Mechanical Properties Of Polymer Composites Research Articles

Study of the Mechanical Properties of Polymer Composites Based on Polyolefins with the Addition of Rice Husk and Compatibilizer

The present work studies the mechanical behavior of rice husk as a reinforcement element in mixtures of polyolefins. The composites were made by polyolefin mixtures of 30% LDPE, 40% HDPE and 30% PP, rice husk and Polybond as a compatibilizer. Samples for the tensile test were prepared by injection and compressive methods. The results confirm that rice husk alongside the compatibilizer bring about positively in the strength of composites. In reference to the adherence of rice husk to the mixture of polyolefins, which was studied from the microstructure of composites, the addition of compatibilizer improves the adherence between the polyolefins and rice husk, and thereby the quality in the fracture surface. These composites are considered to be a good alternative for the recovery of plastic agricultural waste.

Manufacturing and Modeling of Polypropylene-based Hybrid Composites by Using Multiple-Nonlinear Regression Analysis

In this research, artichoke stem particles (AS) and wollastonite (W) were used as an organic and inorganic fillers in order to improve the mechanical properties of polypropylene (PP). In this regard, PP-matrix composites containing AS and W were produced as non-hybrid and hybrid using a high speed thermo-kinetic mixer. Mechanical properties of polymer composites were investigated by the tensile test. Experimental results reveal that the highest modulus of elasticity was obtained in PP-W and the highest tensile strength was obtained in raw PP while the lowest ultimate strain value was obtained in PP-W-AS. Then, multiple-nonlinear regression analysis was employed to determine the effect of weight ratios of W and AS in PP on modulus of elasticity, tensile strength and ultimate strain. Experimental results were expressed with polynomial, rational and trigonometric models. The results show that the proposed models have well fitted with the experimental results. The coefficient of determination (R2) values were found between 0.95 and 1 in all models. Also, boundedness check control of the proposed models which gives information about whether models are realistic or not was carried out by calculating the maximum and minimum values produced by the relevant model.

Prediction of Selected Mechanical Properties of Polymer Composites with Alumina Modifiers.

Forecasting is one of the cognitive methods based on empirical knowledge supported by appropriate modeling methods that give information about the way the relations between factors and how the phenomenon under study will develop in the future. In this article, a selection is made of a suitable architecture for a predictive model for a set of data obtained during testing of the properties of polymer composites with a matrix in the form of epoxy resin with trade name L285 (Havel Composites) with H285 MGS hardener (Havel Composites), and with the addition of the physical modifier noble alumina with mass percentages of 5%, 10%, 15%, 20% and 25% for the following grain sizes: F220, F240, F280, F320, F360, respectively. In order to select the optimal architecture for the predictive model, the results of the study were tested on five types of predictive model architectures results were tested on five types of prediction model architectures, with five-fold validation, including the mean square error (MSE) metric and R2 determined for Young’s modulus (Et), maximum stress (σm), maximum strain (εm) and Shore D hardness (⁰Sh). Based on the values from the forecasts and the values from the empirical studies, it was found that in 63 cases the forecast should be considered very accurate (this represents 63% of the forecasts that were compared with the experimental results), while 15 forecasts can be described as accurate (15% of the forecasts that were compared with the experimental results). In 20 cases, the MPE value indicated the classification of the forecast as acceptable. As can be seen, only for two forecasts the MPE error takes values classifying them to unacceptable forecasts (2% of forecasts generated for verifiable cases based on experimental results).

