Processing Of Polymer Composites Research Articles

Surface quality formation at polymer composite details’ abrasive processing

The article presents the results of studies of the process of abrasive processing of parts made of polymer composite materials. Special features of processing of polymer composites, technology of production of preform by hydroabosive cutting are described. Studies have been carried out and stages of preparation of a part made of polymer composite material for “gluing” operation have been described. Dependencies for determination of surface roughness during hydroabrasive cutting of polymer composite material are given. Studies have been carried out to achieve the necessary surface roughness when gluing blanks. A curvature is given describing the surface roughness, which is necessary to achieve a reliable adhesive connection. Results of theoretical and experimental studies of hydroabrasive cutting process are presented. Technique of the execution, applied tools and equipment are described. The results of theoretical and experimental studies were compared. Their high convergence has been established. The results of experimental studies on preparation of parts from polymer composite materials for gluing are presented. Abrasive tool, processing modes are selected. Design method for abrasive processing of parts made of polymer composite materials is proposed.

Bidirectional Gated Recurrent Deep Learning Neural Networks for Smart Acoustic Emission Sensing of Natural Fiber–Reinforced Polymer Composite Machining Process

Abstract Natural fiber–reinforced polymer (NFRP) composites are increasingly considered in the industry for creating environmentally benign product alternatives. The complex structure of the fibers and their random distribution within the matrix basis impede the machinability of NFRP composites as well as the resulting product quality. This article investigates a smart process monitoring approach that employs acoustic emission (AE)—elastic waves sourced from various plastic deformation and fracture mechanisms—to characterize the variations in the NFRP machining process. The state-of-the-art analytic tools are incapable of handling the transient dynamic patterns with long-term correlations and bursts in AE and how process conditions and the underlying material removal mechanisms affect these patterns. To address this gap, we investigated two types of the bidirectional gated recurrent deep learning neural network (BD-GRNN) models, viz., bidirectional long short-term memory and bidirectional gated recurrent unit to predict the process conditions based on dynamic AE patterns. The models are tested on the AE signals gathered from orthogonal cutting experiments on NFRP samples performed at six different cutting speeds and three fiber orientations. The results from the experimental study suggest that BD-GRNNs can correctly predict (around 87 % accuracy) the cutting conditions based on the extracted temporal-spectral features of AE signals.

Smart Manufacturing Process of Carbon-Based Low-Dimensional Structures and Fiber-Reinforced Polymer Composites for Engineering Applications

Reinforced polymers have gained a significant interest in the research community in recent years due to their enhanced performance as compared to their parent polymers. Nanosized reinforcement-based polymer composites have shown a considerable enhancement in performance as compared to micro-/macro-sized fillers. But achieving a high degree of filler alignment in nanocomposites via conventional manufacturing techniques continues to be a challenging task. Additive manufacturing (AM) is a possible solution to this challenge and has undergone a significant development in recent years. AM is an efficient technique to fabricate nanocomposites in complex shapes which uses a layer-by-layer method to fabricate materials and thereby eliminates the need for multi-step processing and the use of fasteners/joints to fabricate complex structures. Due to a wide range of properties and the existence of carbon in a variety of forms, carbon filler-based polymer matrix composites are suitable for applications in several technical sectors. AM of carbon-based structures and fiber-reinforced polymer composites enables the production of highly customized parts with a high degree of filler alignment. AM techniques which are generally employed for the fabrication of carbon-based fillers/fiber-reinforced polymer composites are fused deposition modeling, stereolithography, direct ink writing and selective laser sintering. Although AM techniques are efficient, some critical issues such as voids and defects between interlayers, the low adhesion strength between filaments, part curling and insufficient curing of layers need to be addressed to utilize its full potential.

