Effect of processing conditions on crystallization kinetics during materials extrusion additive manufacturing

Northcutt, Lily; Orski, Sara V.; Migler, Kalman D.; Kotula, Anthony P.

doi:10.1016/j.polymer.2018.09.018

Cited by 81 publications

(87 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Considering the numerous printing parameters, optimal printing conditions are challenging and may require several iterations of trial and error corrections before printing appropriately [10,16], especially when the polymer is semi-crystalline. Many polymers used for FFF are semi-crystalline, such as polylactic acid (PLA) [17,18], polycaprolactone (PCL) [19], polybutylene terephthalate (PBT) [20], polyethylene (PE) [21] and polypropylene (PP) [22]. Although a wide range of polymer filaments are commercially available for FFF, PLA is the most popular one due to its degradability and availability in various colors and textures.…”

Section: Introductionmentioning

confidence: 99%

Effect of Porosity and Crystallinity on 3D Printed PLA Properties

et al. 2019

View full text Add to dashboard Cite

Additive manufacturing (AM) is a promising technology for the rapid tooling and fabrication of complex geometry components. Among all AM techniques, fused filament fabrication (FFF) is the most widely used technique for polymers. However, the consistency and properties control of the FFF product remains a challenging issue. This study aims to investigate physical changes during the 3D printing of polylactic acid (PLA). The correlations between the porosity, crystallinity and mechanical properties of the printed parts were studied. Moreover, the effects of the build-platform temperature were investigated. The experimental results confirmed the anisotropy of printed objects due to the occurrence of orientation phenomena during the filament deposition and the formation both of ordered and disordered crystalline forms (α and δ, respectively). A heat treatment post-3D printing was proposed as an effective method to improve mechanical properties by optimizing the crystallinity (transforming the δ form into the α one) and overcoming the anisotropy of the 3D printed object.

show abstract

Section: Introductionmentioning

confidence: 99%

Effect of Porosity and Crystallinity on 3D Printed PLA Properties

et al. 2019

View full text Add to dashboard Cite

show abstract

“…As a consequence, the development of interlayer strength and crystallization will become time-dependent [26,27]. Thermal monitoring of the FFF process to extract the non-isothermal temperature profile of a printed layer has been extensively reported in the literature, either by utilizing a thermocouple [28][29][30] or through infrared (IR) thermography [31][32][33][34][35][36][37][38]. Other authors have successfully attempted to model the temperature profiles within consecutively deposited layers [32,[39][40][41][42].…”

Section: Introductionmentioning

confidence: 99%

Assessment of Crystallinity Development during Fused Filament Fabrication through Fast Scanning Chip Calorimetry

et al. 2019

View full text Add to dashboard Cite

Although semi-crystalline polymers are associated with considerably better mechanical properties and thermal stability compared to their amorphous counterparts, using them as feedstock for Fused Filament Fabrication still poses some major challenges. Hence, the development of printed part crystallinity during printing should be fully understood in order to control the developed weld strength, as well as part shrinkage and warpage. Infrared thermography was utilized to record the thermal history of deposited layers while printing a single-layer wall geometry, employing two PA 6/66 copolymers with distinct molecular weights as feedstock. Print settings were varied to establish which settings are essential to effectively monitor final part crystallinity. The resulting temperature profiles were simulated in a Fast Scanning Chip Calorimetry device that allows for the rapid heating and cooling rates experienced by the printed polymer. Both liquefier temperature and print speed were found to have very little influence on the total attained crystallinity. It became apparent that the build plate, set at a temperature above the polymer’s glass transition temperature, imposes a considerable annealing effect on the printed part. A reduced molecular weight was observed to enhance crystallinity even more strongly. The presented methodology proves that Fast Scanning Chip Calorimetry is an effective tool to assess the impact of both print parameters and feedstock characteristics on the crystallization behavior of semi-crystalline polymers over the course of printing.

show abstract

“…Having characterized the crystallization behavior of the materials under isothermal and nonisothermal processing conditions, the work focused on determining the thermal history of the material during the deposition process. Several previous works have already proposed set-ups able to measure the thermal profile of the material during the deposition process, for example by IR thermography or fine thermocouples [19,30]. The printed geometry is the same as previously The large difference in crystallizability of the two materials, as evidenced by isothermal and non-isothermal measurements, might result in different welding performance during printing.…”

Section: In-situ Temperature Measurementsmentioning

confidence: 99%

Fused Deposition Modeling of Polyamides: Crystallization and Weld Formation

et al. 2020

View full text Add to dashboard Cite

International newspapers and experts have called 3D printing the industrial revolution of this century. Among all its available variants, the fused deposition modeling (FDM) technique is of greater interest since its application is possible using simple desktop printers. FDM is a complex process, characterized by a large number of parameters that influence the quality and final properties of the product. In particular, in the case of semicrystalline polymers, which afford better mechanical properties than amorphous ones, it is necessary to understand the crystallization kinetics as the processing conditions vary, in order to be able to develop models that allow having a better control over the process and consequently on the final properties of the material. In this work it was proposed to study the crystallization kinetics of two different polyamides used for FDM 3D printing and to link it to the microstructure and properties obtained during FDM. The kinetics are studied both in isothermal and fast cooling conditions, thanks to a home-built device which allows mimicking the quenching experienced during filament deposition. The temperature history of a single filament is then determined by mean of a micro-thermocouple and the final crystallinity of the sample printed in a variety of conditions is assessed by differential scanning calorimetry. It is found that the applied processing conditions always allowed for the achievement of the maximum crystallinity, although in one condition the polyamide mesomorphic phase possibly develops. Despite the degree of crystallinity is not a strong function of printing variables, the weld strength of adjacent layers shows remarkable variations. In particular, a decrease of its value with printing speed is observed, linked to the probable development of molecular anisotropy under the more extreme printing conditions.

show abstract

Effect of processing conditions on crystallization kinetics during materials extrusion additive manufacturing

Cited by 81 publications

References 32 publications

Effect of Porosity and Crystallinity on 3D Printed PLA Properties

Effect of Porosity and Crystallinity on 3D Printed PLA Properties

Assessment of Crystallinity Development during Fused Filament Fabrication through Fast Scanning Chip Calorimetry

Fused Deposition Modeling of Polyamides: Crystallization and Weld Formation

Contact Info

Product

Resources

About