Different proportions of starch were blended with poly(␤-hydroxybutyrate)-co-poly(␤-hydroxyvalerate) (PHB-V) or poly(-caprolactone) (PCL) by extrusion, and the mechanical (maximum tensile strength, elongation at break and Young's modulus) and thermal properties (by differential scanning calorimetry) were determined. The biodegradability of the blends in soil compost was also assessed after thermal aging for 192, 425, and 600 h at different temperatures. The maximum tensile strength of the PCL50 blend (containing 50% starch) was 35% lower than that of PCL and that of the PHB-V50 blend was 60% lower than that of PHB-V without thermal aging. PHB-V blends were more biodegradable than PCL blends. For the blends prepared, only the biodegradation of PHB-V25 was affected by thermal aging.

No abstract

Gas turbines are very important because they can be used in several areas, such as aeronautics and electric power generation systems. The operation of a gas turbine can be done by less pollutant fuels when compared to traditional kerosene, for example, resulting in less degradation to environment. Gas turbines may fail from a variety of sources, with the possibility of serious damage results. In this work, the structural integrity of the hot disc of an aeronautical gas turbine is addressed. Several numerical analyses have been performed by the finite element method: Temperature Distributions, Thermal Stresses and Dilatations, Structural Stresses and Deformations, Modal Behaviors and Fatigue Analysis. Creep of blades has also been considered. These are the most important failure modes that can happen to the studied hot disc under operating service. All these analysis have been performed considering the boundary conditions at the design point with maximum rotational speed. The mesh of the problem has been strictly evaluated by adaptive refinement of nodes and elements combined with a convergence analysis of results. Then, the material and basic properties of the hot disc have been defined to assure a normal operation free from failures. Therefore, the mechanical drawings of the studied hot turbine disc have been released for manufacturing and the construction of the first prototype of the aeronautical gas turbine is in testing phase showing that the results presented in this work are consistent.