Macromolecular Symposia最新文献

A product's environmental impact spans its entire lifecycle, from creation to disposal. The circular economy aims to eliminate this impact and resource waste by closing resource flow loops. In this perspective, circular design strategies are essential in achieving this goal. The end-of-life products should allow for easy material separation to enable reintegration into production cycles. In this work, design strategies that favor circularity, such as design for disassembly and design for recovery, were considered. The modular redesign of a passenger vehicle seat armrest was conducted with the purpose to achieve modularity, lightness, comfort improvement, easy maintenance, and reconfigurability of the armrest assembly. Finite element virtual tests were performed by using Ansys Workbench, in order to simulate, respectively, a loading condition according to NF F31-119 standard and an act of vandalism to separate the coupled parts of the new armrest. The results obtained in terms of strength and stiffness of the redesigned train seat armrest were considered satisfactory.

Surface modification through forming, micro grooving, micro dimples, and microchannel is known as surface texturing. In addition to other related techniques on the substrate surface, laser and micromachining are used to accomplish this. The surface properties of the Arbofill Fichte biodegradable polymer with four and six passes, hexagonal and square patterns, and laser texturing are presented in this study. The results were focused on surface microscopy and topography of the four textured samples. Based on the acquired results, it is also possible to replace non-biodegradable polymers from other areas of activity.

The integration of new technologies such as the internet of things and artificial intelligence in industrial automation represents the next stages of development in industrial engineering. This paper focuses on studying two automated control methods for recognizing a part on an industrial conveyor belt, enabling remote monitoring of the entire belt's operation. The main objective of this study is to monitor and regulate the functioning of a conveyor in a virtual environment by analyzing parameters resulting from the comparison of the two methods. Identifying the primary object on the conveyor and analyzing data in real time are key aspects of the entire process of simulating automation. Developing applications for identifying parts on the industrial conveyor can enhance the speed of real-time information analysis. Upon identifying a missing object or a nonconformity, an alert system notifies the responsible personnel who can take immediate action.

Ensuring sustainability in the industrial sector is a global priority, encompassing environmental, economic, and social dimensions. Achieving this objective requires the development of efficient strategies for product value retention, including numerical finite element (FE) models to predict component life and optimize resource utilization. For spur gears, as an example, accurate FE models are essential to replicate experimental behavior and estimate the number of cycles to failure (N_f) under operational loads. This study applies the local average strain energy density (SED) method to predict the residual life, that is, N_f, of a spur gear under varying operational loads ranging from 68 kN to 95 kN. A systematic approach was adopted: (i) developing geometric and FE model (using 2-D plane strain elements) of the gear to replicate an existing experimental setup, (ii) determining a suitable control radius R₀ to define the control volume for SED calculation, and (iii) validating the FE model against experimental data. The use of R₀ was instrumental in accurately capturing the energy density distribution, enabling precise residual life predictions. Results showed good agreement between SED values and experimental data, confirming that higher load levels led to increased SED values, which in turn resulted in lower N_f.

The furniture industry is one of the world's most important sectors, but due to the scarcity of wood and its high-cost companies have to look for alternatives. Natural fiber composites represent one alternative because many fibrous plants are easy to cultivate and generate high yields. The purpose of this work is to present formulations of materials that use short fibers such as poplar and willow. The paper presents five formulations of composite materials using willow, poplar, and hemp fibers, mixed with thermoplastic fibers, in different percentages. The consolidation in the form of a fibrous layer is done by Carding Airlaid Fusion Technology (CAFT). From the S5 material (20% willow, 20% poplar, 20% hemp, 5% bicomponent, and 35% polypropylene) twelve boards (marked S5.1–S5.12) are thermoformed by setting-up different parameters. This material was characterized, and the results are presented in the paper.

FDM (fused deposition modeling) 3D-printed parts, based on acrylonitrile butadiene styrene (ABS) with multi-walled carbon nanotubes (MWCNTs), are manufactured to obtain different multi-scale configurations of the internal conductive pathways. By appropriately selecting materials and printing parameters, it is possible to align MWCNTs along the printing direction, leading to an increase of electrical conductivity from 6.88  × 10⁻² S/m before printing to 1.19 × 10¹ S/m of a single printed filament. Consequently, the conductive network arrangement through the sample justifies the higher electrical conductivity parallel to the printing direction (1.22 S/m) than its value perpendicularly measured (7.34 × 10⁻² S/m) in 3D-printed samples. This approach, together with a suitable choice of the electrical contact position, allows controlling the flow of the electrical current, conferring parts the ability to heat up when subjected to an electrical source selectively. This energy-saving strategy can be advantageously applied to print quickly, in a single step, electronic devices, thermistors capable of converting electrical energy into thermal energy, heat exchangers, and electromagnetic interference (EMI) and radio frequency interference (RFI) shielding.

The present study examines the electrical response of nanocomposites to water uptake. Specifically, an electrical signal was employed to detect the amount of water absorbed in a carbon nanotube-based epoxy composite. The investigation focused on changes in the electrical resistance of the composite with a filler content (0.1% by weight) near the electrical percolation threshold. Water penetration results in “non-Fickian” diffusion behavior due to the composite's viscoelastic nature and plasticization effects. The variation in time of the resistance change ratio, similar to that of water absorption, allows associating the electrical resistance measurement for the amount of the absorbed water by the use of a sensitivity factor.

Attempts to identify a solution for a part made of polymeric material that would present increased resistance to bending led to the proposal of a composite-type structure with a matrix of polymeric material and metallic reinforcing elements. Experimental research is designed and materialized to obtain information regarding the behavior of a part of anisotropic composite polymeric material under bending stress. The study confirms the existence of different bending strength values for various positions of the part to the direction of the force applied to the part to generate bending stresses.