect on the ink extrudability of the crosslinking agent, which on the contrary strongly influenced the final properties of the DDS, with a difference in the polymeric matrix toughness and resulting effects on floating time and drug release.

Currently, plastic packaging represents a global challenge and has become a key point of attention for governments, media and consumers due to the visibility of the waste it generates. Despite their high resource efficiency, the perceived non-recyclability of polymeric films risks precluding them from being a relevant packaging solution in a circular economy approach. In this regard, the aim of this study was to implement a strategy to try closing the loop, via the mechanical recycling of post-consumer flexible packaging of small size (denoted as Fil-s) to obtain new films. In particular, two lots of Fil-s were used, which are PE/PP blends differing for the PP content and the presence of polar contaminants. The suitability for film blowing extrusion of these recycled materials, as such and after the addition of a compatibilizer and/or a lamellar nanosilicate, was evaluated. It was first evidenced that the difficulty of producing blown films with the pristine recycled materials, due to the frequent bubble breakages, occurring even at low draw ratios. Moreover, the shear and extensional rheological behavior of all Fil-s based systems was usefully correlated with their processability features, evidencing the key roles of the nanofiller to stabilize the bubble and of the compatibilizer to ensure a uniform film deformation, avoiding its premature breakage. Even if the adopted upgrading strategies allowed the production of blown films with both types of Fil-s, the different components of the recycled matrices were proven to significantly affect their processability and final film performances.

Transport, mechanical and global migration data concern multilayer food packaging films with different layouts, all incorporating a layered silicate/polyamide nanocomposite as oxygen barrier layer, and a low-density polyethylene (LDPE) as moisture resistant layer in direct contact with food. The data are related to “Tuning of co-extrusion processing conditions and film layout to optimize the performances of PA/PE multilayer nanocomposite films for food packaging” by Garofalo et al. (2017) [1] . Nanocomposite multilayer films, with different relative layer thicknesses and clay types, were produced using a laboratory scale co-extrusion blown-film equipment and were analyzed in terms of transport to oxygen and water vapor, mechanical properties and overall migration. The results have shown that all the multilayer hybrid films, based on the copolyamide layer filled with Cloisite 30B, displayed the most significant oxygen barrier improvements and the best mechanical properties compared to the unfilled films. No significant alteration of the overall migration values was observed, as expectable [2] , [3] , [4] . The performance improvement was more relevant in the case of the film with the thinner nanocomposite layer.

The aim of this work was to improve the performances of Fil-s (film-small), a recycled material obtained from plastic flexible film waste that is made of polyethylene and a minor amount of polypropylene, with traces of polar contaminants (polyamides, maleic anhydride, etc.). The idea was to upgrade the material&rsquo, s mechanical properties by applying a nanotechnology-based strategy that takes advantage of the composition of Fil-s. In particular, different amounts of copolyamide (CoPA) and its masterbatch with an organic-modified nanosilicate were melt compounded with Fil-s in a twin-screw extruder. The good affinity between Fil-s and CoPA, proved by means of spectroscopic and rheological analysis, allowed for the obtaining of a well-refined morphology for the neat and hybrid blends. This resulted in very interesting increments of the strain at break, which was particularly impressive (10 times higher) in the case of the blend with the lower amount of copolyamide masterbatch, but without sacrificing the stiffness and strength of Fil-s.

The aim of this research was to develop a robust process capable of producing soft-capsules with hydrophilic core for topical administration by means of an inverse gelation. While this method is extensively studied to prepare particles with oily content, its knowledge space in the case of the proposed application is limited. Therefore, a half-fractional factorial design with 5 factors at two levels with resolution V was employed, to meet the scientific requirements in accordance with the Quality by Design approach. Kojic acid, an unstable skin whitening agent, was selected as the active ingredient for its easy detectability. Soft-capsules where produced through a vibrating nozzle device, dripping a thickened calcium chloride solution into an alginate bath. The experimental design applied revealed the effect of several Critical Process Parameters such as the solution's composition, frequency and flow-rate onto Critical Quality Attributes of the produced soft-capsules as for example drug content, encapsulation efficiency, size, shape and mechanical strength. The overall knowledge gained through the DoE exercise showed that the inverse gelation process was capable of producing soft-capsules with the desired attributes, resistant enough to allow handling during storage, but also easily ruptured when applied onto the skin, without leaving residues.

