Natural fiber-reinforced thermoplastic composites can be an alternative to mineral fiber-based composites, especially when economic and environment concerns are included under the material selection criteria. In recent years, the literature has shown how lignocellulosic fiber-reinforced composites can be used for a variety of applications. Nonetheless, the impact strength and the water uptake behavior of such materials have been seen as drawbacks. In this work, the impact strength and the water uptake of composites made of polypropylene reinforced with fibers from recycled newspaper have been researched. The results show how the impact strength decreases with the percentage of reinforcement in a similar manner to that of glass fiber-reinforced polypropylene composites as a result of adding a fragile phase to the material. It was found that the water uptake increased with the increasing percentages of lignocellulosic fibers due to the hydrophilic nature of such reinforcements. The diffusion behavior was found to be Fickian. A maleic anhydride was added as a coupling agent in order to increase the strength of the interface between the matrix and the reinforcements. It was found that the presence of such a coupling agent increased the impact strength of the composites and decreased the water uptake. Impact strengths of 21.3 kJ/m³ were obtained for a coupled composite with 30 wt % reinforcement contents, which is a value higher than that obtained for glass fiber-based materials. The obtained composites reinforced with recycled fibers showed competitive impact strength and water uptake behaviors in comparison with materials reinforced with raw lignocellulosic fibers. The article increases the knowledge on newspaper fiber-reinforced polyolefin composite properties, showing the competitiveness of waste-based materials.

Es presenta una revisió històrica del telègraf d'Agustin de Betancourt i se n'analitzen les seves característiques tècniques. Es presenten de manera analítica, numèrica i gràfica algunes de les declaracions fetes sobre el telègraf i se'n corregeixen d'altres. Finalment, se'n fa una reconstrucció detallada utilitzant diferents tècniques avançades de CAD, les quals permeten una visió estàtica i dinàmica precisa de cada una de les seves parts.Postprint (author’s final draft

Stiffness of material is a key parameter that allows the use of material for structural or semi-structural purposes. Besides, lightweight materials are increasingly calling the attention of the industry. Environmental impact is also increasing in its importance. Bio-based materials produced from renewable sources can be good candidates for structural purposes combining lightweight and low environmental impact. Nonetheless, similar mechanical properties of commodities have to be reached with such materials. In this work, composite materials from corn stover fibers as a bio-polyethylene reinforcement were produced and tested. The effect of coupling agents to improve the fiber–matrix interface has been evaluated. It has been found that coupling agent content influenced the stiffness of the materials, increasing the Young’s modulus and the material processability. The best performance was achieved for a 6% of coupling agent, corresponding to 4.61 GPa for 50 w/w% of corn stover fibers. Micromechanics showed the impact of the semi-random orientation of the fibers and the lesser impact of its morphology. It was possible to determine a triangular packing of the composites as a hypothesis for future research.

Glass fibre is the most widely used material for reinforcing thermoplastic matrices presently and its use continues to grow. A significant disadvantage of glass fibre, however, is its impact on the environment, in particular, due to the fact that glass fibre-reinforced composite materials are difficult to recycle. Polyamide 6 is an engineering plastic frequently used as a matrix for high-mechanical performance composites. Producing polyamide monomer requires the use of a large amount of energy and can also pose harmful environmental impacts. Consequently, glass fibre-reinforced Polyamide 6 composites cannot be considered environmentally friendly. In this work, we assessed the performance of a road cycling pedal body consisting of a composite of natural Polyamide 11 reinforced with lignocellulosic fibres from stone-ground wood, as an alternative to the conventional glass fibre-reinforced Polyamide 6 composite (the most common material used for recreational purposes). We developed a 3D model of a pedal with a geometry based on a combination of two existing commercial choices and used it to perform three finite-element tests in order to assess its strength under highly demanding static and cyclic conditions. A supplementary life cycle analysis of the pedal was also performed to determine the ecological impact. Based on the results of the simulation tests, the pedal is considered to be mechanically viable and has a significantly lower environmental impact than fully synthetic composites.

The strength of the interphase between the reinforcements and the matrix has a major role in the mechanical properties of natural fiber reinforced polyolefin composites. The creation of strong interphases is hindered by the hydrophobic and hydrophilic natures of the matrix and the reinforcements, respectively. Adding coupling agents has been a common strategy to solve this problem. Nonetheless, a correct dosage of such coupling agents is important to, on the one hand guarantee strong interphases and high tensile strengths, and on the other hand ensure a full exploitation of the strengthening capabilities of the reinforcements. The paper proposes using topographic profile techniques to represent the effect of reinforcement and coupling agent contents of the strength of the interphase and the exploitation of the reinforcements. This representation allowed identifying the areas that are more or less sensitive to coupling agent content. The research also helped by finding that an excess of coupling agent had less impact than a lack of this component.