Mechanical properties of carbon fiber reinforced polyamide produced by CFF method (Continuous Filament Fabrication)

The study presents the influence of content and orientation of continuous carbon fibers (CF) on the static tensile test results of a polyamide matrix (PA) composite, produced using Continuous Filament Fabrication (CFF) technology. Taking the polyamide’s crystalline structure into account, an attempt was also made to produce test specimens under various temperature conditions of the device chamber. The test samples were produced in use of the Mark Two device (Markforged, Great Britain). It has been shown that the content and orientation of the reinforcement in relation to the direction of stresses generated during the static tensile test, has a significant impact on the parameters determined in this test. The dependence presented in the article, confirms that materials in a thermoplastic matrix, reinforced with continuous fibers are a topic in line with the topic of current trends in fields of material engineering and design of structural products. The conducted research proves that the temperature in the working chamber of the Mark Two device affects formation of mechanical properties of PA+CF composites, fabricated using CFF technology. Manufacturing composites at elevated temperature resulted in significant decrease of E and Rm values for 4 out of five tests performed, but a considerable increase in their relative elongation at break was noticed.

Characterization of Polyamide 6/Multilayer Graphene Nanoplatelet Composite Textile Filaments Obtained Via In Situ Polymerization and Melt Spinning

Studies of the production of fiber-forming polyamide 6 (PA6)/graphene composite material and melt-spun textile fibers are scarce, but research to date reveals that achieving the high dispersion state of graphene is the main challenge to nanocomposite production. Considering the significant progress made in the industrial mass production of graphene nanoplatelets (GnPs), this study explored the feasibility of production of PA6/GnPs composite fibers using the commercially available few-layer GnPs. To this aim, the GnPs were pre-dispersed in molten ε-caprolactam at concentrations equal to 1 and 2 wt %, and incorporated into the PA6 matrix by the in situ water-catalyzed ring-opening polymerization of ε-caprolactam, which was followed by melt spinning. The results showed that the incorporated GnPs did not markedly influence the melting temperature of PA6 but affected the crystallization temperature, fiber bulk structure, crystallinity, and mechanical properties. Furthermore, GnPs increased the PA6 complex viscosity, which resulted in the need to adjust the parameters of melt spinning to enable continuous filament production. Although the incorporation of GnPs did not provide a reinforcing effect of PA6 fibers and reduced fiber tensile properties, the thermal stability of the PA6 fiber increased. The increased melt viscosity and graphene anti-dripping properties postponed melt dripping in the vertical flame spread test, which consequently prolonged burning within the samples.

Evaluating additive manufacturing for the production of custom head supports: A comparison against a commercial head support under static loading conditions

The provision of wheelchair seating accessories, such as head supports, is often limited to the use of commercial products. Additive manufacturing has the potential to produce custom seating components, but there are very few examples of published work. This article reports a method of utilising 3D scanning, computer-aided design and additive manufacturing for the fabrication of a custom head support for a wheelchair. Three custom head supports, of the same shape, were manufactured in nylon using a continuous filament fabrication machine. The custom head supports were tested against an equivalent and widely used commercial head support using ISO 16840-3:2014. The head supports were statically loaded in two configurations, one modelling a posterior force on the inner rear surface and the other modelling a lateral force on the side. The posterior force resulted in failure of the supporting bracketry before the custom head support. A similar magnitude of forces was applied laterally for the custom and commercial head support. When the load was removed, the custom recovered to its original shape while the commercial sustained plastic deformation. The addition of a joint in the head support increased the maximum displacement, 128.6 mm compared to 71.7 mm, and the use of carbon fibre resulted in the head support sustaining a higher force at larger displacements, increase in 30 N. Based on the deformation and recovery characteristics, the results indicate that additive manufacturing could be an appropriate method to produce lighter weight, highly customised, cost-effective and safe head supports for wheelchair users.

Study on composite spinning oil for polyester bulked continuous filament with high efficiency

The special spinning oil for modified polyester bulked continuous filament was prepared using compound technology. The mixture of smoothing agent, emulsifier, collecting agent, and antistatic agent at certain proportions shows synergistic effect, which improves the usability of spinning oil on the whole. According to the use of different components, polyoxyethylene ether, polyether, and white oil spinning oil are synthesized, respectively. The basic performances of self-made spinning oil are better than those of a commercially available spinning oil, and its production rate can reach 93%.