Foam injection moulding of a TPO/TPC-blend and the effect of different nucleating agents on the resulting foam structure

Mueller, J.; Spoerrer, A.; Altstaedt, Volker

doi:10.1063/1.4873802

Cited by 3 publications

(2 citation statements)

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“…Leung et al [84] showed that additives with many crevices of small semiconical angles lead to higher quality polymer foams, with a high cell density, a smaller cell size and narrower cell size distribution. Some of the most common fillers, namely talc, calcium carbonate, mica and carbon fibers have been successfully employed to the formation of fine and uniform cell morphologies [179,180,182,[267][268][269][270][271], as well as wood fibers, clay and rubber particles [162,163,165,178,182,184,[272][273][274]. Glass fibers (GF) have been traditionally utilized in many industrial applications due to the increase in stiffness and strength of reinforced thermoplastics, creep resistance and service temperature [275].…”

Section: Chapter 5: Pp 20gf -Mucell® Foamsmentioning

confidence: 99%

Characterization of microcellular plastics for weight reduction in automotive interior parts

Monterde¹

2017

Kunststoffe Im Automobilbau 2017

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Section: Chapter 5: Pp 20gf -Mucell® Foamsmentioning

confidence: 99%

Characterization of microcellular plastics for weight reduction in automotive interior parts

Monterde¹

2017

Kunststoffe Im Automobilbau 2017

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“…According to the classical nucleation theory explained in Chapter 2 [83], undissolved gas trapped at the filled/polymer interface promotes the occurrence of multitude of sites for cell formation requiring much lower activation energy for bubble nucleation, accelerating cell nucleation and the development of a large number of cells with small cell size. Moreover, the added fillers increase melt strength of the material [267],…”

Section: Morphology and Apparent Densitymentioning

confidence: 99%

Characterization of microcellular plastics for weight reduction in automotive interior parts

Gómez Monterde

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The present PhD thesis is framed within the Industrial Doctorate Plan promoted by the Generalitat de Catalunya and has been developed in cooperation between the Universitat Politècnica de Catalunya-BarcelonaTech, the Centre Català del Plàstic, SEAT SA and Volkswagen AG. The research project has as main objective the characterization of microcellular plastics obtained by injection molding, motivated by a concern to reduce weight, cost and carbon footprint in automotive plastic parts. First, cylindrical bars and square plates made of Acrylonitrile-Butadiene-Styrene (ABS) and 20% Glass Fiber reinforced-Polypropylene (PP 20GF) were injection molded and foamed through the MuCell® technology. Shot volume was found as the most influencing parameter on cell structure and tensile and flexural properties. The effect of mold temperature and injection speed was secondary and not statistically significant for the mechanical performance. Tensile and flexural properties decreased almost linearly with the apparent density, whereas impact resistance was strongly reduced during foaming. Glass fibers contributed to partially overcome the loss of properties due to the reduction in density. Cells act as crack arrestors by blunting the crack tip. However, once the crack is propagating, cells acting as stress concentrators lead to a decrease in fracture toughness. Because of the low amount of blowing agent injected during the foaming process, no significant changes in the thermal properties were determined as compared to that of the solid counterpart. Simulation of the microcellular injection molding process with Moldex 3D® software and prediction models of the mechanical properties based on the apparent density and morphological characteristics provided a good approach to the experimental results. On the other hand, the Core Back tool technology was also employed in this study. By pulling the core and increasing the final thickness of the part, the apparent density decreased but the bending stiffness was greatly enhanced. Finally, a new alternative foaming technology, called IQ Foam® and developed by Volkswagen AG, was used to produce rectangular plates and compare their properties to that of the obtained by MuCell® process. By using a minimum amount of blowing agent, foamed plastic parts through IQ Foam® obtained through this process exhibited thicker solid skins and lower cell densities, but consequently higher mechanical properties. Additional benefits such as cost-effectiveness, easy-to-use and machine-independence are also offered by this new emerging technology. La presente tesis doctoral se enmarca dentro del Plan de Doctorats Industrials convocado por la Generalitat de Catalunya y se ha desarrollado como colaboración entre la Universitat Politècnica de Catalunya-BarcelonaTech, el Centre Català del Plàstic, SEAT SA y Volkswagen AG. El proyecto de investigación tiene como principal objetivo la caracterización de plásticos microcelulares, motivado por el interés en reducir peso, coste e impacto ambiental en piezas de plástico de automoción. En primer lugar, se obtuvieron mediante moldeo por inyección barras cilíndricas y placas cuadradas fabricadas con Acrilonitrilo-Butadieno-Estireno (ABS) y Polipropileno reforzado con un 20% de fibra de vidrio (PP 20GF), espumadas con la tecnología MuCell®. El volumen de dosificación es el parámetro más influyente sobre la estructura celular y las propiedades a tracción y a flexión. El efecto de la temperatura de molde y velocidad de inyección, en cambio, es secundario y no introduce variaciones estadísticamente significativas sobre el rendimiento mecánico. Las propiedades a tracción y flexión se reducen de manera prácticamente lineal con la disminución de densidad, mientras que la resistencia a impacto decrece drásticamente debido a la espumación. El efecto reforzante de las fibras de vidrio contribuye a compensar parcialmente la caída de propiedades debido a la reducción de densidad. Las celdas tienden a enromar el frente de grieta, retrasando así el inicio de propagación. Sin embargo, una vez la grieta comienza a propagar, las celdas actúan como concentradores de tensión provocando una disminución en la tenacidad a fractura. El reducido contenido de agente espumante inyectado durante el proceso de espumación no es suficiente para producir cambios en las propiedades térmicas en comparación con las del material macizo. La simulación del proceso de inyección microcelular con el software Moldex 3D® y los modelos de predicción de propiedades mecánicas basados en la densidad y características morfológicas proporcionaron valores cercanos a los obtenidos experimentalmente. Por otro lado, en este trabajo también se estudió el efecto de la tecnología de molde Core Back en combinación con el proceso de espumado mediante moldeo por inyección. A través del movimiento de la cavidad y el aumento del espesor final de la pieza inyectada, la densidad aparente se reduce al mismo tiempo que la rigidez a flexión se incrementa considerablemente. Finalmente, una nueva tecnología de espumación desarrollada por Volkswagen AG, llamada IQ Foam®, se utilizó para la inyección de placas rectangulares y la comparación de sus propiedades con las de placas análogas obtenidas mediante el proceso MuCell®. Mediante la utilización de un contenido mínimo de agente espumante, las placas espumadas con IQ Foam® exhibieron mayores espesores de piel y menores densidades celulares, y por tanto, propiedades mecánicas ligeramente superiores. Esta nueva tecnología ofrece también otras ventajas, como una menor inversión inicial, facilidad de operación y posibilidad de utilización en cualquier máquina de inyección convencional.

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Microcellular PP/GF composites: Morphological, mechanical and fracture characterization

Gómez-Monterde

Sánchez‐Soto

Maspoch

2018

Composites Part A: Applied Science and Manufacturing

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Foam injection moulding of a TPO/TPC-blend and the effect of different nucleating agents on the resulting foam structure

Cited by 3 publications

References 5 publications

Characterization of microcellular plastics for weight reduction in automotive interior parts

Characterization of microcellular plastics for weight reduction in automotive interior parts

Characterization of microcellular plastics for weight reduction in automotive interior parts

Microcellular PP/GF composites: Morphological, mechanical and fracture characterization

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