Sara Filippi - Academia.edu (original) (raw)

Papers by Sara Filippi

Advances in Colloid and Interface Science, 2015

During the last decades, the number of vehicles per citizen as well as the traffic speed and load... more During the last decades, the number of vehicles per citizen as well as the traffic speed and load has dramatically increased. This sudden and somehow unplanned overloading has strongly shortened the life of pavements and increased its cost of maintenance and risks to users. In order to limit the deterioration of road networks, it is necessary to improve the quality and performance of pavements, which was achieved through the addition of a polymer to the bituminous binder. Since their introduction, polymer-modified asphalts have gained in importance during the second half of the twentieth century, and they now play a fundamental role in the field of road paving. With high-temperature and high-shear mixing with asphalt, the polymer incorporates asphalt molecules, thereby forming a swallowed network that involves the entire binder and results in a significant improvement of the viscoelastic properties in comparison with those of the unmodified binder. Such a process encounters the well-known difficulties related to the poor solubility of polymers, which limits the number of macromolecules able to not only form such a structure but also maintain it during high-temperature storage in static conditions, which may be necessary before laying the binder. Therefore, polymer-modified asphalts have been the subject of numerous studies aimed to understand and optimize their structure and storage stability, which gradually attracted polymer scientists into this field that was initially explored by civil engineers. The analytical techniques of polymer science have been applied to polymer-modified asphalts, which resulted in a good understanding of their internal structure. Nevertheless, the complexity and variability of asphalt composition rendered it nearly impossible to generalize the results and univocally predict the properties of a given polymer/asphalt pair. The aim of this paper is to review these aspects of polymer-modified asphalts. Together with a brief description of the specification and techniques proposed to quantify the storage stability, state-of-the-art knowledge about the internal structure and morphology of polymer-modified asphalts is presented. Moreover, the chemical, physical, and processing solutions suggested in the scientific and patent literature to improve storage stability are extensively discussed, with particular attention to an emerging class of asphalt binders in which the technologies of polymer-modified asphalts and polymer nanocomposites are combined. These polymer-modified asphalt nanocomposites have been introduced less than ten years ago and still do not meet the requirements of industrial practice, but they may constitute a solution for both the performance and storage requirements.

Polymer, 2002

Blends of low density polyethylene (LDPE) or polyamide 6 (PA6) with two types of functionalized p... more Blends of low density polyethylene (LDPE) or polyamide 6 (PA6) with two types of functionalized polyethylenes compatibilizers, namely: poly(ethylene-co-acrylic acid) (Escor5001 by Exxon) and ethylene–glycidylmethacrylate copolymer (Lotader GMA AX8840) in the LDPE/compatibilizer or PA6/compatibilizer composition 80/20w/w, have been prepared. The morphology, crystal structure, isothermal crystallization behavior and microhardness of the blends have been studied by optical and electron microscopy, DSC,

Journal of the Taiwan Institute of Chemical Engineers, 2013

ABSTRACT Ethylene copolymers with different polar comonomers, such as vinyl acetate, methyl acryl... more ABSTRACT Ethylene copolymers with different polar comonomers, such as vinyl acetate, methyl acrylate, glycidyl methacrylate, and maleic anhydride, have been used to prepare polymer/clay nanocomposites by static annealing of their mechanical mixtures with different organoclays containing two long alkyl tails. The nanostructure of the products and the dispersion of the silicate particles have been monitored by X-ray diffraction and microscopic analyses. The effect of the preparation conditions has also been addressed through the characterization of selected samples with similar composition prepared by melt compounding or solution blending. The results show that intercalation of the copolymer chains occurs rapidly within the galleries of most of the investigated organoclays, independent of whether shear stress is applied to the molten mixtures. Solution blending, though leading to effective and uniform dispersion of clay primary particles within the polymer bulk, resulted unable, without subsequent thermal treatments, to lead to intercalation. However, the micron-sized polymer/clay mixtures prepared from solution change even more rapidly into intercalated nanocomposites upon static melting. Most of the polymer/organoclay couples gave thermodynamically stable intercalated/exfoliated structures. Nevertheless, the highest levels of exfoliation, together with excellent dispersion of the clay particles, have been obtained for the nanocomposites prepared by melt compounding from polymer–clay couples with optimal match of polar characteristics.

