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At present just about 30% of the waste plastic collected is efficiently recycled, while the rest is incinerated, disposed in landfills, or can end up in compost and be released in the environment, inducing a very negative effect on safety and health of flora and fauna. Sustainable management of hardly recyclable plastic waste generated by light weight single use packaging and agricultural films can be improved by applying biotechnological approaches, combining microorganisms, new enzymes, earthworms, and insects to work collaboratively, not only to promote the degradation of these plastics but also to obtain, by-products of the biodegradation process to be valorized as fertilizers, functional polysaccharides, etc. In order to develop a feasible process, mapping and characterization of the most diffused agri-food waste plastic were conducted isolating the main types of plastic involved. Plastic waste in agriculture is mainly constituted by polyethylene (PE) both linear low density (LLDPE) and high density (HDPE), polypropylene (PP) and polystyrene (PS), whereas in food packaging polyethylene is still present together with a large presence of polypropylene, polystyrene and polyethylene terephthalate (PET). Combining plastic presence and availability of organisms for their degradability, representative samples of plastics (PE, PET, PS) were selected for analysis of deterioration and potential subsequent biodegradation by enzymes and organisms. To monitor the plastic degradability by enzymes, and larvae, methods for the plastic analysis were set, outlining some differences in virgin and post consumer plastic in particular after use in agriculture, assessing the possibility to monitor the degradability of plastic with time and different treatments, in particular, some evidence of polyethylene degradability from larvae of Tenebrio molitor was observed.

This study focused on the development of a novel biocomposite material formed by a thermoplastic biodegradable polyester, poly(butylene succinate-co-adipate) (PBSA), and a carbonaceous filler as biochar (BC) derived by the pyrolysis of woody biomass waste. Composites with various BC contents (5, 10, 15, and 20 wt.%) were obtained by melt extrusion and investigated in terms of their processability, thermal, rheological, and mechanical properties. In all the composites, BC lowered melt viscosity, behaving as a lubricant, and enhancing composite extrudability and injection moulding at high temperatures up to 20 wt.% of biochar. While the use of biochar did not significantly change composite thermal stability, it increased its stiffness (Young modulus). Differential scanning calorimeter (DSC) revealed the presence of a second crystal phase induced by the filler addition. Furthermore, results suggest that biochar may form a particle network that hinders polymer chain disentanglement, reducing polymer flexibility. A biochar content of 10 wt.% was selected as the best trade-off concentration to improve the composite processability and cost competitiveness without compromising excessively the tensile properties. The findings support the use of biochar as a sustainable renewable filler and pigment for PBSA. Biochar is a suitable candidate to replace more traditional carbon black pigments for the production of biodegradable and inexpensive innovative PBSA composites with potential fertilizing properties to be used in agricultural applications.

Molecular weight distributions are widely used to evaluate the effects of aging or modifiers in bituminous binders. As with polymers, the most common techniques to obtain the distributions can be subdivided into two main groups, depending on whether or not they use a solvent. In the first group, the dimension of the molecules is evaluated in a diluted unperturbed state, while, in the second, the dimension derives from the bulk, where aggregated or interacting molecules may behave as single entities. However, the calibration curves used in the bulk are tuned in order to homogenize the results derived from the two approaches. This sort of contradiction, plus the high number of experimental uncertainties, suggest that the term “apparent” should be used for both distributions. These aspects are well known in the field of polymers but have received less attention in the case of bitumens, which are even more complex. This paper pinpoints the advantages and disadvantages of the two techniques, thus highlighting the most appropriate use. Bulk methods are preferred when evaluating properties that are strictly dependent on the microstructure, such as the level of aging and the effects of additives or modifiers. Diluted methods should be used when the molecular size matters, such as in quantifying the presence of polymers or rejuvenators. Both techniques should be used for comparative studies only.

The δ-method has been developed to estimate molecular weight distributions of bitumens from phase-angle master curves. The method uses a correlation between the cross-over frequency(ωC) and the mol...

