Properties Of Polymer Composites Research Articles

Effect of thermal ageing on electrical, mechanical properties of glass fiber reinforced polymer and its impact on service life

The mechanical and electrical properties of polymer composites often degrade due to environmental factors and shorten their service life. This article presents the effect of high temperatures on the mechanical and electrical characteristics of glass fiber reinforced composites and from the measurements, an attempt is made to predict the service life. Electrical conductivity, impedance and resistance are studied with a short-term temperature effect at 30, 60, 120, and 180 °C. The effect of temperature exposure at 120 and 160 °C for 1000, 2000, and 3000 h has been investigated to assess the changes in flexural, compressive, and tensile properties and for prediction of service life. Morphological studies are carried out to support some of the experimental results. The mechanical properties of composites are observed to deteriorate with the duration of aging. Flexural, tensile, and compressive strengths reveal a reduction of 8, 10, and 9%, after aging at 3000 h at 160 °C. The tensile strength and tensile modulus at 120 °C aged for 3000 h exhibit minimal changes as compared to unaged composites. However, with an increase in temperature to 160 °C, there is a reduction in tensile strength and modulus of composites by less than 10%, and 6% compared to composites with nanofillers. The variations in compression strength at 120 and 160 °C is not significant. Based on the reduction of tensile strength with temperature, the service life of composites has been estimated. For a predicted service life of 20 years, composites with nanofillers would be able to retain tensile strength of 90% of tensile strength.

Modifying Effect of Polyethylene Fractions of Different Molecular Weights on the Morphology and Properties of Reactor Polymer Compositions Based on Ultrahigh Molecular Weight Polyethylene

Reactor polymer compositions (RPCs) based on UHMWPE with Mw = 1000 kg mol–1 and low molecular weight HDPE (LMWPE) were studied. Two series of UHMWPE compositions were used to determine the influence of the molecular weight and properties of the LMWPE fraction on the morpho-logy, mechanical and rheological properties of UHMWPE/LMWPE. Сompositions, including from 10 to 80 wt % UHMWPE with Mw = 160 kg mol–1 (PE-160) were obtained in a two-stage process of ethylene polymerization with a metallocene catalyst. They differed in the order of introduction of PE-160 into UHMWPE (PE-160/UHMWPE and UHMWPE/PE-160). Compositions of UHMWPE and LMWPE with Mw = 48 kg mol–1 (PE-48/UHMWPE) with PE-48 content from 6 to 30 wt % were synthesized in a single-stage polymerization of ethylene in the presence of a tandem catalyst. A comparison of the shape and size of particles of nascent polymer products was made using the SEM method. The morphology, tensile, dynamic mechanical and rheological properties of RPC have been studied depending on the method of their preparation, the content of the low molecular weight fraction, its molecular weight and physical and mechanical properties. An increase in the proportion of PE-160 and PE-48 in PE-160/UHMWPE and PE‑48/UHMWPE leads to an increase in RPC crystallinity, tensile modulus and dynamic mechanical modulus with significant deviations from the additivity rule.

Improved coefficient thermal expansion and mechanical properties of PTFE composites for high-frequency communication

With the combined advantages of polymers and ceramic fillers, Polymer-ceramic dielectric composites are widely used in microwave substrates due to their excellent dielectric properties, good mechanical properties, and easy formability. To optimize the properties of polymer composites, it is necessary to enhance the compatibility between polymer matrix and ceramic filler. In this study, to realize polytetrafluoroethylene (PTFE) composites with low dielectric constant, low dielectric loss, good mechanical properties and appropriate coefficient of thermal expansion, PTFE/SiO2 composites were prepared by demulsification treated PTFE and modifying SiO2 with silane treatment. Compared with PTFE composites, the mechanical properties of PTFE/SiO2 composites prepared by the demulsification treatment were improved at a low SiO2 content. Compared with the untreated PTFE composites, treated PTFE composites exhibit better properties such as lower dielectric loss, good mechanical properties and lower CTE. Furthermore, the composites show low dielectric constant and loss even at frequencies up to 10 GHz.