Polymer Testing, 2011

Nanocomposites of maleic anhydride-grafted HDPE (HDMA) and the organoclay Cloisite 20A (20A) have... more Nanocomposites of maleic anhydride-grafted HDPE (HDMA) and the organoclay Cloisite 20A (20A) have been prepared by melt-compounding, solution-blending and static annealing of polymer/clay powder mixtures. It has been shown that solution-blending of HDMA with 20A fails to produce intercalated composites. Fast intercalation was observed when solution-blending HDMA/clay composites were annealed. The nanocomposites prepared in the melt under shear were found to possess high levels of exfoliation.The dependence of the crystallization behaviour, microhardness and flammability of the composites on the preparation conditions has been studied by differential scanning calorimetry, microhardness tests and determination of limiting oxygen index. The results have shown that the reduction of the flammability and the microhardness of HDMA/20A nanocomposites prepared by melt compounding and composite annealing are higher than those for composites prepared by solution blending. Moreover, a nucleation effect of the clay on the polymer matrix crystallization for some samples has been observed. The results have been interpreted by different levels of clay dispersion and degree of clay intercalation/exfoliation, achieved during different preparation procedures.

ABSTRACT The study deals with the effectiveness of maleic anhydride grafted styrene-b-ethylene-co... more ABSTRACT The study deals with the effectiveness of maleic anhydride grafted styrene-b-ethylene-co-propylene copolymer (SEPMA) as compatibilizer precursor (CP) for blends of low density polyethylene (LDPE) with polyamide-6 (PA). The CP was produced by grafting MA onto SEP in the melt. The specific interactions between the CP and the blends components have been investigated through characterizations of the binary LDPE/CP and PA/CP blends. The compatibilizing efficiency of the MA-grafted SEP, as revealed by the thermal properties and the morphology of the compatibilized blends, has been shown to be excellent. The morphology, as well as the mechanical properties of the compatibilized with SEPMA 75/25 w/w and 25/75 w/w LDPE/PA6 blends have been compared with those of the blends compatibilized with maleic anhydride functionalized HDPE sample (1-HDPE-g-MA) and with a commercial maleic anhydride grafted styrene-b-(ethylene-co-1-butene)-b-styrene copolymer (SEBSMA1). The results show that the strong compatibilizing efficiency of SEPMA is comparable with that of SEBSMA1, while 1-HDPE-g-MA exhibits a slightly lower activity, particularly for the blends, in which PA is the matrix phase.

Road Materials and Pavement Design, 2013

ABSTRACT This research focuses on the characterisation and evaluation of wax-modified bitumens fo... more ABSTRACT This research focuses on the characterisation and evaluation of wax-modified bitumens for use in warm mix asphalt (WMA). Wax-modified bitumens were produced by addition of different types of wax to a 50/70 unmodified bitumen. Five different waxes were used, including synthetic hydrocarbons Fischer–Tropsch wax, Montan waxes and amidic-functionalised waxes. A basic structural picture of wax-modified bitumens was initially derived from the analysis of the thermal properties and morphological arrangements. The mechanical properties of the binders were then evaluated by rheometry, which indicated that bitumen modification with synthetic and functionalised waxes provides significant alteration in the overall colloidal structure. A comprehensive analysis of linear viscoelastic spectra depicted the existence of a sequence of structural transitions and relative behavioural processes, which deeply alter the behaviour of the original binder at in-service temperatures. All the rheological dynamics were interpreted in the light of the concept of residual crystallinity. The presence of physical networks generated by contiguous microcrystalline segments was finally hypothesised to explain the gel-like behaviour of the materials.

Polymer Testing, 2007

Polymer/organoclay nanocomposites based on an ethylene–acrylic acid copolymer (EAA), a high-densi... more Polymer/organoclay nanocomposites based on an ethylene–acrylic acid copolymer (EAA), a high-density polyethylene (HDPE) grafted with maleic anhydride (HDMA) and HDPE/HDMA blends with 80/20 and 50/50wt/wt composition have been studied by thermogravimetry in nitrogen and air atmospheres. The following parameters have been determined from the thermogravimetric (TG) and differential thermogravimetric (DTG) curves of the samples: T10, T50, Tmax, the degree of

Polymer Testing, 2009

The calorimetric characteristics, the flammability, the thermal stability and the microhardness o... more The calorimetric characteristics, the flammability, the thermal stability and the microhardness of polyethylene high density/clay nanocomposites (HDPE/clay) have been studied by differential scanning calorimetry, thermogravimetry, determination of limiting oxygen index and microhardness tests. The nanocomposites have been compatibilized by ethylene–acrylic acid copolymer (EAA), acrylic acid grafted HDPE (HDAA) and maleic anhydride grafted HDPE (HDMA). The clay was montmorillonite Cloisite 15A.

