Experimental and numerical analysis of conductive ternary polymer blend composites

Experimental and theoretical analysis of the phase morphology and electrical conductivity of a carbon black (CB)‐filled polypropylene /poly(methyl methacrylate) /ethylene acrylic acid copolymer ternary system were compared. The Cahn‐Hilliard theory was used to model and predict the phase morphology and electrical conductivity as a function of the constituents' characteristics of the ternary system. A method for generating statistically representative microstructures of a co‐continuous ternary polymer system and a numerical method for calculating the resultant electrical conductivity of these ternary polymer systems are presented. Excellent agreement between numerically calculated and experimentally measured results was observed. The developed analytical and numerical models were able to successfully predict the electrical percolation threshold with that of ternary polymer composites containing CB as a conductive medium with minimal experimental input. The combination of experimental and numerical results presented suggests the optimization of the conductive minor phase includes having a conductivity beyond the critical percolation threshold, is at least three orders of magnitude greater than either of the two nonconductive phases, and has a lower viscosity than the other two major phases in order to maximize the phase separation kinetics. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44749.     

风电叶片用双组分聚氨酯胶粘剂的研制

考查了自制缓凝剂用量对混合后胶粘剂黏度和适用期的影响,以及多元醇对胶粘剂强度的影响,添加填料及其他助剂制备了双纽分聚氨酯结构胶。该胶混合后适用期达65min,本体拉伸强度迭39．5MPa,拉伸剪切强度达17．5MPa．且胶片韧性好,应用于风力发电行业的叶片粘接效果好,应用前号广阔。     

The physical and mechanical properties of polymer composites filled with Fe‐powder

In this study, the effect of Fe powder on the physical and mechanical properties of high density polyethylene (HDPE) was investigated experimentally. HDPE and HDPE containing 5, 10, and 15 vol % Fe metal–polymer composites were prepared with a twin screw extruder and injection molding. After this, fracture surface, the modulus of elasticity, yield and tensile strength, % elongation, Izod impact strength (notched), hardness (Shore D), Vicat softening point, heat deflection temperature (HDT), melt flow index (MFI), and melting temperature (T_m) were determined, for each sample. When the physical and mechanical properties of the composites were compared with the results of unfilled HDPE, it was found that the yield and tensile strength, % elongation, and Izod impact strength of HDPE decreased with the vol % of Fe. As compared with the tensile strength and % elongation of unfilled HDPE, tensile strength and % elongation of 15 vol % Fe filled HDPE were lower, about 17.40% and 94.75% respectively. On the other hand, addition of Fe into HDPE increased the modulus of elasticity, hardness, Vicat softening, MFI, and HDT values, such that 15 vol % Fe increased the modulus of elasticity to about 48%. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

Experimental,analytical, and numerical investigation of interphasial stress and strain fields in MWCNT polymer composites

In this investigation, the effect of polymer matrix‐MWCNT interphase on the stress and strain fields developed at the close vicinity of MWCNT was studied. The recently developed concept of the hybrid interphase (Papanicolaou et al., 2002) was applied. According to this concept, the interphase thickness depends on the property considered at the time. The parameter of imperfect bonding between the primary constituent materials is also introduced by means of the degree of adhesion. Experimental findings combined with analytical and numerical results gave a better understanding of the structural and mechanical performance of epoxy resin‐carbon nanotubes composites. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Experimental and numerical investigation on flexural behavior of acrylonitrile-butadiene-styrene polymer

