Papers by Keyword: PLA

Abstract: PLA is a common, eco-friendly polymer for FDM printing. The infill patterns and densities play a significant role in determining the mechanical properties of three-dimensional (3D) printed PLA. In this work, two different infill patterns (Concentric and Rectilinear) and infill densities (30% and 100%) were printed. PLA filaments were characterized using Fourier transform infrared spectroscopy (FTIR), Thermogravimetric analysis (TGA), and Scanning Electron Microscopy analysis (SEM) techniques. The tensile test results revealed that the 100% concentric pattern has the highest ultimate tensile strength of 67.5 MPa, while the 100% rectilinear pattern shows 63.6 MPa. On the other hand, the 30% infill density samples show low strength, 32.4 MPa for concentric and 20.8 MPa for rectilinear infill patterns. Similar results can be derived from elastic modulus, yield strength, and stress at break results, while 30% concentric shows the maximum elongation rate of 0.016.

Abstract: Polylactic acid (PLA) has emerged as a promising alternative to conventional petroleum –based plastics due to its biodegradability, renewable sourcing, and lower environmental impact. However, PLA exhibits a slow crystallization kinetics compared to other semi-crystalline polymers, such as polyethylene (PE) or polypropylene (PP), resulting in an amorphous structure after processing. This amorphous morphology can adversely influence the mechanical properties and overall performance of PLA components. The present study investigates the cold crystallization behavior of PLA using Differential Scanning Calorimetry (DSC) with the objective of developing an empirical model capable of describing crystallinity as joint function of holding temperature and time. The resulting model is intended to serve as a practical reference for industrial applications, facilitating improved control of PLA’s microstructure and mechanical performance.

Abstract: The use of 3D-printing simplifies and accelerates the development of moulds for a thermoforming process. This article examines several aspects of the effective design of 3D-printed polymer moulds. The focus is on prototyping and applications in engineering education. Experiments are conducted on PLA mould to determine the actual temperature loads and permanent deformations. Measures to improve the durability of the moulds are discussed and approaches to material and cost optimization are investigated. Examples of the use of PLA-moulds in thermoforming are presented.

Abstract: This study was prepared on the bending and buckling analyses of the 2D honeycomb structure beam with a pocket section on it. In the study, two different materials,PLA and ABS, were selected to be examined for the beam. The aim of the study was to determine the buckling modes and critical buckling loads of lattice beams using numerical methods. Besides, bending analyses were conducted. As a result of bending analyses, the displacement (u_y), equivalent von Mises stress (σ_von), shear stress (τ_xy) and normal stress (σ_yy) behaviours for two different materials were obtained. It was determined that the ABS material deformed more than the PLA material beam. In this direction, important findings were obtained for understanding the bending and buckling behavior of lattice beams.

Abstract: The article presents the results of a study of the physical and mechanical properties of a biopolymer gravel composite made on the basis of polylactide (PLA) and natural gravel. The developed composite is intended for filtration elements of hydrogeological wells. The biopolymer-gravel composite was tested for compressive strength. The results showed that the biopolymer gravel composite is characterized by sufficient mechanical strength and resistance to the effects of the aquatic environment, which confirms the feasibility of its use as an environmentally safe material for filtration elements of hydrogeological wells. The obtained data can be used for further optimization of the composition of the composite material and the development of new biopolymer block gravel filters of hydrogeological wells.

Abstract: This study investigates polymer component manufacturing using fused deposition modeling, specifically focusing on the thermoplastic PLA-Cu in open-source FDM machines. Mechanical characteristics are explored, emphasizing infill density, pattern, and nozzle temperature. FDM-produced PLA-Cu specimens, varying in infill (60%, 80%, 100%) and patterns (TRIANGLE, HEXAGON, LINE), reveal superior mechanical properties in those with 100% density, TRIANGLE pattern, and a 210° nozzle temperature. ASTM-standard tests measure tensile and flexural strength, and scanning electron microscopy examines micro-morphology. Results indicate a correlation between increased strain rate and higher yield stress and elastic modulus in PLA-Cu specimens, emphasizing its engineering potential.