Polymer Engineering and Science, 2004

ABSTRACT

Polymer Engineering & Science, 2006

The chemical transformations taking place when poly-(ethylene terephthalate) (PET) or poly(ethyle... more The chemical transformations taking place when poly-(ethylene terephthalate) (PET) or poly(ethylene naphthalate) (PEN) are blended in the melt with different low molar mass substances containing hydroxyl, carboxyl, or amine functional groups have been investigated as models of the transreactions, undergone by the polyesters in reactive blending operations. The polyester molecular weight changes caused by the alcoholysis, acidolysis, aminolysis, and esterolysis reactions have been monitored by torque-rheometry, using a Brabender Plasticorder static mixer. The degradation of the polyesters by hydrolysis was also studied, under similar conditions, by the addition of a water-releasing substance (wet polyamide-6), and was shown to occur quite rapidly, although most of the added water was lost by flash vaporization caused by the high temperature of the polyester melt. It has been shown that the rate constants of the reactions leading to breakage of the inner ester bonds of the polyester macromolecules decrease in the following order: aminolysis (with aliphatic amines, either primary and secondary) > alcoholysis (with aliphatic alcohols) Ϸ hydrolysis > acidolysis (with aromatic acids) ≥ acidolysis (with aliphatic acids) Ͼ Ͼ aminolysis (with aromatic amines) > alcoholysis (with phenols) Ͼ Ͼ esterolysis. POLYM. ENG. SCI., 46:139 -152, 2006.

Polymer Engineering & Science, 2010

Morphology, thermal properties, and microhardness of ethylene-glycidyl methacrylate copolymer (EG... more Morphology, thermal properties, and microhardness of ethylene-glycidyl methacrylate copolymer (EGMA)/clay and ethylene-acrylic ester-glycidyl methacrylate terpolymer (EAGMA)/clay nanocomposites with different clay concentrations have been studied. The results have shown that EGMA and EAGMA are highly compatible with the organoclays Cloisite 1 20A (Cl20A) and Cloisite 1 30B (Cl30B). Intercalated structures are formed in the whole range of Cl20A loadings investigated, whereas partial degradation of the Cl30B organoclay was observed. The thermal characteristics and microhardness of EGMA/clay nanocomposites suggest that the filler dispersion deteriorates at high concentration. The concentrated EGMA/Cl20A nanocomposites have been used as masterbatches to prepare ternary high density polyethylene (HDPE)/Cl20A and low density polyethylene (LDPE)/Cl20A nanocomposites. Diffractometric characterization and scanning electron microscopy observations of these materials have shown that the intercalated structure of the starting EGMA/Cl20A masterbatches is preserved after dilution with the polyolefins. The results suggest that the silicate platelets remain localized within the EGMA droplets in the diluted nanocomposites. The latter display improved microhardness, whereas the mechanical properties, including elongation at break, are comparable with those of the neat polyolefins. Considerable enhancement of the flame retardant properties has been observed for the ternary nanocomposites. POLYM.

Polymer Engineering & Science, 2009

LDPE/PA-6 blends (75/25 wt/wt) were added with SEBS-g-MA (S) and/or an organoclay (20A) using dif... more LDPE/PA-6 blends (75/25 wt/wt) were added with SEBS-g-MA (S) and/or an organoclay (20A) using different compounding sequences and the morphology and the properties of the blends or composites were investigated. An XRD study of the nanocomposites with pure polymers showed that 20A is intercalated by LDPE or PA-6 chains, whereas it is exfoliated by S if the clay concentration does not exceed 10 wt%. The SEM investigation showed that both S and 20A behave as efficient emulsifying agents for the LDPE/PA-6 blends. However, their effect on the mechanical properties was found to be opposite: S enhanced toughness but lowered the stiffness, whereas 20A improved the elastic modulus but impaired the impact properties. When used together, these additives failed to have synergistic effects and the blends mechanical properties could not be improved strongly. A possible interpretation for this behavior was suggested, considering that the anhydride groups of S can competitively interact with the amine end groups of PA-6 and with the surface of the silicate layer of 20A. Nevertheless, an optimization of the compounding procedure and the use of appropriate proportions of S and 20A allow the preparation of composites with excellent morphology and a satisfactory balance of stiffness and toughness. FIG. 6. SEM micrographs of the cryofractured surfaces, etched with formic acid of LD/PA blends filled with: (a) no organoclay, (b) 5 phr of 20A, and (c) 10 phr of 20A. FIG. 7. Viscosity curves of LD, PA, and their 75/25 blends without and with different 20A loadings.

