@inproceedings{54b3f139fe054801b0d83395e1866b78,
title = "Modelling of the aging behavior of polyamide 12 powder during laser melting proceb",
abstract = "Concerning individualization, the requirements to products have increased. Additive manufacturing technologies, such as selective laser melting allow manufacturing of complex parts without tools and forms. Due to this additive manufacturing procebes comply, in opposite to conventional techniques, with these increased demands on procebing technology. Due to the high temperature during procebing, a degradation of the used plastic powder occurs. The non-molten material in the building chamber, the so-called partcake, can be removed after building from the finished component and reused for another proceb. To realize reproducible part properties refreshing of partcake powder with 30 up to 50 % virgin powder is necebary. However, these refreshing strategies lead to varying component properties due to an undefined aging state. Previous investigations on oven aged powder for selective laser melting showed for short periods of storage near the melting point thermally induced post condensation is the predominate aging effect. Due to post condensation the molecular weight and thus the viscosity increases. This paper focuses on the modeling of the post condensation proceb to define the aging state of polyamide 12 powder in laser melting proceb. Therefore the rheological behavior of PA 12 powder in dependency of time and temperature is investigated. Isothermal viscosity measurements are conducted in order to describe the post condensation reaction with a model. With knowledge of the kinetics of the post condensation reaction the state of aging can be predicted in a second step. Thus expected useful life of the powder can be calculated in dependency of the building chamber temperature. These results are then compared with viscosity values of defined aged PA 12 powder to validate the determined model.",
keywords = "Aging, Modelling, Polyamide 12, Selective Laser Melting",
author = "Dietmar Drummer and Katrin Wudy and Maximilian Drexler",
note = "Publisher Copyright: {\textcopyright} 2015 AIP Publishing LLC.; 30th International Conference of the Polymer Processing Society, PPS 2014 ; Conference date: 06-06-2014 Through 12-06-2014",
year = "2015",
month = may,
day = "22",
doi = "10.1063/1.4918514",
language = "English",
series = "AIP Conference Proceedings",
publisher = "American Institute of Physics Inc.",
editor = "Jana, {Sadhan C.}",
booktitle = "Proceedings of PPS-30",
}