Editorial: biodegradable materials

This Special Issue “Biodegradable Materials” features research and review papers concerning recent advances on the development, synthesis, testing and characterisation of biomaterials. These biomaterials, derived from natural and renewable sources, offer a potential alternative to existing non-biodegradable materials with application to the food and biomedical industries amongst many others. In this Special Issue, the work is expanded to include the combined use of fillers that can enhance the properties of biomaterials prepared as films. The future application of these biomaterials could have an impact not only at the economic level, but also for the improvement of the environment

Valorisation of local agro-industrial processing waters as growth media for polyhydroxyalkanoates (PHA) production

International audiencePolyhydroxyalkanoates (PHA) are bacterial polyesters usually produced from costly sugars or volatile fatty acids (VFAs). In this work, two processing waters rich in vegetable proteins and reducing sugars, i.e., a mixture of saccharose and stachyose in Leguminous Processing Water (LPW) and a mixture of glucose and fructose in Fruit Processing Water (FPW), were tested as growth medium for PHA production in a two-stage fermentation with a unique marine bacterial species: Halomonas i4786. In preliminary shake flask experiments, it was shown that the two media can effectively support the bacterial growth and the accumulation of PHA (evaluated using Nile Red staining). In batch cultivation mode in a 5-L fermentor, PHA productivities of 1.6 g L−1 and 1.8 g L−1 were further achieved within 72 h, in LPW and FPW respectively. Polymer characterization by Differential Scanning Calorimetry and Steric Exclusion Chromatography indicated that the two substrates led to the biosynthesis of polymers with different chain length, distribution and crystallinity. To summarize, these results show that by-products derived from local agri-food industry can be used as a user-adapted and cost-effective source to produce bio-sourced and biodegradable plastic material

Properties of Biodegradable Poly (butylene adipate-co-terephtalate) and Sodium Caseinate Blends.

International audienceSodium caseinate (NaCAS) was blended with commercially available biodegradable polyester, poly (butylene adipate-co-terephtalate) (PBAT) with the aim to obtain environmentally friendly materials for packaging applications with increased oxygen barrier properties. Mechanical properties (tensile strength, elongation, and Young's modulus) of such blends were determined versus ratio of protein to polyester, plasticizer type and content, and relative humidity conditions. Among the two plasticizers tested, glycerol (Gly) and triethanolamine (TEA), Gly was the most efficient for the improvement of mechanical properties (high strains for low stresses) of PBAT/NaCAS blends. The maximum content of protein in blends to keep interesting mechanical properties was about 30% w/w. At this level, the material still exhibits interesting mechanical properties, that is, maximum tensile strength of 20-25 MPa for elongation at break about 25%. Protein-specific water solubility was determined from a 280-nm absorbance method. PBAT/NaCAS materials exhibit good resistance to water, and NaCAS specific solubility was kept under 7 wt % after 48 h immersion in water even for samples containing 30% w/w NaCAS. The PBAT/NaCAS materials also showed an increase of oxygen barrier properties as NaCAS content increased, leading to materials with oxygen permeability lower than 40,000 cm3 lm m 2 d 1 atm 1, which is half the initial value of PBAT

Synthesis and characterisation of bio-based polyester materials from vegetable oil and short to long chain dicarboxylic acids

International audiencePolyester-​type polymers were efficiently prepd. from broccoli seed oil and several carboxylic diacids. The polyesters were prepd. through a simple two-​step process including oxidn. of the insaturations to oxiranes followed by ring opening with dicarboxylic acids under basic conditions. Eight polymer materials derived from different fatty diacids (from 5 C to 16 C) and an arom. diacid were prepd. and characterised. Rubber-​type crosslinked biobased materials exhibited low Tg values comprised between -​5 and +5 °C depending on the diacid type and length

Morphology and functional properties of commercial polyhydroxyalkanoates: A comprehensive and comparative study