In this work the relationships between system composition, polymer–organoclay interaction, morphology and rheological response, under shear, and elongational flow, of different melt compounded polylactic acid (PLA)/organoclay nanocomposites are investigated, with the aim to properly select the better organoclay for a well-specified PLA grade and processing technology. Polylactide nanocomposites are prepared using two commercial polylactide grades (PLA 4032D and PLA 2003D) and two different organomodified montmorillonites (Cloisite 30B and Nanofil SE3010). FTIR analysis evidences the occurrence of stronger polymer/organoclay interactions for the system PLA4032D1C30B, resulting in a higher clay dispersion and exfoliation levels. Moreover, rheological tests at low shear rates show that, if PLA 2003D is used as polymer matrix (differing from PLA4032D by the presence of a high molecular weight tail), a better dispersed nanomorphology can be obtained with Nanofil SE3010, characterized by a double d-spacing compared to Cloisite 30B, despite the higher polar character of this latter nanofiller. On the other hand, elongational rheological measurements evidence for NSE3010-based hybrids a marked extensional thickening, whilst the stronger polar interactions between the phases in both the polylactide grades filled with C30B, determine increments in elongational viscosity, but inhibit the strain hardening behavior. POLYM. COMPOS., 00:000–000, 2015. V C 2015 Society of Plastics Engineers

In this work it was investigated the possibility to use a low-cost sustainable filler, obtained from municipal solid waste incinerator (MSWI) residues stabilized by COlloidal Silica Medium to Obtain Safe inert (COSMOS) technology, for the development of new eco-friendly PP-based composites. The eco-composites were prepared by melt compounding and tested to verify the effects of the filler addition on the thermal, mechanical and electrical properties of PP. Moreover, in order to check the possible filler capacity to act as adjuvant for conventional flame-retardants, ternary PP composite systems, containing also a commercial non-halogenated flame-retardant in the formulation, were produced and characterized. The obtained results demonstrate that the MSWI residues can be an effective reinforcement for engineering value-added eco-composite materials.

Flexible plastic packagings are rapidly gaining market share since they offer significant functional benefits. However, they also pose a challenge from a recycling perspective. In fact, due to the presence of different polymeric fractions and to contamination by organic substances and out-of-target materials, such as paper and metals, the mechanical properties of the recycled material are relatively poor. Addition of nanoparticles to plastic waste can offer the combinations of improved properties and processing, and reduce operational cost. Moreover, in recent studies it was demonstrated that they can also act as blend compatibilizers. The aim of this study is the upgrading of Fil-s (acronym for film-small), a fraction of mixed plastic waste stream obtained by the separation and mechanical recycling of post-consumer packaging films of small size. Physical, chemical and rheological characterization evidenced that Fil-s stream is mainly composed of polyethylene and a smaller fraction of polypropylene. With the purpose to improve the performances of Fil-s, lamellar and acicular organoclays were melt compounded with the recycled material in a twin-screw extruder. Moreover, in order to enhance the compatibility between the polyolefin components and the nanofiller dispersion in the mixed polymer matrix, the functionalization of Fil-s with maleic anhydride (MAH) was realized by reactive extrusion. Morphological, thermal, rheological and mechanical properties of the functionalized materials and the nanocomposite systems were extensively discussed. The positive effect of the MAH-grafting on the compatibilization between the two polyolefin components of Fil-s was pointed out and an interesting improvement in ductility of Fil-s was obtained. The further addition of the nanoclays also significantly increased the stiffness of the systems.

The aim of this work is to investigate possible solutions to realize antimicrobial-incorporated biodegradable coatings for active food packaging films. At this purpose, the antimicrobial agent (Ethyl-Nα-dodecanoyl-L-arginate, LAE), a cationic surfactant, was added at different percentages to a PLA coating solution, which was spread on a BOPET substrate. Films were characterized in order to obtain information on LAE interaction with the polymer matrix and its effect on thermal stability and functional performance of the films. To assess the films activity and to verify the efficacy of such solutions, microbial tests were carried out using E. Coli CECT 434 strain as pathogenic agent.The aim of this work is to investigate possible solutions to realize antimicrobial-incorporated biodegradable coatings for active food packaging films. At this purpose, the antimicrobial agent (Ethyl-Nα-dodecanoyl-L-arginate, LAE), a cationic surfactant, was added at different percentages to a PLA coating solution, which was spread on a BOPET substrate. Films were characterized in order to obtain information on LAE interaction with the polymer matrix and its effect on thermal stability and functional performance of the films. To assess the films activity and to verify the efficacy of such solutions, microbial tests were carried out using E. Coli CECT 434 strain as pathogenic agent.