Fabrication and microwave absorption properties of BaTiO3 -SrTiO3-Ni0.5Zn0.5Fe2O4 polymer nanocomposites

In this present work, barium titanate (BaTiO3), strontium titanate (SrTiO3) and nickel zinc ferrite (Ni0.5Zn0.5Fe2O4) were used to prepare electromagnetic wave absorption composite. Homogeneous polymer composites containing of BaTiO3 -SrTiO3 – Ni0.5Zn0.5Fe2O4 was produced by the physical mixing method. Surface morphology of polymer composites was characterized by scanning electron microscopy (SEM). Microwave absorbing and electromagnetic parameters were recorded by vector network analyzer (VNA).The influence of the ratio of nickel-zinc magnetic particles into the dielectric materials was studied. Microwave absorption properties of polymer composites were determined by complex permittivity measurement and the effects of the barium titanate, strontium titanate and nickel-zinc magnetic particles on the microwave absorption properties were examined in the frequency range of 2–16 GHz. Real and imaginary parts of complex permittivity and permeability were determined by reflection/transmission technique. The dielectric interactions between two different dielectric materials were investigated and the role of Ni0.5Zn0.5Fe2O4 ferrite in the composite has been explored. Results showed that The RL of absorber composites with thickness of 3.0 mm reached a maximum value of −9.47 dB in the frequency range from 2.00 to 16.00 GHz and demonstrated that the nanocomposites could be use as electromagnetic absorber.

Atomistic to Mesoscopic Modelling of Thermophysical Properties of Graphene-Reinforced Epoxy Nanocomposites.

This research addresses the need for a multiscale model for the determination of the thermophysical properties of nanofiller-enhanced thermoset polymer composites. Specifically, we analyzed the thermophysical properties of an epoxy resin containing bisphenol-A diglyceryl ether (DGEBA) as an epoxy monomer and dicyandiamide (DICY) and diethylene triamine (DETA) as cross-linking agents. The cross-linking process occurs at the atomistic scale through the formation of bonds among the reactive particles within the epoxy and hardener molecules. To derive the interatomic coarse-grained potential for the mesoscopic model and match the density of the material studied through atomic simulations, we employed the iterative Boltzmann inversion method. The newly developed coarse-grained molecular dynamics model effectively reproduces various thermophysical properties of the DGEBA-DICY-DETA resin system. Furthermore, we simulated nanocomposites made of the considered epoxy additivated with graphene nanofillers at the mesoscopic level and verified them against continuum approaches. Our results demonstrate that a moderate amount of nanofillers (up to 2 wt.%) increases the elastic modulus and thermal conductivity of the epoxy resin while decreasing the Poisson's ratio. For the first time, we present a coarse-grained model of DGEBA-DICY-DETA/graphene materials, which can facilitate the design and development of composites with tunable thermophysical properties for a potentially wide range of applications, e.g., automotive, aerospace, biomedical, or energy ones.

Effect of Curing Process on Tensile and Flexural Properties of 3D Woven Structural Polymer Composites

Effect of Curing Process on Tensile and Flexural Properties of 3D Woven Structural Polymer Composites

ABOUT THE DEVELOPMENT, APPLICATION AND INNOVATIONS OF POLYMER COMPOSITES

The physical-mechanical, thermophysical, and other important properties of polymer composites primarily depend on the polymer fillers used as modifiers. Examples of fillers include substances that act as structural modifiers, additives, mineral additives, and so on. As studies conducted in this area show, modifiers for various purposes are used to improve chemical and physical-mechanical parameters. The article provides information about the development and production of polymer composite materials. The possibility of obtaining and using composite materials in various fields of technology is shown. In addition, a review of studies that provide a broad understanding of polymer composite materials is also collected. It has been shown that the use of polymer composite materials can lead to significant advances in modern manufacturing. The article also provides information on or-ganic and inorganic fillers with different properties. Based on this, the results of studies carried out in the direction of obtaining polymeric materials using carbon, carbon graphite, fiberglass, etc. are summed up. The nanocomposites of the new generation demonstrate innovative results. This paper shows innovative applications of polymer composite materials for various purposes. All this makes it possible to use the rich mineral resources of Azerbaijan in the production and operation of polymer composite materials

