A simple and efficient strategy was developed for the identification of material devices’ polymers and the extraction of the additives contained within. In this study, the focus is put on the presence of phthalate esters in French medical devices, mainly on diethylhexyl phthalate (DEHP), being reported as toxic, endocrine disruptor plasticisers. Their presence was investigated across seven standard medical devices, especially concerning newborn exposure, and compared with results obtained in similar materials from the past decades. Only traces of DEHP, below the limit of quantification (< 6 ppm) were detected in one of the samples by GC–MS using a standard for identification and quantification. This study shows that phthalates’ presence in medical devices used in French hospitals has been greatly diminished, to the benefit of healthier hospital environments.

Recycling polystyrene on an industrial scale remains challenging. One of the key challenges lies in the formation of nonintentionally added substances (NIAS) arising from polymer manufacturing, polymer or additive degradation, and contaminants. This study aims at investigating the interactions between the polystyrene matrix and five common additives (antioxidants, UV stabilizer, brominated flame retardant, inorganic flame retardant). The main objective is to evaluate the impact of these interactions on NIAS formation and polymer rheological behavior. Our previously developed simple and efficient extraction was used to recover additives, and NIAS and was adapted for the low solubility additive decabromodiphenyl ether, to reach combined extraction efficiency (considering additives and their degradation products) between 81.3 and 100 wt %. Extracts were identified by 1H, 31P nuclear magnetic resonance (NMR), and LC-MS and quantified by LC-MS with limits of quantification (LOQ) as low as 0.21 ng/L. Extended investigation of the rheological behavior showed the impact of processing parameters and presence of additives. Chemical interaction between additives also highly impacted NIAS production, leading to either a decrease (up to 8.5-fold) or an increase (up to 3.5-fold) formation of NIAS. The present work contributes to the better understanding of interactions present during PS processing or recycling, highlighting the challenges linked to polystyrene mechanical recycling and the production of potentially toxic species.

Miscanthus (Miscanthus Andersson) is a perennial grass for which biomaterials market has taken growing interest. Our objective was to evaluate the effect of stem internode position in Miscanthus × giganteus and Miscanthus sinensis and the impact of its anatomy and biochemical composition on internode-based composites' mechanical properties. Stems' bottom and top internodes were sampled for two genotypes of each species in two different years and separately added to a polypropylene matrix, and the mechanical properties of the internode-reinforced composites were measured. Before composite production, the internodes were extensively phenotyped for biochemical composition and anatomy. Stems' bottom and top internode-based composites yielded different modulus (3203 and 2988 MPa, respectively), while tensile strength was similar (36.4 and 36.5 MPa, respectively). Significant genotype × internode interactions occurred for most variables, mainly due to differences among species, since both Miscanthus sinensis clones proved to be more stable than both Miscanthus × giganteus clones for modulus (4% and 10.2%, respectively). Regarding tensile strength, the species showed small but opposite differences between internodes. Tensile strength and modulus were rather close only in the top internodes, where good mechanical properties were associated with the lowest values of vascular bundles number and section area and highest parenchyma tissue, while opposite results were obtained in the bottom ones, only for tensile strength. Miscanthus sinensis species proved to be interesting for the stability improvement of composite mechanical properties. It appears essential for experimental purposes to stratify the sampling by internode in order to be representative of the whole stem.

The paper reports viscosity data for aqueous solutions of hydroxypropyl cellulose (HPC) in the presence of poly(Nvinylpyrrolidone) (PVP) in dilute, semidilute and concentrated regimes. The two polymers are miscible over the entire range of composition. In dilute solution, mixed isolated coils with more extended chain conformation are formed and binary polymer-polymer interactions are favored when a small amount of PVP is added to HPC solutions. The viscosity increases in semidilute and concentrated regimes due to chain entanglements and a pronounced synergistic effect was observed upon the addition of a small amount of PVP to the HPC isotropic solution. The intermolecular hydrogen bonding between the hydroxyl groups of HPC and the carbonyl groups of PVP influences the overall flow behavior.

An efficient one-step extraction method was developed for the recovery of additives and Non-Intentionally Added Substances (NIAS) from polystyrene, performed at room temperature for 2.33 hours, without grinding to avoid fostering the formation of NIAS unrelated to polymer processing. Solvent use (39.2 mL/g) was greatly reduced compared to extraction conditions previously reported. The study of NIAS is analytically challenging but with high importance since their presence is a potential threat to human health and to the environment while reducing plastic potential recyclability. For an understanding of NIAS formation and influence of processing parameters, a systematic approach was taken, using virgin polystyrene mixed with known quantities of standard additives as model materials (Irganox_1076, Tinuvin_326, Irgafos_168). The degradation of one additive was identified by NMR and GC-MS. Precise multiple-point quantification with internal standard was performed by GC-MS, measuring a 5.1 wt% Irgafos_168 degradation, with additives LOD ranging from 0.55-0.95 ppm. Evaluation of analytical challenges, such as matrix effects, was discussed and quantified. This method will help the quality control of virgin and recycled PS materials, including food contact ones, and improve the knowledge of PS processing impact on NIAS formation.