This work is a preliminary study about the use of hemp powder as filler in a biopolymer, i.e. polylactic acid (PLA), and the following use of such composites in the 3D printing via FDM technique. In particular, hemp powder (diameter between 75 and 180 µm) was added via melt-compounding into PLA 4043D at three different volume percentages (1, 3 and 5%). Rheological properties of the blends were determined using a rotational rheometer resulting in a decrease of complex viscosity at increasing hemp loading. PLA/hemp filaments (diameter of 2.85 mm) were produced using a single screw extruder. Dynamic mechanical analysis (DMA) on PLA/hemp filaments reported an increase of storage modulus at increasing hemp volume fraction, but compared to the neat PLA filament only the PLA+5%H blend has a higher storage modulus. Finally, filaments were used to print, using a commercial printer (Ultimaker 3, Netherlands), dog-bone specimens for tensile tests. PLA/hemp printed samples exhibited always higher elastic modulus than PLA specimens and it increases at increasing hemp content.This work is a preliminary study about the use of hemp powder as filler in a biopolymer, i.e. polylactic acid (PLA), and the following use of such composites in the 3D printing via FDM technique. In particular, hemp powder (diameter between 75 and 180 µm) was added via melt-compounding into PLA 4043D at three different volume percentages (1, 3 and 5%). Rheological properties of the blends were determined using a rotational rheometer resulting in a decrease of complex viscosity at increasing hemp loading. PLA/hemp filaments (diameter of 2.85 mm) were produced using a single screw extruder. Dynamic mechanical analysis (DMA) on PLA/hemp filaments reported an increase of storage modulus at increasing hemp volume fraction, but compared to the neat PLA filament only the PLA+5%H blend has a higher storage modulus. Finally, filaments were used to print, using a commercial printer (Ultimaker 3, Netherlands), dog-bone specimens for tensile tests. PLA/hemp printed samples exhibited always higher elastic modulus than...

Multilayer films of a conventional linear low-density poly(ethylene/α-octene) (LLDPE) and a metallocene linear low-density poly(ethylene/α-hexene) (mLLDPE) copolymers were produced by cast co-extrusion process. Coextruded films were obtained by varying the position and the relative thicknesses of the two polymers. Mechanical (tensile and impact) tests, permeability, haze and hot tack measurements were carried out on the produced films in order to verify the effect of layer composition and position on the performances of the coextruded samples. Thermal and atomic force microscopy characterizations of the three-layer structures were also performed to correlate the resulting morphology with the film properties. The experiments demonstrated that, at fixed composition, the structures having the mLLDPE copolymer as external layers exhibit generally better mechanical performances and a widening in the sealability temperature window due to a lowering of 5℃ in the seal-initiation temperature, with only a small increase (max 3.5%) in the film haze percentages. The oxygen permeability values do not seem to be significantly affected by the structure composition and layout.

In this work, extensional behavior in non-isothermal and isothermal conditions of copolyamide-based nanocomposites was analyzed and correlated to bubble stability in the film blowing processing of these materials. The higher values of transient extensional viscosity and melt strength of the nanocomposites, compared to the neat matrix, imply that they are able to better resist the extensional external force during bubble formation. Oxygen barrier and mechanical properties of the films were investigated and correlated to the resulting polymer crystal structure and filler morphology. At the higher draw ratios and blow up ratios the nanocomposite specimens were present essentially in the mesomorphic β-form, nevertheless, significant improvements in barrier and mechanical properties of the hybrid films were observed, likely due to a good dispersion and orientation of the silicate platelets in the polymer matrix.