INVESTIGATION OF MODIFIED POLYACRYLAMIDE FOR OIL DISPLACEMENT

At present, the use of surfactants and water-soluble polyelectrolytes, which act as stabilizing and selective agents, is inextricably linked with the successful solution of the technological issues in the world of chemical, oil and other industries. The purpose of the work is to synthesize and study the physicochemical properties of modified polyacrylamide with gossypol resin and further crosslinking in the presence of potassium persulfate and sodium sulphate to displace oil. Methods. To establish the spectral characteristics of the modified PAA, IR spectra have been taken on an IR-Fourier spectrometer. For the structural-elemental composition (SEM), a Jeol JSM-6490l V electron microscope has been used. The viscosity of modified PAA solutions has been measured in a Ubellode capillary viscometer with a hanging level. Results and discussion. The studies, carried out by the authors of the study of the colloid-chemical properties of polymer composites, allow us to conclude that the reagents obtained during the hydrolysis of vat residues of fatty acids distillation with sodium hydroxide with further cross-linking in the presence of potassium persulfate and sodium sulphate have good surfaceactive and emulsifying properties, which is important when displacing oil from layers. The surface tension of polymer compositions has been studied. With an increase in the concentration of the solution, the surface tension decreases, i.e., the surface activity increases. Conclusion. The research results show that the injection of a polymer reagent solution can increase the oil displacement efficiency by 6-7%.

Experimental assessment of the efficiency of deep learning method in predicting the mechanical properties of polymer concretes and composites

The current study is an attempt to investigate the usefulness of a deep learning-based method, backpropagation deep neural network (DNN) for the prediction of the mechanical properties of basalt fiber and nanoclay reinforced polymer concrete (PC) composite. To accurately evaluate the efficiency of the DNN model, instead of building the dataset from the experimental data available in the literature, all training and validation data are prepared from the experimental investigation conducted in this work. First, the mechanical properties of neat epoxy, and its combination with fly ash, silica sand, crushed basalt, basalt fiber, and nanoclay (67 different combinations) are experimentally obtained. The obtained results are used to construct three datasets. Then, three independent DNN models are presented so that the weight percentage of the ingredients is six input variables and compressive, flexural, and splitting tensile strengths of the PC are the output parameters. The DNN models including three hidden layers and the structures of 6-13-13-11-1 are selected as optimal configurations. The prediction accuracy of the validation specimens remains satisfying with the maximum relative errors of 3.49%, 3.45%, and 4.43% for compressive, flexural, and splitting tensile strength, respectively. The statistical criteria R2, RMSE, and MAE for tensile strength are calculated 0.9953, 0.4471, and 0.3219, respectively. The DNN model for tensile strength shows a higher accuracy than compressive and flexural strength. The obtained results have proven the effectiveness of the deep learning method for predicting the properties of PC, even with a small dataset (67 experimental data points). Finally, partial dependence plots (PDPs) are implemented within the presented DNN models to analyze the sensitivity of the predicted mechanical properties to each single input variable. Using the obtained results, it is possible to predict the mechanical properties of PC without fabricating and testing the specimens, as well as obtain the optimal weight percentage of resin and fillers to achieve the maximum compressive, flexural, and tensile strength. This information is useful in designing and optimizing the composition of the PC.