International audiencePHA is a bacterial biopolyester with growing industrial interest but still limited commercial availability. This study was dedicated to the characterization of some industrially mature PHAs, commercially available on an industrial scale. Such investigation was first devoted to the physico-chemical analysis of four grades of PHA provided by three different suppliers in order to determine their respective molar masses. Then, the study of their crystallization behaviour revealed a fast process with a relatively high level of crystallinity. Tensile tests brought information about the ageing effect on the mechanical properties of this fragile material. Finally, the investigations of the oxygen and water vapor barrier properties made in parallel with polypropylene (PP), polyamide 6 (PA6), polystyrene (PS) and polylactide (PLA) provided a good insight on the potential use of PHA for application in food packaging

Shape memory epoxy vitrimers based on waste frying sunflower oil

International audienceThermoset polyesters are prepared from epoxidized waste frying sunflower oil (ESO), commercially available epoxy compounds and glutaric acid. Influence of the nature and concentration of bi- and trifunctionnal epoxy compounds on mechanical properties is studied. Static and dynamic mechanical tests are performed. The molar amount of commercial epoxy compounds used ranges from 20% to 80% regarding the molar amount of ESO. It enables to obtain thermosetting polyesters with glass transition temperatures ranging from 6 degrees C to 102 degrees C, as well as storage modulus ranging from 8 GPa to 14 GPa. 40% of trifunctional epoxy compound and 60% of commercial epoxy compound are found to be the best compromises between bio-based content and mechanical properties. Furthermore, shape memory and vitrimer behavior of those epoxy-acid based networks with 60% of commercial epoxy compounds are evaluated both qualitatively and quantitatively by cyclic thermo-mechanical and stress relaxation tests. Excellent shape memory behavior with fixity ratios above 94% and recovery ratios above 98% is demonstrated. A transesterification catalyst is needed to obtain good vitrimer behavior. Overall, thanks to the previously mentioned properties of those partially biobased thermosets polyesters, industrial applications such as protective coatings, foams and temperature-memory polymer actuators might be considered

Characterization and selection of waste oils for the absorption and biodegradation of VOC of different hydrophobicities

International audienceThe purpose of this study was to test different kinds of industrial waste oils to be implemented as Non-Aqueous-Phase for Volatile Organic Compounds absorption and degradation in a process coupling a packed column and a Two-Phase Partitioning Bioreactor. Engine, hydraulic, transformer and vegetable oils were tested. The VOC targeted were: n-heptane, ethyl acetate, isopropanol, methylisobutylketone, toluene, m-xylene and 1,3,5-trimethylbenzene. Several parameters were determined: volatility, viscosity, VOC partition coefficients and toxicity. Results allowed to conclude that hydraulic, transformer and vegetable oils are technically appropriate for the process. According to availability and cost data of waste oils, hydraulic oil was selected

Studies of a furanoside as antimycobacterial agent loaded into a biodegradable PBAT/sodium caseinate support.

International audienceAn improved synthesis of n-octyl β-D-galactofuranoside was described using micro-wave activation. The resulting alkyl furanoside showed antibacterial activity against Mycobacterium smegmatis, a non-pathogenic model of Mycobacterium tuberculosis. It was further incorporated into a biodegradable PBAT/sodium caseinate polymer. The resulting biomaterial loaded with 5% of the pharmacophore retained the mycobacteriostatic properties and developed a mycobactericidal activity on contact and at the periphery of the film

Resonant mechanical vibration of a polymer PVC film under modulated optical excitation

International audienceThe mechanical response of plasticized thin PVC films under a modulated optical radiation pressure excitation is investigated as a function of the plasticizer content. A resonant behavior with different quality factor depending on the plasticizer content is investigated. The higher the content, the larger the resonant width. A significant thinning of the film is observed, whatever the plasticizer content. The surface tension of the air/solid interface is extracted and shown to hardly vary. The loss factor which is known as the ratio of dissipated energy to stored energy is, on the other hand, dependent on the plasticizer content. In particular, the optical studies reveal that all the energy is always stored at the film interfaces with a dissipation described by the well-known loss factor E\" of the Young’s modulus