Miscanthus biomass can be used to produce lightweight concrete. However, cell wall polymers leached in the alkaline cementitious medium can disturb cement setting. This is the case for grass lignin and grass arabinoxylan due to their specific alkali solubility. The main objective of this paper was to study the impact of lignin and of arabinoxylan from miscanthus biomass on the hydration of Portland cement and by electrical conductivity. To this end, dioxan lignin (DL) and arabinoxylan (AX) were extracted from miscanthus by methods preserving the main structural specificities of the native polymers. These DL and AX fractions were added to Portland cement (1-5% w/w in cement) and their impact on the electrical conductivity of cement/water mixtures was time-monitored. The novelty of this study lies in using polymers structurally similar to those of miscanthus fibers rather than commercially available ones, such as kraft lignin (KL). The addition of DL or of KL to cement/water mixture differently affected the electrical conductivity, which is most likely assignable to the severe structural degradation of KL during kraft process. The conductivity curves suggested that cement hydration was substantially delayed when DL % in cement was 3% or more while lower values had no impact. The results support the hypothesis that the access of water to cement grains was impeded by the adsorption of ionized lignin entities at their surface. When co-added to the cement (1.6 wt% each), the DL and AX fraction delayed cement hydration more substantially than when the same amounts were separately added. This unexpected synergy suggests that the miscanthus lignin and arabinoxylan polymers form lignin-carbohydrate complexes efficiently adsorbed on cement grains.

Concrete blocks prepared with Portland cement and miscanthus-based aggregates were prepared in order to check if the miscanthus genotype may influence their mechanical properties and to perform an environmental assessment. To produce lightweight, load-bearing concrete blocks using miscanthus stem fragments as aggregates in a single mixing method turned out to be impossible, although trying to optimize the concrete formulation. The results show that genotypes and size of miscanthus fragments controlled the mechanical properties of the final blocks. The lower was the amount of light elements such as leaves and sheath, the better were the mechanical properties of the blocks. When comparing genotypes with the same leaf/stem ratio, it was not possible to see a correlation between the biochemical composition of the stem and the compressive strength of the blocks. A probable explanation is the small variation of biochemical composition between genotypes. Using life cycle analysis tools, miscanthus block were not found to be competitive with conventional alternatives (concrete block and lightweight pumice block) when trying to increase compressive strength above 3 MPa. However, compared to non-load bearing alternatives (light clay brick), blocks integrating miscanthus had a better global environmental performance mainly due to a favorable climate change impact. The present work also points out the risk of decreasing the environmental performances when cultivating the crop on land in competition with food, because of the impacts of indirect consequences of Land Use Change.

Miscanthus ( Miscanthus Andersson) is a perennial grass that is attracting growing interest from the biomaterial industry. Our aim was to compare miscanthus genotypes varying in stem solidness, a measure of degree to which pith fills cavity between the outer walls of the stem, and analyze whether this trait influences the mechanical properties of polypropylene composites reinforced with miscanthus particles. Six contrasting genotypes were chosen from a Miscanthus sinensis population to determine morphological variables, stem solidness, and mechanical properties of polypropylene composites including 30% of milled miscanthus particles of two sizes of 100 < × < 200 μm and 200 < × < 300 μm. Although aboveground biomass of miscanthus was closely related to the aboveground volume of the plant, namely stand volume, a few genotypes showed contrasting aboveground biomass production for similar stand volumes. This generated contrasting ratio between aboveground biomass and stand volume, namely plant‐specific weights, for similar plant volumes. A principal component analysis showed that fully pith‐filled stems, namely solid stems, were explained by a large stand volume and plant‐specific weights as well as small stem cross‐sections. Genotypes showing partially filled stems were taller with larger stem cross‐sections but smaller plant‐specific weights. They revealed high lignin and p ‐coumaric acid contents. Compared to neat‐polypropylene, Young's modulus increased significantly by 139% and 134% and tensile strength by 39% and 36% for genotypes with partially filled stems compared to genotypes with fully pith‐filled stems, respectively. This difference in reinforcing capacity was similar to that of two particle sizes (139% and 134% for Young's modulus, 41% and 34% for tensile strength, respectively). A good tensile strength was obtained with large cross‐stem section, plant height and lignin and p ‐coumaric acid contents. It decreased with plant‐specific weight, hemicellulose and ferulic acid contents. Wider morphological variations in other progenies or Miscanthus species should be explored further using the techniques reported here.

The improvement of cellulosic biomass-polymer composites needs to evaluate what occurs at the biomass-matrix interface during crystallization. Different well-defined maize tissues were obtained by original dry fractionation processes, without chemical treatment. Their morphological features were identified by optical and scanning electron microscopies. For each type of tissue, a small fragment was sandwiched between two films of isotactic polypropylene. The composite was subjected to quiescent isothermal conditions, followed in-situ by polarized optical microscopy. Focus of the heterogeneous nucleation at the surface of maize tissues showed that in all cases, more or less numerous semi-crystalline entities originated from the tissue surface, indicating a moderate nucleating activity. Different crystallization behaviors were observed as a function of the tissue. Growth rates of surface layers were generally higher that the growth rates of bulk spherulites. The differences were small, but significant. They were discussed within the frame of kinetic theory of growth.

