This study explores the shape-morphing behavior of 4D-printed structures made from Polylactic Acid (PLA), a prominent bio-sourced shape-memory polymer. Focusing on the response of these structures to thermal stimuli, this research investigates how various printing parameters influence their morphing capabilities. The experimental approach integrates design and slicing, printing using fused deposition modeling (FDM), and a post-printing activation phase in a controlled laboratory environment. This process aims to replicate the external stimuli that induce shape morphing, highlighting the dynamic potential of 4D printing. Utilizing Taguchi’s Design of Experiments (DoE), this study examines the effects of printing speed, layer height, layer width, nozzle temperature, bed temperature, and activation temperature on the morphing behavior. The analysis includes precise measurements of deformation parameters, providing a comprehensive understanding of the morphing process. Regression models demonstrate strong correlations with observed data, suggesting their effectiveness in predicting responses based on control parameters. Additionally, finite element analysis (FEA) modeling successfully predicts the performance of these structures, validating its application as a design tool in 4D printing. This research contributes to the understanding of 4D printing dynamics and offers insights for optimizing printing processes to harness the full potential of shape-morphing materials. It sets a foundation for future research, particularly in exploring the relationship between printing parameters and the functional capabilities of 4D-printed structures.
The transition to a biobased economy necessitates utilizing renewable resources as a sustainable alternative to traditional fossil fuels. Bioconversion is a way to produce many green chemicals from renewables, e.g., biopolymers like PHAs. However, fermentation and bioconversion processes mostly rely on expensive, and highly refined pure substrates. The utilization of crude fractions from biorefineries, especially herbaceous lignocellulosic feedstocks, could significantly reduce costs. This presentation shows the microbial production of PHA from such a crude stream by a wild-type thermophilic bacterium Schlegelella thermodepolymerans [1]. Specifically, it uses crude xylose-rich fractions derived from a newly developed biorefinery process for grassy biomasses (the ALACEN process). This new stepwise mild flow-through biorefinery approach for grassy lignocellulosic biomass allows the production of various fractions: a fraction containing esterified aromatics, a monomeric xylose-rich stream, a glucose fraction, and a native-like lignin residue [2]. The crude xylose-rich fraction was free of fermentation-inhibiting compounds meaning that the bacterium S.thermodepolymerans could effectively use it for the production of one type of PHA, polyhydroxybutyrate. Almost 90% of the xylose in the refined wheat straw fraction was metabolized with simultaneous production of PHA, matching 90% of the PHA production per gram of sugars, comparable to PHA yields from commercially available xylose. In addition to xylose, S. thermodepolymerans converted oligosaccharides with a xylose backbone (xylans) into fermentable xylose, and subsequently utilized the xylose as a source for PHA production. Since the xylose-rich hydrolysates from the ALACEN process also contain some oligomeric xylose and minor hemicellulose-derived sugars, optimal valorization of the C5-fractions derived from the refinery process can be obtained using S. thermodepolymerans. This opens the way for further exploration of PHA production from C5-fractions out of a variety of herbaceous lignocellulosic biomasses using the ALACEN process combined with S. thermodepolymerans. Overall, the innovative utilization of renewable resources in fermentation technology, as shown herein, makes a solid contribution to the transition to a biobased economy.[1] W. Zhou, D.I. Colpa, H. Permentier, R.A. Offringa, L. Rohrbach, G.J.W. Euverink, J. Krooneman. Insight into polyhydroxyalkanoate (PHA) production from xylose and extracellular PHA degradation by a thermophilic Schlegelella thermodepolymerans. Resources, Conservation and Recycling 194 (2023) 107006, ISSN 0921-3449, https://doi.org/10.1016/j.resconrec.2023.107006. [2] S. Bertran-Llorens, W.Zhou. M.A.Palazzo, D.I.Colpa, G.J.W.Euverink, J.Krooneman, P.J.Deuss. ALACEN: a holistic herbaceous biomass fractionation process attaining a xylose-rich stream for direct microbial conversion to bioplastics. Submitted 2023.
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This report was produced within the framework of the RAAK PRP project ‘Veiligheid op de werkvloer’. Personal protective equipment (PPE) is used on a daily basis by millions of people all over the EU, voluntarily or as a result of EU legislation. In this report we deal specifically with the textile/garment aspects of PPE. In this context we must consider the fact that PPE encompasses a huge area with hundreds of different applications of materials and systems tuned to specific needs;from a materials point of view it represents a complex area due to the large diversity of labour conditions. Textiles and clothing represent an area where PPE is an important area of attention. On a global scale it is an area of much research. Safety and comfort are becoming more and more important and these aspects must be in balance. Uncomfortable systems will not be used and put safe working at risk. Thus there is a continuous need for technological innovation to improve the effectiveness of PPE systems. Specialization and specific combinations aimed at use under well-defined conditions contributes to finding a good balance between comfort and safety. The design of products, taking into account the individual needs represent an area of intensive research: Safety directed ‘fashion design’.The ultimate goal is the development of proactive systems by which workers (but capital goods as well) are optimally protected. There is also a lot of attention for maintenance and cleaning since protective functions may deteriorate as a result of cleaning processes. Another important point is standardization because producers need directions for product development and supply of goods. In our overview we make a distinction between static and dynamic systems. Static systems provide passive protection, simply by being a part of an equipment that separates the worker from the danger zone. Dynamic systems are more ‘intelligent’ because these can react to stimuli and subsequently can take action. These dynamic systems use sensors, communication technology and actuators. From this research the following may be concluded: 1. Safety is obtained by choice of materials for a textile construction, including the use of coatings with special properties, application of specific additives and he use of special designed fibre shapes. 2. The architecture and ultimate construction and the combinations with other materials result in products that respond adequately. This is of great importance because of the balance comfort – safety. But a lot can be improved in this respect. 3. Insight in human behaviour, ambient intelligence and systems technology will lead to new routes for product development and a more active approach and higher levels of safety on the work floor. Consequently there is a lot of research going on that is aimed at improved materials and systems. Also due to the enormous research area of smart textiles a lot of development is aimed at the integration of new technology for application in PPE. This results in complex products that enhance both passive and active safety. Especially the commissioners, government and industry, must pay a lot of attention to specifying the required properties that a product should meet under the specific conditions. This has a cost aspect as well because production volumes are usually not that large if for small groups of products specific demands are defined. We expect that through the technology that is being developed in the scope of mass customization production technologies will be developed that allows production at acceptable cost, but still aimed at products that have specific properties for unique application areas. Purchasing is now being practiced through large procurements. We must than consider the fact that specification takes place on the basis of functionality. In that case we should move away from the current cost focus but the attention should shift towards the life cycle
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