Rheology is the most widely used technique to evaluate the performance and aging of bituminous binders. Since there are many available rheological tests, there is also a wide range of aging indexes and it is not easy to choose the most appropriate one, because a single value may hardly be adequate for different properties or operating conditions. In order to generalize the usefulness of an index, a good starting point is deriving it from a set of data, such as the master curves of linear viscoelastic functions. Then, the problem is the quantification of aging in a single numerical value from continuous curves, covering a wide range of frequencies/temperatures. In this work, a summary of the aging indexes derived from the master curves is reported and discussed. The indexes are applied to a bituminous binder either with or without the addition of an organo-modified layered silicate. The apparent molecular weight distributions and relaxation spectra were also calculated from the master curves and used to characterize the effect of aging on the binder properties and structure. In this way, an interesting parallelism was observed between the SARA fractions and the populations derived from a deconvolution analysis of the apparent molecular weight distributions.

Polymer additives are widely used to improve the performance of road bitumens including their resistance to hardening during oxidation, although their oxidative inhibitor effect has not been well documented. This study aims to investigate the effect of laboratory-simulated ageing on the microstructure, and rheological properties of Polymer Modified Bitumens (PMBs) prepared with a Styrene-Butadiene-Styrene (SBS) copolymer and sulphur as a cross-linker. The laboratory ageing was conducted through the Rolling Thin Film Oven (RTFO) and the Pressure Aging Vessel (PAV) procedures. The unaged and aged binders were characterised using the Multiple Stress Creep and Recovery (MSCR) test, Gel Permeation Chromatography (GPC) and fluorescence microscopy. The MSCR test showed that the cross-linked polymer had a higher capability of mitigating the effect of bitumen hardening on the rheological response, while for the PMBs without cross-linking, the polymer effects decreased significantly after RTFOT ageing. The GPC results showed that the aromatics, resins and asphaltenes fractions of the unmodified bitumens shifted towards heavier molecules after one cycle of PAV ageing but showed limited variation with further ageing. Similar behaviour was observed for the uncross-linked polymer binders, while for the cross-linked polymer binder, the behaviour depended on the polymer concentration.

Contracaecum rudolphii (s. l.) is a complex of sibling species of anisakid nematodes having the fish-eating birds belonging to the Family Phalacrocoracidae as final hosts. The great cormorant Phalacrocorax carbo sinensis is parasitized by C. rudolphii A and C. rudolphii B. Adults and L4 specimens of C. rudolphii (s. l.) (N = 3282) were collected in cormorants from brackish and freshwater ecosystems of Central Italy. Third-stage larvae of Contracaecum (N = 882) were obtained from the fish species Dicentrarchus labrax, Anguilla anguilla, Aphanius fasciatus, Atherina boyeri, Leuciscus cephalus, Barbus barbus, and Carassius carassius captured in the same geographical areas of cormorants’ standings. Contracaecum rudolphii A and C. rudolphii B were identified by a multilocus genetic approach: allozymes, sequences analysis of the mtDNA cox2, and ITS region of rDNA gene loci. Differential distribution of the two parasite species was observed in different aquatic environments. Contracaecum rudolphii B outnumbered C. rudolphii A in wintering cormorants from freshwater ecosystems; the opposite trend was found in cormorants from brackish water. Analogously, C. rudolphii A larvae were more prevalent in brackish water fish, while C. rudolphii B larvae were found infecting only freshwater fish. The findings seem to confirm that C. rudolphii A and C. rudolphii B would have a life-cycle adapted to brackish and freshwater environments, respectively. A differential feeding behavior of wintering cormorants, the ecology of the infected fish species, and abiotic factors related to early stages of the parasites are supposed to maintain the distinctiveness of the two parasite species’ life cycles in the two different aquatic ecosystems.

