FG Polymerbasierter Leichtbau
Refine
Year of publication
Document Type
Way of publication
- Open Access (18)
Keywords
- polymer composites (5)
- recycled carbon fibers (5)
- General Chemical Engineering (3)
- General Chemistry (3)
- global recycling projects (3)
- practical recovery and reuse (3)
- recycling (3)
- wind turbine blades (3)
- 3D printing (2)
- Composites (2)
Institute
A well-known method of doping powders in the industry is mechanical alloying synthesis. This method synthesizes metal powders by grinding them in high-energy mills, which prevents the achievement of well-dispersed particles throughout the volume and control of particle morphology, size, and agglomeration. In the present work, rhenium doping of IN 713C was carried out in a polyester network system based on organic acids and diols with specially selected catalysts and experimental parameters leading to the complexation of Rhenium ions. In addition, neutral reagents were used in this research, contributing to the greening of many key industries. The obtained IN 713C powder with rhenium showed high dispersion without agglomeration effect and reasonable flowability. Depending on the polymerization process parameters, the morphology of the rhenium particles on the surface of IN 713C can be modified. The IN 713C powder, with and without rhenium, was used in the SLM process to fabricate IN 713C alloy samples. The study examines the effect of rhenium doped IN 713C on the microstructure and hardness changes of the alloy produced by the 3D-printing methods. This type of chemical modification methods can effectively enhance the hardness and affects the elongation of dendrites in the structure of IN 713C alloys manufactured by the additive methods.
Composite pressure vessels are commonly manufactured using the wet filament winding process, where various process parameters can influence the performance of the finished component. In this study two designs of wet filament wound 6.8-liter type 4 composite pressure vessels were manufactured. Both differ only by the internal pressure used during the filament winding, which primarily influences the residual stress state in the composite structure. An extensive experimental study was carried out, including 10 slow burst tests and strain measurements with fiber optic sensors. Significant differences can be observed in the performance of the two designs even though the used stacking sequence, materials and other manufacturing parameters are the same for both designs. A discussion of the differences in the behavior of both cylinder types is provided, including the strain distribution in slow burst tests and failure mechanism.
Hole-drilling method is a standardized technique for obtaining residual stresses in isotropic structures. Previous studies provide a foundation that enables the use of this method to investigate orthotropic structures, such as fiber-reinforced composites. In this study, the incremental hole-drilling method was applied to investigate residual stresses in filament wound type 4 composite pressure vessels. The investigated composite cylinders were manufactured with different internal pressure functions during the winding process, to achieve distinct residual stress states. Additionally, the influence of the initial loading under sustained internal pressure and increased temperature on the stress distribution was investigated. It was shown that the residual stress state can be influenced by varying the internal pressure in the winding process. After testing at sustained load and increased temperature, a stress redistribution was observed, which took place due to creep phenomena. Finally, a discussion of the challenges for the application of the hole-drilling method to composite pressure vessels is provided.
Recycled PET-G (rPET-G) composites reinforced with flax fiber were obtained. To improve interfacial adhesion, the fiber was treated by washing and finishing with bio-based epoxidized soybean oil and admixture acid. The effect of fiber surface treatment on its properties and those of the composites was evaluated by TGA, FT-IR and SEM, as well as by contact angle, flexural and tensile measurements. The results indicated delayed degradation of the treated flax fiber with a fiber mass loss of about 4 wt%. The flexural strength and modulus increased for the washed and finished flax fiber compared to the untreated one. While the tensile properties were influenced by structural effects resulting from the fiber treatment. These findings contribute to the development of more sustainable and high-performance natural fiber-reinforced thermoplastic composites.
SH-SSQ as a modifier for superior mechanical properties and improved plasticity of 3D printed PLA
(2025)
This work confirms that the use of silisequioxanes in the modification of polymeric and composite materials to change their properties is possible in the range of low modifier concentrations, not exceeding 2.5%. This study investigates the impact of (3-thiopropyl)polysilsesquioxane (SSQ-SH) on the properties of polylactide (PLA) for 3D printing. Microscopic analysis using SEM and EDS mapping proved that SSQ-SH is well dispersed in the polymer matrix in the concentration range of 0.25–2.5 wt%, agglomerations were observed at 5 wt% concentration, which reduces the homogeneity of the material and is also reflected in the mechanical test results. Mechanical testing shows SSQ-SH enhances flexibility and toughness, with the most significant improvements observed at 1 wt% and 1.5 wt% concentrations. Specifically, elongation at break increases by up to 56% and impact strength by up to 37% compared to unmodified PLA. These results suggest SSQ-SH is an effective plasticizer, improving interlayer adhesion and reducing brittleness. The optimal SSQ-SH concentrations for maximizing mechanical performance and material integrity are 1 wt% and 1.5 wt%. Part of the produced samples was conditioned in a climatic chamber, it was observed based on DSC and XRD analysis that the crystallinity of the materials significantly increases after exposure to UV radiation, which is also confirmed by microscopic observations. This study highlights the potential of SSQ-SH in improving the performance of 3D printed PLA materials and efficient modification is possible even in the range of low modifier concentrations, not exceeding 2.5%.
Leichtbau spielt nicht nur bei Automobilen mit Verbrennungsmotoren, sondern auch bei Elektrofahrzeugen eine wichtige Rolle. Die dafür genutzten Materialverbunde lassen sich häufig jedoch nicht recyceln. Bei Mercedes-Benz setzt man deshalb seit Kurzem im Interieur auf Monomaterialsandwiche. Diese verbessern nicht nur die Recyclingfähigkeit, sondern bringen teilweise auch mehr Leistung.
Lightweight construction plays an important role not only in cars with combustion engines but also in electric vehicles. However, the composite materials used for this purpose are often not recyclable. Mercedes-Benz has therefore recently started developing mono-material sandwiches for the interior. These not only improve recyclability, but also increase performance in some cases.
Carbon fiber-reinforced plastic (CFRP) components are known for their exceptional resilience and ultra-lightweight nature, making them the preferred choice for applications requiring high mechanical loads with minimal weight. However, the intricate and anisotropic structure of CFRP components poses challenges, resulting in expensive repairs and testing. This complexity also leads to increased waste generation. Yet, innovative recycling processes offer a solution by reintegrating carbon components into a closed material cycle, promoting sustainability and circular economy principles. This work focuses on recycled CFs (rCFs) obtained through a continuous recycling method for CFRP primary recyclate from composite pressure vessel. Furthermore, re-purposing of the separated matrix material for secondary energy sources makes the process, a 100% recycling route. This closed-loop approach addresses conventional pyrolysis challenges and contributes to more efficient utilization of CFRP waste components. rCF and recycled polyethylene terephthalate (rPET) polymers were compounded through an extrusion process. Test specimens were then fabricated according to standard test norms to evaluate the resulting tensile and bending properties. The tensile and flexural modulus of the rCF-rPET obtained are 6.80 and 4.99 GPa, respectively. The need for enhancing the quality of rCF is apparent. Suggestive and potential implications and the marketability of rCF-rPET compounds are also discussed.