MESO fiber – a novel approach to reinforce micro parts

Abstract

Carbon and glass fibers are common materials to reinforce polymers for injection molding. As these established fibers feature diameters of 4.5 lm or more, parts produced my micro injection molding (lIM) cannot be reinforced in a satisfying way. Carbon nano tubes (CNTs) feature diameters up to 0.5 lm, but are high in price and difficult to process. Consequently, in the range of reinforcement materials, a gap between 0.5 and 4.5 lm can be denoted, that shall be filled by a novel reinforcing element named MESO -fiber. It shall be derived from commercially available carbon fibers. Basing on commercially available carbon fibers (4.9 lm) from a UMS roving 800 tex (Toho Tenax Co., Ltd. Chiyoda, Tokyo, Japan) experiments were performed to reduce them in diameter. This included etching with strong acids and oxidizing agent up to 24h, treatment with an open air plasma system from PlasmaTreat GmbH for a few minutes and exposition to hot ambient air at temperatures between 495 -505 8C at times between 6 to 9 hours. Additionally the influence of removing the sizing as a pretreatment using acetone and ambient air at 350, 400 and 450 8C, respectively, was analysed. Chemical treatment showed no influence mentionable. Plasma treatment showed a significant influence with some fibers showing massive corrosion, some reduced in diameter to app. 1 lm with a smooth surface. Thermal treatment showed ambiguous results and nor clear trend could be observed. Differing from literature, carbon fibers were affected at temperatures lower than 450 8C. Depending on combination of pretreatment and treatment the fibers showed mediocre or massive corrosion at different extents or featured a porous structure. Chemical treatment appeared to be unsuitable as no influence could be observed. Thermal treatment showed to be a not very promising approach, as no clear correlation could be observed, the fiber featured a poor quality and processing time was considerably long. Although no stable process could be found, Plasma treatment showed the best result with a very short time for treatment. So this approach can be considered as the most promising for an in line production of MESO-fibers.Keywords: carbon fiber / MESO / micro injection molding / plasma / reinforcement / Carbon-und Glas-Fasern sind übliche Elemente um Kunstoffe im Spritzguss zu verstärken. Da jedoch sämtliche dieser etablierten Fasern Durchmesser von 4,5 lm und mehr aufweisen, können Bauteile im Mikro Spritzguss (MicroInjectionMolding -lIM) nur unzureichend verstärkt werden. Carbon nano tubes (CNTs) sind zwar in Durchmessern bis hinauf zu 0,5 lm verfügbar, jedoch sehr hoch im Anschaffungspreis und schwierig in der Verarbeitung. Folglich lässt sich in einer Über-sicht der Verstärkungselemente eine Lücke im Bereich von 0,5 lm bis 4,5 lm beobachten, welche durch ein neuartiges Verstärkungselement, der MESO-Faser gefüllt werden soll. Diese soll von kommerziell verfügbaren Carbon-Fasern abgeleitet werden. Mit kommerziell erhältlichen Carbon-Fasern (4,9 lm) aus einem UMS roving 800 tex (TohoTenax ...