In this study, non-chlorinated solvents such as cyclohexanone (CYC) and three ionic liquids, (ILs) (1-ethyl-3-methylimidazolium dimethylphosphate, [EMIM][DMP], 1-ethyl-3-methylimidazolium diethylphosphate, [EMIM][DEP] and 1-ethyl-3-methylimidazolium methylphosphite, [EMIM][MP]) were tested to extract polyhydroxyalkanoates (PHAs) from the purple non-sulfur photosynthetic bacterium (PNSB) Rhodovulumsulfidophilum DSM-1374. The photosynthetic bacterium was cultured in a new generation photobioreactor with 4 L of working volume using a lactate-rich medium. The extracted PHAs were characterized using a thermogravimetric analysis, differential scanning calorimetry, infrared spectroscopy, proton nuclear magnetic resonance and gel permeation chromatography. The most promising results were obtained with CYC at 125 °C with an extraction time of above 10 min, obtaining extraction yields higher than 95% and a highly pure poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHB-HV) with around 2.7 mol% of hydroxylvalerate (HV). A similar yield and purity were obtained with chloroform (CHL) at 10 °C for 24 h, which was used as the referent solvent Although the three investigated ILs at 60 °C for 4 and 24 h with biomass/IL up to 1/30 (w/w) obtained PHAs strongly contaminated by cellular membrane residues, they were not completely solubilized by the investigated ILs.

The use of rejuvenators (RJ) is critical to increasing the amount of recycled asphalt in new mixtures. However, their usage and classification have not achieved a consistent common practice. One of the properties that lacks a comprehensive investigation is their re-aging tendency. In this work, mineral oil from the automotive industry (MO), a waste domestic cooking vegetable oil (VO), and biodiesel (BD) produced from VO were tested as rejuvenators of a laboratory-aged unmodified binder. Infrared spectroscopy and thermogravimetric analysis were used to gather preliminary information on the single RJs. Then, their compatibility with the aged binder was tested at low and high temperature through contact angle and diffusion tests. Finally, their re-aging tendency was determined by using rheological parameters. The RJs showed adequate compatibility and diffusivity, being the VO slightly better than the others are. All the RJs provided a visible restoration of the initial binder properties. The main differences between the three oils are displayed during the second life cycle of the binder (simulated by aging the rejuvenated binders). In this case, the VO and MO do not provide any relevant concerns, while the BD tendency to evaporate slightly above 120 °C may represent a problem during the production and the paving of the mixture. VO and MO blends showed a good aging resistance and may provide a promising life cycle, with the VO being the recommended RJ.

Glycidyl azide-butadiene block copolymers are potential binders for solid propellants. The azidic part contributes to the overall energy outputs, while the butadiene block improves the mechanical properties. Synthetic strategies proposed in literature are not appropriate for production of large-scale quantities. The mesylation of one homopolymer, followed by reaction with the OH terminal groups of the second is proposed here. The reaction is simple and does not show the drawbacks of the previously suggested alternatives. The block copolymers can be used as “partially” energetic binders. Moreover, they work well as compatibilizer in mechanical blends of the two homopolymers, that otherwise rapidly segregate in two distinct phases.

Cystic fibrosis (CF) is a progressive genetic disease caused by mutations in the gene that produces the CF transmembrane conductance regulator (CFTR) protein. The malfunction of the CFTR protein causes a thick buildup of mucus in the lungs that clogs the airways and traps bacteria, thus leading to infections, extensive lung damage and respiratory failure. Micro-delivery systems are currently being investigated as an efficient way to cross the viscous and complex architecture of the CF mucus. In this study, we produced synthetic and natural microparticles (MPs) based on poly(dl‑lactide‑co‑glycolide) (PLGA) or gellan gum through tailored water/oil emulsion procedures. Morphological and physico-chemical characterizations were carried out on both classes of MPs showing particles having diameters within suitable ranges to reach the CF airways. In vitro biocompatibility tests were also performed on both MPs using a human lung cancer cell line (A549) demonstrating that treatment with MPs induces no cytotoxic effects. Both classes of MPs were loaded with a mucolytic agent (N‑acetyl cysteine, NAC) and their release kinetics evaluated using high performance liquid chromatography (HPLC). The analysis pointed out that the amount of NAC released from MPs resulted in a dose-dependent increment, with a rapid release kinetic to satisfy the requirement for inducing an early mucus degradation. Finally, mucolytic action of NAC-loaded MPs was evaluated in an artificial sputum model through its rheological analysis obtaining the lowest viscosity profile after the addition of drug-loaded MPs. Taken together, gained results allowed us to select suitable MPs as potential drug targeting platforms having a mucolytic action for CF treatment.