MODELING OF THE INSTRUMENTAL MICROGEOMETRY IN THE PROCESS OF ITS WEARING AT CUTTING OF COMPOSITE MATERIALS

The most difficult problem during the machining of polymer composite materials is the intensive wear of the tool, which leads not only to a decrease in its working capacity, but also sharply worsens the quality of the operations performed. In this paper, we consider the process of wear of the cutting edge of a tool as a change in its microgeometry with respect to the initial state. The physical nature of abrasive wear as a process of contact interaction of the flank surface of a tool with a destroyed filler and intense heat due to friction is considered. Based on the laws obtained experimentally, we can conclude that the initial geometry of the cutting edge of the tool already sharply changes during the running-in period and by the beginning of stationary wear takes on some form, which later changes only quantitatively without distortion of the stable worked-in shape. In fact, we can say that the initial geometry of the cutting edge, selected for some rational reasons or as a result of solving the optimization problem, serves only for effective cutting during the running-in period, after which its influence on the further operation of the tool under stationary wear is not significant.An analysis of the wear process of the cutting edge of the tool during the processing of polymer composites showed that there is a strong correlation between the appearance of wear, the growth of power loading, thermal stress and the appearance of various defects of the treated surface. Various models of describing changes in the microgeometry of the cutting edge in the form of geometric models with their advantages and disadvantages are presented. The modern experimental achievements in studying the nature of changes in microgeometry in the process of wear are examined in detail. On this basis, an assumption was made about the one-parameter nature of changes in the geometry of the cutting edge in the process of interaction with the composite. The further development of the study and the creation of a mathematical model are proposed, linking the change in the tool’s microgeometry over time as a function of one parameter, depending on the initial geometry of the tool.

Assessing the Influence of the Sourcing Voltage on Polyaniline Composites for Stress Sensing Applications

Polyaniline (PANI) has recently gained great attention due to its outstanding electrical properties and ease of processability; these characteristics make it ideal for the manufacturing of polymer blends. In this study, the processing and piezoresistive characterization of polymer composites resulting from the blend of PANI with ultra-high molecular weight polyethylene (UHMWPE) in different weight percentages (wt %) is reported. The PANI/UHMWPE composites were uniformly homogenized by mechanical mixing and the pellets were manufactured by compression molding. A total of four pellets were manufactured, with PANI percentages of 20, 25, 30 and 35 wt %. Fourier-transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), differential thermal analysis (DTA), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) were used to confirm the effective distribution of PANI and UHMWPE particles in the pellets. A piezoresistive characterization was performed on the basis of compressive forces at different voltages; it was found that the error metrics of hysteresis and drift were influenced by the operating voltage. In general, larger voltages lowered the error metrics, but a reduction in sensor sensitivity came along with voltage increments. In an attempt to explain such a phenomenon, the authors developed a microscopic model for the piezoresistive response of PANI composites, aiming towards a broader usage of PANI composites in strain/stress sensing applications as an alternative to carbonaceous materials.

Information support of the measuring device for choosing a thermophysical experiment data processing algorithm

This paper addresses the problem of constructing a subsystem of informational decision-making support for choosing the optimal method and algorithm for calculating the thermophysical properties of polymer composites, which allows minimizing the error in determining properties under given experimental conditions. The subsystem is based on a modified hierarchy analysis method. It is built on the alternative use of four algorithms for the calculation of thermophysical properties and is included as a module in the application software of an intelligent data-measuring device for studying the curing process of polymer composites. Using simulation modeling, an assessment of the possibility of using algorithms for calculating thermophysical properties under various combinations of experimental conditions was made. The structure, composition, principles of construction, purpose, capabilities and parameters of the main modules of the applied software of the data-measuring device are described.

Additive manufacturing of functional polymer-based composite with enhanced mechanoluminescence (ZnS:Mn) performance

Triboluminescence (TL) is a phenomenon of light emission induced by impact, stress, fracture, or an applied mechanical force. This phenomenon can be used to detect, evaluate, and predict mechanical failures in composites. In this report, we utilized manganese-doped zinc-sulphide (ZnS: Mn) and Polystyrene (PS) composite to fabricate a TL functional part via additive manufacturing. The morphology of the particles inside the polymer matrix were studied using scanning electron microscopy and micro CT scan. Thermoanalytical techniques such as differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were carried out to evaluate the thermal transitions and degradation of the composites. The mechanoluminescence performance of the printed samples is evaluated by three-point flexural test and observed to depend on processing conditions that can be utilized to achieve a strong light signal at different mechanical loads. The polymer composite fabrication and processing reduced particle size, enhanced particle dispersion, and altered the mechanical properties of the polymer to help increase the mechanoluminescence response up to 10 times in the 3D printed parts. The unique mechanoluminescence properties of 3D printed luminescent composite have great potential for structural monitoring applications.

Microwave processing of carbon fibre polymer composites: a review

Microwave processing of carbon fibre-reinforced polymer (CFRP) composites is gaining increasing attention as an alternative to conventional thermal processing techniques. It has the potential to reduce part processing times and alleviate the bottleneck that often exists in composite component production. The present study reviews the current research and the state-of-the-art of microwave processing of CFRP composites. The benefits and limitations of microwave processing compared with traditional thermal processing methods are examined. The mechanical properties of microwave-cured composites are compared against conventionally-cured counterparts with varying levels of success. Current industrial microwave heating technologies are also examined. It is evident that microwave processing of polymer composites is promising but has notable limiting factors which have stunted its uptake in industry. Due to their prevalence in literature, CFRP composites with thermosetting matrices are the focus of this review. However, potential applications to carbon fibre-reinforced thermoplastics are also briefly described.

