Process–structure–property relationships in semicrystalline polymer-based nanocomposites

A key characteristic of the manufacture of void free components by 3D printing using fused filament fabrication (FFF) is that this generative process always produces new welded joints between the hot strand leaving the nozzle and the previously deposited and already solidified area. These contact conditions determine the local temperature gradient and the local deformation gradients in the contact. These in turn can have a decisive effect on the morphology and mechanical behavior of the component. In this work, the influence of three different geometric contact conditions under two different machine parameter sets on the morphology and mechanical properties was investigated. The results show that ultimately a parameter simply calculated from the process settings and geometric boundary conditions, the mean contact temperature, is decisive for the properties of the component. If this value is above the melting temperature of the material, quasi‐homogeneous morphologies with decent mechanical properties can be achieved in any case. However, if the mean contact temperature is below the melting temperature, the deformation conditions during strand deposition have a significant influence on morphology and properties. The paper describes this behavior using the example of three contact geometries typically encountered in 3D printing with FFF. The discussed correlations between the morphology and the mechanical properties of the printed FFF samples lead to a better understanding of the process and ultimately to the conclusion that the path generation that is, the slicing strategy should take these facts into account in the future in order to be able to exploit the material‐intrinsic performance potential in 3D printing as well.

Section: Introductionmentioning

confidence: 99%

The importance of local process conditions on the properties of fused filament fabrication printed polypropylene components

Xu¹,

Huang²,

Schlarb

2023

Laser transmission welding of poly(lactic acid) and polyamide66/sepiolite nanocomposites

Navas‐Martos¹,

Yebra‐Rodríguez²,

Rubia

2018

Influence of sepiolite nanoclay on the properties of the resulting join between poly(lactic acid) (PLA) and different Polyamide66 (PA66)/nanoclay nanocomposites was studied in this work. Six different polymer nanocomposites based on PA66 were manufactured through a melt compounding process by adding a fixed 1.64 wt % of a commercial IR absorber additive and the respective weight percentages of sepiolite to the polymer matrix. Several nanocomposite/PLA joints were finally performed by means of the transmission laser welding technology and the resulting weldings were characterized in terms of mechanical properties by performing peeling and shearing tests. Furthermore, both welded and mechanically tested samples were also analyzed by scanning electron microscopy in order to study the morphology of the weld seam. The results of the performed tests show that the addition of sepiolite to the PA66 improves the welding performance only in those cases in which the percentage of sepiolite of the nanocomposites is higher than 5 wt %. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46638.

Effects of nanoparticle size and concentration on optical, toughness, and thermal properties of polycarbonate

Nomai

Schlarb

2019

The influences of size and content of silicon dioxide (SiO 2 ) nanoparticles on the morphological, optical, toughness, and thermal properties of polycarbonate (PC) were investigated. The PC nanocomposites were prepared using a twin-screw extruder followed by injection molding. The scanning electron microscope (SEM) micrographs displayed an adequate level of nano-SiO 2 particle distribution within the PC matrix but still revealed some agglomerated particles. Upon increasing the content of nanoparticles, slightly larger agglomerates formed. These agglomerated particles caused a reduction in material transparency due to light loss via reflection and scattering. However, the incorporation of nano-SiO 2 into the PC matrix greatly improved toughness properties and slightly increased glass-transition temperature (T g ), in conjunction with filler content (up to 4 vol %). This was particularly in the case with the smaller sized nano-SiO 2 , which not only significantly improved toughness but also enhanced optical properties of the PC nanocomposites.