Experimental Research on Polymer-Based Coaxial Sealing Systems of Hydraulic Cylinders for Small Displacement Velocities

Reducing friction in the coaxial sealing systems of hydraulic cylinders is one of the solutions for increasing the energy efficiency of industrial actuations. This is a requirement, particularly in the case of small velocities that carry the risk of eigen-vibrations and/or stick-slip. The authors discuss the experimental research conducted on three coaxial sealing systems made from thermoplastic polymer and polyurethane type materials. The paper presents the equipment and method used for the experimental determination of static and kinematic friction coefficients and discusses the subsequent results obtained to test different working parameters. The experimentally determined friction coefficients yielded a range of materials recommended for coaxial seals such as to minimize the occurrence of jerky operation.

Mechanical Properties of Nylon Parts Produced by Fused Deposition Modeling

Fused deposition modeling (FDM) is a widely used additive manufacturing technique for producing polymeric parts. While most commonly used FDM filaments are PLA and ABS, nylon is a widely used thermoplastic polymer in industry. This study investigated the mechanical properties of FDM-produced specimens made of nylon and quantified the effect of process parameters such as raster orientation and nozzle temperature on the mechanical properties. As the nozzle temperature increases, specimens become stronger with higher elongations at the break. This is mainly due to the improved fusion between the layers, provided by an expansion of the heat-affected zone. On the other hand, specimens with diagonal raster orientation exhibit higher elongations than those with perpendicular and parallel raster. The findings also emphasize the synergistic effects between nozzle temperature and printing orientation, showing that optimization should consider the two parameters together. Overall, FDM can produce strong nylon parts with adequate ductility suitable for load-bearing applications. However, achieving such results requires a detailed optimization of process parameters.

Influence of Machining Parameters on the Surface Quality of Technical Plastics

The article deals with the evaluation of the influence of conventional methods of machining on the surface quality of selected technical plastics. The thermoplastic polymer polyoximethylene (POM-C) Ertacetal C and polyamide (PA 6) Ertalon 6SA were selected for machining. Both materials are suitable for machining and are used for the production of precision mechanical components (e.g. gears, plain bearings, guides, etc.), but also in electronics and electrical engineering. In all these applications, the quality of machined surfaces is important, especially for functional surfaces that interact with other surfaces. Test specimens from these materials were turned and milled. The technological conditions of machining (revolutions per minute n, cutting speed vc , feed f, depth of cut ap ) were adapted to achieve approximately the same surface roughness values. The milled samples were machined with and without cooling medium (for drought). Turning was performed only dry. As the cutting speed vc increased, the surface roughness of the turned Ertacetal C material decreased, while milling led to a deterioration in the roughness as the cutting speed vc increased. Similar behavior was observed for Ertalon 6SA. The process fluid led to a deterioration in the roughness of the milled surfaces of both plastics. Turned surfaces showed worse roughness than milled surfaces.

Effect of Heat Treatment on the Properties of Polyetheretherketone and its Composite

Polyetheretherketone (PEEK) is a semicrystalline thermoplastic polymer with high chemical resistance, thermal stability and excellent mechanical properties. In the present work, neat PEEK and 3% bioactive glass/PEEK composites were annealed at various temperatures (100 °C, 200 °C and 300 °C) for (30 and 60) min and characterized with mechanical and density tests, differential scanning calorimetery and Fourier transform infrared spectroscopy. Results manifested bioactive glass powder enhanced the properties of the PEEK matrix. Thermal annealing at (200 and 300 °C) had a positive influence on the mechanical properties and density owing to increase in the level of crystallinity, whereas annealing at (100 °C) had not effect on the properties.

Mixed or Contaminated Waste Plastic Recycling through Microwave - Assisted Pyrolysis

A single type of thermoplastic polymer is easily recycled through a mechanical process, but this way can’t be followed in the presence of mixed or contaminated plastic. In this case, one of the main followed solutions is a thermochemical process and among them, microwave-assisted pyrolysis is one of the emerging technologies. This chapter offers an update of the microwave-assisted pyrolysis of mixed or contaminated waste plastic as a very promising example of chemical recycling. Furthermore, some unpublished results in this field will be reported such as the pyrolysis of waste lead containing polyethylene coming from end cycle batteries or the pyrolysis of waste polypropylene from facemasks used for covid protection. Finally, some examples of pilot plants will be described and commented as well as several industrial cooperations.