Browsing by Keyword "Ageing"
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Item Ageing, disability and technology(2007) Azkoitia, Jose Miguel; Eizmendi, Gorka; Azkoitia, Jose Miguel; Craddock, Gerald; Tecnalia Research & InnovationPopulation ageing is one of the main problems of the advanced countries, which are defining tools to face the challenges derived from it. Technology development is opening new market opportunities and is presenting its candidature as one of the key tools to face consequences derived from this evolution. This paper presents FIK project as an example of this approach and as an initiative aiming to transform this challenge into an economic opportunity.Item Effect of different thermal treatments on the mechanical performance of poly(L-lactic acid) based eco-composites(2010-04-15) Dobreva, T.; Benavente, R.; Pereña, J. M.; Pérez, E.; Avella, M.; García, M.; Bogoeva-Gaceva, G.; Tecnalia Research & InnovationPLLA-based eco-composites reinforced with kenaf fiber and rice straw and containing red or yellow pigments have been studied. The mechanical behavior of the composites was tested by DMTA at two different annealing temperatures (65°C and 85°C) and times (15 min and 120 min) as well as at two preparation conditions: vacuum drying and long time at room temperature. A decrease of microhardness was observed during the water absorption tests. Moreover, the rice straw-based composites absorbed more water than the kenaf-ones. Generally, the dyed NFs composites presented better water resistance than undyed ones. The pigments improved the adhesion and led to better mechanical performance. The natural fibers favored the cold crystallization process of PLLA and shifted the cold crystallization peak temperature to lower values, as it was confirmed by DSC measurements. The values of tensile storage modulus obtained after different preparation condition were strongly affected by the process of physical ageing. According to, tan d parameter, the samples stored at room temperature for a long time showed the highest amorphous content. The PLLA eco-composite reinforced with kenaf fibers, dyed with the red pigment, and annealed at 85°C for 2 h displays the best mechanical properties.Item Wood-plastics composites with better fire retardancy and durability performance(2009-11) García, M.; Hidalgo, J.; Garmendia, I.; García-Jaca, J.; Tecnalia Research & Innovation; VALORIZACIÓN DE RESIDUOS; BIOECONOMÍA Y CO2; ECOEFICIENCIA DE PRODUCTOS DE CONSTRUCCIÓNThis study concerns the preparation and study of wood-plastic composites (WPCs). The matrix used was high density polyethylene. Results showed that the addition of wood fibres increased mechanical properties (tensile, flexural and compression) of the neat plastic remarkably. Additives such as fire retardants and light stabilizers were added to improve properties like fire retardancy and durability performance. The addition of fire retardants could lead to auto-extinguishing materials when ammonium polyphosphate or aluminium hydroxide were used. Outdoor durability depended on both the light stabilizer and the fire retardant added to the formulation. The fire retardant worsened the outdoor durability. However, stabilized fire retarded-WPCs showed much lower fading than non-stabilized non-fire retarded composites and several industrial samples. Stabilized composites with aluminium hydroxide as fire retardant showed the best overall results with a fading degree even lower than the stabilized non-fire retarded composite.Item Zirconia-multiwall carbon nanotubes dense nano-composites with an unusual balance between crack and ageing resistance(2011-06) Garmendia, N.; Grandjean, S.; Chevalier, J.; Diaz, L. A.; Torrecillas, R.; Obieta, I.; Tecnalia Research & InnovationYttria stabilized zirconia (Y-TZP) ceramics are used in a wide variety of applications, such as orthopaedic and dental implants. Y-TZP offers indeed a unique combination of biocompatibility and mechanical properties (high crack resistance for a ceramic). However, the major drawback of Y-TZP is their lack of stability: zirconia is prone to ageing, especially under humid atmosphere. Increasing the ageing resistance of Y-TZP led so far to a decrease of toughness and crack resistance. Here we show that the addition of a small volume fraction of multiwall carbon nanotubes (MWCNT) in a polycrystalline nano-structured Y-TZP sintered under specific conditions (Spark Plasma Sintering) leads to a material exhibiting a balance between ageing and crack resistance never reached before.