Band 40, Heft 4

Optimization is generally referred to as making the best and most effective use of materials. Optimization plays the most significant role when it comes to the field of research and development. Developing new products needs the best results with optimal time, cost, and resources. Especially in the case of industrial experiments, optimizing materials can save time, money, and manual power. So, it is necessary to have a comprehensive knowledge of various optimizing techniques currently adopted in industry. Hence this review covers the multiple types of polymer matrix composites manufacturing techniques currently adopted in industry, focusing on the manufacturing problems from the optimization perspective. Also, this review addresses some of the optimization approaches that current researchers attempt at every step of their research journey. Generally, optimization has to be coupled with the advancement of the manufacturing process that provides an ideal solution for cost reduction, energy consumption minimization, and improved competitiveness while assuring the end products’ quality. Stochastic algorithms such as Genetic Algorithms and Particle Swarm Optimization are examples of advanced statistical optimization techniques adopted by researchers in solving process parameters. Furthermore, experimental approaches such as the Taguchi Method and Response Surface Methodology for polymer matrix composite manufacturing optimization are also discussed in this review. Last but not least, a brief overview of how 3D printing can benefit the fabrication of polymer matrix composites is mentioned.

Nowadays, fiber-reinforced composites have gained attention due to their potential to replace conventional materials in numerous applications. Researchers have shown considerable interest in using natural fiber–based composites for structural applications in the building, aerospace, defense, military, and automotive sectors. These materials possess unique characteristics that enhance their appeal. Kenaf fiber has become a preferred reinforcement material for composites due to its rapid growth in various climatic conditions and economic viability. It is increasingly recognized as an eco-friendly alternative to glass fiber composites. To enhance the performance of composites, researchers have found that the use of filler materials and chemical treatments significantly improve the mechanical characteristics and reduce the organic content in composite laminates. This study provides an overview of various chemical treatments that have been studied for kenaf fiber, the mechanical properties, and the applications of kenaf fiber in various fields. It explores the impact of chemical treatments on the surface of kenaf fiber and the mechanical properties of the composites created with various amounts of natural and synthetic fillers.

Poly(methyl methacrylate) microspheres are used in various fields of application including clinical dentistry and surgery. Creating new technological schemes and modernizing already known technologies of poly(methyl methacrylate) microspheres production have developed rapidly during the last 50 years. In this work, the influence of suspending agents (type, concentration etc.) on the average size of microspheres is shown. Poly(2-acrylamido-2-methylpropane sulfonic acid) and its sodium salt are proposed as very effective suspending agents, allowing to produce microspheres of required size under various conditions. The effect of initiator concentration and stirring speed on average size of particles is also investigated. A technological scheme is proposed in accordance to experimental data.

In this study, the influence of artificial aging on the mechanical and thermal properties and VOC emissions of medical grade polypropylene (PP) is investigated. For the investigations, tensile test specimens were produced on an injection molding machine. To test the long-term stability of the materials, the ASTM 1980 guideline was adopted at the temperatures of 65 °C, 90 °C and 120 °C. The thermal, mechanical and emission properties were tested using differential scanning calorimetry (DSC), tensile tests and GC-MS analysis before and after artificial aging. The results of the tensile tests show a decrease in elongation at break with increasing temperature and storage time. Similarly, the results of the DSC measurements show an increase in melting enthalpy, which indicates post-crystallization in the material. The GC-MS results show that the emissions due to artificial aging decrease with increasing temperature and storage time, so that the emissions of the samples stored at 120 °C are almost zero.

Polycarbonate (PC) – fiber composites are high heat resistant, and thermal interface materials for electronics applications because of their good thermal stability, impact resistance, strength, low scratch resistance, and low fracture toughness. This research intends to enhance the functional behaviour of PC poly-fiber composites promoted with unidirectional carbon fibers (CF) and 1–5 wt% of 50 nm silicon carbide (SiC) particles with epoxy-based coupling agent, prepared via compression moulding associated with hot pressing. The synthesized PC composite samples PC1, PC2, PC3, and PC4, containing 0, 1, 3, and 5 wt% of nano SiC, were subjected to mechanical testing and the results are compared to find the optimum behaviour. The PC4 composite sample of PC/5 wt% SiC/CF/PC laminate showed optimal performance, and transmission electron microscope (TEM) analysis confirmed the presence of SiC and CF as effective interfaces to the PC matrix. The PC/5 wt% SiC/CF/PC hybrid nanocomposite provides optimum fracture toughness (5.5 MPa 0.5 ), improved hardness (94HV), superior flexural strength (188 MPa) and enhanced yield (96 MPa) & tensile strength (105 MPa), which are greater than those of pure PC laminates. The PC4 composite is proposed for automotive seat frame applications.

