Band 44, Heft 1

In recent decades of research, organic coatings have been considered the most effective and economical measure for corrosion protection of metals. However, defects in organic coatings created during the curing reaction provide corrosion channels for corrosive media, which in turn accelerate the failure of metallic materials. Functional nanomaterials are considered to be the key to solving this challenge. Metal organic frameworks (MOFs) materials, as an emerging nanomaterial, show great potential as a durable and efficient nano-corrosion filler in organic anti-corrosion coatings. Therefore, this paper reviews the application of MOFs materials as solid corrosion inhibitors, small molecule corrosion inhibitor vehicles and modified graphene oxide in anti-corrosion coatings and looks forward to the prospect of research on their application in engineering practice.

This study investigates the impact of gamma irradiation on the properties of waste coffee grounds (WCG)/high-density polyethylene (HDPE) composites. The composites were manufactured with 20 wt% of unirradiated and irradiated WCG at 10 and 20 kGy doses of gamma radiation. Through the utilization of a two-roll mill followed by a hydraulic press. The properties of the composites were analyzed through several methods, including contact angle measurements, hardness and tensile tests, thermogravimetric analysis (TGA), and scanning electron microscopy (SEM), in order to understand the influence of gamma irradiation. The addition of WCG decreased the tensile strength of the composite. However, gamma irradiation at 10 and 20 kGy led to substantial improvements in thermal stability and tensile strength compared to unirradiated samples. The SEM images showed the alterations within the fiber-matrix interface that corroborated the enhanced tensile properties after the treatment. While FTIR spectra confirmed the changes in functional groups of WCG caused by the irradiation process, gamma irradiation treatment not only increases fiber-matrix adhesion but also significantly improves the water resistance of the composites. These results suggest that gamma irradiation can be used for the modification of agro-waste materials as a beneficial process and the fabrication of high-performance, environmentally friendly composites.

Focusing on the study of the phase separation behavior of triblock copolymer and linear low-density polyethylene (LLDPE) systems helps to understand the influence of microstructure on the properties of poly(vinylcyclohexane)-b- poly(ethylene)-b-poly(vinylcyclohexane) (PVCH-PE-PVCH/LLDPE) blends. We prepared a series of blends of LLDPE and PVCH-PE-PVCH and explained their compatibility from the microstructure. The research findings indicate that despite having similar block compositions, PVCH-PE-PVCH with a higher molecular weight exhibits significantly stronger phase separation and crystallization ability compared to PVCH-PE-PVCH with lower molecular weight. In PVCH-PE-PVCH/LLDPE blends, the addition of 10 %, 20 %, and 30 % LLDPE induces earlier crystallization and crystal phase separation of polyethylene (PE) fragments. In addition, compared to the lower molecular weight of PVCH-PE-PVCH, the higher molecular weight of PVCH-PE-PVCH exhibits a higher tendency for independent crystallization and shows significant crystal phase separation during the cooling crystallization process when blended with LLDPE. The PE segments in the lower molecular weight of PVCH-PE-PVCH can more easily enter the nanoscale domain of LLDPE. Impact fracture electron microscopy also reveals better compatibility between the lower molecular weight of PVCH-PE-PVCH and LLDPE compared to the higher molecular weight of PVCH-PE-PVCH. Furthermore, the blends of lower molecular weight of PVCH-PE-PVCH and LLDPE exhibit a greater growth rate in elongation at break.

Ultra-high molecular weight polyethylene (UHMWPE) generally does not have high resistance to wear and are characterised by poor thermal stability when exposed to long working condition. To address these shortcomings, this study used hybrid graphene nanoplatelets (GN) and titanium nitride (TiN) nanoparticles to significantly enhance the wear resistance and thermal stability of UHMWPE. The nanocomposites were prepared by solvent mixing and hot compression process. Scanning electron microscope showed uniform dispersion of the nanoparticles in the UHMWPE matrix. The developed UHMWPE showed improved wear resistance and thermal stability relative to the pure UHMWPE. For instance, the wear rate reduced from 6.7 × 10 −3  mm 3  N −1  m −1 and 3.67 × 10 −2  mm 3  N −1  m −1 for pure UHMWPE to 2.687 × 10 −5  mm 3  N −1  m −1 and 1.34 × 7 × 10 −4  mm 3  N −1  m −1 for UHMWPE–2 wt% GN–10 wt% TiN at applied loads of 10 N and 20 N respectively. This is about 100 % increment in wear resistance at the respective applied loads compared to the pure UHMWPE. The thermal stability of the fabricated nanocomposites was studied using the thermogravimetric analyser (TGA). The addition of nanoparticles significantly reduced the thermal decomposition of UHMWPE matrix. The enhanced properties of the UHMWPE–GN–TiN nanocomposites may be attributed to the network structures formed from the dispersion of the GN and TiN nanoparticles in the UHMWPE matrix with promoted molecular chains interlocking.

