scholarly journals Process-Induced Fiber Orientation in Fused Filament Fabrication

2018 ◽  
Vol 2 (3) ◽  
pp. 45 ◽  
Author(s):  
Tom Mulholland ◽  
Sebastian Goris ◽  
Jake Boxleitner ◽  
Tim Osswald ◽  
Natalie Rudolph
Keyword(s):  
Thermal Conductivity ◽  
Fiber Orientation ◽  
Polyamide 6 ◽  
Thermoplastic Composite ◽  
Micro Computed Tomography ◽  
Twin Screw Extrusion ◽  
Fused Filament Fabrication ◽  
Screw Extrusion ◽  
Twin Screw ◽  
Thin Walled

As the applications for additive manufacturing have continued to grow, so too has the range of available materials, with more functional or better performing materials constantly under development. This work characterizes a copper-filled polyamide 6 (PA6) thermoplastic composite designed to enhance the thermal conductivity of fused filament fabrication (FFF) parts, especially for heat transfer applications. The composite was mixed and extruded into filament using twin screw extrusion. Because the fiber orientation within the material governs the thermal conductivity of the material, the orientation was measured in the filament, through the nozzle, and in printed parts using micro-computed tomography. The thermal conductivity of the material was measured and achieved 4.95, 2.38, and 0.75 W/(m·K) at 70 °C in the inflow, crossflow, and thickness directions, respectively. The implications of this anisotropy are discussed using the example of an air-to-water crossflow heat exchanger. The lower conductivity in the crossflow direction reduces thermal performance due to the orientation in thin-walled parts.

Self-Extinguishing and Non-Drip Flame Retardant Polyamide 6 Nanocomposite: Mechanical, Thermal, and Combustion Behavior

2018 ◽  
Vol 1 (1) ◽  
pp. 1-13 ◽  
Author(s):  
Hao Wu ◽  
Rogelio Ortiz ◽  
Renan De Azevedo Correa ◽  
Mourad Krifa ◽  
Joseph H. Koo
Keyword(s):  
Maleic Anhydride ◽  
Flame Retardant ◽  
Polymer Matrix ◽  
Flame Retardants ◽  
Polyamide 6 ◽  
Twin Screw Extrusion ◽  
Elongation At Break ◽  
Combustion Behavior ◽  
Screw Extrusion ◽  
Twin Screw

AbstractIncorporation of flame-retardant (FR) additives and nanoclay fillers into thermoplastic polymers effectively suppresses materials flammability and melt dripping behavior. However, it largely affects other properties, such as toughness and ductility. In order to recover the lost toughness and ductility of flame retardant polyamide 6, various loadings of maleic anhydride modified SEBS elastomer were added and processed by twin screw extrusion. TEM images showed exfoliated nanoclay platelets and reveals that the clay platelets well dispersed in the polymer matrix. By balancing the ratio of flame retardants, nanoclay and elastomers, formulation with elongation at break as high as 76% was achieved. Combining conventional intumescent FR and nanoclay, UL-94 V-0 rating and the LOI value as high as 32.2 were achieved. In conclusion, effective self-extinguishing and non-drip polyamide 6 nanocomposite formulations with significant improvement in toughness and ductility were achieved.

scholarly journals Rheological characterization of polymer-based nanocomposites with different nanoscale dispersions

e-Polymers ◽  
2005 ◽  
Vol 5 (1) ◽  
Author(s):  
Dong Gi Seong ◽  
Tae Jin Kang ◽  
Jae Ryoun Youn
Keyword(s):  
Storage Modulus ◽  
Extensional Flow ◽  
Rheological Behaviour ◽  
Polyamide 6 ◽  
Twin Screw Extrusion ◽  
Rheological Characterization ◽  
Melt Compounding ◽  
Transmission Electron ◽  
Screw Extrusion ◽  
Twin Screw

AbstractPolyamide 6 - clay nanocomposites with different nanoscale dispersions were prepared by melt compounding via twin-screw extrusion and their internal structures were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The rheological behaviour of these nanocomposites in shear and extensional flow were investigated using an Advanced Rheometric Expansion System and an Elongational Melts Rheometer in connection with the analysis by XRD and TEM. Nanocomposites with fully exfoliated structure and with poorly dispersed structure showed very different rheological behaviour. In general, addition of clay increased the viscosity and the storage modulus of nanocomposites, but different rheological behaviours were observed depending upon the degree of clay dispersion in the polymer matrix. In shear flow, only the exfoliated nanocomposite showed solid-like plateau behaviour in storage modulus and strong shear-thinning behaviour in shear viscosity. In extensional flow, only fully exfoliated nanocomposites showed strain-hardening behaviour, which is caused by the interaction between nanoparticles as well as between polymer molecules and nanoparticles.