Organo-modified nanoclays may improve the fire resistance of polymers and bitumen. However, in some cases the nanoclay determines a reduction in the limiting oxygen index (LOI). In polymers, this effect is attributed to an increase of viscosity that limits the dripping of the molten samples during combustion. However, in the case of bitumen this explanation is not sufficient because the reduction is not always associated to high viscosities. In contrast, the mass losses recorded by thermogravimetry in well-defined temperature regions seems to correlate with LOI. Both viscosity and decomposition kinetic of the binders suggest that the nanoclays establish a high degree of interaction with the bitumen, thus determining a significant re-arrangement of its colloidal structure.

Nanocomposites based on maleated poly(styrene-(ethylene-co-butylene)-styrene) copolymer (SEBSgMA) and organo-modified layered double hydroxide (OLDH) have been formulated with the aim to investigate the effects of interfacial interactions between the grafted maleic anhydride groups of the copolymer and the OLDH nanolayers on the rheological properties of nanocomposites. The spectroscopic analysis indicates the establishment of specific polymer/nanofiller interactions, whose extent has been highlighted through morphological and rheological investigations. Specifically, oscillatory melt rheology and shear relaxation tests have been considered in order to deeply investigate the interfacial bridging interactions. Obtained results highlight that SEBSgMA-based nanocomposites containing a high amount of OLDH show solid-like rheological behavior, quite similar to that of crosslinked polymers, attributable to the formation of a gel-like structure.

Polymer additives are used to improve the properties of road bitumens including their oxidative resistance. However, their usage as anti-oxidative materials remains relatively unclear. This study aims to investigate the changes in the morphology and the rheological response of polymer modified bitumens used in road pavement construction caused by ageing. An elastomer (radial styrene butadiene styrene, SBS) and a plastomer (ethyl vinyl acetate, EVA) polymer were mixed with one base bitumen at three polymer concentrations. The bitumens were RTFO and PAV aged. The morphology of the bitumens was captured by fluorescence microscopy while the rheological properties were measured by means of the multiple stress creep and recovery (MSCR) test. The results show that the morphology of the SBS modified bitumen degrades with ageing as a function of polymer concentration and dispersion, with higher dispersion being more resistant. The morphology of the EVA modified bitumen has a low ageing susceptibility irrespective of polymer concentration. The MSCR response of EVA modified bitumens does not differ from that found for unmodified bitumen, where the hardening produces a decrease in the non-recoverable compliance. In the case of SBS modified bitumen, the degradation of the polymer backbone affects the bitumen hardening as much as the polymer phase dispersed and networked in the bitumen phase. Furthermore, in the case of the elastomer, the average percent recovery is in agreement with the variation of the morphology with ageing. Therefore, the use of the average percent recovery as a valuable rheological index of the integrity of the polymer network can be advocated.

Starting from the eighties, the use of nanoadditives registered an increasing attention in the scientific and patent literature, especially for the case of polymeric nanocomposites. In the last decade, this involved bituminous materials, modified either with nanosized fillers or with polymeric nanocomposites. One of the expected benefits is an increased resistance of the binder to aging. After a short introduction underlining the uncertainties and risks of artefacts in aging tests, a review is given, focusing on the antiaging properties of layered silicates, which are by far the most important nanoadditives for bitumens. Together with layered silicates, other materials such as nanohydrated lime, nanosilica, and layered double hydroxides are mentioned. Preparation and characterization of the binary bitumen/layered silicate and ternary bitumen/layered silicate/polymer systems are described in order to individuate the aspects that influence the antiaging effect. Even if the available literature is quite abundant and unanimously confirms that nanoadditives may improve bitumen durability, there is a lack of studies clarifying the involved mechanisms. As it is for conventional fillers, it seems to be a combination of physical and chemical interactions. Nanoadditives with different chemistries, porosities, and interlayer spacings differently absorb the polar components from the bitumen, thus affecting their predisposition to oxidative aging.

