Alejandra Costantino; Leandro Ramajo; Julio Viana; Caren Rosales; Antonio Pontes; Valeria Pettarin
Abstract
Carbon nanotubes are currently added to polymers to avoid extra-stages in the electrostatic painting process. However, the attained particle network after processing a final part could affect the mechanical properties and thermal stability of nanocomposites. It is then important to evaluate not only ...
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Carbon nanotubes are currently added to polymers to avoid extra-stages in the electrostatic painting process. However, the attained particle network after processing a final part could affect the mechanical properties and thermal stability of nanocomposites. It is then important to evaluate not only the functional properties, but also the overall performance of these pieces. In this work, boxes of polypropylene (PP) modified with multi-walled carbon nanotubes (MWCNT) were injection molded. Morphology induced by processing was characterized at different locations of the moldings to correlate the influence of in-homogeneities and flow pattern with the overall performance of the molded boxes. PP/MWCNT presented a better aesthetic quality and a markedly better thermal stability than pure PP. It was confirmed that the nanocomposite has high dielectric permittivity, low dielectric losses and relatively good DC conductivity. Regarding mechanical properties, MWCNT induced a slight improvement in flexural elastic modulus. Although fracture initiated at practically the same loading levels for both materials, the propagation energy was deteriorated by MWCNT presence. Differences in both electrical and mechanical behavior were found trough out the PP/MWCNT pieces as result of distinct MWCNT orientation and distribution. It was then concluded that processing has a great influence on parts performance.
C. Rosales; A. Costantino; G. Palazzo; C. Bernal; R. Defacio Dutra; V. Pettarin
Abstract
One of the big engineering challenges in recycling thermoplastics is to manufacture competitive products in terms of mechanical properties such as toughness or strength. This process by which recycled waste is transformed into materials with improved performance, adding value and widening their application ...
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One of the big engineering challenges in recycling thermoplastics is to manufacture competitive products in terms of mechanical properties such as toughness or strength. This process by which recycled waste is transformed into materials with improved performance, adding value and widening their application field, is known as upcycling. One of the strategies to improve PE/PP blends performance is to add a special compatibilizer, and this is the aim of the present work. To achieve this objective, four different commercial masterbatch compatibilizers based on copolymers were added to pristine blends. The compatibilizer that induced the best performance in virgin blends was selected to be applied in post-consumer recycled (PCR) blends, after minimizing its dosage to diminish costs. All blends were prepared simulating industrial processing conditions. Microstructure and morphology of blends were analyzed by DSC and SEM. Tensile and fracture studies were carried out at quasi-static loading conditions. Fracture surfaces were studied by SEM. It was observed that results found for pristine blends were consistent with those of recycled blends, and the addition of compatibilizing masterbatches improved the performance of both pristine and recycled PP/PE blends, in spite of the unpredictable composition and the presence of impurities of PCR blends.
Caren Rosales; Diego Brendstrup; Celina Bernal; Valeria Pettarin
Abstract
Due to the large volume consumption of plastics, the treatment of the resulting solid waste is becoming a major concern. Polyethylene and polypropylene are two of the most abundant polymers in waste. Recycling them as a blend is an attractive way to reduce the impact of plastic wastes. This work is focused ...
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Due to the large volume consumption of plastics, the treatment of the resulting solid waste is becoming a major concern. Polyethylene and polypropylene are two of the most abundant polymers in waste. Recycling them as a blend is an attractive way to reduce the impact of plastic wastes. This work is focused on the relationship between material morphology and tensile behavior, both under static and dynamic loading conditions, of PP/LLDPE blends with varying relative content. Blends present a biphasic morphology with distinctive characteristics that depends on blend composition. Their tensile properties are significantly affected by composition and corresponding morphology: mechanical behavior varied from ductile to brittle under both quasi-static and dynamic loading conditions. The blend with the better and most reliable behavior was found to be the one with 75% of LLDPE, and in a next work it will be used to obtain a ternary composite reinforced with recycled rubber particles obtained from scrap tires.
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