Journal of Reinforced Plastics and Composites

The condensation mechanism of the insulators’ surface, increase the surface electrical conductivity. The electrical conductivity of the insulator creates a high level of leakage current and causes the failure. Difference between the dew point and the surface temperature of the insulator which occur due to radiative cooling mechanism, is the major reason of the moisture condensation on the polluted insulator surface. To compensate for the temperature difference, carbon nanotubes (CNTs) are being added to the silicone rubber housing material. The main idea of this research is based on generating joule heating by reducing the surface resistance of high voltage insulators. For this purpose, a developed model based on Halpin–Tsai formulation for tensile modulus of nanocomposites is joined with the conventional power-law model for the effective electrical conductivity of silicone rubber matrix carbon nanotube composite (SMCNT). SMCNT samples are prepared with the addition of various CNT volume fractions to high temperature vulcanizing (HTV) silicone rubber by melt-blending method. The developed model reveals that the high fraction of thinner and longer CNT, thicker interphase, higher concentration of percolated CNT, lower waviness of CNT, and higher conductivity of CNT can make a higher effective conductivity for SMCNT.

Dynamic Mechanical Analysis (DMA) is conducted to measure the viscoelastic nature of a material. The commercial DMA equipment calculates the complex modulus (E*) by assuming a constant Poisson’s ratio. In this work, a method is developed for the simultaneous measurement of Poisson’s ratio and complex modulus (E*) for carbon fiber (CF) reinforced Acrylonitrile Butadiene Styrene (ABS) composites using in-situ optical measurements and digital image correlation. The computation of E* includes shear deflection and relaxes the assumption of constant Poisson’s ratio to obtain accurate values. DMA was conducted on 3D printed CF-ABS composite specimens with oscillating displacement of 10 µm and static load of 1 N at 1 Hz loading frequency. The results in this work reveal that CF-ABS composite does not have a constant Poisson’s ratio over temperature. Additionally, applying the Poisson’s ratio correction results in higher values for the complex modulus. This work is beneficial for composites where the shear deflection component should not be neglected, and where variation of Poisson’s ratio with respect to temperature is important.

In this paper, the strain energy density (SED) is used to study the over-examination to tire in flywheel test induced by pressure correction process. Flywheel test is the main method for evaluating tire durability, which cannot be measured on flat ground due to the variable road conditions. “Pressure Correction” is a necessary step in flywheel tests, but this process can lead to an over-examination of tire durability, which means the tire durability will be underestimated. However, it is impossible to obtain the tire durability from ideal flat ground test, so this paper utilizes the finite element method (FEM) to simulate the tire rolling condition on flat ground and differently sized flywheels, and the SED is used to evaluate the over-examination of tire durability in flywheel test. According to the results, a flywheel with too small diameter has a large amount of over-examination, and the amount caused by a large flywheel is acceptable. This methodology can be a guideline to assess the over-examination on different sized flywheel tests relative to the flat ground, and for the certain tire in this study, flywheels with 3–5 times the tire diameter appear to have an acceptable over-examination.

Fiber reinforced polymer composites (FRPCs) have gained great progress in a wide range of applications from construction and building structures to automobile and vehicle systems. During the operational lifetime, some FRPCs are exposed to various environmental conditions such as thermal cycles and thermal shocks. Fluctuation of the ambient temperature in the forms of thermal shocks or thermal cycles is one of the most important factors that deteriorate the durability and performance of the FRPCs. Compared to ceramic composites, less attention has been paid to the effects of thermal shocks and thermal cycles on the physical/mechanical properties of FRPCs. A comprehensive insight for the future advancements in this field is essential to possibly reduce the failure risks of FRPCs under thermal shocks and thermal cycles. The present work provides a comprehensive review on the physical/mechanical behavior of FRPCs under thermal cycles and thermal shocks. This work also provides a broad review on several factors that determines mechanical behavior of FRPCs, such as polymeric matrix, fiber type, incorporated nanofillers and fiber/polymer interface. Recent studies denoting important aspects and possible problems in mechanical performance of FRPCs under thermal shocks are also summarized.

Optimization of 3D printing factors has been the underlying issue for the last decade. Herein, a 3D-printing procedure was operated to fabricate continuous fiber-reinforced composites in various shape-filled cellular structures based on Kevlar fiber and polylactic acid The efficient processing parameters in bending performance have been systematically studied, such as printing path, fiber orientation, infill density, cell length, and layer thickness. A three-point bending test revealed that, as the effective density increased, there was an irrefutable rise in strength and stiffness of CFRCs with different infill structures. Structural parameters like cell length could improve bending performance; this effect was evaluated by adjusting the fiber orientations along the stretching direction. Furthermore, a finite element model was developed, and its results were verified with the experimental results. The sample of the rhombus-filled cellular CFRCs with a layer thickness of 0.1 mm was found to have the highest bending strength and modulus of 53.61 MPa and 2728.41 MPa, respectively. Since mechanical behavior mostly depends on numerous microstructural factors, plenty of prototypes should be designed to achieve the required bending strength and flexural modulus—this work is a pattern guide to reduce the number of printed samples.