Storage stability is one of the main problems of polymer modified asphalts and the use of elemental sulfur is probably the most effective solution, even if not free from inconveniences. Here ten commercially available vulcanization accelerators were tested as potential alternative to sulfur and added to asphalts modified with SBS. Mixing asphalt and polymer at 180 °C, out of the 10 products two gave performance comparable to sulfur, while some of the other additives became effective only at mixing temperature of 210 °C and a few did not work at all. A qualitative correlation between the thermal stability and the effectiveness of the additives was attempted through the thermogravimetric analysis.

Ethylene copolymers with different polar comonomers, such as vinyl acetate, methyl acrylate, glycidyl methacrylate, and maleic anhydride, were used for the preparation of polymer/clay nanocomposites by statically annealing their mechanical mixtures with different commercial or home-made organically modified montmorillonites containing only one long alkyl tail. The nanostructure of the products was monitored by X-ray diffraction, and the dispersion of the silicate particles within the polymer matrix was qualitatively evaluated through microscopic analyses. The effect of the preparation conditions on the structure and the morphology of the composites was also addressed through the characterization of selected samples with similar composition prepared by melt compounding. In agreement with the findings reported in a previous paper for the composites filled with two-tailed organoclays, intercalation of the copolymer chains within the tighter galleries of the one-tailed clays occurs easily, independent of the application of a mechanical stress. However, the shear-driven break-up of the intercalated clay particles into smaller platelets (exfoliation) seems more hindered. A collapse of the organoclay interlayer spacing was only observed clearly for a commercial one-tailed organoclay – Cloisite® 30B – whereas the same effect was almost negligible for a home-made organoclay with similar structure.

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.

Polymer modified asphalts (PMA) and warm mix asphalts (WMA) are technologies widely adopted in the paving industry. The first one is well established, while the second one is relatively new, but rapidly growing since it guarantees economic and environmental advantages. Until now PMA and WMA have been used disjointedly, but it would be useful to combine them to keep the advantages of both. One of the adopted solutions to obtain a warm effect is the addition of waxes to the asphaltic binder. Therefore, a “warm mix polymer modified asphalt” may be potentially obtained with a ternary asphalt/polymer/wax system. However, the final warm effect and performances of the binder will depend on the interactions between the three components. A preliminary investigation was done by mixing asphalt, styrene-butadiene-styrene block copolymer and a wax chosen among the following three categories: paraffinic, partially oxidized and maleic anhydride functionalized. The morphological and calorimetric analyses and solubility tests allowed identifying different behaviors depending on the wax type, which may preferentially interact either with the asphalt or with the polymer, thus influencing the whole binder structure. With regard to the ternary mixes, it was found that: (i) the paraffinic wax preferentially resides in the polymer-rich phase, and slightly enhances the asphalt-polymer compatibility; (ii) the partially oxidized wax prefers the asphaltene-rich phase and reduces the compatibility; (iii) it is not clear where the functionalized wax is located, but it has a considerable compatibilizing effect and strongly alters the colloidal equilibrium of the asphalt-polymer blend. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

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.

Due to their chemical composition, asphalt binders and mixtures are quite flammable and tend to produce smoke and poisonous gases while burning. Therefore, fire reaction of asphalt pavements is a topic of increasingly interest to improve fire safety in highway tunnels. Different asphalt binders and mastics containing aluminium hydroxide and magnesium hydroxide as inorganic flame retardants (FRs) were analysed through Thermo-Gravimetric Analysis (TGA) and Limiting Oxygen Index (LOI) test. Due to the lack of technical specifications for LOI measurements of asphaltic materials, a specific sample geometry and preparation as well as a testing procedure were developed and applied. The comparison between the two techniques indicated that both thermal stability and flammability are strictly related to asphalt composition. Moreover, the Thermo-Gravimetric test can be preventively used to select the most appropriate FR filler, whose decomposition temperature (together with particle size) is a factor of primary importance. Among the different flame retardants tested, the aluminium hydroxide showed the most important increase in LOI with respect to the unmodified binders. On the contrary, the SBS-modified binder, probably due to the unsaturated nature of the polymeric modifier, showed an increased flammability when compared with the base asphalt binders.