Preparation of Polypropylene Graft Maleic Anhydride (PP-g-MA) via Twin Screw Extrusion

2010 ◽  
Vol 93-94 ◽  
pp. 451-454 ◽  
Author(s):  
Rittirong Pruthtikul ◽  
Pitcha Liewchirakorn
Keyword(s):  
Maleic Anhydride ◽  
Polyamide 6 ◽  
Standard Test ◽  
Acid Number ◽  
Test Method ◽  
Reactive Blending ◽  
Twin Screw Extrusion ◽  
Screw Extrusion ◽  
Twin Screw ◽  
Izod Impact

Polypropylene (PP) samples grafted with Maleic Anhydride (MA) were prepared by reactive blending via co-rotating twin screw extrusion. The PP was functionalized in the presence of an optimized amount of precursor, Dicumyl Peroxide (DCP) and MA. The amounts of MA grafted on PP were checked by standard test method for acid number. Maleated PP as a compatibilizer with the highest acid number was added to PP/Polyamide 6 (PA6) and blended in the twin screw extrusion. It was found that the PP-g-MA enhanced tensile properties as well as the izod impact properties of notched samples of PP/PA6/PP-g-MA blends compared to neat polypropylene. The scanning electron microscope confirmed the good adhesion of PA6 on PP matrix.

The Effect of Molding Process and Test Conditions on the Thermal Conductivity of Polypropylene/Graphite Composites

2012 ◽  
Vol 588-589 ◽  
pp. 1702-1708
Author(s):  
Sha Yan ◽  
Ying Liu ◽  
Da Ming Wu ◽  
Hui Lin Yuan
Keyword(s):  
Thermal Conductivity ◽  
Twin Screw Extrusion ◽  
Molding Process ◽  
Injection Speed ◽  
Melt Index ◽  
Conductive Composites ◽  
Screw Extrusion ◽  
Twin Screw ◽  
Lower Temperature ◽  
Graphite Composites

The thermal conductive composites prepared by twin-screw extrusion extrudes polypropylene and graphite.This paper studies the influence of molding process on the thermal conductivity.The experimental results show that thermal conductivity of composites changes with the screw rotate speed changing,obtaining the maximum when the screw rotate speed is 300r/min.Results indicate that the opposite trend with thermal conductivity and the melt index and injection speed,and the injection temperature has not a big influence on the thermal conductivity. The crystallization influences the electrical conductivity and density of some points of molding samples.In addition,the test condition has cast impact on thermal conductivity,in the lower temperature(lower than the Debye temperature),the thermal conductivity of composites increased with the of temperature and humidity increasing.

On mechanical, thermal and morphological investigations of almond skin powder-reinforced polylactic acid feedstock filament

2019 ◽  
pp. 089270571988601 ◽  
Author(s):  
Rupinder Singh ◽  
Ranvijay Kumar ◽  
Pawanpreet ◽  
Mohit Singh ◽  
Jatenderpal Singh
Keyword(s):  
Polylactic Acid ◽  
Mechanical Performance ◽  
Melt Flow Index ◽  
Extrusion Process ◽  
Melt Processing ◽  
Flow Index ◽  
Twin Screw Extrusion ◽  
Fused Filament Fabrication ◽  
Screw Extrusion ◽  
Twin Screw

The almond skin powder is one of the biodegradable and biocompatible food wastes that can be used as reinforcement in polylactic acid (PLA) for preparation of biomedical scaffolds/implants (for high mechanical performance) by fused filament fabrication. The present study deals with the melt processing of almond skin powder as reinforcement from 0 wt% to 5 wt% in the PLA matrix by twin-screw extrusion process. The results of the study suggested that reinforcing the almond skin powder as 2.5 wt% in the PLA matrix mechanically strengthens the feedstock filaments but the increase in the proportion up to 5 wt% reduces the mechanical strength to a significant level. A similar trend has been observed in differential scanning calorimeter observations for thermal stability analysis. As regard to the rheological property is concerned, the melt flow index shows a significant reduction with reinforcement of almond skin powder in PLA. The results are also supported by photomicrographic analysis (for surface properties) and Taguchi-based optimization of twin-screw extrusion process parameters (for multifactor optimization).

Thermal Conductivity Measurements of Nylon 11-Carbon Nanofiber Nanocomposites

2009 ◽  
Vol 131 (9) ◽  
Author(s):  
Arden L. Moore ◽  
Antonette T. Cummings ◽  
Justin M. Jensen ◽  
Li Shi ◽  
Joseph H. Koo
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanofiber ◽  
Effective Medium Theory ◽  
Twin Screw Extrusion ◽  
Medium Theory ◽  
Interface Thermal Resistance ◽  
Screw Extrusion ◽  
The Matrix ◽  
Twin Screw ◽  
Nylon 11

Carbon nanofibers (CNFs) were incorporated into nylon 11 to form nylon 11-carbon nanofiber nanocomposites via twin screw extrusion. Injection molding has been employed to fabricate specimens that possess enhanced mechanical strength and fire retardancy. The thermal conductivity of these polymer nanocomposites was measured using a guarded hot plate method. The measurement results show that the room temperature thermal conductivity increases with the CNF loading from 0.24±0.01 W/m K for pure Nylon 11 to 0.30±0.02 W/m K at 7.5 wt % CNF loading. The effective medium theory has been used to determine the interface thermal resistance between the CNFs and the matrix to be in the range of 2.5–5.0×10−6 m2 K/W from the measured thermal conductivity of the nanocomposite.

Sign in / Sign up

Export Citation Format

Share Document