The feasibility of perlite particles used in poly(ε-caprolactone) (PCL)/poly(lactic acid) (PLA) composite films by melt blending is explored to improve their mechanical property and analyze their antibacterial effect. The effect of perlite content on the mechanical, thermal, hydrophilic, and antibacterial properties of composite films is investigated. Results show that incorporation of 10 wt% perlite in PCL/PLA film improves the tensile strength and hydrophilicity by 1.2 times and 25 %, respectively. After perlite addition, the melting crystallization and glass transition temperature of PCL/PLA film are improved. The presence of perlite also confers antibacterial benefits to the composite film. PLA-based materials are used in the fields of medical materials and food packaging, and their ability to degrade in seawater has been a long-standing goal. In this study, the addition of PCL and perlite not only increases various properties and antibacterial effects, but the blending of inorganic materials and organic materials can destroy the link strength of polymer chain segments of organic materials and help them degrade in seawater. The prepared composite film features broad prospects for the development and application of various fields, such as food packaging and medical materials, reduce white pollution in the ocean.

Predictive maintenance techniques are increasingly important in Industry 4.0; they can be applied to nonreturn valves to mitigate waste from improper replacement. To improve such predictive maintenance, this study used four nonreturn valves with different outer diameters to investigate the effects of wear on process variables and product quality under different process parameters. The results indicated that melt temperature (process parameter) had the most substantial influence on the amount of melt backflow. The process variables are the screw position at the end of the packing stage, the slope of the screw position during the packing stage, and peak pressure. The study investigated the influence of nonreturn valve wear on the entire molding process over different periods. The findings can be extended to prediction models for developing process windows and realizing the predictive maintenance of nonreturn valves in injection molding machines.

Based on the tuna swarm optimization-based support vector machine (TSO-SVM) and the multi-objective sparrow search algorithm (MOSSA), this paper proposes a multi-objective optimization approach for injection molding of thin-walled plastic components, addressing the issues of warpage deformation and volume shrinkage that compromise molding quality. Firstly, data samples are obtained based on the Box–Behnken experimental design and computer-aided engineering (CAE) simulation. Subsequently, SVM is employed to build a predictive model between the experimental factors and quality objectives. Additionally, the TSO is applied to optimize the hyperparameters of SVM, aiming to enhance its regression performance and prediction accuracy. Finally, the MOSSA is employed for multi-objective optimization, combined with the CRITIC scoring method for decision-making, to obtain the optimal combination of process parameters. The obtained parameters are then validated through simulation in Moldflow software. After optimization, the warpage deformation is reduced to 0.5085 mm, and the volume shrinkage rate is decreased to 7.573 %, representing a significant reduction of 40.9 % and 18.1 %, respectively, compared to the pre-optimized results. The remarkable improvement demonstrates the effectiveness of the method based on TSO-SVM and MOSSA for the efficient monitoring of the injection molding process.

This study explores the use of focused electron beam (FEB) dot irradiation and tensile stress to control crazing formation in polymers at the microscale. Polyethylene (PE) containing carbon was subjected to FEB dot irradiation at 5–20 kV of accelerating voltage, followed by nominal strains of 0–70 %. The results revealed that FEB irradiation affects the structure and mechanical properties of PE. The Raman spectroscopy showed a glassy polymer of amorphous structure with the intensity changed after irradiation, which led to craze formation at the location of the electron beam dot irradiation after the tensile deformation. Rhombus-shaped crazes were observed at the locations of the electron beam irradiation in the dot area, which were evenly distributed and sized. Our findings provide insights into the control of crazing location in polymers and provide a promising approach to controlling the different shapes and sizes of crazing in polymers for future applications.