Since the mid-20th century, intraocular lenses (IOLs) have been widely used in cataract surgery to restore vision in patients with refractive issues, replacing the natural lens of the eye. In this study, we spectroscopically characterized silicone IOLs using Fourier Transform Infrared (FTIR) spectroscopy, optical transmission measurements, and wettability investigations after exposing the lenses to UV irradiation for several hours. The results provide valuable insights into the material composition, UV protection, and overall optical quality of IOLs, which are crucial for optimizing and improving the selection of these devices for clinical use. Moreover, the experimental results explain why this material has become less commonly employed for intraocular lenses. Prolonged exposure to UV radiation induces modifications in the surface layers, increasing wettability and compromising optical properties, including a significant reduction in visible light transmittance.

As a biodegradable material, polylactic acid (PLA) is widely used in healthcare industries, however, its bacterial properties cannot meet the requirements. Chitin, a natural antibacterial agent, is difficult to directly melt blend with PLA due to agglomeration. In order to enhance the compatibility between chitin and PLA, in this study, firstly, chitin was decomposed by cellulase to prepare enzymolysis chitin (EC). The viscosity and particle size of EC were measured and the optimal enzymolysis conditions were chosen. Then, the modified chitin antibacterial agent (MCAA) was prepared by mixing EC with glyceryl triacetate (GTA) and polyethyleneglycol (PEG), and the biodegradable PLA/MCAA composite was prepared by melt blending. Finally, the tensile, thermal, antibacterial properties, and the micromorphology of the PLA/MCAA composite were investigated. The results show that at a pH of 6.4 and a temperature of 55 °C, EC exhibited low viscosity and particle size after an enzymatic hydrolysis time of 4.5 h. Compared with PLA, PLA/MCAA composite exhibited better antibacterial effects against Escherichia coli and Staphylococcus aureus . Furthermore, in comparison to the PLA/chitin composite, there was less agglomeration in the PLA/MCAA composite, and the particle distribution of MCAA was more uniform.

Reliable process models are a valuable asset in polymer extrusion to reduce downtimes and rejects, to improve process efficiency, and to accelerate the development of new screw designs. With ongoing progress in computational capabilities, increasing attention is paid to modeling techniques that infer predictions directly from the process data. Out of these, symbolic regression is an attractive option for process engineers, since it provides information as ready-to-use analytical mathematical expressions. However, extensive workload for data curation and model generation impedes obtaining regression models of high precision and general validity. In polymer extrusion, integrating domain knowledge into the regression data is already known to support the search for accurate prediction models. To assess this benefit systematically and quantitatively, we developed symbolic regression models for the pumping characteristics of single-screw extruders from three-dimensional fluid dynamics simulations, including different modules of domain knowledge at data preprocessing: Initially, models are created (i) using theory of similarity only, followed by models that further (ii) accept derived physical parameters as additional input features, (iii) combine additional input features with logarithmic scaling, and (iv) correct a theoretical approximation equation. For each case of data preprocessing, the regression models are evaluated in terms of their interpolation and extrapolation capabilities, their structural complexities, and their required training times. This study demonstrates that symbolic regression is most efficient on the original dimensionless data if nonlinear trends in dimensionless space remain below second order or within one decade. Once stronger nonlinearities occur, however, capturing these nonlinearities with prior theoretical approximations substantially enhances extrapolation capability and computational efficiency, albeit at the price of larger models.

Technical polymer profiles are often extruded while dragging them into a water bath. However, complex profiles may require additional forming tools. For example, geometrically complex profiles, such as PVC-window frames, require the use of a series of calibrators for satisfying severe geometric requirements. Calibrators are also required for rapid and homogeneous cooling as well, they must however be designed in such a way to minimize the temperature gradient along the profile thickness and hence to minimize the residual stresses of thermal origin. Within the context of numerical simulation of extrusion flows, a calibrator brings an additional downstream constraint to the kinematic equation which governs the extrudate surface shape. In the present paper, we propose a simple engineering approach for modelling calibrators used in profile extrusion, and we apply it to the non-isothermal simulation of the extrusion process for a 3D non-symmetric profile.

Modification of polymer matrices with carbon nanomaterials is a common practice for producing strong and wear-resistant composites. However, carbon nanomaterials are still not widely used in industry due to low-throughput synthesis methods. In this work, the strength and thermophysical properties of a composite based on polylactide modified with few-layer graphene were studied. The introduction of few-layer graphene leads to increase the flexural strength, thermal conductivity and wear resistance of polylactide. Few-layer graphene was obtained by self-propagating high-temperature synthesis. This method is easily scalable and allows to obtain few-layer graphene from carbohydrates. The work discusses the properties of synthesized few-layer graphene and the mechanisms of its interaction with polylactide.