Simulation Studies Underlying the Influence of Filler Orientation on the Electrical Properties of Short Carbon Fiber Conductive Polymer Composites: Implications for Electrical Conductivity Regulation of Micro/Nanocomposites

The electrical properties of conductive polymer composites are critical in applications, and the electrical conductivity regulation through micro/nanofiller orientation is attracting broad attention. For short carbon fiber (SCF) conductive polymer composites (SCFCPCs), the electrical properties and SCF conductive network topology of SCFCPCs with different SCF orientations are analyzed with a numerical model. The results demonstrate that an increase in the degree of SCF orientation from 0 (SCFs perpendicular to conductivity direction) to 1 (SCFs parallel to conductivity direction) first leads to a corresponding increase and then a decrease in the electrical conductivity of SCFCPCs. The highest electrical conductivity is achieved while the degree of SCF orientation is increased to approximately 0.6, which is a higher SCF orientation state compared to random orientation. Moreover, it is identified that more SCFs in conductive networks do not necessarily guarantee a higher electrical conductivity. The electrical conductivity of the SCF conductive networks also depends on the degree of SCF orientation. Evidently, the less-oriented SCFs tend to build in-layer conductive networks, while the highly oriented SCFs tend to build interlayer ones, which apply a greater contribution to the electrical conductivity. Overall, the results of this study reveal why the highest electrical conductivity occurs at a higher SCF orientation rather than a random SCF orientation. The clarified influence and mechanism provide indications for the electrical conductivity regulation of micro/nanocomposites by adjusting the conductive filler orientation.

Fabrication and testing of bioinspired microstructured alumina composites with sacrificial interpenetrating polymer bonds

Bioinspired composites exhibit well-defined microstructures, where anisotropic ceramic particles are assembled and bonded by an organic matrix. However, it is difficult to fabricate these composites where both the ceramic particles and organic matrix work together to unlock toughening mechanisms, such as shear dissipation, particle rotation and interlocking, etc, that lead to stiff, strong, and tough mechanical properties. Here, we produce composites inspired by seashells, made of alumina microplatelets assembled in complex microstructures and that are physically bonded by a small amount of interpenetrated polymer network (IPN) made of polyacrylamide (PAM) and poly-N-isopropylacrylamide (PNIPAM). The fabrication employs magnetically assisted slip-casting to orient the microplatelets as desired, and in situ gelation of the IPN, followed by drying. The process was successful after carefully tuning the slip casting and gelation kinetics. Samples with horizontal, vertical, and alternating vertical and horizontal microplatelets orientations were then tested under compression. It was found that the IPN threads bonding the microplatelets acted as sacrificial bonds dissipating energy during the compression. Paired with the alternating microstructure, the IPN significantly enhanced the compressive toughness of the composites by 205% as compared to the composites with horizontal or vertical orientation only, with less than 35% reduction on the stiffness. This study demonstrates that microstructure control and design combined with a flexible and tough matrix can effectively enhance the properties of bioinspired ceramic polymer composites.

Effect of Alternate Cycle Temperature on the Tribological Performance of Polyimide Composites

Due to the huge impact of temperature on mechanical and tribological properties of polymer composites, polyimide composites reinforced with glass fiber and aramid fiber were fabricated. The composites were treated by the alternate temperature from-50 °C to 150 °C with 200 cycles. The comparation of the test results were analyzed and discussed before and after alternate temperature treatment.

Effect of carbons' structure and type on AC electrical properties of polymer composites: predicting the percolation threshold of permittivity through different models.

The online version contains supplementary material available at 10.1007/s00396-023-05120-2.