Hybrid polymer composite materials. Part 2. Preparation technology

The main methods (pressing and winding) of the processing of hybrid polymer composites to obtain items were examined. Advantages and disadvantages of the methods were noted. Good combinations of different-module fibers (carbon, glass, boron, organic) in hybrid polymer materials are described, which allow one to prepare materials with high compression strength on the one hand, and to increase fracture energy of samples and impact toughness on the other hand.

Additive Manufacturing of Anisotropic Concrete: a Flow-Based Pultrusion of Continuous Fibers in a Cementitious Matrix.

For the tens past years, important development has been achieved on the adaptation of additive manufacturing to the construction industry using concrete. They mostly concerns control rheology at fresh state, setting time, and technology advances. Nevertheless, the reinforcement of 3D printed part remains an open question. Different reinforcement protocols have been proposed in the literature, often based on traditional way of reinforcement. In this context, the aim of this paper is to present an alternative way to reinforce extruded concrete or other pasty materials inspired by the composite industry. The present patented manufacturing methodology is based on extrusion-based additive manufacturing, inspired by pultrusion and co-extrusion process of polymer composites, but taking full advantage of the specific rheological behaviour of cementitious matrix. It consists in the continuous addition of numerous continuous yarn in the extruded mortar before the final extrusion. A comparison between those processes is made. Depending on the number of yarns and their sizes, this process is showed to provide ductility for limited amount of reinforcement and have the potential to be an alternative to passive rebar traditionally used in concrete by providing a true reinforcement in traction to the structure for larger number of yarns, changing extruded concrete in unidirectional composite with brittle matrix. Using appropriate matrix formulation, the mastering of its yield stress during the extrusion is showed to be the most important process parameters.

INFLUENCE OF THE STRUCTURE OF EPOXY COMPOSITE FILLED WITH DISCRETE FIBERS ON IMPACT FRACTURE OF VEHICLE PARTS

The influence of the content of a mixture of discrete organic fibers on the mechanical strength and nature of destruction of epoxy composites is investigated. It is proved that the introduction of fiber additive into an epoxy binder at an optimum content (q = 0.01 wt.%) increases the impact strength of polymer composites 1.8 times in comparison with the epoxy matrix. It is shown that the growth of impact strength is connected with self-regulation of the structure of composites filled with discrete fibers during the cross-linking process of polymer composites. To determine the resistance of the developed composite materials to impact shocks, changes in spectra of crack propagation during impact shocks with time are investigated and deformation dependences of specimens on shocks are found. The destruction surface of composite materials filled with fiber additive is investigated by the optical microscopy method. An ordered structure of composite materials at the optimum content of a mixture of discrete organic fibers (without fragile areas on the destruction surface and visible granules) is found, which allows one to state the thermodynamic equilibrium in heterogeneous systems after their cross-linking. This additionally indicates a high index of mechanical strength of developed epoxy composites.

Flow visualization of additive alignment in polymer matrix depending on location of gate orifice

Thermoplastic polymer composites are considered as substitutes for metallic materials because of their advantages in terms of superior corrosion resistance, mass-productivity, lightness, etc. However, their applications are limited owing to their low melting temperature and electrically and thermally insulating characteristics. Numerous experiments are carried out to overcome these limitations and enhance physical properties by analyzing and controlling additive alignment. To achieve enhancement, it is important to understand the rheology of the additive in a polymer matrix and the resulting alignments inside the mold during the molding process. In this study, a flow visualization experiment was carried out to simulate an injection molding process of polymer composites with carbon fiber as an additive. The alignment of carbon fiber is analyzed as it travels through the gate orifice of the mold channel. An experimental device consisting of a ball-milled-carbon-fiber and Polydimethylsiloxane mixture, syringe pump and tubing, high speed camera with microscope, and lighting system is set up to visualize the additive alignment and orientation inside the mold channel. Two configurations of the gate orifice are used as mold channels. The location, length, and angle of additives were calculated by analyzing images acquired through flow visualization experiments. The orientation of fibers is observed to be determined by the relative amplitudes of velocity gradient components. In addition, it was observed that the position of the gate affects the average angle of the additives in the mold channel.