Polymer Degradation and Stability, 2011

... Sara Filippi1*, Massimo Paci1, Giovanni Polacco1, Nadka Tzankova Dintcheva2, Pierluigi Magagn... more ... Sara Filippi1*, Massimo Paci1, Giovanni Polacco1, Nadka Tzankova Dintcheva2, Pierluigi Magagnini1 1Dipartimento di Ingegneria Chimica, Chimica Industriale e Scienza dei ... above, was formed into 2 mm thick tablets of 20 mm diameter at room temperature with a Carver press ...

Polymer, 2003

The interfacial tension of the uncompatibilized and compatibilized blends of low density polyethy... more The interfacial tension of the uncompatibilized and compatibilized blends of low density polyethylene (LDPE) and polyamide 6 (PA6) has been measured by the breaking thread method. Different types of compatibilizer precursors have been used: poly(ethylene-co-acrylic acid) (Escor 5001, by Exxon) having 6wt% concentration of acrylic acid; an ethylene-acrylic acid zinc ionomer (Iotek 4200); a triblock copolymer with polystyrene end blocks

Polymer, 2003

The effectiveness of a commercial ethylene-glycidylmethacrylate copolymer (Lotader GMA AX 8840) a... more The effectiveness of a commercial ethylene-glycidylmethacrylate copolymer (Lotader GMA AX 8840) as a compatibilizer precursor (CP) for blends of low density polyethylene (LDPE) with polyamide-6 (PA) has been evaluated by an investigation of the thermal properties and the morphology of binary (LDPE/CP and PA/CP) and ternary (LDPE/PA/CP) blends, as well as by solvent fractionation experiments. It has been demonstrated that the epoxy groups of the CP react quite easily, during melt blending, with both the amine and the carboxyl end groups of PA to give CP-g-PA copolymers, which, depending on the relative amounts of PA and CP, may be partially cross-linked. The composition of the graft copolymers has been approximately determined by gravimetric and calorimetric measurements. The compatibilizing efficiency of the CP employed in this work has been found to be comparable to that of the ethylene -acrylic acid copolymers, and lower than that of a maleic anhydride-functionalized polyethylene, which had been used in previous works. q

Molecular Crystals and Liquid Crystals, 2001

... Cryst and Liq Cryst., 200l, Vol, 372, pp 37 50 © 2001 Taylor and Francis Inc Segregation of L... more ... Cryst and Liq Cryst., 200l, Vol, 372, pp 37 50 © 2001 Taylor and Francis Inc Segregation of Liquid Crystalline Mesophases During the Transesterification of PET with Sebacic Acid, Hydroquinone and 4-Hydroxybenzoic Acid ROSSANA MILIE', LILIA MINKOVA2, SARA FILIPPIl ...

Materials and Structures, 2014

ABSTRACT The present contribution focuses on the modification of a 160/220 bituminous binder with... more ABSTRACT The present contribution focuses on the modification of a 160/220 bituminous binder with clay and polymer/clay nanocomposites. Bitumen/polymer/clay ternary blends were prepared using styrene–butadiene–styrene, ethylene vinyl acetate and ethylene methylacrylate copolymers mixed with an organomodified montmorillonite. Dynamic mechanical analyses were performed in the extended domain of stress, temperature and frequency to analyse the thermorheological behaviour of the blends. The time–temperature superposition principle was applied to shift the experimental data recorded at different temperatures and generate master curves of the linear viscoelastic functions. For all blends, the mechanical response of the system was found to be strongly and intimately influenced by the nanocomposite modification. In some cases, a solid-like behaviour appears and delays the Newtonian transition. Morphological analyses performed with fluorescence microscopy allowed to associate the binder properties with the presence of clay silicates, which alter the colloidal equilibrium of the bitumen and enhances the compatibility between bitumen and polymers. Based on the morphological and rheological results, a structural model of the prepared blends is proposed.

Macromolecular Symposia, 2003

Abstract Two grades of low density polyethylene (LDPE) were blended with polyamide-6 (PA) in the ... more Abstract Two grades of low density polyethylene (LDPE) were blended with polyamide-6 (PA) in the 75/25 and 25/75 wt/wt ratios and shaped into ribbons with a Brabender single screw extruder. An ethylene-acrylic acid copolymer (EAA) was used in the 2 phr ...

Macromolecular Symposia, 2001

Macromolecular Materials and Engineering, 2006

... Full Paper. Organoclay Nanocomposites from Ethylene–Acrylic Acid Copolymers. Sara Filippi 1 ,... more ... Full Paper. Organoclay Nanocomposites from Ethylene–Acrylic Acid Copolymers. Sara Filippi 1 ,; Cristina Marazzato 1 ,; Pierluigi Magagnini 1,* ,; Liliya Minkova 2 ,; Nadka Tzankova Dintcheva 3 ,; Francesco P. La Mantia 3. Article first published online: 26 OCT 2006. ...

