Biobasierte Polyamide mit Cellulosefasern

Verfahren – Struktur – Eigenschaften

Feldmann, Maik Wilhelm

kassel university press, ISBN: 978-3-89958-599-5, 2013, 193 Pages
(Schriftenreihe Institut für Werkstofftechnik - Kunststoff- und Recyclingtechnik 12)

Zugl.: Kassel, Univ., Diss. 2012

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Content: Engineering plastics reinforced with cellulosic fibres offer higher thermo-mechanical properties than composites with polyolefines used as matrix. Additionally, it is possible to produce a composite that consists completely of renewable raw materials by using bio-based polyamides. Up to now, only experiments with low-melting PA 11 can be found in literature. Higher melting (bio-) polyamides in combination with cellulosic fibres as reinforcement have not been described and are not employed in applications until now. The thermal resistance of cellulosic fibres limits their application as reinforcement fibres in engineering plastics.

In this study natural fibres as well as man-made cellulose fibres were used as reinforcement fibres. Completely bio-based PA 10.10, approximately 62% bio-based PA 6.10, and common PA 6 were used as matrix polymers. The melt temperatures for these polyamides range between 200°C and 220°C. The gentle processing of the cellulosic fibres was achieved using the new impregnation method developed in this study. Here, endless yarn is saturated with melt. In contrast to the known two-step pultrusion method and common compounding process using a twin screw extruder, this method results in significant improvements in the mechanical properties of the manufactured composites. The notched impact strength of PA 6.10 with 30 wt-% man-made cellulose fibres was increased by a factor of 2.5. This can be explained by the longer fibres in the composite, as well as by the lower amount of thermal and mechanical damage in the fibres. The heat resistance (HDT-A) was investigated using DMA and it was observed to reach the same level as glass fibre reinforced polyamides at over 200°C with a fibre amount of 30 wt.-%. It was also proven that the stiffness of polyamide composites can be increased with both natural and man-made cellulose fibres. The strength can also be significantly improved with man-made cellulose fibres. However, in comparison to glass fibre reinforced polyamides, an approximately 12% lower density was achieved. Furthermore, tests show that compounds made of PA 10.10 with 20 wt.-% man-made cellulose fibres are suitable for the manufacture of completely bio-based components of a good quality and higher impact strength than PA GF compounds.

The selection of cellulosic reinforcement fibres, the manufacturing process as well as processing via injection moulding have an essential influence on the mechanical properties of the composite. This study illustrates the potential of bio-based polyamides with cellulosic reinforcement fibres. Thus, it represents a fundamental basis for the establishment of completely bio-based engineering composite materials for series production.

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