Calcium Carbonate as Functional Filler in Polyamide 12-Manipulation of the Thermal and Mechanical Properties

Fabio Ippolito,Patrick Gane,Tim Claypole,Gunter Hübner

doi:10.3390/pr9060937

Fabio Ippolito, Patrick Gane + Show 2 more

Open Access

https://doi.org/10.3390/pr9060937

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Abstract

Adjusting the thermal response properties of a polymeric compound can significantly improve the usability in a selective laser-sintering process. As previously shown, combining a precise amount of coarse and narrow size distribution fine calcium carbonate fillers results in a potential optimization of the thermal properties of a polyamide 12 matrix. Additionally, up to 60% of the normally associated lost ductility can be re-gained by surface modification, thus functionalizing the filler. To optimize the functionality further this study combines a precisely defined particle size ratio of fillers adopting a specially selected surface modification using amino hexanoic acid. Morphology of the carbonate filler was also investigated. The range of effect of each parameter on the thermal response and mechanical properties was studied. The results show that the thermal properties have large potential to be optimized, without reducing the ductility significantly, by adjusting the morphology and size ratio of coarse and fine filler particles. The compound properties were demonstrated using a twin-screw extruder, indicating the potential for producing a preparate composite for additive manufacturing.

Highlights

As it was already shown through the particle size distribution measurement, the coarse ground calcium carbonate filler “c-G” shows a much higher presence of ultrafine particles, than the
As it was already shown through the particle size distribution measurement, the coarse ground calcium carbonate filler “c-G” shows a much higher presence of ultrafine particles, than the precipitated calcium carbonate filler with a comparable median dv50, “c-P.”
Calcium carbonate-polyamide 12 composites have been produced via twin-screw compounding using a range of designed calcium carbonate blends of different particle size and morphology filler materials together with an illustration of surface functionalization

Summary

Introduction

Previous work illustrated the role of a functional filler in a polyamide 12 polymer matrix with respect to its physical properties relating to particle size and thermal response. An open question remaining is whether it is possible to find an optimum between the contrasting effect of particle number loading, related to particle size per unit loading, and the thermal capacity distribution of those particles in the polymer matrix. The second open question is whether changing particle morphology at a given particle size renders a further opportunity of optimizing the filler functionality in the polymer matrix. We address this question by adopting a precipitated calcium carbonate exhibiting nested crystal structure in the form of an aggregate of scalenohedral calcite

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Conclusion