Predictive models, which enable the prediction of nanocomposite properties from their morphologies and account for polymer orientation, could greatly assist the exploitation of this new class of materials in more diversified and demanding market fields. This article focuses on the prediction of effective elastic properties (Young's moduli) of polymer nanocomposite films (copolyamide-6/nanoclay) using 3D analytical (based on the Mori-Tanaka theory) and 3D finite element (FE) models. The analytical model accounts for the orientation of polymer chains induced by drawing. 3D FE model exploits the representative volume element concept and accounts for the nanocomposite morphology as determined from transmission electron microscopy experiments. Model predictions were compared with experimental results obtained for nanocomposite films produced by means a pilot-scale film blowing equipment and collected at different draw ratios. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012

The aim of this work is to investigate the effects of elongational flow on the nanoscale arrangement of the silicate inside polyamide-based nanocomposites. Hybrids, at different loadings of a commercial organoclay, were produced by melt compounding using two polyamide matrices, a nylon-6, and a copolyamide with simi- lar molecular weight and rheological properties. The elongational flow characteriza- tion was performed under both isothermal and nonisothermal conditions by using, respectively, an elongational rheometer (SER) and a fiber-spinning technique. The extensional rheological response of melt-compounded nanocomposites, correlated to TEM and X-ray analyses, was used to probe the nanostructural modifications devel- oped during the uniaxial stretching. The results demonstrated that isothermal and nonisothermal elongational flow can modify the nanomorphology of the nanocompo- site hybrids affecting the degree of silicate exfoliation as well as the extent of silicate orientation upon the stretching direction. The entity of structural modifications induced by the stretching were highly dependent on the initial nanomorphological state and on the polymer-clay affinity. V C 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 981-993, 2009

Copolyamide nanocomposites, based on sepiolite needle-like clay, were prepared through melt extrusion at different silicate loadings. The hybrid materials were characterized in terms of both thermal and rheological properties. A fine dispersion of the nanoparticles was evidenced by the dynamic rheological behavior of the composites. Moreover, the presence of sepiolite does not cause changes in the overall crystallinity degree and crystal structure compared to the neat polymer. The effect of an increasing percentage of nanofiller on the mechanical performances of the nanocomposites was also evaluated. A remarkable combination of high stiffness and toughness, not already found in literature for this kind of nanocomposites, was achieved at the lower silicate amount.

Currently, the growing consumption of polymer products creates large quantities of waste materials resulting in public concern in the environment and people life. The efficient treatment of polymer wastes is still a difficult challenge and the recycling process represents the best way to manage them. Recently, many researchers have tried to develop nanotechnology for polymer recycling. The products prepared through the addition of nanoparticles to post-used plastics could offer the combination of improved properties, low weight, easy of processing and low cost which is not easily and concurrently found by other methods of plastic recycling. In this study materials, obtained by the separation and mechanical recycling of post-consumer packaging films of small size (

The blown extrusion of poly(lactic acid) presents several challenges mainly due to its poor elongation properties. This work deals on the possibility to enhance the processabiliy of PLA by film blowing by functionalizing the polymer with nanosilicates. In particular, two types of polylactic acid (PLA 4032D and PLA 4042D) and different types of filler, selected from montmorillonites (Cloisite 30B) and bentonites (Nanofil SE3010) families, were used to prepare the hybrid systems by using a twin-screw extruder. The interaction between the polymer and the clay was evaluated by FTIR analysis and correlated to the structure of the obtained nanocomposites in terms of clay dispersion. All the samples were then submitted to rheological measurements both in shear and elongational mode.

This work deals on the possibility to improve performances of PLA-based nanocomposite films, for packaging applications, through conveniently tuning materials and processing conditions in melt compounding technology. In particular, two types of polylactic acid and different types of filler selected from montmorillonites and bentonites families were used to prepare the hybrid systems by using a twin-screw extruder. The effect of biaxial drawing on morphology and properties of the nanocomposites, produced by film blowing, was investigated.

The present work focuses on the possibility of conveniently tuning materials in PLA based nanocomposites in order to improve their processability in manufacturing processes where extensional flow is mainly involved. Nanocomposites at a constant silicate loading were produced by melt compounding, using a commercial polylactide grade (PLA 4032D) and two different organo-silicates (Cloisite 30B and Nanofil SE3010). A morphological characterization in solid and molten state, realized by TEM investigations and shear rheological measurements, firstly pointed out the influence of composition on the nanostructure of the hybrid systems. All the samples were then submitted to uniaxial stretching and the rheological response of the different nanocomposites was correlated to the initial nanostructure and the different polymer-clay affinity.