Abstract: The Fused Filament Fabrication (FFF) process plays a crucial role in additive manufacturing (AM), therefore the optimization of certain parameters has a significant impact on the performance of 3D-printed components. In this study, the flexural behavior of Polylactic Acid (PLA) samples manufactured by FFF process is investigated. The influence of the infill density (ID) and the outer shell (OS) on the main physical and mechanical characteristics is studied in detail. The used IDs are 10%, 30%, 50%, 70%, and 90%, and the samples are manufactured with and without OS. All samples are manufactured with rectilinear infill pattern. The geometry of the samples and the experimental program follow the ISO 178 standard. The tests were performed at room temperature, with a test speed of 5 mm/min. The results indicate that main flexural properties (stiffness, strength, strain and fracture energy) are significantly superior in OS samples. Moreover, an increase in properties is obtained with the increase of the ID, regardless of the OS configuration. It was found that specimens without OS exhibited plastic deformation at all IDs, while those with OS demonstrated a quasi-brittle fracture pattern at IDs below 50%. Further analysis of the specific properties (specific strength and specific modulus) showed that an ID of 10% is optimal for 3D-printed structures with OS, while an ID of 90% is optimal for structures without OS. Thus, the importance of ID and OS parameters should not be neglected in the design of 3D printed structural components.

Abstract: 3D printing, commonly referred to as Additive Manufacturing (AM), enables the creation of both simple and complex three-dimensional objects. While AM encompasses a variety of manufacturing techniques, Fused Filament Fabrication (FFF), is the most prevalent method. FFF constructs 3D models layer-by-layer by extruding molten material in a specified pattern. This paper examines the fracture properties of components produced through the FFF process. To achieve this, Single Edge Notched Bend (SENB) specimens were fabricated from polylactic acid (PLA) thermoplastic material. Various printing parameters were explored, including infill density (40, 70, and 100%), infill patterns (grid, cubic, and concentric), and printing directions (0, 45, and 90°). Three-point bending (3PB) tests were conducted at room temperature (25 °C) in accordance with ASTM D5045-14 standards. The 3PB results indicate that the mode I fracture toughness values are significantly affected by the printing parameters examined, with the greatest variations linked to infill density, followed by infill pattern and printing direction. Additionally, the fracture mechanisms associated with SENB specimens produced under different parameters exhibited distinct characteristics.

Abstract: Electrospinning (ES) is a vital technique for producing ultrafine polymer fibers and is widely used in various applications. However, conventional electrospinning setups with some polymer solutions face challenges like bead formation and inconsistent fiber diameters. Integrating airflow into the system helps stretch the fiber and speed up the evaporation of polymer jets, thereby improving fiber morphology. Despite these benefits, incorporating airflow complicates the setup and makes it less user-friendly, as achieving precise laminar airflow toward the jets is difficult. To address these problems, we developed a novel electrospinning attachment featuring easily adjustable slits incorporating controlled airflow with a pressure regulation system. The design allows for convenient adjustment of airflow direction through replaceable slits and blades. Its simplicity allows for easy blade replacement at different angles to control airflow toward the polymer jet. In our experiments, we tested two different slits angles of 30° and 60° (3D printed) to the setup. The results showed that controlled airflow significantly reduced bead formation and produced more uniform fiber diameters. With a 60° slit angle at 0.1 bar, the average fiber diameter was 647.6 nm, decreasing to 526.4 nm at 0.2 bar. Conversely, fibers spun with a 30° slit angle had an average diameter of 712.6 nm at 0.1 bar, with minimal change at 0.2 bar. These findings indicate that controlled laminar airflow with adjustable slit angles substantially improves the properties of electrospun fiber mats.

Abstract: This paper discusses the fire and heat resistance of a polylactic acid/Hemp/Polypropylene hybrid laminated composite. Hybrid composites had their impacts analysed, specifically with regards to the fibre composition and stacking order. Using a hot press, the hybrid composites were created. In this work, Hemp/Polypropylene-reinforced polylactic hybrid composites with thermogravimetric, differential calorimetric, dynamic mechanical, and flamability properties were reported. Thermomechanical studies show that hybridization affects the laminate’s viscoelastic characteristics and thermal stability. Hybrid composites' burning rates were also evaluated for this flammability test. Most of the Hemp layers in sample C7 had the most char residue (10%), while sample C8 had the highest decomposition temperature (450°C). When it comes to hybrid composites, however, the C5 sample offers the best results, with a large char production and a low burning rate of just 36 mm/min. Also, viscoelastic properties like storage and loss modulus are best in class for the C5 sample, which is a hybrid composite. Keywords: Hemp; flammability Polypropylene; PLA; TGA; DSC.