Macromolecular Symposia最新文献

The scope of the presented study is the environmental impact during the production phase of partially bio-based polybutylene succinate (PBS), which is an alternative to conventional plastics such as polyethylene (PE) and polypropylene (PP) or other biopolymers such as polylactic acid (PLA). The PBS investigated in this study is made from bio-based succinic acid, which is produced from collected plant waste, and petrochemical-based 1,4-butanediol. The study focuses on comparing the environmental impact of partially bio-based PBS to bio-based PLA and petrochemical-based PP. The following environmental impact categories were identified as key indicators for assessing the manufacturing phase of plastics and analyzed: global warming potential, land use, fossil energy consumption, and water scarcity. As a result, PBS can be a sustainable thermoplastic alternative based on the cradle-to-grave analysis used. Additionally, environmental impacts from the current use of petrochemical 1,4-butanediol can be further decreased.

The application of additive manufacturing is increasing due to the capability of manufacturing complex-shaped structures for lightweight applications, which are used in aerospace, automobile, and other transportation industries. Typically, lightweight honeycomb sandwich structures consist of two parts: a core that provides shear stiffness and skin layers with high tensile and compressive strength. An innovative way of producing corresponding sandwich components is hybrid additive manufacturing, whereby both the core and the skin are produced directly in the required size and geometry from fiber-reinforced thermoplastics. Therefore, this current study focuses on systematic investigations on the design, fabrication, and analysis of 3D-printed honeycomb sandwich structures using various additive manufacturing techniques such as Fused Filament Fabrication (FFF) and Automatic Tape Laying (ATL). The light-weight honeycomb sandwich structures were fabricated in different cell sizes of 4, 8, and 10 mm using FFF with glass fiber-reinforced polyethylene (HDPE/GF20) and polyamide 6 (PA6/GF30). The fabricated sandwich structures are provided with additional skin on the bottom and top layers with unidirectional glass fiber-reinforced thermoplastic tapes (UD tapes) from polyethylene (PE/GF40-UD) and polyamide 6 (PA6/GF60-UD) using ATL, followed by a comprehensive analysis using morphological and mechanical test methods. The obtained experimental results are meticulously documented and compared.

Within this study, the processing behavior, resulting morphology, and mechanical properties of unidirectional glass fiber-reinforced polybutylene succinate (PBS/GF) composites were investigated. Therefore, a commercial grade of partially bio-based PBS with a melt flow index of 22 g/10 min (190°C, 2.16 kg) was evaluated regarding the eligibility for processing of continuous unidirectional fiber-reinforced thermoplastic composites (UD tapes). The production of the PBS-based tapes was investigated by a melt impregnation process with two different widths of 50 and 100 mm for a production speed of 3 m/min. Thus, besides the processing of initial PBS tapes, the possibility for process optimization as well as the scale-up was investigated. It was found that the shear viscosity of the PBS significantly influences the impregnation process. Investigations on scale-up and optimization of processing parameters like melt throughput, fiber spreading, and die gap showed potential for improvements. As a result, a maximum fiber mass content of 64.5% could be reached, resulting in a tensile modulus of 37.0 GPa and a tensile strength of 406.4 MPa parallel to the fiber orientation for a tape width of 50 mm. This reflects a higher tensile modulus but lower tensile strength of the investigated reference based on polypropylene (PP) and could be improved by the use of an additional coupling agent. Thus, the unidirectional glass fiber-reinforced PBS tapes can be a suitable bio-based alternative for lightweight applications based on thermoplastic composites.

Additive Manufacturing (AM) processes, particularly fused filament fabrication (FFF), significantly advance the manufacturing industry, yet warpage in printed polymer parts remains a persistent issue. A key factor in reducing warpage is the adhesion between the substrate and the printed product. Thus, this study evaluates the adhesion properties of acrylonitrile butadiene styrene (ABS), glycol-modified polyethylene terephthalate (PETG), and polyamide 12 (PA12) to the printing bed. Different adhesives, such as polyvinyl acetate (PVA), polyvinyl pyrrolidone (PVP), and polyetherimide (PEI), are investigated to improve the print bed adhesion. It was found that the surface energy of the print bed could significantly increase from 13.99 mN/m up to 63.16 mN/m when using these adhesives. Additionally, it was found that a higher print bed temperature leads to a reduced displacement during printing and thus a higher print bed adhesion. The adhesion performance is quantitatively assessed through uniaxial shear tests, evaluating the interfacial shear strength. The highest interfacial shear strength and thus the highest print bed adhesion was found for the PA12 printing material and the PVA adhesive with a value of 7.3 MPa. Based on these results, this study provides an important contribution to improving the dimensional accuracy of FFF printed components.

Cover:

This issue of Macromolecular Symposia contains selected papers presented at the Polymertec 2024, organized by the Merseburg University of Applied Sciences HoMe (HS Merseburg), Merseburg, Germany, the Fraunhofer Institute for Microstructure of Materials and Systems (IMWS), Halle (Saale), Germany and the Institute of Polymer Materials (IPW), Merseburg, Germany. It was held in present mode at the university campus in Merseburg, Germany from June19 to June 20, 2024. The cover shows an edited version of the journal logo.

The advancements in additive manufacturing technologies have revolutionized the manufacturing industry in recent years, enabling unprecedented design flexibility and also simultaneously accelerating the production time of individual components. The differences in the pre-processing phase have been argued to have a significant influence on the production quality of the 3D-printed part. Moreover, the interface between the CAD software and the slicing software is decisive for the quality of the generated G-code, which is used in 3D printing. This work aims to evaluate multiple commercial and open-source CAD platforms and review their functionality in designing 3D models and their inherent complexities for additive manufacturing by FDM. A specimen design was modeled using multiple commercial and open-source CAD platforms in combination with slicer software. The G-codes for the selected software platforms were generated and analyzed to evaluate the accuracy and flexibility in designing amongst the selected CAD platforms in combination with the slicer software. From the study, significant insights were gained about the relative strengths of the individual CAD and slicer combinations and also their inherent drawbacks. This data was used to evaluate the combinations in terms of the accuracy and design flexibility of each of these combinations. Such an analysis of the aforementioned software tools can provide significant insights into the optimization of the additive manufacturing process and contribute towards the efficient conversion of 3D designs into functional parts. Furthermore, this comparison and evaluation of the CAD software can play a crucial role in both visualizing and realizing the additive manufacturing process.