In azidic binders for solid propellants, the N3 functionality is introduced by substitution of a halogen or tosyl group, but recently the mesyl group has been suggested as an alternative. The mesylate group has two advantages, mainly related to its small dimensions and low cost. Poly(glycidyl azide) and poly 3-azidomethyl-3-methyl oxetane were prepared by using both tosylate and mesylate precursors. The azidation kinetics were studied at three different temperatures while keeping all other operating parameters the same. The results confirmed the good potential of the mesylate precursors for the production of azidic binders.

Polymeric binders for solid propellants are usually based on hydroxyl-terminated polybutadiene (HTPB), which does not contribute to the overall energy output. Azidic polyethers represent an interesting alternative but may have poorer mechanical properties. Polybutadiene–polyether copolymers may combine the advantages of both. Four different ether-butadiene-ether triblock copolymers were prepared and azidated starting from halogenated and/or tosylated monomers using HTPB as initiator. The presence of the butadiene block complicates the azidation step and reduces the storage stability of the azidic polymer. Nevertheless, the procedure allows modifying the binder properties by varying the type and lengths of the energetic blocks.

The development of bituminous binders with an intrinsic fuel resistance is required to limit pavement damage and maintenance operations in those areas, such as airport systems and industrial areas and filling stations, where the risk of fuel spilling exists. This paper focuses on the study of the interactions between bitumen and fuel to attain a composition of modified binders with enhanced fuel resistance. Several different modifiers, including polymeric materials, recycled crumb rubber, and synthetic waxes, were added to a base bitumen. All blends were studied with special reference to their chemical composition and subjected to a solubility test consisting of a controlled immersion in kerosene (jet fuel A-1). The results were interpreted on the basis of the compositional characteristics which determine the interactions occurring between bitumen and modifiers. Among the formulations with enhanced fuel resistance, those based on synthetic waxes appeared to be the most interesting ones.

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.

Polymer–clay nanocomposites have been prepared by melt blending of commercial organoclay Cloisite 15A with blends of polyethylenes (PE) and maleic-anhydride-grafted PE (PE/PE-g-MA) with wide range of composition. Three types of PE/PE-g-MA blends with different molecular structure, namely blends of high-density PE (HD) with HD-g-MA (HDMA), blends of low-density PE (LD) with LD-g-MA (LDMA), and blends of linear low-density PE (LL) with LL-g-MA (LLMA) were used. The influence of the molecular structure of the PE matrixes and the compatibility between the blend components on the morphology of the nanocomposites was studied. The thermal properties, microhardness, and transparency of the nanocomposites were investigated. The influence of the degree of exfoliation/intercalation on the materials characteristics is discussed.

Ternary systems, bitumen/ethylene-vinyl acetate (EVA)/organoclay, were prepared by two mixing methods (physical mixing and melt blending) and then studied in small amplitude oscillations, start-up of shear flow and repeated creep and recovery tests. The effect of mixing method and the role of two organoclays on the rheological properties of the studied systems were investigated. Improved thermomechanical properties of bitumen/EVA/organoclay nanocomposites, prepared by melt blending, were demonstrated by the low accumulated strain/compliance in the repeated creep and recovery tests. Structural differences between the studied systems were reflected in the behavior of the dynamic phase angle, specifically in the shape of the derivative of phase angle w.r.t. the reduced frequency. Similarly, the structural differences between the prepared nanocomposites were reflected by the behavior of the stress growth function η+ in the transient experiments. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

The effect of the addition of two different organoclays as a third component in polymer-modified asphalts has been investigated. Ternary mixtures were prepared by adding clay and poly(ethylene-co-vinyl acetate) to the asphalt, either separately, or in the form of a premixed master batch. The performed characterizations allowed the determination of how the two methods of mixing influence the interactions between asphalt and polymer and therefore the final rheological properties. In particular, it was shown that the clay had a compatibilizing effect on asphalt and polymer and that a high compatibility between clay and polymer led to a better dispersion of the polymer in the asphalt, thus influencing the final rheological properties of the studied systems.