Acrylonitrile-butadiene-styrene (ABS) is an extensively utilized rubber-toughened amorphous thermoplastic in industry. Compared to other amorphous thermoplastics, the most promising mechanical quantity of ABS is its high impact resistance. Thus, understanding the mechanical response of ABS to multiaxial loads is of the great industrial concern. The primary objective of this study was to characterize the flexural response of ABS by conducting three-point bending tests at two distinct deformation rates of 5 and 10 mm/s to figure out the deformation rate effect on the flexural response of ABS. It was observed that the ABS act stiffer with an increased deformation rate. Numerical implementation of three-point bending tests for each deformation rate was performed using the semi-analytical material model (SAMP-1) available in Ls-Dyna finite element code. The simulations for each deformation rate were run depending on SAMP-1 and Von-Misses yield surface formulations to figure out the effect of nonidentical material behavior of ABS in tension, compression, and shear on flexural response. The percentage error in the predicted peak force values considering the compression and shear test data (SAMP-1) and without it (Von Misses) was 3% and 7% for deformation rate of 5 mm/s and 5% and 12% for deformation rate of 10 mm/s. Hence, predicting the flexural behavior of ABS accurately, dissimilar material behavior needs to be taken into consideration. Moreover, associated and nonassociated flow rule effects on the flexural response of ABS were numerically investigated and there was no significant influence observed on the flexural response of ABS.     

Experimental and numerical investigation on three-point bending behaviors of unidirectional warp-knitted composites

This study develops a novel specimen model, which considers the progressive damage of the layers, the knitting yarns, and the interlaminar cohesive zone, to investigate the flexural properties and the interlaminar shear properties of the unidirectional warp-knitted composites. Three-point bending tests are conducted as verification of the numerical model. Improved strain-based Hashin criteria are proposed to analyze the shear nonlinearity. Results show that specimens with small span-to-thickness ratios exhibit obvious nonlinear behaviors and the corresponding simulation results are sensitive to the value of the shear nonlinear factor. Failure mechanism and stress distributions are analyzed based on numerical simulations. The effect of the specimen size on bending behaviors is discussed. The influence of the width is found to be negligible but that of the span-to-thickness ratio is significant. The ranges of the span-to-thickness ratio corresponding to different failure modes are given. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48132.     

A comparative investigation of the tribological behavior and scratch response of polyester powder coatings filled with different solid lubricants

Employing coatings is one of the most effective methods to reduce friction and protect contacting surfaces from wear. The deposition of protective coatings from thermosetting polymer powders has witnessed a rapid growth as an ecological, economic and energy efficient technology. During the last few decades, many new deposition techniques have been developed, and more and more tribological coatings have been made available. In this context, our present investigation tried, firstly to analyze the friction and wear behavior of electrostatically sprayed polyester powder coatings deposited on an aluminum substrate and secondly to focus on the response of these thermosetting coatings to micromechanical deformation under scratch test loading. The effect of graphite and hexagonal boron nitride (hBN) solid lubricant fillers on the friction and wear behavior of polyester composite coatings was evaluated using a reciprocating tribometer under dry friction condition. The experimental findings show that the additions of graphite or hBN are effective in enhancing the wear life of polyester powder coatings. Meanwhile, under the same sliding conditions, the wear results revealed that the polyester coating filled with only 10 wt.% of graphite has a higher anti-wear ability compared to the polyester coating filled with the same weight fraction of hBN. Thus, the two reinforcing polyester matrix fillers play an important role in reducing the plastic deformation of the coatings and enhance the formation of thick third body between the sliding parts as the fraction of solid lubricant increases from 0 wt.% to 10 wt.%. From the scratch analyses, we deduced that coatings scratch behavior is severely affected by the kind and amount of fillers inside the polyester matrix. In fact, the best friction characteristic and scratch resistance are observed in the case of polyester coatings filled with very low amount of hBN (5 wt.%).     