Ballistic clothing is a crucial safety element that helps to save lives of its wearers. According to the protection level, the ballistic vest is reinforced by one or two armor panels designed to resist to attacks destinated to upper parts of the body. The resistance behavior of ballistic body armor depends on several factors. The most important factors are related to the ballistic fabric properties such as the type of fabric, its thickness, its structure, its strength and strain, and the type of the employed resin. In this review paper, the factors influencing the ballistic performances of soft armor panel and hard armor panel are presented. They are investigated based on an in-depth review of previous research studies and experimental test results. This paper also reports the various methods developed by the researchers to improve the performance of ballistic materials. Thus, ballistic material manufactures and researchers could find some guidelines on promising materials and structures that can be used to build efficient body armors.

In this paper, we used two monomers, 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA) and m,m'-diaminobenzophenone (m, m’-DABP), to produce polyamide acid and then converted it to polyimide (PI). The effects of phosphoric acid (H₃PO₄) molarity (1, 2, and 3 M) on the structural, thermal, mechanical, and electrical characteristics of the polyimides/polyaniline (PI/PANI) nanocomposites were studied. Two sharp reflection peaks were developed by the addition of PANI to PI. When 3 M H₃PO₄ is added, the crystalline sharp peak loses some of its intensity. The complex formation of PI/PANI-H₃PO₄ was confirmed by Fourier transform infrared spectroscopy studies. The surface morphologies of the H₃PO₄ complex with nanocomposites were investigated by using a scanning electron microscope. From differential scanning calorimetry studies, the glass transition temperatures of nanocomposites decrease dramatically with an increase in H₃PO₄. Microhardness, flexural strength, and young modulus all dropped as acid molarity increased, although elongation at break increased as H₃PO₄ molarity increased. After the addition of H₃PO₄, a drop in the dielectric constant and an increase in ionic conductivity were observed.

In this study, a novel mixing device under convergent–divergent elongational flow is developed, mainly contains vane conveying unit and wedge channel unit, generating multi-source pulsating pressure in the mixing procedure to induce phase transition. During the design process, some mathematical works and simulations are conducted to optimize the structural design. High-density polyethylene (HDPE)/expanded graphite (EG) composites are fabricated by phase transition assisted melting mixing. The composites feature lower melt resistance and improved tensile modulus. Furtherly, the prepared HDPE/EG composites exhibit a greater increment of dielectric constant when adding more EG, but always maintain low dielectric loss about 0.05 in low frequency. These results show the excellent exfoliation and dispersion effect, confirming that this new designed equipment and phase transition effect complement each other with fabulous effect in the preparation of filler reinforced polymer.

Flake micaceous iron oxide (MIO) pigment is a natural flake pigment, together with nano silica (NS) used to increase mechanical properties and corrosion resistance of coatings based on epoxy resin Epotec YD011X75 cured with Domide G5022. MIO and NS were dispersed into epoxy resin Epotec YD011X75 by mechanical stirring combined with ultrasonic vibration. The structural morphology of the materials was characterized by Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), and Transmission Electron Microscopy (TEM). Functional groups in epoxy/curing agent/MIO polymers analyzed using Fourier Transform Infrared Spectroscopy (FTIR). The thermal property of the material is evaluated by Thermogravimetric and Differential Scanning Calorimetry (TG-DSC). Epoxy coatings with flake micaceous oxide iron, nano silica, phosphate zinc pigment (P), talc filler powder (T), additives, and solvents are prepared by grinding and mechanical stirring. The mechanical properties of epoxy coatings were evaluated by standards for epoxy coatings. The anti-corrosion properties of the coatings on steel were evaluated by the salt fog spray method and electrochemical method. The research results have fabricated two formulations of epoxy coatings based on epoxy resin Epotec YD011X75 with the most appropriate mass ratio of YD011X75/(MIO/P/T) is 40/60 (wt/wt); of which one does not have nano silica (epoxy coating MIO2); one with 1 wt% nano silica (epoxy coating MIO5). The thermal stability of epoxy coating MIO5 is better than epoxy coating MIO2. The decomposition temperature of 50 wt% of epoxy coatings MIO5 and MIO2 is 528.34°C and 470.53°C. The formed epoxy coatings achieve the physical chemistry properties, mechanical properties, and corrosion resistance properties of steel for epoxy coatings, in which the epoxy coating MIO5 is better than the epoxy coating MIO2.

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