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Sustainable lignin polymer foaming using high pressure carbon dioxide
Citation Link: https://doi.org/10.15480/882.5108
Publikationstyp
Conference Presentation
Date Issued
2021
Sprache
English
Institut
TORE-DOI
Contribution to Conference
Biobased Polylactic (PLA) foams are cellular materials with distinctive characteristics namely its good biocompatibility and biodegradability, enabled it to be incorporated in various applications such as food packaging, drug delivery, and tissue engineering scaffolds.[1] However, the low melt strength and low crystallization rate of PLA negatively affect cell growth causing non-uniform cellular structure and cell collapse[2]. Natural organic fibers such as lignin present an effective method that can significantly improve the crystallization kinetics of PLA and provide nucleation sites[3][2].
Conventionally, the foaming of polymeric blends is obtained by the addition of a chemical or physical blowing agents; the chemical agent does not give a good control of the porosity and also implies the presence of residues while the physical agents such as chlorofluorocarbons are known for their contribution to the depletion of the ozone layer. The recent focus has been steered into the use of carbon dioxide (CO2) as it offers lower operating condition, relative ease of handle and additionally acts as plasticizer due to its solubility in molten polymers [4] However complete understanding of the CO2 foaming process, particularly nucleation, is lacking [5]
This research aims to gain complete understanding of the lignin PLA foaming process using CO2. To accomplish this goal, the experimental work is divided into two main parts: the experimental work in the first part focuses on investigating the foaming behavior of various extruded lignin PLA blends with lignin percentages of 10-30 wt %, The foaming is done via Batch CO2 and compared to other blowing agents foaming such as sodium bicarbonate and microspheres. The lignin PLA foams are then characterized by their cellular structure, volume expansion ratio and density. The second part investigates lignin PLA extrusion process coupled with continuous CO2 foaming; where CO2 acts as a solvent for the molten polymeric blend in the extruder barrel and reaches saturation, thermodynamic instability later introduced by lowering pressure which leads to nucleation at the extruder die [6]. The solubility of CO2 in the lignin PLA blend and its influence on the nucleation mechanism is thoroughly studied as the key point, which can possibly permit a control over the pore generation and growth of the lignin PLA foam by varying the operating conditions.
Conventionally, the foaming of polymeric blends is obtained by the addition of a chemical or physical blowing agents; the chemical agent does not give a good control of the porosity and also implies the presence of residues while the physical agents such as chlorofluorocarbons are known for their contribution to the depletion of the ozone layer. The recent focus has been steered into the use of carbon dioxide (CO2) as it offers lower operating condition, relative ease of handle and additionally acts as plasticizer due to its solubility in molten polymers [4] However complete understanding of the CO2 foaming process, particularly nucleation, is lacking [5]
This research aims to gain complete understanding of the lignin PLA foaming process using CO2. To accomplish this goal, the experimental work is divided into two main parts: the experimental work in the first part focuses on investigating the foaming behavior of various extruded lignin PLA blends with lignin percentages of 10-30 wt %, The foaming is done via Batch CO2 and compared to other blowing agents foaming such as sodium bicarbonate and microspheres. The lignin PLA foams are then characterized by their cellular structure, volume expansion ratio and density. The second part investigates lignin PLA extrusion process coupled with continuous CO2 foaming; where CO2 acts as a solvent for the molten polymeric blend in the extruder barrel and reaches saturation, thermodynamic instability later introduced by lowering pressure which leads to nucleation at the extruder die [6]. The solubility of CO2 in the lignin PLA blend and its influence on the nucleation mechanism is thoroughly studied as the key point, which can possibly permit a control over the pore generation and growth of the lignin PLA foam by varying the operating conditions.
DDC Class
540: Chemie
600: Technik
620: Ingenieurwissenschaften
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Sustainable Lignin Polymer Foaming Using High Pressure Carbon Dioxide ProcessNET2021.pptx
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