Repositório Colecção: Resumos alargados em actas de encontros científicos internacionais com arbitragem
https://hdl.handle.net/1822/3721
Resumos alargados em actas de encontros científicos internacionais com arbitragem2024-03-29T00:05:59ZEffect of clay amounts on morphology and mechanical performances in multiscale PET composites
https://hdl.handle.net/1822/89826
Título: Effect of clay amounts on morphology and mechanical performances in multiscale PET composites
Autor: Barbosa, C. N.; Chabert, F.; Nassiet, V.; Viana, J. C.; Pereira, Paulo A. A.
Resumo: This work presents an investigation of the properties of poly(ethylene terephthalate)/glass fibres/nanoclay multiscale composites. The aim is to demonstrate the effect of adding various clay amounts on the morphology and mechanical performance of multiscale PET composites. Multiscale composites were prepared by adding 0.5, 1.0, 3.0, and 5.0 wt% of Cloisite15A montmorillonite: Initially, a masterbatch of pure PET blended with 10 wt% of Cloisite15A was obtained in a co-rotating twin screw extruder. The multiscale composites were then blended, via mechanical mixing, and injection moulded by adding the masterbatch to the glass fibre reinforced matrix. The morphological and mechanical characterizations of all compounds are discussed. X-ray diffraction (XRD) and transmission electron microscopy (TEM) revealed that the characteristic (001) peak of the nanocomposite obtained by extrusion (masterbatch) shifted to the lower angle region stating an intercalated structure. However, the subsequent injection moulding process changed the morphological structure of the multiscale nanocomposites reducing the basal distance mostly for small loadings of nanoclay. The addition of nanoclay to PET matrices increases the degree of crystallinity, the clay platelets possibly playing the role of nucleating agent, as revealed by DSC and FTIR. The time relaxation spectra broaden as seen by DMA, as the ratio of clay/polymer interfaces increases. The yield stress of composites with 0.5 and 1 wt% of C15A content are enhanced. For more than 3% of nanoclay, the yield stress decreases. The Young's modulus is increased when adding C15 nanoclay. Indeed, clay exfoliation was not attained, but the intercalated particle dispersion improved the stiffness properties of PET/glass fibres/nanoclay composites.
<b>Tipo</b>: conferencePaperDevelopment and characterization of renewable source composites to replace petrol-based polymers into interior door trims
https://hdl.handle.net/1822/89816
Título: Development and characterization of renewable source composites to replace petrol-based polymers into interior door trims
Autor: Loureiro, N. C.; Esteves, J. L.; Viana, J. C.; Ghosh, Satyabrata
Resumo: The Mechanical properties of PHA/PLA blends can be optimized trough the variation of the PHA contents on the blend. It's possible to predict the flexural and tensile properties recurring to Rule of Mixtures, Kerner-Uemura-Takayanagi, Nicolai-Narkis and Béla-Pukánsky models. All of them will validate the experimental obtain values and they anticipate a good adhesion between both phases. Nevertheless, for low levels of incorporation of PHA (up to 30%), where PLA is expectantly the matrix, the experimental data seems to deviate from the perfect adhesion models, suggesting a decrease on the adhesion between both polymeric phases. The impact energy varies over 157% over the entire blend composition. It's possible to identify that for blends with PHA weight fraction lower than 50% the impact strength of the blend is higher than the pure base polymers. The highest synergetic effect is found for the blend PHA/PLA of 30/70. The second maximum is found for the inverse composition. PLA has a Heat Deflection Temperature substantially lower than PHA. For the blends, the HDT increases with the increment upon the % of incorporation of PHA. Up to 50% PHA (PLA as matrix), the HDT is practically constant and equal to PLA value. Over this point (PHA matrix), the HDT of the polymer blends increases linearly with % of addition of PHA.
<b>Tipo</b>: conferencePaperNanoparticles-effect on the mechanical and electrical properties of pet-based hybrid composites
https://hdl.handle.net/1822/89811
Título: Nanoparticles-effect on the mechanical and electrical properties of pet-based hybrid composites
Autor: Barbosa, C. N.; Pereira, Paulo A. A.; Gonçalves, F.; Viana, J. C.
Resumo: This study aims at demonstrating the effect of adding different weight percentages (in the range of [1-10] wt%) of nanoclays, NC, and carbon nanofibers, CNF, on the mechanical and electrical properties of unreinforced and 20% glass fiber, GF, reinforced poly(ethylene terephthalate), PET, obtained by compression and injection molding technologies. All composites showed a good dispersion of the nanoparticles into the PET matrices. The electrical resistivity is detrimentally affected by the injection molding process and the presence of GF. Both nanoparticles tailored differently the envisaged mechanical properties of the final composites, but an increment upon the initial modulus and reduction on the deformation capabilities was found. Hybrid composites showed an improved behavior with a small increment upon the weight.
<b>Tipo</b>: conferencePaperLinking mould filling and structural simulations
https://hdl.handle.net/1822/89756
Título: Linking mould filling and structural simulations
Autor: Barbosa, Carlos Nuno Veiga; Viana, J. C.; Franzen, Markus; Baranowski, Thomas; Simões, Ricardo João Ferreira
Resumo: Computer Aided Engineering (CAE) is common standard in the development process within the automotive industry. For thermoplastic components, for example, the manufacturing process is commonly simulated with injection moulding simulation software and passive safety with explicit crash software. Currently both disciplines are only linked within the simulation of fibre reinforced thermoplastics to take into account the fibre orientation from injection moulding simulation within crash simulation due to the significant influence of the fibre orientation on mechanical part properties. This work proposes a methodology that allows consideration of moulding conditions on the mechanical behaviour of unreinforced injection moulded components by coupling injection moulding simulation (Moldflow) and crash simulation (LS-DYNA (R)/RADIOSS (R)). A newly developed dedicated computer application allows to directly consider results from injection simulation within crash simulations. The manufacturing boundary conditions that most influence the mechanical behaviour are combined within the thermomechanical indices (TMI) methodology, and mapped onto each finite element within the crash simulation. Mathematical functions have been used to correlate the TMI to important mechanical properties of the moulded polymer. A user defined material model can read those indices and translate them to local mechanical properties.
<b>Tipo</b>: conferencePaper2024-03-20T13:57:15ZThe use of cellulosic fibers wastes to increase the mechanical behaviour of biodegradable composites for automotive interior parts
https://hdl.handle.net/1822/89599
Título: The use of cellulosic fibers wastes to increase the mechanical behaviour of biodegradable composites for automotive interior parts
Autor: Loureiro, N. C.; Esteves, J. L.; Viana, J. C.
Resumo: The best way to obtain cellulosic fibers is to use the pulp wastes from the paper plants. The pre-processing of the fibers is a very complex and chemically heavy set of operations. At the end, a small part of the fibers will be rejected and removed from the production system. Actually these rejected fibers are being incinerated at the furnace that dries the raw-wood. This means that after a set of chemical treatments, that ends with a bleach, the fibers will be incinerated driving to a waste of money, once that all the efforts applied to the treatment are not useful, and by other side, the incineration can release some non-healthy emissions. It is possible to use these rejected fibers in composite applications where their mechanical properties can improve the matrix performance. We will present in this paper the influence of incorporation of these rejected fibers into a biodegradable PLA and PHA blended matrix to replace, in some applications, the petrol-based polymers used into the automotive interior trims. The mechanical, and thermal properties will be assessed and compared with the properties of the petrol-polymers normally used in this type of applications.
<b>Tipo</b>: conferencePaper