Advances in Colloid and Interface Science, 2015

During the last decades, the number of vehicles per citizen as well as the traffic speed and load... more During the last decades, the number of vehicles per citizen as well as the traffic speed and load has dramatically increased. This sudden and somehow unplanned overloading has strongly shortened the life of pavements and increased its cost of maintenance and risks to users. In order to limit the deterioration of road networks, it is necessary to improve the quality and performance of pavements, which was achieved through the addition of a polymer to the bituminous binder. Since their introduction, polymer-modified asphalts have gained in importance during the second half of the twentieth century, and they now play a fundamental role in the field of road paving. With high-temperature and high-shear mixing with asphalt, the polymer incorporates asphalt molecules, thereby forming a swallowed network that involves the entire binder and results in a significant improvement of the viscoelastic properties in comparison with those of the unmodified binder. Such a process encounters the well-known difficulties related to the poor solubility of polymers, which limits the number of macromolecules able to not only form such a structure but also maintain it during high-temperature storage in static conditions, which may be necessary before laying the binder. Therefore, polymer-modified asphalts have been the subject of numerous studies aimed to understand and optimize their structure and storage stability, which gradually attracted polymer scientists into this field that was initially explored by civil engineers. The analytical techniques of polymer science have been applied to polymer-modified asphalts, which resulted in a good understanding of their internal structure. Nevertheless, the complexity and variability of asphalt composition rendered it nearly impossible to generalize the results and univocally predict the properties of a given polymer/asphalt pair. The aim of this paper is to review these aspects of polymer-modified asphalts. Together with a brief description of the specification and techniques proposed to quantify the storage stability, state-of-the-art knowledge about the internal structure and morphology of polymer-modified asphalts is presented. Moreover, the chemical, physical, and processing solutions suggested in the scientific and patent literature to improve storage stability are extensively discussed, with particular attention to an emerging class of asphalt binders in which the technologies of polymer-modified asphalts and polymer nanocomposites are combined. These polymer-modified asphalt nanocomposites have been introduced less than ten years ago and still do not meet the requirements of industrial practice, but they may constitute a solution for both the performance and storage requirements.

Polymer, 2002

Blends of low density polyethylene (LDPE) or polyamide 6 (PA6) with two types of functionalized p... more Blends of low density polyethylene (LDPE) or polyamide 6 (PA6) with two types of functionalized polyethylenes compatibilizers, namely: poly(ethylene-co-acrylic acid) (Escor5001 by Exxon) and ethylene–glycidylmethacrylate copolymer (Lotader GMA AX8840) in the LDPE/compatibilizer or PA6/compatibilizer composition 80/20w/w, have been prepared. The morphology, crystal structure, isothermal crystallization behavior and microhardness of the blends have been studied by optical and electron microscopy, DSC,

Journal of the Taiwan Institute of Chemical Engineers, 2013

ABSTRACT Ethylene copolymers with different polar comonomers, such as vinyl acetate, methyl acryl... more ABSTRACT Ethylene copolymers with different polar comonomers, such as vinyl acetate, methyl acrylate, glycidyl methacrylate, and maleic anhydride, have been used to prepare polymer/clay nanocomposites by static annealing of their mechanical mixtures with different organoclays containing two long alkyl tails. The nanostructure of the products and the dispersion of the silicate particles have been monitored by X-ray diffraction and microscopic analyses. The effect of the preparation conditions has also been addressed through the characterization of selected samples with similar composition prepared by melt compounding or solution blending. The results show that intercalation of the copolymer chains occurs rapidly within the galleries of most of the investigated organoclays, independent of whether shear stress is applied to the molten mixtures. Solution blending, though leading to effective and uniform dispersion of clay primary particles within the polymer bulk, resulted unable, without subsequent thermal treatments, to lead to intercalation. However, the micron-sized polymer/clay mixtures prepared from solution change even more rapidly into intercalated nanocomposites upon static melting. Most of the polymer/organoclay couples gave thermodynamically stable intercalated/exfoliated structures. Nevertheless, the highest levels of exfoliation, together with excellent dispersion of the clay particles, have been obtained for the nanocomposites prepared by melt compounding from polymer–clay couples with optimal match of polar characteristics.