TiO2 nanowire formation and GO reduction through a hydrothermal reaction to improve the thermal conductivity of epoxy composites

AbstractThe thermal path must be properly configured to improve the thermal properties of polymer composites. Three‐dimensional (3D) thermally conductive networks can be used as an excellent means for building high‐speed conductive pathways in polymer composites. Titanium dioxide (TiO2) nanowire (NW)/reduced graphene oxide (rGO)/epoxy (EP) composite material has a 3D foam structure and focuses on TiO2 NW formation and rGO gelation through a hydrothermal process. The thermal conductivity of the synthetic composite material through filler loading at 50 wt.% and heat transfer path formation was 805% higher than that of pure EP, and the thermal conductivity was superior to that of the composite material with randomly dispersed fillers. Therefore, this work describes an advanced process to improve the thermal conductivity of polymer composites significantly.

Dielectric and mechanical properties of TiO2/polyimide composites with low dielectric constant

AbstractWith the advent of 5G era, the high millimeter‐wave frequency band, poor signal penetration and large loss make 5G communication more dependent on low dielectric constant materials. Therefore, the research and development of low dielectric polymer materials has become a hot spot in recent years. With its good chemical corrosion resistance, thermal stability, high dispersion and high mobility, titanium dioxide (TiO2) as a high function fine inorganic material is doped in polymer systems to improve the electrical properties of polymer composites. In recent years, a large number of studies have used spherical TiO2 nanoparticles doped on the polymer matrix, however, there is almost no research on doping nanolinear TiO2 nanoparticles on the polymer matrix. Here, TiO2 nanowires were prepared by hydrothermal method, and the prepared TiO2 nanowires were added to polyimide (PI). TiO2/PI monolayer and three‐layer composite films with good dielectric and mechanical properties were prepared by in‐situ polymerization. Fourier transform infrared spectoscopy, scanning electron microscopy and X‐ray diffraction were used to characterize the structure and test the properties of the composites. During the initiation process, the thermal initiation reaction of the composite membrane was completed. The composite film with good mechanical properties and excellent dielectric properties were obtained by adding titanium oxide nanowires, which can meet the requirements of its use in the field of microelectronic devices.

Targeted Pre-Treatment of Hemp Fibers and the Effect on Mechanical Properties of Polymer Composites

Research on plant-fiber-reinforced composites has gained significant research interest since it generates composites with exceptional mechanical properties; however, the potential of hemp fibers can only be fully exploited if the fibers are well separated from the bundle to achieve cellulose-rich fibers. This is because well-separated bast fibers that are long and exhibit higher fiber aspect ratio enhance the mechanical properties of the composite by influencing property translations upon loading. A key feature for successful implementation of natural fibers is to selectively remove non-cellulosic components of hemp fiber to yield cellulose-rich fibers with minimal defects. Targeted pre-treatment techniques have been commonly used to address the aforementioned concerns by optimizing properties on the fiber’s surface. This in turn improves interfacial bonding between the fibers and the hydrophobic polymer, enhances the robustness of hemp fibers by improving their thermal stability and increases resistance to microbial degradation. In this study, we comprehensively review the targeted pre-treatment techniques of hemp fiber and the effect of hemp fiber as a reinforcement on the mechanical properties of polymeric composites.

Effect of fiber content and wear parameters on abrasive wear behaviour of abutilon indicum fiber reinforced epoxy composites and its prediction using ANFIS

Applications of natural fiber-reinforced composites are growing tremendously from the last two decades, due to their exceptional properties over synthetic fiber-reinforced composites. For many engineering applications, better mechanical and tribological properties are the major requirements of polymer composites. As a result of this, investigation of the wear properties of polymer composites is an important characteristic. For this purpose, a three-body abrasive wear analysis was carried out using a pin-on disc experimental setup as per ASTM G 99 standards. The main aim of the present study is to investigate the specific wear of the abutilon indicum fiber reinforced epoxy composite with variations of fiber content, load, speed, and time. An emery polishing paper of grade 1/0 was attached to the disc to find the wear against the abrasive particles. The box-Behnken design was used to carry out the experimental trials and the results are noted down. The highest specific wear rate was observed to be 2.9 E12 at 10 ​wt% of fiber and at 30 ​N load. Wear properties were predicted using the ANFIS technique and compared with the experimental values. Moreover, SEM analysis was also carried out on the wear samples to study morphology and revealed that the worn surface contains micro-cracks, matrix debonding, and debris.

