Recycled polypropylene composites reinforced with quill from chicken feathers were prepared by extrusion process. Chicken feathers, a worldwide waste without any relevant application, may potentially replace nonrenewable reinforcements in composites. The effects of quill reinforcement on the density, as well as the thermal, thermo-mechanical and morphological properties of the composites, were evaluated. Quill showed an excellent compatibility with the polypropylene matrix, revealed by the good dispersion that was confirmed by the physical appearance observed with aid of scanning electron microscopy. This fact is due to the hydrophobic nature of keratin in quill. All of the composites showed higher storage modulus than simple polymer, particularly for the lowest quill content. In addition, the composite materials also had a lower density. The transition temperature remained almost unaltered compared with polypropylene. However, the thermal stability was observed to be strongly related to the quill content. Thus, this study reports a successful industrial process applied to a new natural reinforcement material: quill, used to synthesize composites with an amply used polymer: polypropylene; which can open an important gate towards the extended exploitation of keratin quill as a novel and renewable reinforcement material.

The use of 2D nanocarbon materials as scaffolds for the functionalization with different molecules has been rising as a result of their outstanding properties. This chapter describes the synthesis of graphene and its derivatives, particularly graphene oxide (GO) and reduced graphene oxide (rGO). Both GO and rGO represent a tunable alternative for applications with biomolecules due to the oxygenated moieties, which allow interactions in a either covalent or non-covalent way. From here, other discussed topics are the biofunctionalization with keratin (KE) and chitosan (CS). The noncovalent functionalization is based primarily on secondary interactions such as van der Waals forces, electrostatics interactions, or π-π stacking formed between KE or CS with graphenic materials. On the other hand, covalent functionalization with KE and CS is mainly based on the reaction among the functional groups present in those biomolecules and the graphenic materials. As a result of the functionalization, different applications have been proposed for these novel materials, which are reviewed in order to offer an overview about the possible fields of application of 2D nanocarbon materials. In a nutshell, the objective of this work is as follows: first, overhaul different aspects about the synthesis of graphene chemically obtained, and second, make a review of different approaches in the functionalization of 2D carbon materials with specific biomolecules.

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Highly functionalized reduced graphene oxide (rGO) sheets, decorated with homogenously distributed titanium dioxide (TiO 2 ) nanoparticles, were obtained by optimizing the conditions of a facile solvothermal synthesis route with methanolwater as solvent. These materials show a Raman enhancement apparently at the rGO/TiO 2 interface. Conventional and High Resolution Transmission Electron microscopy (HRTEM) and X-ray diffraction (XRD) show single crystal TiO 2 NPs below 6 nm with an anatase crystalline phase. Fourier Transform Infrared (FT-IR) spectroscopy shows a significant chemical reduction of the graphene oxide. Thermal analysis also confirms the efficient functionalization and in-situ reduction of the graphene oxide sheets. The results show that under mild conditions, the solvent mixture achieves a higher functionalization than pure solvents.

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