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International audience; As a result of growing environmental consciousness, the issues of sustainability and industrial ecology are guiding the development of the next generation of materials and processes. Renewable resources such as hemp hurds in the field of green polymeric materials with their new range of applications represent an important basis in order to fulfil the ecological objective of creating eco-friendly materials. This work deals with the impact of several chemical treatments of hemp hurds on the properties of hemp–starch composite which is made of 100% of natural resources. Two compositions were manufactured, the first one with untreated hemp hurds in starch matrix and the second one with treated hemp hurds in starch matrix. A set of chemical treatments was performed to solubilize hemicelluloses and lignin seal surrounding the cellulose bundle in the first step and then a coupling agent was used to provide a stable bond between hemp hurds and starch matrix. The influence of the treatments on hemp hurds characteristics was investigated by scanning electron microscopy (SEM), differential thermal analysis (DTA), thermogravimetric analysis (TGA) and attenuated total reflectance spectroscopy (ATR). Moreover, the mechanical properties of green composites were studied and it seems that alkaline treatment followed by silane treatment improves the stiffness of composites according to the results of mechanical properties after treatments.

Biodegradable materials are used in packaging, agriculture, medicine and other areas. In recent years there has been an increase in interest in biodegradable polymers. Two classes of biodegradable polymers can be distinguished: synthetic or natural polymers. There are polymers produced from feedstocks derived either from petroleum resources (non renewable resources) or from biological resources (renewable resources). In general natural polymers offer fewer advantages than synthetic polymers. The following review presents an overview of the different biodegradable polymers that are currently being used and their properties, as well as new developments in their synthesis and applications.

National audience

In this study, polylactide/nanohydroxyapatite (PLA/nHA) composites were produced for fused deposition modelling (FDM), which is an additive manufacturing technology commonly used for prototyping and production applications. First, PLA/nHA composites (0.5%, 1%, 3%, 5 wt.%) were compounded using a twin-screw extruder, subsequently, these were shaped into filaments with a single-screw extruder. Thirdly, specimens for dynamic mechanical analysis (DMA) and tensile testing were FDM printed. Doehlert response surface methodology was applied to optimise the tensile properties of each formulation. A comparison of the mechanical properties of the printed tensile test specimens with injection moulded specimens showed a lower Young's modulus and ultimate strength and a higher storage modulus for the printed samples. Additionally, the same ultimate strength decreased with higher HA content. HA induced nucleation of PLA, but also a reduction of the degradation temperature, as shown by differential scanning calorimetry and thermogravimetric analysis respectively. Oscillatory rheological analysis showed the presence of a Newtonian plateau, followed by a shear thinning behaviour. The first HA addition resulted in a thickening effect, decreasing upon addition of HA, up to a thinning effect at 5 wt.%. In conclusion, this study proves successful printing of PLA/nHA nanocomposites using FDM, which might be promising e.g. for bone tissue engineering.