Polymer Testing, 2011

Nanocomposites of maleic anhydride-grafted HDPE (HDMA) and the organoclay Cloisite 20A (20A) have... more Nanocomposites of maleic anhydride-grafted HDPE (HDMA) and the organoclay Cloisite 20A (20A) have been prepared by melt-compounding, solution-blending and static annealing of polymer/clay powder mixtures. It has been shown that solution-blending of HDMA with 20A fails to produce intercalated composites. Fast intercalation was observed when solution-blending HDMA/clay composites were annealed. The nanocomposites prepared in the melt under shear were found to possess high levels of exfoliation.The dependence of the crystallization behaviour, microhardness and flammability of the composites on the preparation conditions has been studied by differential scanning calorimetry, microhardness tests and determination of limiting oxygen index. The results have shown that the reduction of the flammability and the microhardness of HDMA/20A nanocomposites prepared by melt compounding and composite annealing are higher than those for composites prepared by solution blending. Moreover, a nucleation effect of the clay on the polymer matrix crystallization for some samples has been observed. The results have been interpreted by different levels of clay dispersion and degree of clay intercalation/exfoliation, achieved during different preparation procedures.

ABSTRACT The study deals with the effectiveness of maleic anhydride grafted styrene-b-ethylene-co... more ABSTRACT The study deals with the effectiveness of maleic anhydride grafted styrene-b-ethylene-co-propylene copolymer (SEPMA) as compatibilizer precursor (CP) for blends of low density polyethylene (LDPE) with polyamide-6 (PA). The CP was produced by grafting MA onto SEP in the melt. The specific interactions between the CP and the blends components have been investigated through characterizations of the binary LDPE/CP and PA/CP blends. The compatibilizing efficiency of the MA-grafted SEP, as revealed by the thermal properties and the morphology of the compatibilized blends, has been shown to be excellent. The morphology, as well as the mechanical properties of the compatibilized with SEPMA 75/25 w/w and 25/75 w/w LDPE/PA6 blends have been compared with those of the blends compatibilized with maleic anhydride functionalized HDPE sample (1-HDPE-g-MA) and with a commercial maleic anhydride grafted styrene-b-(ethylene-co-1-butene)-b-styrene copolymer (SEBSMA1). The results show that the strong compatibilizing efficiency of SEPMA is comparable with that of SEBSMA1, while 1-HDPE-g-MA exhibits a slightly lower activity, particularly for the blends, in which PA is the matrix phase.

Road Materials and Pavement Design, 2013

ABSTRACT This research focuses on the characterisation and evaluation of wax-modified bitumens fo... more ABSTRACT This research focuses on the characterisation and evaluation of wax-modified bitumens for use in warm mix asphalt (WMA). Wax-modified bitumens were produced by addition of different types of wax to a 50/70 unmodified bitumen. Five different waxes were used, including synthetic hydrocarbons Fischer–Tropsch wax, Montan waxes and amidic-functionalised waxes. A basic structural picture of wax-modified bitumens was initially derived from the analysis of the thermal properties and morphological arrangements. The mechanical properties of the binders were then evaluated by rheometry, which indicated that bitumen modification with synthetic and functionalised waxes provides significant alteration in the overall colloidal structure. A comprehensive analysis of linear viscoelastic spectra depicted the existence of a sequence of structural transitions and relative behavioural processes, which deeply alter the behaviour of the original binder at in-service temperatures. All the rheological dynamics were interpreted in the light of the concept of residual crystallinity. The presence of physical networks generated by contiguous microcrystalline segments was finally hypothesised to explain the gel-like behaviour of the materials.

Polymer Testing, 2007

Polymer/organoclay nanocomposites based on an ethylene–acrylic acid copolymer (EAA), a high-densi... more Polymer/organoclay nanocomposites based on an ethylene–acrylic acid copolymer (EAA), a high-density polyethylene (HDPE) grafted with maleic anhydride (HDMA) and HDPE/HDMA blends with 80/20 and 50/50wt/wt composition have been studied by thermogravimetry in nitrogen and air atmospheres. The following parameters have been determined from the thermogravimetric (TG) and differential thermogravimetric (DTG) curves of the samples: T10, T50, Tmax, the degree of

Polymer Testing, 2009

The calorimetric characteristics, the flammability, the thermal stability and the microhardness o... more The calorimetric characteristics, the flammability, the thermal stability and the microhardness of polyethylene high density/clay nanocomposites (HDPE/clay) have been studied by differential scanning calorimetry, thermogravimetry, determination of limiting oxygen index and microhardness tests. The nanocomposites have been compatibilized by ethylene–acrylic acid copolymer (EAA), acrylic acid grafted HDPE (HDAA) and maleic anhydride grafted HDPE (HDMA). The clay was montmorillonite Cloisite 15A.