Processing and Testing of Epoxy Polymer Composites using Tender Palm Shoot Fiber and Aluminium Particles as Hybrid Reinforcements

Every year tons of plant and animal wastes are produced in the world. Some of these waste products may find some potential application in our day-to-day life. Also pure polymers are non-biodegradable and usually don’t possess requisite mechanical strength. For the first time, tender palm shoots are used as fiber reinforcement in the epoxy resin. The main objective is to compare and fabricate natural fiber reinforced hybrid epoxy composites with tender palm shoots, palymra fiber, as natural reinforcements which are generally leftovers and Aluminium powder as conductive filler by hand lay-up process at various weight percentages. Different mechanical properties, water absorption characteristics, flammability and electrical conductivity are evaluated as per ASTM standards. The test results show that these composites can be used as alternative materials for low tensile and high impact applications.

Homogeneously Dispersed Carbon Nanofiber/High-Density Polyethylene Nanocomposite Compatibilized by Dilakylimidazolium Tetrafluoroborate

High-density polyethylene (HDPE) was used in this study as a matrix for accommodating carbon nanofiber (CNF) along with ionic liquid, to investigate the effect of nanofibers loading on the morphological thermal and rheological properties of the composites. The nanocomposite materials were prepared via melt processing using dilakylimidazolium tetrafluoroborate (ionic liquid) as a compatibilizing agent. The samples blended with imidazolium ionic liquid exhibited higher thermal stability, while DSC analysis showed the clear miscibility of ionic liquid in the HDPE matrix with a single endothermic peak. The influence of CNF (ranging from 0, 0.5, 1, and 2 wt.%) and ionic liquid concentration on the viscoelastic parameters was investigated. The rheological analysis showed the shear-thinning behavior of the composites. An improvement in the viscoelastic properties was observed as the nanofiber concentration increased. Composites blended with ionic liquid (HDPE/CNF/IL) exhibited slightly lower values of complex viscosity and modulus over the corresponding HDPE/CNF nanocomposites. Therefore, it is also significant that the reduction in melt viscosity is an additional benefit for polymer composite processing as a result of the wetting effect by polymer-ionic liquid combinations.

Design and fabrication of a low-cost pilot-scale melt-processing system

Melt processing of polymeric materials is a ubiquitous technique for forming, shaping, refining and homogenizing polymers and polymer composites. Melt-processing techniques are the primary manufacturing method of consumer and industrial thermoplastic parts, especially when using commodity polymers with high-throughput production. Melt-processing, however, is underutilized in academic laboratories when developing high value-added materials due to the capital expense of the equipment and relatively large-scale required to carry out such processing. These concerns make pilot-scale melt-processing challenging, particularly for the development of new polymers or polymer composites where materials can only be generated in small-scale at reasonable costs. The current study designs and evaluates a bench-top, sub-milliliter volume extrusion and injection-molding device, which sources parts from current 3D printer technology at minimal expense. The plans presented will open this convenient technique to academic research laboratories interested in pilot-scale experiments. A systematic approach to melt processing of PLA, PLGA, and PCL polymer composites is demonstrated. Characterization of the dispersion of pharmaceuticals, small molecules and nanoparticles in melt processed polymers is presented as a demonstration of potential utility.

Processing and thermal characteristics of human hair fiber-reinforced polymer composites

Human hair is a biofiber having an exceptional chemical composition, higher strength in tension, and slow decomposition rate. In the present work, composites are fabricated by simple hand layup technique with epoxy matrix and different proportions of hair fiber (0, 5, 10, 15, and 20 wt%). Physical, mechanical, microstructural, and thermal characterization of the composite samples has been done by following the proper ASTM standards. A theoretical model has been developed to predict the effective thermal conductivity of the composite. Based on this model, a mathematical correlation between the effective thermal conductivity of the composite and the fiber content is developed. The results obtained from this correlation are in good agreement with the experimental data. This study explores the possibility of fabricating a class of epoxy composites with higher mechanical strength, superior insulation capability, improved glass transition temperature, and a low thermal expansion coefficient.

