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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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

New liquid crystalline copolyesters have been synthesized by melt transesterification of poly(ethylene terephthalate), p(ET), with 4-acetoxybenzoic acid (H), and varying proportions of equimolar mixtures of diacetylated 4,4'-dihydroxybiphenyl (B) and terephthalic acid (T). The solidification of the polymerizing mixture due to segregation of a highly aromatic crystalline phase, which limited the available range of compositions when p(ET) was modified with H only, was shown not to take place when moderate amounts of T and B were added to H. The p(ETHB) copolyesters are shown to posses hgih structural homogeneity, even when the content of p(ET) in the starting mixture is a low as 10 mol-%. The thermal properties of the copolyesters can be changed in a fairly wide range by varying the chemical composition. As a result, the properties of the new LCPs can easily be optimized in view of different applications, such as the production of blends with flexible thermoplastics or of glass fiber-reinforced composites.