In this work the correlation between the thermoformability of different grades of polylactide acid (PLA 4032D, PLA 4042D and PLA 2003D) and their mechanical, thermal, and rheological properties was explored. In particular, hot tensile tests, at different stretching temperatures and crosshead speeds, were performed in order to identify an optimum windows of temperature and strain rate for improved thermoforming performance. The properties measured from the creep experiments were correlated with the propensity of PLA sheet to sag, while the unrecovered strains by the creep recovery tests were associated to mold replication attitude of the materials investigated.

A phenomenon that can represent a great problem in melt processing is extrudate distortion. This effect can range in intensity from a loss of gloss to gross distortion and is the factor that limits the production rate in certain processes such as the blown film extrusion of linear low-density polyethylene (LLDPE). The aim of this work was to investigate the effects that molecular weight distribution and short-chain branch length have on the observed melt fracture phenomena for poly(ethylene/α-olefin) resins with similar weight comonomer content and molecular weight. The flow stability analysis conducted in this study has shown that, even increasing of few carbon atoms the short-chain branch length of the resins, the surface melt fracture phenomena are reduced and/or eliminated. Moreover, the comparison between the metallocene (mLLDPE) and conventional LLDPE samples, with the same comonomer (hexene), showed that the metallocene-catalyzed resin exhibits early onset and more severe melt fracture, due to its narrower molecular weight distribution. POLYM. ENG. SCI., 52:1968–1977, 2012. © 2012 Society of Plastics Engineers

This work focuses on the possibility of improving performance properties of polylactide films for packaging applications by melt mixing silicate nanoparticles within PLA matrix. Nanocomposites at various silicate loadings were produced by cast‐film extrusion using two different temperature profiles. Oxygen barrier and mechanical properties of the produced films were investigated and correlated to their nanostructure through analytical techniques sensitive to different aspect of the same morphology, such as TEM, XRD and rheological analyses.

The aim of the present study is to correlate the features of the elongational flow-induced morphology to the mechanical properties of polyamide based nanocomposite fibres. Particular attention was paid to modelling the mechanical behaviour of the hybrids which were produced by fibre spinning technique and collected at different draw ratios.Tensile properties of as-spun and stretched fibres were investigated and correlated to their nanostructure through analytical techniques sensitive to different aspects of the hybrids morphology, such as X-Ray diffraction and TEM analysis. In particular, the TEM images of the nanocomposite systems showed intercalated/exfoliated morphology in all hybrids. For this reason, a three-phase Halpin-Tsai model, based on polyamide-6 matrix, exfoliated clay platelets and nanolayer intercalated clusters, was used to fit the experimental data.This method was applied to calculate the Young’s modulus of nanocomposite fibres both as-spun and stretched ones. Moreover, the model was used for predicting the effect of various morphological parameters including the exfoliation degree, clay layer and cluster aspect ratio.

This work focuses on the study of uniaxial elongational flow and its effects on morphology and stiffness of polyamide-6 based nanocomposites prepared by melt compounding. The elongational flow characterization was realized by converging flow method and fiber spinning technique. During the haul-off tests, fibers of the neat polyamide-6 and the hybrids (at 3 and 6 wt% of silicate) were collected at different draw ratios. Mechanical properties of the produced fibers were investigated and correlated to their nanostructure through analytical techniques sensitive to different aspects of morphology, such as DSC and TEM analysis. Rheological results, obtained with a capillary rheometer, indicate that the shear viscosity decreases with the silicate loading, while the extentional viscosity increases. Moreover, the presence of the silicate in polymer matrix leads to enhancements of draw-down force and reduction of the breaking draw ratio. In hybrid fibers an enhanced degree of exfoliation of the filler was observed upon drawing. Moreover, DSC analyses suggest that the crystalline structure of the fibers is the result of two opposite effects: the presence of the silicate which stabilizes the γ form and the drawing which promotes the α crystal phase. The degree of silicate exfoliation and the amount of the different crystal phases strongly affect the tensile properties of the fibers.