Creation of Structural Polymer Composite Materials for Functional Application Using Physicochemical Modification

The various aspects of physicochemical modification of the components of structural materials of functional application based on classical composites and nanocomposites are analyzed. Potential applications of such materials are briefly described. Ultrasonic cavitation treatment is considered as a basic method of physical modification when obtaining the indicated classes of composites. The influence of ultrasonic treatment modes on the technological and operational properties of reactoplastic polymers, as well as on the hardening of reinforced composites based on them, is investigated. Technical means of ultrasonic cavitation processing of liquid binders and polymer composites based on them are briefly described. An effective spectrum of interrelated structural and technological parameters of ultrasonic treatment has been characterized, which is established by calculation and experimentally-statistically. The design issues of the technological processes of obtaining polymer composites of functional application are analyzed. The efficiency of creating carbon fiber composite materials, as well as the prospects for creating of these materials based on reinforcing fabric with nanomodified fillers, is described. The methods of obtaining functional nanomodified carbon-composites with improved physicomechanical and operational properties, in particular with increased strength and electrical conductivity, are characterized. The effectiveness of the ultrasonic treatment and production of nanomodified thermoplastic composite materials by extrusion method is considered. Some issues of forming products from intelligent polymer composites are analyzed. The results of the survey can be used in the design of advanced technologies for the creation of functional polymer composites of functional application.

International Conference Baltic Polymer Symposium 2018

PrefaceThe issue contains selected papers of XVIII international conference Baltic Polymer Symposium (BPS), which was held in Jurmala, Latvia, from 12th of September until 14th of September of 2018.The conference is annually organized by the technical universities of the three Baltic States. Since the first event in 2001, range of the topics, covered by the conference, has comprised all aspects of modern Polymer Science, including synthesis, processing, recycling, development and characterization of polymer composites as well as revealing the possibilities of nanotechnologies. During its eighteen years of course BPS has gained considerable popularity and at the moment it is an awaited event not only for the polymer scientists but also among the researchers working in the related fields of Materials Science and Nanotechnologies due to increasing multidisciplinary of the research area. Participation in BPS offers great possibilities of showing yourself, learning, getting new experience and ideas, as well as founding new contacts. Symposium is an excellent chance for young researchers to improve their ability to present the achievements of their research to the international community.Baltic Polymer Symposium 2018 in Jurmala was visited by participants not only from the three Baltic States, but also by participants from Sweden, Spain, Taiwan, Germany, Czech Republic, Poland, Ukraine, Belarus and Russia. During the conference 5 plenary lectures were given by world-recognized scientists as well as the representative of SKELOTON technologies, global leader in ultracapacitor technology. The audience was introduced with most recent novelties in the research field of polymer materials science during 28 oral and 71 poster presentations.

Montmorillonite–triclosan hybrid as effective antibacterial additive with enhanced thermal stability for protection of plastic electrical components

The majority of parts used in the electrical apparatus are made of polymer materials; however, pure polymers do not provide the antibacterial functionality. Therefore, in order to add such property to them it is necessary to use antibacterial additives. The study concerned intercalation of triclosan (TCS) as biocide into montmorillonite (MMT) interlayer spaces was performed in order to increase TCS resistance to high-temperature treatment, which is necessary during polymer composite processing. The obtained MMT + TCS hybrids were tested for structural and antibacterial properties. The degree of biocide intercalation was assessed using X-ray diffractometry, by analyzing changes in MMT interlayer distance, and thermal analysis was performed to assess the effect of the intercalation process on the thermal stability of TCS. Antibacterial tests against Gram-negative bacteria (Escherichia coli) and Gram-positive bacteria (Staphylococcus aureus) were also carried out on the obtained MMT + TCS powders in order to confirm the bactericidal properties of TCS released from the clay after the intercalation process. As a final proof of concept, the hybrid powder, namely MMT with incorporated TCS, was incorporated into polycarbonate matrix and antibacterial activity of modified polymer samples was tested. The obtained results have proven that montmorillonite–triclosan hybrid is an effective antibacterial additive with enhanced thermal stability which can be applied for protection of plastic parts used in electrical devices.

Preparation, development, outcomes, and application versatility of carbon fiber-based polymer composites: a review

The high strength to weight ratio of carbon fiber has made it as an attractive energy-saving material over the conventional strength-bearing materials like steel. Realizing the trend, the high-weight steel is being progressively replaced by the low-weight and corrosion-resistant carbon fiber composites in many strength applications. The carbon fiber-reinforced polymer matrix composite (PMC) have thereby become forefront material in aerospace, automobile, sporting goods, and other applications which demand high strength and high modulus. Moreover, the gradual reduction of its cost curtsy to the extensive research in the field of carbon fiber technology in recent years has been opened its market in different construction applications. This review is the discussion of carbon fiber loaded a variety of polymer matrix composites where the structural importance of these composites has been emphasized. The objective of this discussion is to provide information on the whole spectrum of carbon fiber-based polymeric composites. It also includes brief discussion about preparation and properties of carbon fibers along with processing, fabrication, and structural applications of these carbon fiber-based polymer composites.