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 ® 20A (Cl20A) and Cloisite ® 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. P O LYM . ENG. SCI., 50:1306-1314, 2010. © 2010 Society of Plastics Engineers.

The effect of the addition of clay as a third component in polymer modified asphalts has been investigated. After a preliminary investigation on the binary asphalt/clay and polymer/clay blends, the tertiary blends were prepared by adding the clay and polymer to the asphalt, either separately or in the form of a premixed master batch. Intercalated nanocomposites with comparable interlayer distances and glass transition temperatures were obtained in both cases. However, the results show that the mixing procedure significantly affected the final rheological properties. The master curves built in the linear viscoelastic range and represented in both the frequency and the temperature domains help to visualize and evaluate such differences.

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 50/50 wt/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 conversion at 450 °C and the residue. The study of the non-isothermal degradation kinetics of the neat polymers and their nanocomposites has allowed the determination of the activation energy of degradation, the rate of degradation and the reaction order. The analysis of all parameters has led to the conclusion that in the presence of clay, the thermal stability in nitrogen atmosphere decreases, while the thermal stability in air increases. Moreover, the effect of clay on the degradation behavior of the polymer matrix is more pronounced for the nanocomposites having fully exfoliated structure than that of the nanocomposites containing intercalated clay stacks. The results have been interpreted by the better dispersion of the clay layers in the exfoliated nanocomposites, leading to a better barrier effect for the oxygen flow in air and to an increase in the number of clay catalytic sites in nitrogen.

Ethylene–acrylic acid copolymers (EAAs) and commercial montmorillonite clays organically modified with dimethyldihydrogenatedtallowammonium ions (Cloisite ® 15A and 20A) were used for the synthesis of nanocomposites by melt-compounding, static melting of polymer/clay mixtures and solution-intercalation in order to compare the effectiveness of these procedures and to shed light on the thermodynamics and the kinetics of the intercalation process. The preparation from solution was made by the use of several solvents, such as toluene, xylene, chloroform, etc., which were then removed from the hybrids by precipitation in different non-solvents or by evaporation. Particular attention was paid to the effect of the thermal treatments which are often used when processing the composites prepared from solution. X-ray diffraction (XRD) of the solution-blended composites showed that no intercalation of the EAAs inside the clay galleries can be achieved if solvent removal is made by precipitation in non-solvents or by room-temperature evaporation. On the contrary, intercalation was found to occur very rapidly (in less than 1 min) when both the hybrids prepared from solution and the mechanical blends of powdered components were melted in the absence of shear. Polymer intercalation was also found to occur, though with a lower rate, upon annealing the powder mixtures at temperatures lower than the EAA melting point. Microscopic observations made by polarized optical microscopy, scanning electron microscopy and transmission electron microscopy showed that the clay particles dispersion is appreciably lower for the composites prepared from solution, compared to those produced in the melt under shear flow conditions. The hybrids obtained by static melting of powder mixtures, on the other side, were expectedly found to comprise micron sized clay agglomerates, although intercalation was demonstrated also for these materials by XRD. The structure of the intercalated silicate layers stacks, characterized by an interlayer spacing of 4.0 nm, was shown to be independent of the preparation procedure and to correspond to thermodynamic equilibrium.

Nanocomposites of the organically modified clay Cloisite® 15A (CL15A) dispersed in HDPE‐g‐MA were prepared by melt‐compounding. Microcomposites of the same clay with HDPE were also obtained with similar procedures. The spherulitic morphology of the polymer matrix was evidenced by optical microscopy in thin films, whereas the structure of the up to 2‐mm–thick, compression‐molded samples was investigated by WAXD and SAXS. Preferred orientation of both the clay and the HDPE crystallites were evidenced in the microcomposites and, to a greater extent, in nanocomposites, whereas in HDPE and HDPE‐g‐MA control specimens hardly any anisotropy was detected. The degree of orientation of PE crystals increases with CL15A concentration, but also with clay exfoliation, with lower cooling rates and decreasing sample thickness. The orientation of the clay platelets parallel to the compression‐molded surface appears to be determined by the platelets anisotropy and by shear in the mixing and the compression‐molding procedur...

