Influence of titanium oxide-based colourants on the morphological and tribomechanical properties of injection-moulded polyoxymethylene spur gears

Abstract

<jats:title>Abstract</jats:title> <jats:p>Regardless of colouration for functional or aesthetic purposes, technical polymer parts, like gears, require consistent properties. However, there is a lack of research into the effect of colourants on the tribomechanical properties of gears. Therefore, the effects of two pigments, titanium dioxide (white) and chrome antimony titanium oxide (yellow), and three delivery methods, masterbatch, liquid colour and direct compounding, on part morphology, dimensions, tribological and mechanical performance of injection-moulded polyoxymethylene (POM) spur gears are investigated in this paper. The white pigment accelerates the crystallisation of POM, causing fine and highly-crystalline morphological structures and smaller dimensions. However, the yellow pigment decelerates crystallisation, resulting in a coarser morphology with highly crystalline core material and bigger parts. Furthermore, the delivery method affects only the tribomechanical properties. Using a masterbatch decreases loads at break and increases deflection at break, since the carrier material acts as an impact modifier and a weak spot. The liquid colour decreases wear due to lubricating properties, whereas the pure pigments increases abrasion, especially in combination with a coarse microstructure. However, the effects of carrier systems and changes in morphology are always superimposed. Considering the performance and tolerance of technical components, colourants have to be carefully selected to ensure beneficial properties.</jats:p>

The Influence of the Hybridization Process on the Mechanical and Thermal Properties of Polyoxymethylene (POM) Composites with the Use of a Novel Sustainable Reinforcing System Based on Biocarbon and Basalt Fiber (BC/BF)

“…It should be added that in the case of polymers with high crystallization kinetics, such as POM, attempts to change the crystalline phase morphology are usually not effective. An example here is not only research on the use of composite fillers [69,71], but also experience in the preparation of polymer blends [72][73][74][75].…”

Determination of the single point uncertainty of customized polymer gear wheels using structured-light scanning with various polygonization settings

“…Lower cooling rates in the material can lead to a similar effect by allowing more time for the material itself to form nucleation centres (Richaud, 2014). In the case of POM two commonly used pigments, white titanium dioxide (Wacharawichanant et al, 2012) and carbon black (Richaud, 2014), show nucleating effects. One consequence of higher crystallinity is increased shrinkage and therefore deviations from desired geometric dimensions.…”

“…In pin-on-disk tests materials with a finer, highly crystalline morphology showed improved tribological properties, especially reduced wear rates (Künkel, 2005). However, even with titanium dioxide showing nucleation properties on POM (Wacharawichanant et al, 2012), a chemically related pigment, chrome antimony titanium rutile, showed de-nucleating effects and a related decrease in mechanical and tribological properties (Schubert et al, 2019). Thus, due to the complex interactions of pigment, carrier system and base polymer there is no general approach to predict whether a colourant has a nucleating, denucleating or no effect on the base polymer.…”

“…Research on the influence of pigments and other nanoparticles, like carbon nanotubes (Yousef et al, 2016) or organoclay (Jose and Alagar, 2011), on the mechanical and tribological properties also show no general trends. Particle material, size and dosage highly influence whether nanoparticles have beneficial or disadvantageous effects (Wacharawichanant et al, 2012).…”

Temperaturen in einfachen Gleitkontakten numerisch abschätzen

“…Um dies zu ermöglichen, werden die eingesetzten Kunststoffe mit Verstärkungsstoffen, internen Schmiermitteln und synergetisch wirkenden Funktionszusätzen auf die tribologischen Beanspruchungen angepasst. Die Auswirkungen diverser gebräuchlicher Füll-und Verstärkungsstoffe auf die tribologischen Eigenschaften von Kunststoffcompounds sind in der Literatur ausführlich beschrieben [1][2][3][4][5][6][7][8][9][10][11][12].…”