Polymer Engineering and Science, 2004

ABSTRACT

Polymer Engineering & Science, 2006

The chemical transformations taking place when poly-(ethylene terephthalate) (PET) or poly(ethyle... more The chemical transformations taking place when poly-(ethylene terephthalate) (PET) or poly(ethylene naphthalate) (PEN) are blended in the melt with different low molar mass substances containing hydroxyl, carboxyl, or amine functional groups have been investigated as models of the transreactions, undergone by the polyesters in reactive blending operations. The polyester molecular weight changes caused by the alcoholysis, acidolysis, aminolysis, and esterolysis reactions have been monitored by torque-rheometry, using a Brabender Plasticorder static mixer. The degradation of the polyesters by hydrolysis was also studied, under similar conditions, by the addition of a water-releasing substance (wet polyamide-6), and was shown to occur quite rapidly, although most of the added water was lost by flash vaporization caused by the high temperature of the polyester melt. It has been shown that the rate constants of the reactions leading to breakage of the inner ester bonds of the polyester macromolecules decrease in the following order: aminolysis (with aliphatic amines, either primary and secondary) > alcoholysis (with aliphatic alcohols) Ϸ hydrolysis > acidolysis (with aromatic acids) ≥ acidolysis (with aliphatic acids) Ͼ Ͼ aminolysis (with aromatic amines) > alcoholysis (with phenols) Ͼ Ͼ esterolysis. POLYM. ENG. SCI., 46:139 -152, 2006.

Polymer Engineering & Science, 2010

Morphology, thermal properties, and microhardness of ethylene-glycidyl methacrylate copolymer (EG... more Morphology, thermal properties, and microhardness of ethylene-glycidyl methacrylate copolymer (EGMA)/clay and ethylene-acrylic ester-glycidyl methacrylate terpolymer (EAGMA)/clay nanocomposites with different clay concentrations have been studied. The results have shown that EGMA and EAGMA are highly compatible with the organoclays Cloisite 1 20A (Cl20A) and Cloisite 1 30B (Cl30B). Intercalated structures are formed in the whole range of Cl20A loadings investigated, whereas partial degradation of the Cl30B organoclay was observed. The thermal characteristics and microhardness of EGMA/clay nanocomposites suggest that the filler dispersion deteriorates at high concentration. The concentrated EGMA/Cl20A nanocomposites have been used as masterbatches to prepare ternary high density polyethylene (HDPE)/Cl20A and low density polyethylene (LDPE)/Cl20A nanocomposites. Diffractometric characterization and scanning electron microscopy observations of these materials have shown that the intercalated structure of the starting EGMA/Cl20A masterbatches is preserved after dilution with the polyolefins. The results suggest that the silicate platelets remain localized within the EGMA droplets in the diluted nanocomposites. The latter display improved microhardness, whereas the mechanical properties, including elongation at break, are comparable with those of the neat polyolefins. Considerable enhancement of the flame retardant properties has been observed for the ternary nanocomposites. POLYM.

Polymer Engineering & Science, 2009

LDPE/PA-6 blends (75/25 wt/wt) were added with SEBS-g-MA (S) and/or an organoclay (20A) using dif... more LDPE/PA-6 blends (75/25 wt/wt) were added with SEBS-g-MA (S) and/or an organoclay (20A) using different compounding sequences and the morphology and the properties of the blends or composites were investigated. An XRD study of the nanocomposites with pure polymers showed that 20A is intercalated by LDPE or PA-6 chains, whereas it is exfoliated by S if the clay concentration does not exceed 10 wt%. The SEM investigation showed that both S and 20A behave as efficient emulsifying agents for the LDPE/PA-6 blends. However, their effect on the mechanical properties was found to be opposite: S enhanced toughness but lowered the stiffness, whereas 20A improved the elastic modulus but impaired the impact properties. When used together, these additives failed to have synergistic effects and the blends mechanical properties could not be improved strongly. A possible interpretation for this behavior was suggested, considering that the anhydride groups of S can competitively interact with the amine end groups of PA-6 and with the surface of the silicate layer of 20A. Nevertheless, an optimization of the compounding procedure and the use of appropriate proportions of S and 20A allow the preparation of composites with excellent morphology and a satisfactory balance of stiffness and toughness. FIG. 6. SEM micrographs of the cryofractured surfaces, etched with formic acid of LD/PA blends filled with: (a) no organoclay, (b) 5 phr of 20A, and (c) 10 phr of 20A. FIG. 7. Viscosity curves of LD, PA, and their 75/25 blends without and with different 20A loadings.

Polymer Degradation and Stability, 2011

... Sara Filippi1*, Massimo Paci1, Giovanni Polacco1, Nadka Tzankova Dintcheva2, Pierluigi Magagn... more ... Sara Filippi1*, Massimo Paci1, Giovanni Polacco1, Nadka Tzankova Dintcheva2, Pierluigi Magagnini1 1Dipartimento di Ingegneria Chimica, Chimica Industriale e Scienza dei ... above, was formed into 2 mm thick tablets of 20 mm diameter at room temperature with a Carver press ...