Experimental investigation and numerical simulation of liquid supported stretch blow molding

An innovative production process for PET bottles ad containers is analyzed in this article. Liquid Bi‐Orientation (LBO) is a liquid supported stretch blow molding (SBM), which combines the separate blowing and filling phases of conventional SBM. The process modification is mainly characterized by forming the bottle using the desired liquid product instead of pressurized air. Consequently, possible improvements evolve regarding production cycle time, energy consumption and machine footprint. To make use of these capabilities, comprehensive process understanding is required, which can be increased using numerical simulation methods. Therefore, in this article, an LBO process model is set‐up and experimentally evaluated. The model explicitly considers the fluid‐structure interaction between liquid and PET, which significantly influences the PET forming behavior. The key simulation parameters namely the strong rate and temperature dependency of PET and a realistic process parameter determination are also included. The model is evaluated using two different methods to show the reliability of the process prediction. POLYM. ENG. SCI., 55:933–944, 2015. © 2014 Society of Plastics Engineers     

Experimental investigation and numerical simulation of mass transfer during drop formation

The solvent extraction features mass transfer between drops and the surrounding immiscible liquid. Previous study indicated that drop formation plays an important role in extraction because 10–50% of total mass transfer occurs in this stage. It is necessary to have thorough understanding about the mechanism of mass transfer between the drop phase and continuous phase during drop formation. In this work, the level set approach was adopted to capture the interface, and unsteady mass transfer during drop formation was formulated and numerically simulated in an axisymmetric cylindrical coordinate system by solving the fluid motion coupled with mass transfer equations. Drop formation time and mass transfer parameters from the numerical simulation were compared with experimental data in the MIBK–acetic acid–water solvent extraction system. The numerical predictions were found in good agreement with the experimental measurements.     

Optimization and numerical simulation analysis for molded thin‐walled parts fabricated using wood‐filled polypropylene composites via plastic injection molding

Plastic injection molding is discontinuous and a complicated process involving the interaction of several variables for control the quality of the molded parts. The goal of this research was to investigate the optimal parameter selection, the significant parameters, and the effect of the injection‐molding parameters during the post‐filling stage (packing pressure, packing time, mold temperature, and cooling time) with respect to in‐cavity residual stresses, volumetric shrinkage and warpage properties. The PP + 60 wt% wood material is not suitable for molded thin‐walled parts. In contrast, the PP + 50 wt% material was found to be the preferred type of lignocellulosic polymer composite for molded thin‐walled parts. The results showed the lower residual stresses approximately at 20.10 MPa and have minimum overpacking in the ranges of ?0.709% to ?0.174% with the volumetric shrinkage spread better over the part surface. The research found that the packing pressure and mold temperature are important parameters for the reduction of residual stresses and volumetric shrinkage, while for the reduction of warpage, the important processing parameters are the packing pressure, packing time, and cooling time for molded thin‐walled parts that are fabricated using lignocellulosic polymer composites. POLYM. ENG. SCI., 55:1082–1095, 2015. © 2014 Society of Plastics Engineers     

A comparative investigation of bio waste filler (wood apple‐coconut) reinforced polymer composites

During the last century natural fibers are used as reinforcement in polymer composite has been continuously growing in the composite industry. This polymer matrix composite has wide range of application in hostile environment where it is exposed to external attacks such as solid particle erosion. The mechanical properties of different polymer composites are also most important characteristics. An attempt has been made to compare the mechanical and tribological properties of the both biowaste wood apple and coconut shell particulate polymer matrix composite. The results show that maximum flexural strength is obtained 78.19 MPa for wood apple shell and 68.25 MPa for coconut shell at 15 wt% filler content. The wood apple particulate composite shows best erosion and mechanical properties than coconut particulate composite. POLYM. COMPOS., 35:180–185, 2014. © 2013 Society of Plastics Engineers     

Damping analysis of polyurethane/polyacrylate interpenetrating polymer network composites filled with graphite particles