The thermal and dynamic mechanical properties of miscanthus stem fragments and differences between genotypes and positions along the stem are studied in relation with their biochemical and structural characteristics. The starting degradation temperature does not correlate to the biochemical composition. However, the first DTG peak temperature is negatively correlated to hemicelluloses content and positively correlated to lignin and pcoumaric contents. A pronounced genotypic effect is evidenced on fragments elastic moduli while limited effect of the position along the stem is found. This is mostly related to ferulic and p-coumaric acid contents of stem fragments for which a strong correlation to elastic moduli is evidenced. Our results highlight that genotypic effect, position along the stem, stem fragment dimensions and mechanical properties of miscanthus stem fragments are strongly interconnected in relation with their respective biochemical and structural characteristics. This opens interesting perspectives for identifying key biological traits that need to be optimized for a better selection of performing miscanthus genotypes targeted to polymer composite applications.

This study was devoted to identifying specific biochemical traits that may be addressed in maize breeding programs for improving lignocellulosic composition for biomass utilization in the composites. To this aim, six maize contrasted genotypes were cultivated, harvested and compared in term of their capability to reinforce a low-density polyethylene (LDPE) matrix. Stem biochemical composition and histological pattern of a given internode were evaluated to determine the traits that impacted the mechanical properties of the maize-LDPE composites. Across genotypes, maize stems with higher concentrations of total cell wall residue, lignin, p-coumaric acids and cellulose in conjunction with lower concentrations of ferulic acids and hemicellulose yielded better composite performances. This strong influence of hydroxycinnamic acids is a new finding. Cellulose is found to be the component dominating the mechanical properties of the fragments since the effects of cell wall residue and cellulose are following the same pattern towards composite properties. Contrary to expectations, the correlations between the histological structure of stems and the mechanical properties of the composites prepared with stem fragments is complex and cannot be interpreted in a simple manner. The two most contrasted genotypes in terms of mechanical performances (Cm484 and F2bm3) have the most contrasted biochemical and histological parameters.

Belowground materials from two miscanthus species were ground into fragments for preparing polyethylene composites. Both species show a lot of similarities in terms of polysaccharides, lignin and cell wall-linked p-coumaric and ferulic acids contents. The structures of polysaccharides and of lignins are markedly different in the miscanthus belowground and aboveground biomass. The non-cellulosic fraction of the samples comprises a high level of xylose, with the arabinose to xylose ratio about twice as high as that observed for analogous stem samples, suggesting that belowground arabinoxylans are more substituted than stem ones. The mechanical properties of the belowground miscanthus-polyethylene composites correlate with several of their compositional traits, with similar trends as for plant stem-polyethylene composites with positive correlations for lignin and p-coumaric acid contents and negative correlations for most non-cellulosic sugars.

Three types of treatments of miscanthus were performed, alkali, silanization and the combination of both. There is a direct inverse relation between the amount of sugar-containing molecules extracted from miscanthus and the mechanical strength of the concrete blocks. The use of alkali treated stems as fillers increased remarkably the strength of the blocks, and this was even higher when the alkali treated fibers were coated with silica, with a compression strength of 11 MPa compared with an initial 2.2 MPa. The use of alkali-treated stems result in a faster cement hydration, compared to untreated ones suggesting that specific sugars or other components released from the alkali-treated plant may favor cement hydration. A remarkable decrease of the cellulose and xylose content is observed for the miscanthus pieces after being soaked in a cement-water-sand mixture, these two molecules being adsorbed on cement particles.

The prediction of the morphology of ternary polymer blends requires a good knowledge of the values of the three interfacial tensions. We selected three polymers, either biobased or biodegradable, polyamide (PA), poly[(butylene adipate)-co-terephthalate] (PBAT) and polylactide (PLA), and we accurately measured their interfacial tensions using the retraction method, varying the molar mass or inverting the phases. The following values of interfacial tension were obtained: (PBAT/PLA) = 3.3 +/- 0.7mNm(-1), (PA/PLA) = 5.6 +/- 0.3mNm(-1) and (PBAT/PA) = 3.0 +/- 0.4mNm(-1). These values were used to calculate the spreading coefficients giving rise to two negative coefficients and one coefficient close to zero. Ternary blends with various compositions, two different levels of viscosity for PBAT and different processing conditions were prepared. There was a very good agreement between the predictions of the spreading theory, when using the values of interfacial tension of the right order of magnitude, and the observed morphologies, whatever the polymer serving as a matrix. When PLA or PBAT was chosen as the matrix, the ternary blend morphology was composed of composite droplets, presenting a partial wetting morphology, dispersed in the polymer matrix. This morphology was observed whatever the composition, the viscosity of the PBAT phase and the processing conditions. A further calculation of the free energy confirmed this morphology. The formation process of this semi-encapsulated morphology was observed during blending. (c) 2018 Society of Chemical Industry