Polymer, 2003

The interfacial tension of the uncompatibilized and compatibilized blends of low density polyethy... more The interfacial tension of the uncompatibilized and compatibilized blends of low density polyethylene (LDPE) and polyamide 6 (PA6) has been measured by the breaking thread method. Different types of compatibilizer precursors have been used: poly(ethylene-co-acrylic acid) (Escor 5001, by Exxon) having 6wt% concentration of acrylic acid; an ethylene-acrylic acid zinc ionomer (Iotek 4200); a triblock copolymer with polystyrene end blocks

Polymer, 2003

The effectiveness of a commercial ethylene-glycidylmethacrylate copolymer (Lotader GMA AX 8840) a... more The effectiveness of a commercial ethylene-glycidylmethacrylate copolymer (Lotader GMA AX 8840) as a compatibilizer precursor (CP) for blends of low density polyethylene (LDPE) with polyamide-6 (PA) has been evaluated by an investigation of the thermal properties and the morphology of binary (LDPE/CP and PA/CP) and ternary (LDPE/PA/CP) blends, as well as by solvent fractionation experiments. It has been demonstrated that the epoxy groups of the CP react quite easily, during melt blending, with both the amine and the carboxyl end groups of PA to give CP-g-PA copolymers, which, depending on the relative amounts of PA and CP, may be partially cross-linked. The composition of the graft copolymers has been approximately determined by gravimetric and calorimetric measurements. The compatibilizing efficiency of the CP employed in this work has been found to be comparable to that of the ethylene -acrylic acid copolymers, and lower than that of a maleic anhydride-functionalized polyethylene, which had been used in previous works. q

Molecular Crystals and Liquid Crystals, 2001

... Cryst and Liq Cryst., 200l, Vol, 372, pp 37 50 © 2001 Taylor and Francis Inc Segregation of L... more ... Cryst and Liq Cryst., 200l, Vol, 372, pp 37 50 © 2001 Taylor and Francis Inc Segregation of Liquid Crystalline Mesophases During the Transesterification of PET with Sebacic Acid, Hydroquinone and 4-Hydroxybenzoic Acid ROSSANA MILIE', LILIA MINKOVA2, SARA FILIPPIl ...

Materials and Structures, 2014

ABSTRACT The present contribution focuses on the modification of a 160/220 bituminous binder with... more ABSTRACT The present contribution focuses on the modification of a 160/220 bituminous binder with clay and polymer/clay nanocomposites. Bitumen/polymer/clay ternary blends were prepared using styrene–butadiene–styrene, ethylene vinyl acetate and ethylene methylacrylate copolymers mixed with an organomodified montmorillonite. Dynamic mechanical analyses were performed in the extended domain of stress, temperature and frequency to analyse the thermorheological behaviour of the blends. The time–temperature superposition principle was applied to shift the experimental data recorded at different temperatures and generate master curves of the linear viscoelastic functions. For all blends, the mechanical response of the system was found to be strongly and intimately influenced by the nanocomposite modification. In some cases, a solid-like behaviour appears and delays the Newtonian transition. Morphological analyses performed with fluorescence microscopy allowed to associate the binder properties with the presence of clay silicates, which alter the colloidal equilibrium of the bitumen and enhances the compatibility between bitumen and polymers. Based on the morphological and rheological results, a structural model of the prepared blends is proposed.

Macromolecular Symposia, 2003

Abstract Two grades of low density polyethylene (LDPE) were blended with polyamide-6 (PA) in the ... more Abstract Two grades of low density polyethylene (LDPE) were blended with polyamide-6 (PA) in the 75/25 and 25/75 wt/wt ratios and shaped into ribbons with a Brabender single screw extruder. An ethylene-acrylic acid copolymer (EAA) was used in the 2 phr ...

Macromolecular Symposia, 2001

Macromolecular Materials and Engineering, 2006

... Full Paper. Organoclay Nanocomposites from Ethylene–Acrylic Acid Copolymers. Sara Filippi 1 ,... more ... Full Paper. Organoclay Nanocomposites from Ethylene–Acrylic Acid Copolymers. Sara Filippi 1 ,; Cristina Marazzato 1 ,; Pierluigi Magagnini 1,* ,; Liliya Minkova 2 ,; Nadka Tzankova Dintcheva 3 ,; Francesco P. La Mantia 3. Article first published online: 26 OCT 2006. ...