Browsing by Keyword "Polyurethane"
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Item Development of a Novel Biobased Polyurethane Resin System for Structural Composites(2022-10-27) Echeverria-Altuna, Oihane; Ollo, Olatz; Larraza, Izaskun; Elizetxea, Cristina; Harismendy, Isabel; Eceiza, Arantxa; Tecnalia Research & Innovation; POLIMEROSPolyurethanes are gaining increasing interest for their use as structural components subjected to cyclic loads, such as leaf springs. Thermoset polyurethane (PUR) based technology offers some advantages, such as fatigue resistance, low viscosity, and fast curing. However, current PUR formulations present two major drawbacks: their petrochemical origin and high reactivity. The aim of this work was to develop a novel biobased PUR (BIO-PUR) with the required mechanical properties and processability for manufacturing structural composites by resin transfer moulding (RTM). For this purpose, a high functionality and high hydroxyl index castor-oil-based polyol was used combined with a biobased glycerol (BIO-Gly) to increase the crosslinking density and improve the final properties of the BIO-PUR. The viscosity and reactivity of the different systems were studied by means of rheology tests and differential scanning calorimetry (DSC). Thermal and mechanical properties were studied by dynamic mechanical analysis (DMA) and flexural tests. Furthermore, the RTM process of a representative part was simulated and validated through the manufacturing and testing of plates. The properties of the BIO-PUR resin systems were strongly influenced by the addition of biobased glycerol and its effect on the crosslinking density. The combination of a high functionality and hydroxyl index biobased polyol with the biobased glycerol resulted in a high-performance BIO-PUR with the required reactivity and final properties for structural applications.Item Effect of Different Nanoparticles on Mechanical Properties and Curing Behavior of Thermoset Polyurethane Adhesives(2014-10-03) Rodriguez, R.; Perez, B.; Florez, S.; POLIMEROSThree different kinds of nanoparticles (nano-Al2O3, nano-SiO2, and nano-CaCO3) were incorporated into a thermoset polyurethane adhesive. The influence of the type of nanoparticle and concentration on nanoadhesives mechanical, rheological properties, and dispersion degree was analyzed. It was found that as nanoparticle concentration increases tensile strength and Young’s modulus increases. However, there was a maximum concentration from which mechanical properties were reduced. Nanoadhesive mechanical properties were controlled by nanoparticles specific surface area, hardness, and surface treatment. In addition, it was found that the addition of nanoparticles accelerates nanoadhesives curing rate.Item Effect of the biobased polyols chemical structure on high performance thermoset polyurethane properties(2022-12-16) Echeverria-Altuna, O.; Ollo, O.; Larraza, I.; Gabilondo, N.; Harismendy, I.; Eceiza, A.; POLIMEROS; Tecnalia Research & InnovationThe sustainability of the polymeric materials has become a fundamental challenge; therefore, the development of new biobased formulations has gained increasing interest. Thermoset polyurethanes (PURs) present high performance and are a competitive solution for structural composites. However, polyols used in the PUR synthesis are typically from petrochemical origin. Nowdays, a broad range of biobased polyols is available in the market, but there is not yet a specific formulation for high performance PURs composites. The aim of this work was to study the effect of biobased polyols' characteristics in the PUR processing and final properties. In addition, biobased polyol features to synthesize BIO-PURs suitable for structural applications were stablished. The viscosity and reactivity were studied by means of rheology and differential scanning calorimetry (DSC). Thermal and mechanical properties were studied through thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA) and flexural tests. The results obtained demonstrated the dramatic influence of polyols’ nature on BIO-PUR/PUR properties and their effect on the crosslink density. It was observed that using a high functionality and high hydroxyl index biobased polyol, it was possible to synthesize high performance BIO-PUR suitable for structural composites.Item Effect of the catalyst system on the reactivity of a polyurethane resin system for RTM manufacturing of structural composites(2022-03) Echeverria-Altuna, Oihane; Ollo, Olatz; Calvo-Correas, Tamara; Harismendy, Isabel; Eceiza, Arantxa; Tecnalia Research & Innovation; POLIMEROSThe high versatility of polyurethanes (PU’s) is encouraging the development of new formulations for new appli cations, like their use as a matrix for structural composites. PU’s based technology offers some advantages, such as fatigue resistance and fast curing cycles. However, their high reactivity hinders some manufacturing processes like Resin Transfer Moulding (RTM). This work aimed to achieve a PU resin (PUR) formulation with the required latency and reactivity for the RTM. For this purpose, different catalytic systems based on an epoxide and LiCl were investigated. The reactivity of the systems was evaluated through Differential Scanning Calorimetry (DSC) and rheology tests, and the curing reaction and viscosity were modelled. Furthermore, the RTM process of a representative composite part was simulated. Results demon strated the processability improvements when the LiCl was incorporated into the isocyanate component of the formulation combined with a monool or a diol. It was observed that these combinations contribute to the encapsulation of the LiCl between the as formed urethane groups by hydrogen bonding, providing the desired latency and acting as a delayed action catalyst. Once the reaction started and the encapsulation was deactivated, an alkoxide was formed to act as a catalyst. En capsulation was more effective with the diol, providing a higher latency.Item Thermal and fire behavior of isophorone diisocyanate based polyurethane foams containing conventional flame retardants(2018-03-10) Eceiza, I.; Barrio, A.; Martín, L.; Veganzones, M. A.; Fernández-Berridi, M. J.; Irusta, L.; BIOECONOMÍA Y CO2This work reports on the fire behavior of isophorone diisocyanate-based polyurethane foams containing different conventional flame retardants (FRs) such as melamine, ammonium polyphosphate, aluminum hydroxide, expandable graphite, and their combinations. The foams were obtained in a laboratory scale and characterized in terms of their morphology, density, thermal stability, and fire behavior. According to atomic force microscopy, the incorporation of FRs decreased the phase separated domain size. The cellular structure of the foams was examined qualitatively by scanning electron microscopy while the quantitative analysis of the surrounding skin was performed by optical microscopy and Image J. The FR containing foams showed more and smaller cells. The thermogravimetric analysis showed that the FRs had no influence in the initial degradation temperature of the foams. However, the obtained residue values were higher than the theoretical ones, indicating that there was some type of interaction between the FRs and the foams. The fire behavior of polyurethane foams was studied by the cone calorimeter and the data showed that the introduction of expandable graphite and combinations of ammonium polyphosphate/melamine to the reference foam gave rise to a significant reduction in the total heat release. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45944.