A review on mechanical properties of hybrid polymer composites

The purpose of the present work is to evaluate research work on fiber-reinforced hybrid composites that have exceptional mechanical properties. Polymers are replacing metal materials as a solution to issues including corrosion, weight, flexibility, and other issues. Hybrid polymers provide the extra benefit of improving mechanical qualities like tensile, impact, and flexural. Nanocomposites, bio nanocomposites, and biopolymers were offered for each form of hybrid composite, along with thermoplastic and thermoset polymers. Through the examined studies, composites are frequently reinforced with fibres for improved mechanical properties. The experimental findings showed that natural fibre stacking patterns had an impact on the mechanical characteristics of natural hybrid composites. Nearly all hybridization of various reinforcing fibres showed synergistic impacts on the mechanical characteristics of the hybrid composite. The finer mechanical characteristics of hybrid polymers supplemented with nanoparticles, however, can be viewed as a favourable property trait. Due to the hybrid composite material's constituent polymers maintaining their separate identities, it exhibits substantial physical and chemical properties in addition to those of the individual polymers.

Electromagnetic Shielding Enhancement of Butyl Rubber/Single-Walled Carbon Nanotube Composites via Water-Induced Modification.

Electromagnetic properties of polymer composites strongly depend on the loading amount and the completeness of the filler's dispersive structure. Improving the compatibility of single-walled carbon nanotubes (SWCNTs) with isobutylene butyl rubber (IIR) is a good solution to mitigate aggregation. The change in configuration of poly-oxyethylene octyl phenol ether (OP-10) was induced using water as the exposed hydrophilic groups linking with water molecules. The SWCNT and IIR/SWCNT composites were then prepared via wetly-melt mixing at a relatively high temperature to remove water, and they were then mixed with other agents after vacuum drying and cured. The SWCNTs were dispersed uniformly to form a good network for a lower percolation threshold of the wave-absorbing property to 2 phr from 8 phr. With 8 phr SWCNTs, the tensile strength of the material improved significantly from 7.1 MPa to 15.1 MPa, and the total electromagnetic shielding effectiveness of the material was enhanced to 23.8 dB, a 3-fold increase compared to the melt-mixed material. It was demonstrated that water-induced modification achieved good dispersion of SWCNTs for electromagnetic shielding enhancement while maintaining a wide damping temperature range from -55 °C to 40 °C with a damping factor over 0.2.

Torsional Vibrations in the Resonance of High-Speed Rotor Bearings Reduced by Dynamic Properties of Carbon Fiber Polymer Composites.

The present study deals with the harmful torsional resonance vibrations of textile rotor bearings, the amplitudes of which are reduced mainly by the use of high-capacity damping materials, characterized by an internal hierarchical structure and macroshape, added into the machine mechanical system. The additional materials are polymer matrix composites reinforced either by carbon nanofibers or carbon chopped microfibers and either aramid or carbon continuous fibers. The macroshape is based on a honeycomb with internal cavities. Torsional vibrations arise in mechanical systems as a result of fluctuations in the low-level pressing load of the flat belt driving the rotor-bearing pin and the changing of kinematic conditions within it, which, in the resonance area, leads to cage slip and unwanted impulsive torsional vibrations. Moreover, this occurs during high-frequency performance at around 2100 Hz, i.e., 126,000 min-1. The condition, before the redesign, was characterized by significantly reduced textile rotor-bearing life due to significant impulse torsional vibrations in the resonance area. The study showed a significant reduction in average and maximum torsional amplitudes in the resonance area by 33% and 43%, respectively. Furthermore, the paper provides visualization of the propagation of a stress wave at the microscale obtained by the explicit finite element method to show the dispersion of the wave and the fibers as one of the sources of high damping.