Self-reinforced composites based on polypropylene fiber and graphene nano-platelets/polypropylene film

Self-reinforced polymer composites (SrPCs) have many advantages such as light weight, easy recyclability, improved bonding, and low cost. However, the enhancement of mechanical properties of SrPCs is generally restricted by the composite structure and the narrow processing temperature window. The combination of graphene and self-reinforcing mechanism is a potential method to realize a significant improvement in the mechanical properties of polymer composites. It is necessary to study the self-reinforcing mechanism on adjusting the orientation of graphene, so as to reduce the amount of graphene and improve the mechanical properties. This paper presents SrPCs that combine polypropylene (PP) fibers and graphene nano-platelets (GnPs)/PP composite films through film stacking. The unidirectionally arranged PP fibers form narrow channels which facilitate the orientation of GnPs during the impregnation process. The prepared GnPs/PP SrPCs were characterized in comparison with neat PP. At a very low GnPs content of only 0.019 wt%, the tensile strength and modulus of PP were increased by 152% and 186%, respectively, and the interfacial adhesion force of PP SrPCs was improved by 280%. Numerical simulation was successfully conducted to evaluate the processing temperature and the mechanism of graphene orientation in the film stacking process. It proved that the GnPs were highly oriented over the region of unidirectional fibers by the flow field. This new technical method can be potentially used in the industrial manufacturing of economical graphene/polymer nanocomposites with superior mechanical properties.

Direct Visualization of Interfacial Regions between Fillers and Matrix in Rubber Composites Observed by Atomic Force Microscopy-Based Nanomechanics Assisted by Electron Tomography.

In order to explain or predict the macroscopic mechanical properties of polymer composites with complex nanostructures, atomic force microscopy (AFM)-based nanomechanics is one of the most appropriate tools because the local mechanical properties can be obtained by it. However, automatic force curve analysis based on contact mechanics would mislead us to the wrong conclusion. The purpose of this study is to elucidate this point by applying AFM nanomechanics on a carbon black (CB)-reinforced isoprene rubber (IR). The CB aggregates underneath the rubber surface prevent us from quantitatively evaluating the ratio of CB and interfacial polymer region (IPR), which is an important parameter to determine the macroscopic mechanical properties. In order to overcome this problem, transmission electron microtomography was incorporated to investigate the 3D structure in the same field of view as AFM nanomechanics. As a result, it was found that there are buried structures that do not appear in the AFM topographic image. In addition, we were able to reveal the existence of a force curve with an inflection point, which is characteristic of such "false" IPRs. To put it another way, we evidenced the existence of true IPRs for the first time by combining these state-of-the-art techniques.

An Experimental Study on the Effect of Nanomaterials and Fibers on the Mechanical Properties of Polymer Composites

This study aims to explore the tensile and impact properties (tensile strength, modulus of elasticity, and impact strength) of polypropylene (PP)-based nanocomposites reinforced with graphene nanosheets, nanoclay, and basalt fibers. The response surface methodology (RSM) with Box–Behnken design (BBD) was adopted as the experimental design. An internal mixer was used to prepare compounds consisting of 0, 0.75 and 1.5 wt% graphene nanosheets, 0, 10 and 20 wt% basalt fibers, and 0, 3 and 6 wt% nanoclay. The samples were prepared by a hot press machine for mechanical testing. The tensile tests were run to determine the tensile strength, and modulus of elasticity, and the Charpy impact tests were performed to assess the impact strength. It was found that the addition of basalt increased the tensile strength, modulus of elasticity, and impact strength by 32%, 64% and 18%, respectively. Also, the incorporation of the low-weight graphene nanosheets increased the tensile and impact strength by 15% and 20%, respectively, Adding graphene nanosheets generally improved the modulus of elasticity by 66%. Similarly, the addition of nanoclay improved the tensile strength by 17% and increased the modulus of elasticity by 59%, but further addition of it decreased the impact strength by 19%. The values obtained by this experiment for the mechanical property were roughly close to the data yielded from desirability optimization.