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.

A model study for the recycling of the interior upholstery plastic parts of end-of-life cars has been carried out by reprocessing the homogenized scraps of an upholstery farm in the presence of different compatibilizer precursors, such as an ethylene-glycidylmethacrylate copolymer (EGMA), a maleic anhydride functionalized thermoplastic elastomer (SEBS-MA), etc. The investigated scraps contained recycled polyethylene (from agricultural uses) and poly(ethylene terephthalate), as the main components, plus minor proportions of polypropylene, polyamide-6, and other additives, including an ethylene copolymer (EC), probably an ethylene-acrylic acid copolymer, which is used to compatibilize the carpets' backing and increase their flexibility. The reactive blending experiments were carried out using a Brabender Plasticorder static mixer and a Brabender twin-screw compounder, and the products were characterized by rheometry, differential scanning calorimetry, scanning electron microscopy, stress–strain measurements, etc. It was shown that EGMA was most effective for the reactive compatibilization of the polyolefin and poly(ethylene terephthalate) components of the scraps. It was also found, however, that the EC contained in the upholstery backing neutralizes in part the functional epoxy groups of EGMA, thus reducing its compatibilizing efficiency. The results suggest that substitution of EC with an inert flexibilizing agent, such as an ethylene-propylene copolymer, and use of small amounts (∼ 5%) of an EGMA compatibilizer, might allow recycling of used upholstery into injection moldable plastic articles. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1716–1728, 2005

Ethylene/acrylic acid copolymers (EAA) with different acrylic acid (AA) contents have been used as compatibilizer precursors (CPs) for blends of two grades of lowdensity polyethylene (LDPE) with polyamide-6 (PA). In the first part of the work, binary blends of the CPs with LDPE and with PA have been studied in order to get an insight into the interactions of the EAA copolymers with the blends components. It has been shown that the CPs form immiscible, yet highly compatible, blends with LDPE. Investigation of the binary CP/PA blends provided evidence that acidolysis reactions occur between the carboxyl groups of the CPs and the amine and amide groups of PA, with formation of CP/PA graft (CP-g-PA) copolymers, although these reactions need relatively long times to go to completion. In the second part of the work, ternary LDPE/PA/CP blends have been prepared and characterized with a number of techniques. It has been shown that the addition of only 1-2 phr of CP into the LDPE/ PA blends is sufficient to enhance interfacial adhesion, to improve the minor phase droplet dispersion and to hinder coalescence. The effectiveness of the investigated CPs increases with an increase of the AA content from 6 to 11 wt.-%. Partial neutralization of the carboxyl groups of EAA with zinc also seems to improve the CP efficiency and this effect is thought to result from an acceleration of the acidolysis reactions responsible for the formation of CP-g-PA copolymers.

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 80/20 w/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, WAXS and microhardness tests. The peculiarities in the new characteristics of the blends investigated have been revealed. The isothermal crystallization rate of both LDPE and PA6 decreases in the presence of the two types of compatibilizers. The crystallization enthalpy only of the LDPE blends is a function of the crystallization temperature. In the presence of the compatibilizer, PA6 or LDPE crystallize into spherulites with dimensions smaller than those of the corresponding neat polymers. The crystallites dimensions and degree of crystallinity do not change in LDPE/compatibilizer blends, while there are strong reductions of the degree of crystallinity and the crystallites dimensions of the components in the PA6/compatibilizer blends if compared to those of the neat polymers. The microhardness values of the PA6/compatibilizer blends are lower than the corresponding additive values, while the microhardness of LDPE/compatibilizer blends corresponds to the additive values. The results have been interpreted by different types of interactions between the functionalized polyethylenes and LDPE or PA6, correspondingly. The results indicate that the compatibilization efficiency of Escor towards PA6 is higher than that of Lotader.