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Evaluation of the Zero Shear Viscosity, the D-Content and Processing Conditions as Foam Relevant Parameters for Autoclave Foaming of Standard Polylactide (PLA)

DOI zum Zitieren der Version auf EPub Bayreuth: https://doi.org/10.15495/EPub_UBT_00005390
URN to cite this document: urn:nbn:de:bvb:703-epub-5390-7

Title data

Standau, Tobias ; Long, Huan ; Murillo Castellón, Svenja ; Brütting, Christian ; Bonten, Christian ; Altstädt, Volker:
Evaluation of the Zero Shear Viscosity, the D-Content and Processing Conditions as Foam Relevant Parameters for Autoclave Foaming of Standard Polylactide (PLA).
In: Materials. Vol. 13 (March 2020) Issue 6 . - No. 1371.
ISSN 1996-1944
DOI der Verlagsversion: https://doi.org/10.3390/ma13061371

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Project financing: Deutsche Forschungsgemeinschaft

Abstract

In this comprehensive study, the influence of (i) material specific properties (e.g., molecular weight, zero shear viscosity, D-content) and (ii) process parameters (e.g., saturation temperature, -time, -pressure, and pressure drop rate) on the expansion behavior during the autoclave foaming process were investigated on linear Polylactide (PLA) grades, to identify and evaluate the foam relevant parameters. Its poor rheological behavior is often stated as a drawback of PLA, that limits its foamability. Therefore, nine PLA grades with different melt strength and zero shear viscosity were systematically chosen to identify whether these are the main factors governing the foam expansion and whether there is a critical value for these rheological parameters to be exceeded, to achieve low density foams with fine cells. With pressure drop induced batch foaming experiments, it could be shown that all of the investigated PLA grades could be foamed without the often used chemical modifications, although with different degrees of expansion. Interestingly, PLAs foaming behavior is rather complex and can be influenced by many other factors due to its special nature. A low molecular weight combined with a high ability to crystallize only lead to intermediate density reduction. In contrast, a higher molecular weight (i.e., increased zero shear viscosity) leads to significant increased expandability independent from the D-content. However, the D-content plays a crucial role in terms of foaming temperature and crystallization. Furthermore, the applied process parameters govern foam expansion, cell size and crystallization.

Further data

Item Type: Article in a journal
Keywords: polylactide; biofoams; zero shear viscosity; melt strength; batch foaming; pressure drop rate; low density; small cell size
DDC Subjects: 500 Science > 540 Chemistry
600 Technology, medicine, applied sciences > 620 Engineering
Institutions of the University: Faculties > Faculty of Engineering Science > Former Professors > Chair Polymer Materials - Univ.-Prof. Dr.-Ing. Volker Altstädt
Faculties
Faculties > Faculty of Engineering Science
Faculties > Faculty of Engineering Science > Chair Polymer Materials
Faculties > Faculty of Engineering Science > Former Professors
Language: English
Originates at UBT: Yes
URN: urn:nbn:de:bvb:703-epub-5390-7
Date Deposited: 08 Apr 2021 08:13
Last Modified: 08 Apr 2021 08:13
URI: https://epub.uni-bayreuth.de/id/eprint/5390

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