In fused filament fabrication/fused deposition modeling (FFF/FDM), the mechanical properties of Polyamide 6 (PA6) are strongly governed by thermal conditions during printing, particularly the build chamber temperature, which controls cooling rate, crystallinity, and interlayer bonding. This study evaluated three build chamber temperatures (30, 40, and 50°C) while keeping all other parameters constant to determine their effects on tensile strength, impact toughness, and microstructure. Five specimens per condition were tested for tensile and impact properties, and fracture surfaces were characterized by scanning electron microscopy (SEM). The results demonstrate a clear temperature dependence: increasing the chamber temperature from 30 to 50°C enhanced tensile strength from 21.32 to 24.61 MPa and impact toughness from 13.58 to 14.35 kJ/m2, whereas 40°C yielded the lowest values of 16.09 MPa and 11.37 kJ/m2. SEM observations suggested that specimens printed at 50°C exhibited improved filament fusion and fewer interlaminar voids, resulting in a more homogeneous and ductile fracture surface, whereas specimens printed at 40°C showed less uniform interlayer bonding and a more heterogeneous defect distribution. These observations are consistent with enhanced interlayer bonding under more favorable thermal conditions. The findings indicate that approximately 50°C is the optimal build chamber temperature within the investigated range, providing improved mechanical reliability of FFF/FDM-printed PA6 parts and a basis for optimizing the processing window for load-bearing applications.
This study reports the structural, morphological, mechanical and dielectric behavior of solution-cast poly(methyl methacrylate) (PMMA) films containing trace fractions (0.5 and 1
Conventional breath figure (BF) templating techniques shows significant potential in surface patterning used for constructing micro/nanoscale architectures in recent years. However, BF remains ineffective for the patterned regulation of three-dimensional structures in microscale materials, limiting its practical application in surface functionalization. In this work, we propose a novel solvent-induced chain conformation modulation strategy, enabling both forward patterning and reverse pore erasure on polyacrylonitrile (PAN) microspheres. By treating the microspheres with solvents of different polarities (e.g., isopropanol, tetrahydrofuran), reversible regulation of surface morphology from raspberry-like rough textures to smooth interfaces was achieved. After carbonization, the surface morphology of the microspheres exhibited a strong correlation with their electromagnetic (EM) absorption performance. The rough surface structure enhanced interfacial polarization and energy dissipation, leading to excellent EM wave absorption performance (minimum reflection loss: –30.48 dB, maximum effective absorption bandwidth: 3.84 GHz). This work not only establishes a versatile patterning strategy for microscale materials but also provides fundamental insights for designing high-efficiency EM absorbing materials.
This review emphasizes the use of natural reinforcements in polymer matrices, achieved by application of advanced 3D printing technologies, to foster sustainable engineering practices. The environmental issues associated with the use of conventional petroleum-based plastics have risen, biodegradable and eco-friendly plastics are gaining in demand, making the use of biopolymer matrices and natural fillers more critical. Using additive manufacturing technologies, geometry can be controlled precisely, material usage is minimized, and design flexibility is maximized, and creating lightweight, mechanically optimized, and environmentally friendly composite parts. Recent advances in material development, printing technologies, and post-processing techniques have helped to broaden the applications of bio-reinforced composites in the energy sector, automotive industry, structural, and biomedical industry. Experimental results indicate that these composites can be optimized based on the type of reinforcement, compatibility of the fiber and matrix, and the method used for 3D printing. The mechanical and functional results of FDM, SLS, and SLA/DLP vary, and this needs to be carefully matched with the requirements of the application. There are still some knowledge gaps regarding long-term durability, environmental stability, and replicability under real-world conditions. This review elucidates the possibilities and constraints of 3D printed bio-reinforced polymer composites, and their potential to reduce the environmental impact while also fulfilling the functional requirements of contemporary engineering processes. Standardized experimental protocols, optimization of material formulations, and scalable manufacturing strategies should be the subject of future research to enable the complete exploitation of the sustainable and circular economy potential of these composites.
Collision-induced unfolding of trp-cage and ubiquitin is studied using molecular dynamics simulations of protein ion drift in helium. We first simulate the drift of protein ions in a strong electric field, where they become activated, increasing their internal energy through collisions with gas molecules. We then simulate the drift of activated protein ions in a weak field, where they cool to a temperature close to the gas temperature. To reduce the time required for activation and cooling, the simulations are carried out at gas pressures significantly higher than the experimental ones. The internal temperature of proteins reaches steady-state values within a few nanoseconds. Their radius of gyration changes almost simultaneously with the change in temperature or even somewhat faster. For both trp-cage and ubiquitin, it increases significantly upon protein activation and returns to nearly its pre-activation value upon protein cooling. This indicates that upon activation these proteins adopt unfolded conformations and upon cooling they become compact again. The collision cross section is calculated based on the mobility determined under conditions where the protein temperature is close to the gas temperature. These calculations show that activated and then cooled proteins have collision cross sections close to those of non-activated proteins. This is in contrast to the results of ion mobility experiments, in which activated proteins have larger collision cross sections after cooling than non-activated ones. The distance between the N and C termini in activated and then cooled proteins differs from the distance between these ends in non-activated proteins. This indicates that, despite similar radii of gyration, these proteins differ significantly in conformation.