The graphite‐filled polyurethane/poly(methyl methacrylate‐butyl methacrylate) (PU/P(MMA‐BMA)) semi‐interpenetrating polymer networks (IPNs) were synthesized by sequential method. The influences of graphite particle content and size on the 60/40 PU/P(MMA‐BMA) IPNs were studied. The damping properties of IPN composites were evaluated by dynamic mechanical thermal analysis (DMA) and cantilever beam resonance methods. The mechanical performances were investigated using tensile and hardness devices. DMA results revealed that the incorporation of graphite particles improved damping properties of IPNs significantly. The 5% graphite‐filled IPN composite exhibited the widest temperature range and the highest loss factor (tan δ) when the test frequency was 1 Hz. As to the damping properties covering a wide frequency range from 1 to 3,000 Hz, the addition of graphite particles broadened the damping frequency range (Δf, where tan δ is above 0.3) and increased the tan δ value of IPNs. Among them, the composite with 7.5% graphite showed the best damping capacity. And the hardness and the tensile strength of IPN composites were also improved significantly. POLYM. COMPOS., 2013 © 2013 Society of Plastics Engineers     

Experimental investigation and numerical simulation of injection molding with micro‐features

Injection molding of thin plates of micro sized features was studied in order to manufacture micro‐fluidic devices for bioMEMS applications. Various types of mold inserts—CNC‐machined steel, epoxy photoresist, and photolithography and electroplating produced nickel molds—were fabricated and tested in injection molding. The feature size covers a range of 5 microns to several hundred microns. Issues such as surface roughness and sidewall draft angle of the mold insert were considered. Two optically clear thermoplastics, PMMA and optical quality polycarbonate, were processed at different mold and melt temperatures, injection speeds, shot sizes, and holding pressures. It was found that the injection speed and mold temperature in injection molding greatly affect the replication accuracy of microstructures on the metal mold inserts. The UV‐LIGA produced nickel mold with positive draft angles enabled successful demolding. Numerical simulation based on the 2D software C‐MOLD was performed on two types of cavity fillings: the radial flow and the undirectional flow. The simulation and experimental data were compared, showing correct qualitative predictions but discrepancies in the flow front profile and filled depth.     

采用时温等效法预测风轮叶片用EP结构胶的长期蠕变性能

应用时温等效原理预测了两种风轮叶片用玻纤增强EP(环氧树脂)结构胶的长期蠕变性能,通过对比时温叠加主曲线与为期2 d的实际蠕变曲线,验证了时温等效原理在风轮叶片用EP结构胶中使用的有效性。研究结果表明:利用时温等效原理推导得到的主曲线,可大概预测EP结构胶的长期蠕变性能;对比了改性EP结构胶A和普通市售EP结构胶B的蠕变性能,发现改性产品具有相对更好的长期抗蠕变性能(尤其是在高温和高应力环境中时)。     

A review of conductive polymer composites filled with low melting point metal alloys

Metal alloys with low melting temperatures may be blended into polymers to improve their electrical conductivity. We review the preparation, morphology, and electrical conductivity of polymer composites based on low melting point metal alloys, with or without additional filler particles. Since such alloys can be liquid under melt processing conditions, the composite morphology is determined by phenomena such as coalescence of liquid metal drops, orientation of the liquid metal phase, or selective wetting of a second filler by the liquid metal. None of these phenomena appear in conductive composites based on more common conductive fillers such as carbon black, carbon nanotubes, or metal particles. The published literature suggests that composites based on low melting metal alloys, with or without additional non‐melting filler particles, can have much higher percolation thresholds and much higher electrical conductivity (～1,000 S/m) than those based on fillers such as carbon black or carbon nanotubes. Changes in other properties such as rheological or mechanical properties are also discussed. POLYM. ENG. SCI., 58:1010–1019, 2018. © 2017 Society of Plastics Engineers     

A three-dimensional Monte Carlo model for electrically conductive polymer matrix composites filled with curved fibers

