No abstract

In this work we present the thermal characterization of the full scope of polyhydroxyalcanoate and poly(lactic acid) blends obtain by injection molding. Blends of polyhydroxyalcanoate and poly(lactic acid) (PHA/PLA) were prepared in different compositions ranging from 0-100% in steps of 10%. The blends were injection molded and then characterized by differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and wide angle X-ray diffraction (WAXD). The increment of PHA fraction increased the degree of crystallinity of the blend and the miscibility of the base polymers as verified by the Fox model. The WAXD analysis indicates that the presence of PHA hindered the PLA crystallization. The crystallization evolution trough PHA weight fraction (wf) shows a phase inversion around 50-60%. SEM analyses confirmed that the miscibility of PHA/PLA blends increased with the incorporation of PHA and became total for values of PHA higher that 50%.

No abstract

O PDF relativo ao artigo que solicita, não se encontra disponível em Acesso Aberto. Motivos: O editor não permite o depósito e disponibilização em acesso aberto do PDF que solicita. Para consultar o documento deve aceder ao endereço do editor.

Fiber reinforced composites are widely used in the production of parts for load bearing structures. It is generally recognized that composites can be affected both by monotonic and cyclic loading. For assembly purposes, drilling is needed, but holes can act as stress concentration notches, leading to damage propagation and failure. In this work, a batch of carbon/epoxy plates is drilled by different drill geometries, while thrust force is monitored and the hole’s surrounding region is inspected. Based on radiographic images, the area and other features of the damaged region are computed for damage assessment. Finally, the specimens are subjected to Bearing Fatigue tests. Cyclic loading causes ovality of the holes and the loss of nearly 10% of the bearing net strength. These results can help to establish an association between the damaged region and the material’s fatigue resistance, as larger damage extension and deformation by cyclic stress contribute to the loss of load carrying capacity of parts.

This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

XLPE is a thermoset polymer used by ALCOBRE to insulate cooper wires. The wastes of this polymer can’t be discarded in the regular industrial waste and all the wastes costs of this material are expensive. The XLPE needs to be segregated and then a certified waste company transports this waste to identified dumping areas. In this work we try to study the incorporation of the XLPE on a LLDPE matrix.The LLDPE is a thermoplastic polymer used by ALCOBRE to coat copper wires.In this work the mechanical behaviour of XLPE/LLDPE blends is investigated in a wide range of compositions. The mechanical properties can be optimized by varying the XLPE contents of the blend. The flexural and tensile properties were estimated by different models: the rule of mixtures, Kerner-Uemura-Takayanagi model, and Nicolai-Narkis model. This work also considers the adhesion between the two material phases. The results anticipate a good adhesion between both phases. For the tensile modulus, a linear relationship is found, which indicates a good adhesion between the phases along the composition range. The increase of XLPE in the mixture decreases the bending and tensile stress. For tensile stress, the Nicolai-Narkis model is suitable for modelling behaviour by inducing good adhesion between phases. In relation to the module, it is possible to verify that in relation to the bending module the incorporation of XLPE does not affect the module. However, the traction module will be affected with the XLPE quantity in the mixture.

No abstract