Studies about microplastics in various environments highlighted the ubiquity of anthropogenic fibers. As a follow-up of a recent study that emphasized the presence of man-made fibers in atmospheric fallout, this study is the first one to investigate fibers in indoor and outdoor air. Three different indoor sites were considered: two private apartments and one office. In parallel, the outdoor air was sampled in one site. The deposition rate of the fibers and their concentration in settled dust collected from vacuum cleaner bags were also estimated. Overall, indoor concentrations ranged between 1.0 and 60.0 fibers/m. Outdoor concentrations are significantly lower as they range between 0.3 and 1.5 fibers/m. The deposition rate of the fibers in indoor environments is between 1586 and 11,130 fibers/day/m leading to an accumulation of fibers in settled dust (190-670 fibers/mg). Regarding fiber type, 67% of the analyzed fibers in indoor environments are made of natural material, primarily cellulosic, while the remaining 33% fibers contain petrochemicals with polypropylene being predominant. Such fibers are observed in marine and continental studies dealing with microplastics. The observed fibers are supposedly too large to be inhaled but the exposure may occur through dust ingestion, particularly for young children.

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Synthesis of fully eco-friendly thermosets based on renewable resorcinol diglycidyl ether (RE) hardenered with different biobased diamines having aliphatic, cyclic, or aromatic backbones were prepared. Two diamines were successfully synthesized from d-limonene and allyl-eugenol by thiol–ene addition in the presence of cysteamine hydrochloride to obtain cyclic diamine-limonene (DA-LIM) and aromatic diamine-allyl eugenol (DA-AE), respectively. New thermosets RE/HDMA (hexamethylene diamine), RE/DA-LIM, and RE/DA-AE were further obtained by an epoxy-amine curing process. Thermal stability, flammability, and mechanical properties were investigated by thermogravimetric analysis (TGA), pyrolysis combustion flow calorimeter (PCFC), and dynamic mechanical analysis (DMA), respectively. Although the α transition temperature T α of the cyclic and aromatic biobased thermosets were lower than the one based on HDMA (∼95 °C instead of 110 °C), the flexural moduli were comparable (>2 GPa). Interestingly though, it was observed that their fracture toughness behavior (K IC and G IC) is attractive, as the G IC of the cyclic biobased resin RE/DA-LIM (208 J/m2) is practically two times greater than that of RE/HMDA (90 J/m2). Indeed, the fully biobased thermosets containing cyclic or aromatic diamines offer an outstanding compromise between high stiffness and high fracture toughness properties. In terms of thermal stability, RE/DA-AE exhibits a char yield higher than RE/DA-LIM (21% vs 10%) which could lead to a potential material having better flame retardancy. These results suggested that the aromatic biobased epoxy/amine resin would be well suited for reinforced composite materials and could potentially be used as an alternative to current thermosets.

Poly(hydroxyalkanoates) PHAs are synthesized by many bacteria as inclusion bodies and their biodegradability and structural diversity have been studied with a view to their potential application as biodegradable materials. A method based on FT-IR was developed to carry out rapid qualitative and quantitative analysis of PHAs in Pseudomonas, when they were grown on sodium octanoate. Using absorbance of the ester band of PHAs, a rapid method was reported to distinguish PHB and PHO and to determine polymer content in intact bacteria. Relative areas in which the C=O area was normalized to the area of the peak representing the amid group (1656 cm(-1)) characteristic of bacteria were calibrated to the polymer content which was determined after solvent extraction. Polymer contents vary from 0% to 53% and depend on the nature of the bacteria. Among 27 strains of Pseudomonas belonging to the rRNA homology group I, a very low amount of bacteria were able to produce PHB. The majority of strains were able to produce a copolymer, PHO, in which the major constituent unit is 3-hydroxyoctanoate. The FT-IR results were further confirmed by gas chromatography analysis after methanolysis of polymer, but FT-IR method requires less preparation of sample than gas chromatography and it is very useful for screening a large variety of Pseudomonas.

The graft copolymerization of 2-hydroxyethylmethacrylate (HEMA) onto poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBHV) films has been investigated. The graft copolymerization was conducted in aqueous media using benzoyl peroxide (BPO) as chemical initiator. PHBHV films were prepared by solvent casting. Different parameters affecting the graft yield were studied such as monomer concentration, initiator concentration, and reaction time. The extent of grafting has been modulated by the preparation conditions, in particular the concentration of HEMA. However, it is interesting to note that the initiator concentration had only a slight influence on the graft yield. Characterization of the grafted PHBHV films assumed that the graft copolymerization not only occurred on the film surface but also took place into the film bulk. Differential scanning calorimetry showed that crystallinity dramatically decreased with increasing graft yield, indicating that graft copolymerization hindered the crystallization process. Wettability has been obviously improved by grafting a hydrophilic monomer such as HEMA for high graft yield (>130%).