A three-dimensional (3-D) Monte Carlo model is developed for predicting electrical conductivity of polymer matrix composites filled with conductive curved fibers. The conductive fillers are modeled as a 3-D network of finite sites that are randomly positioned. The percolation behavior of the network is studied using the Monte Carlo method, which leads to the determination of the critical fiber volume fraction (or the percolation threshold). The effect of fiber curliness on the percolation behavior is incorporated in the current model by using 3-D arm-shaped fibers, each of which needs five independent geometrical parameters (i.e., three coordinates for its vertex and two orientation angles) for its identification. There are three controlling parameters for such fibers, namely the fiber arm length, the fiber aspect ratio, and the fiber arm angle. The new model also considers the sample size and scaling effects. The simulation results reveal an exponential relationship between the fiber aspect ratio and the percolation threshold: the higher the aspect ratio, the lower the threshold. It is also found that the curliness largely influences the percolation threshold: the more curved the fiber, the higher the threshold. However, the effect of curliness diminishes with the increase of the fiber aspect ratio. With the percolation threshold obtained from the Monte Carlo model, the effective electrical conductivity of the composite is then determined by applying the theory of percolation. The numerical results indicate that the composite conductivity decreases as the fibers become more curved and as the fiber aspect ratio decreases. These predicted trends of the percolation threshold and composite conductivity are in good agreement with existing experimental and simulation results.     

Dielectric properties and morphology of polymer composites filled with dispersed iron

The dielectric properties and the structure of various metal–polymer composites, based on a polymer matrix of polyamide (PA), polyethylene (PE), polyoxymethylene (POM), or blend PE/POM filled with dispersed iron (Fe) particles, have been investigated in this work. In PE–Fe, PA–Fe, and POM–Fe composites the filler spatial distribution is random. In the PE/POM–Fe composites, the polymer matrix is two‐phase and the filler particles are localized only in the POM phase, resulting in an ordered distribution of the dispersed filler particles within the blend. The concentration and frequency dependence of the dielectric permittivity, ε′, and the dielectric loss tangent, tanδ, are described in terms of the percolation theory. The experimental values of the critical exponents (namely, s, r, and y) are in good agreement with those predicted by the theory for the composites with random filler distribution. The PE/POM–Fe composites demonstrate low value of the percolation threshold, P_C, and high values of the critical exponents r and y. This is attributed to the specific structure of these composites. A schematic model for the morphology of the composites studied has been proposed. This model explains the peculiar behavior of the PE/POM–Fe composites by assuming ordered distribution of the filler particles in a binary polymer matrix. The proposed model is in good agreement with the results of optical microscopy. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 3013–3020, 2003     

Experimental investigation on the abrasive wear behavior of nanoclay‐filled EVA/LDPE composites

The article presents the results of experimental investigation on three‐body abrasive wear behavior of nanoclay‐filled EVA/LDPE (NC‐EVA/LDPE) composites. NC‐EVA/LDPE composites with and without compatibilizer were prepared by Brabender Co‐Twin extruder (Make: CMEI, Model: 16CME, SPL) and poly(ethylene‐co‐glycidyl methacrylate) was used as the compatibilizer. The mechanical properties were evaluated using Universal testing machine. In three‐body wear tests, silica sand particles of size 200–250 μm were used as dry and loose abrasives. Three‐body abrasive wear studies were carried out using dry sand/rubber wheel abrasion test rig. The effect of abrading distance on the abrasive wear behavior of neat EVA, EVA/LDPE, and NC‐EVA/LDPE composites was reported. The results showed that the wear volume loss is increased with increase in abrading distance and the specific wear rate decreased with increase in abrading distance. However, the presence of nanoclay filler in EVA/LDPE composite showed a promising trend. Abrasive wear volume of the composites was correlated with mechanical properties such as hardness, tensile strength, and percentage elongation. However, higher weight percentage of LDPE in EVA increased the wear rate. The results indicate that NC‐EVA/LDPE with compatibilizer composite exhibits good abrasive wear resistance compared with NC‐EVA/LDPE without compatibilizer. Attempts to explain these differing trends are made in this work by analyzing the features observed on the worn surface samples by employing scanning electron microscopy (SEM). POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers