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[EN] Dielectric Thermal Analysis (DETA) of a series of new thermoset obtained by click chemistry was performed. The new thermosets were obtained by a dual-curing process consisting in a first photochemical thiol-ene, followed by a thermal thiol-epoxy starting from an allyl-terminated hyperbranched poly(ethyleneimine) (HBPEI) and different proportions of diglycidylether of bisphenol A (DGEBA) and the corresponding stoichiometric proportions of pentaerythritol tetrakis (3-mercaptopropionate, PETMP). The dielectric behaviour was obtained experimentally supressing the conductive effects. Two sub-Tg intramolecular non-cooperative gamma and beta relaxations and an intermolecular cooperative alpha-relaxation were detected. The gamma-relaxation was ascribed to the dipole orientation of the terminal thiol groups. Two gamma relaxations gamma(epo) and gamma(ene) were observed, according to the influence of the surroundings. Only thermosets with a content of flexible HBPEI/PETMP domains higher than a 50% w/w showed the gamma(ene) relaxation at lower temperatures and higher frequencies. The beta-relaxation was a non-Johari-Goldstein relaxation, ascribed to the dipole transfer of the linear -CH2-O-(C=O)-CH2-CH2- groups of the thiol constrained in the glassy state. The alpha-relaxation was ascribed to the long-term segmental movements of the thermosets, occurring during the transition from the glassy to the rubbery stage. A synergic effect of reducing the rigidity and compactness of the thermosets by the reduction of aromatic moieties of the DGEBA/PETMP units, and the increase of the flexibility induced by the addition of HBPEI/PETMP units affected the macromolecular movement of the thermosets.

[EN] The aim of this work is to define, develop and evaluate a methodology for an improved and more sustainable management of waste, in particular, agricultural residues, turning them into a new source of energy and added-value products. Specific attention is paid to the use of cotton seed (CS) for energy generation. The recovery of energy was carried out through the pyrolysis of this biomass in a fixed bed reactor. An initial definition of the main physico-chemical and thermal properties of the feed was performed. The design and operational parameters of the reactor were set according to the characteristics of the biomass. The thermo-chemical process of pyrolysis was simulated in the first stage by multi-rate linear non-isothermal thermogravimetric (TGA) experiments using argon (Ar) as carrier gas. The thermogravimetric analysis is a widely used technique to assess the thermal stability and decomposition kinetics of biomass. From the kinetic analysis, valuable parameters related to the thermo-chemical process were obtained, such as the activation energy and the pre-exponential factor, both highly dependent on the temperature of reaction. Furthermore, the composition of the raw material was also provided by thermal studies, through the quantification of the different processes of mass loss observed during the heating process. The results were obtained from the TGA measurements, by applying a kinetic methodology based on the combination of the Friedman, Flynn¿Wall¿Ozawa, Kissinger¿Akahira¿Sunose iso-conversional methods and the use of Master Plots permitted to describe mathematically the thermochemical reactions. These results will help define the further use of CS as feedstock in energy recovery processes.

[EN] A series of bionanocomposite films based on chitosan, reinforced with chitin nanocrystals, were developed, and assessed in terms of dielectric behaviour and conductivity by using an experimental methodology that allows avoiding the conductivity contribution and the exclusion of contact and interfacial polarization effects. The dielectric relaxations at low and high frequency and temperatures were modeled by Havriliak-Negami functions. Below the glass transition temperature (Tg), the gamma and beta relaxations were observed, which were related to intramolecular and non-cooperative segmental movements. At higher temperatures, an intermolecular and cooperative macromolecular movement, related to the glass transition, gave rise to alpha-relaxation. In addition, two over-Tg p(I) and p(II) relaxations were found, which were related to the displacement of dipoles in the disordered structure of bionanocomposites. The addition of chitin nanocrystals did not affect the apparent activation energy Ea of the gamma-relaxation. However, it decreased the Ea of the beta-relaxation and increased the free volume at temperatures in the vicinities of the alpha-relaxation. Finally, the electric conductivity of the bionanocomposites was lower than that of neat chitosan and chitin due to the interaction between the-OH and-NH2 groups that reduced the ionic mobility, along with the increase of free volume, with the subsequent separation of phases.

[EN] A blending strategy of virgin and reprocessed polylactide may be postulated as an alternative to reduce the material cost at industrial level, and as a valorisation route to plastic waste management of production scraps. The performance of blends prepared from virgin polylactide and polylactide mechanically reprocessed up to two cycles (PLA-V/R) was assessed in terms of thermo-oxidative stability, morphology, viscoelasticity and thermal kinetics for energetic valorisation. PLA-V/R blends showed appropriate thermo-oxidative stability. The amorphous nature of polylactide was preserved after blending. The viscoelastic properties showed an increment of the mechanical blend effectiveness, which suggested the feasibility of PLA-V/R blends to be used under similar mechanical conditions to those of virgin PLA goods. Finally, it was shown that the energetic valorisation of PLA-V/R blends would result in a more feasible process, due to the lower required activation energy, thus highlighting the advantages of the energetic demand for the process. In conclusion, PLA-V/R blends showed similar processability, service performance and valorisation routes than virgin PLA and therefore could be relevant in the sustainable circular industry of bioplastics.

[EN] Self-reinforced polymer composites (SRCs) are proposed as a suitable alternative for composite development, based in the combination of a polymeric matrix and a polymeric fibre made of the same polymer. SRCs based in polylactide (PLA) could be fully biodegradable and their valorisation routes could presumably be assimilated to those for neat PEA. In this sense, the aim of this study was to develop new self-reinforced PLA-based composites and ascertain their biodegradability. For this purpose, PLA-based SRCs were obtained through a thermo-compression procedure and their biodegradability corroborated under standard conditions (ISO 20200). Moreover, a deep study of the effect of the different factors involved in the biodegradation of the composites such as the temperature, the water and the compost medium was considered relevant to delimitate the long-term properties and valorisation routes for these materials. The macroscopic and microscopic appearance as well as the thermo-oxidative stability, the thermal properties and the molar mass were evaluated. Although degradation was perceived due to the effect of temperature, the synergistic combination of water and temperature and compost was found to play a key role in the biodegradation of these materials. Overall, these SRCs can be considered as promising candidates, since their end-of-life management options can be guaranteed under standardised composting conditions. (C) 2018 Elsevier Ltd. All rights reserved.

[EN] Monitoring and understanding the in vitro behaviour of polyester based scaffolds both comprising the study of the hydrolytic degradation and the cell seeding viability is essential to ensure the desired functionality, according to a given biomedical purpose. As a model case to compare the performance of techniques to monitor the in vitro behaviour, poly(lactide-co-glycolide) (PLGA) scaffolds were chosen. The in vitro hydrolytic degradation of PLGA scaffolds was carried out in water and phosphate buffered saline (PBS). The evolution of the mass loss, the molar mass, the thermal properties and the surface morphology were monitored. The hydrolytic degradation media was correspondingly evaluated by means of the study of the pH, the amount of acid released and the conductivity. In addition, the in vitro biocompatibility regarding the cell culture viability was studied under physiological conditions. The cellular adhesion, cellular ability to proliferate on the scaffold, the scaffold inflammatory profile and the effect of the scaffold degradation compounds on the cells were assessed. A comparative analysis of the exploited techniques in terms of promptness of identification, depth of knowledge, simplicity of obtaining results and cost of the technique was implemented. The results showed that, depending on the balance between the interest in ascertaining the trigger of degradation or deep into the knowledge of the causes and effects of cell culture viability, an appropriate plan of analysis of the validation of polyester-based scaffolds could be designed.

[EN] The thermal stability and decomposition kinetics of PLA/sisal biocomposites was discussed to evaluate the suitability of their use in energy recovery processes such as pyrolysis and combustion. The influence of the addition of sisal up to 30%wt, the presence of coupling agent, and the atmosphere of operation, i.e. inert or oxidative was discussed by means of multi-rate linear non-isothermal thermogravimetric experiments. All biocomposites showed a mean high heating value of 15 MJ/kg indicating their suitability for energy recovery processes. The thermal requirements of PLA/sisal decomposition were assessed in terms of onset decomposition temperature and apparent activation energy. A minimum of 240 degrees C and 174 kJ mol(-1) in inert environment and 225 degrees C and 190 kJ mol(-1) in oxidative environment ensured the feasibility of the reactions regardless the composition of the PLA/sisal biocomposites. The atmosphere of work lead to a greater amount of residue in case of pyrolysis reactions that would need further treatment whereas an oxidative atmosphere resulted in nearly zero final waste stream. The similar kinetics obtained for all samples regardless the amount of sisal or use of coupling agent eases the operability of energy facilities aimed of turning these biowastes into new fuels.

[EN] Blended nanofibrous scaffolds based on polycaprolactone (PCL) and gelatin (Ge) were successfully prepared. A formic/acetic acid (1:1) mixture was used to dissolve PCL/Ge blends from 100/0 to 20/80 %wt in steps of 10 %wt. The hydrolysis of the PCL diluted in the formic/acetic acid mixture was considered as a method for tailoring the surface morphology and physicochemical features of the nanofibrous PCL/Ge scaffolds as a function of the dissolution time. The fibre diameter remained in the nanoscale range for all the studied scaffolds, which is crucial to mimic the extra-cellular matrix size. The reduction of the intrinsic viscosity, molar mass and hydrodynamic radius found for the PCL molecules as a function of the dissolution time, consequently diminished the entanglement capability of the polymeric chains. Subsequently, the fibre diameter decreased as dissolution time increased, for all the studied compositions. While the crystallinity of the scaffolds with high PCL content increased as a function of the dissolution time, the scaffolds with high percentage of Ge showed the lowest crystallinity degree, which was ascribed to the hindering effect of the Ge diffused among the PCL segments. The wettability increased as a function of the Ge content due to the high hydrophilic behaviour of these molecules. It also increased as a function of the dissolution time, due to the more hydroxyl groups available in PCL segments to interact with water molecules. As a whole, the physicochemical assessment of the electrospun scaffolds revealed an effective tailoring procedure to obtain functionalised PCL/Ge scaffolds with specific properties as a function of the dissolution time before electrospinning.

© 2018 Elsevier Ltd Self-reinforced polymer composites (SRCs) are proposed as a suitable alternative for composite development, based in the combination of a polymeric matrix and a polymeric fibre made of the same polymer. SRCs based in polylactide (PLA) could be fully biodegradable and their valorisation routes could presumably be assimilated to those for neat PLA. In this sense, the aim of this study was to develop new self-reinforced PLA-based composites and ascertain their biodegradability. For this purpose, PLA-based SRCs were obtained through a thermo-compression procedure and their biodegradability corroborated under standard conditions (ISO 20200). Moreover, a deep study of the effect of the different factors involved in the biodegradation of the composites such as the temperature, the water and the compost medium was considered relevant to delimitate the long-term properties and valorisation routes for these materials. The macroscopic and microscopic appearance as well as the thermo-oxidative stability, the thermal properties and the molar mass were evaluated. Although degradation was perceived due to the effect of temperature, the synergistic combination of water and temperature ‒and compost‒ was found to play a key role in the biodegradation of these materials. Overall, these SRCs can be considered as promising candidates, since their end-of-life management options can be guaranteed under standardised composting conditions.

[EN] The hydrolysis of the polycaprolactone (PCL) as a function of the dissolution time in a formic/acetic acid mixture was considered as a method for tailoring the morphology of nanofibrous PCL scaffolds. Hence the aim of this research was to establish a correlation between the dissolution time of the polymer in the acid solvent with the physicochemical properties of the electrospun nanofibrous scaffolds and their further service life behaviour. The physico-chemical properties of the scaffolds were assessed in terms of fibre morphology molar mass and thermal behaviour. A reduction of the molar mass and the lamellar thickness as well as an increase of the crystallinity degree were observed as a function of dissolution time. Bead-free fibres were found after 24 and 48 h of dissolution time with similar diameter distributions. The decrease of the fibre diameter distributions along with the apparition of beads was especially significant for scaffolds prepared after 72 h and 120 h of dissolution time in the acid mixture. The service life of the obtained devices was evaluated by means of in vitro validation under abiotic physiological conditions. All the scaffolds maintained the nanofibrous structure after 100 days of immersion in water and PBS. The molar mass was barely affected and the crystallinity degree and the lamellar thickness increased along immersion preventing scaffolds from degradation. Scaffolds prepared after 24 h and 48 h kept their fibre diameters whereas those prepared after 72 h and 120 h showed a significant reduction. This PCL tailoring procedure to obtain scaffolds that maintain the nanoscaled structure after such long in vitro evaluation will bring new opportunities in the design of long-term biomedical patches. (C) 2016 Elsevier Ltd. All rights reserved.

[EN] The dielectric properties of virgin polylactide (PLA) and its reinforced composites with different weight amounts of sisal fibres were assessed at broad temperature (from - 130 degrees C to 130 degrees C) and frequency ranges (from 10(-2)-10(7) Hz), before and after being subjected to accelerated hydrothermal ageing. The synergetic effects of both the loading of sisal and hydrothermal ageing were analysed by means of dielectric relaxation spectra. The relaxation time functions were evaluated by the Havriliak-Negami model, substracting the ohmic contribution of conductivity. The intramolecular and intermolecular relaxations were respectively analysed by means of Arrhenius and Vogel-Fulcher-Tammann-Hesse thermal activation models. The addition of fibre increased the number of hydrogen bonds, which incremented the dielectric permittivity and mainly hindered the non-cooperative relaxations of the biocomposites by increasing the activation energy. Hydrothermal ageing enhanced the formation of the crystalline phase at the so-called transcrystalline region along sisal. This fact hindered the movement of the amorphous PLA fraction, and consequently decreased the dielectric permittivity and increased the dynamic fragility. (C) 2017 Elsevier Ltd. All rights reserved.

[EN] The eco-design considers the factors to prepare biocomposites under an end-of-life scenario. PLA/sisal biocomposites were obtained from amorphous polylactide and sisal loadings of 10, 20 and 30 wt% with and without coupling agent, and subjected to biodegradation in soil according to standard IS0846. Mass loss, differential scanning calorimetry and size-exclusion chromatography were used for monitoring biodegradation. A statistical factorial analysis based on the molar mass M-n, and crystallinity degree X-c pointed out the relevance and interaction of amount of fibre and use of coupling agent with the time of burial in soil., During the preparation of biocomposites, chain scission provoked a similar reduction of M-n, for coupled and non-coupled biocomposites. The amount of fibre was relevant for the increase of Xc due to the increase of nucleation sites. The coupling agent accelerated the evolution of both factors: reduction of M-n, and the consequent increase of Xc, mainly during biodegradation in soil. Both factors should be balanced to facilitate microbial assimilation of polymer segments, since bacterial digestion is enhanced by chain scission but blocked by the promotion of crystalline fractions. (C) 2017 Elsevier Ltd. All rights reserved.

This is the peer reviewed version of the following article: Santonja-Blasco, L., Rodriguez, Isabelle, Sanchez-Ballester, S., Badia, J.D., MESEGUER RICO, FRANCISCO JAVIER, Ribes-Greus, A.. (2017). Protection of high-density polyethylene-silicon composites from ultraviolet-visible photodegradation.Journal of Applied Polymer Science, 134, 43, 45439-. DOI: 10.1002/app.45439, which has been published in final form at http://doi.org/10.1002/app.45439. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving., [EN] The extent of the ultraviolet¿visible (UV¿vis) photoirradiation effect on high-density polyethylene (HDPE) and HDPE¿sili-con (Si) composites is reported in terms of the addition of Si microparticles at contents of 0.1, 1, and 5 wt %. A standard acceleratedUV-vis exposure was applied over 2750 h, corresponding to 22 months in Florida. Thermogravimetry, differential scanning calorimetry,and Fourier transform infrared spectroscopy were used as reliable techniques for monitoring the quality of the HDPE-Si composites. Theincreasing addition of Si microparticles delayed the photodegradation of the HDPE¿Si composites. Because of their strong light-scattering effects, Si microparticles blocked the degradation of ter tiary carbons of the HDPE backbone and reduced the apparition ofvinyl groups; this prevented the structural impoverishment of HDPE-Si composites. Consequently, variations in the crystallization tem-perature (Tc) and melting temperature (Tm), which were indicators of photodegradation, were not modified. In general, the HDPE-Sicomposite formulation with 5 wt % Si microparticles was useful for protecting the material from photodegradation and, thus, should bean environmentally friendly, reliable alternative UV-vis blocker.

[EN] The long-term properties and end-of-life of polymers are not antagonist issues. They actually are inherently linked by the duality between durability and degradation. The control of the service-todisposal pathway at useful performance, along with low-impact disposal represents an added-value. Therefore, the routes of design, production, and discarding of bio-based polymers must be carefully strategized. In this sense, the combination of proper valorisation techniques, i.e. material, energetic and/ or biological at the most appropriate stage should be targeted. Thus, the consideration of the end-of-life of a material for a specific application, instead of the end-of-life of a material should be the fundamental focus. This review covers the key aspects of lab-scale techniques to infer the potential of performance and valorisation of polymers from renewable resources as a key gear for sustainability.