Research and Modeling of Viscoelastic Behavior of Elastomeric Nanocomposites

The paper presents results of studying mechanical properties of polymer composites depending on types of filler particles (granular - carbon black, nanodiamonds; layered - graphene plates; fibrous - single-walled nanotubes). These nanofillers differ greatly from each other in their structure and geometry. A significant difference in behavior of nanocomposites was revealed even with little introduction of particles into the elastomer. The highest level of reinforcement of the matrix was obtained when single-wall nanotubes and detonation nanodiamonds were used as fillers. The viscoelastic properties and the Mullins softening effect [1-4] were investigated in experiments performed with material samples subjected to complex uniaxial cyclic deformation. In these experiments, the amplitude of deformations was changed step by step; and at each step a time delay was specified to complete rearrangement processes of the material structure. It was found that a pronounced softening effect after the first cycle of deformation and significant hysteresis losses occur in the material filled with single-walled nanotubes. These characteristics are insignificant for the rest of nanocomposites until elongation increases twofold. In accordance with the obtained results, a new version of the mathematical model to describe properties of the viscoelastic polymer materials was proposed. The constants of the constitutive relations were calculated for each material; the theoretical and experimental load curves were compared. As a result, the introduced model is able to describe the behavior of elastomeric nanocomposites with a high accuracy. Moreover, this model is relatively easy to use, suitable for a wide range of strain rates and stretch ratios and does not require the entire history of deformation as needed for integral models of viscoelasticity.

Experimental investigation on mechanical properties of polymer composites reinforced with aluminium nitride & rice husk

The current examination work accomplishes the formation of epoxy composites with hybrid fillers of Rice husk and Aluminium nitride. The hybrid filler composites were broadly described to comprehend the morphology and mechanical behaviour. The test conduct is to study the mechanical behaviour of polymer composites reinforced with hybrid micro fillers. Micro particle reinforce of Rice husk (RH) and Aluminium nitride (AIN) in different weight proportionate ranging from 0 to 20 wt% and with suitable combination, so here we developed composite specimen in the ratio of 1:1, 1:3 and 3:1 wt%. The molecular structure and surface morphology of the hybrid filler & its interaction with the continuous phase were examined by utilizing Scanning electron microscope instrument. The X-Ray Diffraction (XRD) affirmed that the AIN particle were glass like i.e crystalline in nature and micro sized. Energy dispersive X-beam spectroscopy (EDS) are used to study the chemical composition of the specimen.

Determination of changes in the mechanical properties of polymer composites with the addition of agglomerates of WC nanopowder

Recently, there has been a growing interest in the development of new composite materials with improved characteristics. The article presents the results of tests of composite specimens based on aramid fabrics modified with WC nanopowder agglomerates obtained from carbide manufacturing waste. The following mechanical characteristics were investigated: transverse bending resistance, fracture resistance and energy absorption during contact with a physical body at high speed. According to the results, the transverse bending resistance increased by 35% at a WC concentration of 5%. When 3% WC powder was added to the matrix composition, the total crack length after impact was almost halved. The largest increase in energy absorption of the samples was about 30% at 1% additive concentration. The significant increase in the investigated parameters can be explained by the complex morphology of the embedded particles. In further investigations it is planned to study in detail the mechanism of distribution of nanodispersed WC powder additive in the volume of the modified material.

Dynamic mechanical behavior of natural fibers reinforced polymer matrix composites – A review

The environmental awareness and rapid development in the area of material science attracted the researchers into natural based materials on account of their chemical resistance, ease of fabrication, low density, specific strength, inexpensiveness and favourable mechanical properties. However, some cellulose fibres extracted from natural sources have somewhat high mechanical properties nearer to those of synthetic fibres. Composites using natural fibres as reinforcement have shown favourable results. These natural fiber reinforced composites often considered as high performance reinforcements in polymer composites. DMA had become important for both industry and academia. DMA is an effective thermal analysis tool for the determination of elastic nature of a composite material with respect to of time, frequency, temperature and combination of these. A dynamic mechanical analysis utilizes applied force and deformation data to evaluate the stiffness changes in a material under varied temperatures. DMA measures elastic nature with reference to storage modulus (E’), loss modulus (E”), damping factor (Tan delta) and glass transition temperature (Tg). These properties will be very helpful to measure the performance characteristics of polymer composite materials including both thermosets and thermoplastics. Now a days, most effective and flexible DMA instruments under different modes are available. Dynamic Mechanical Analysis (DMA) is currently used by rubber manufacturers to study the performance of their materials. For the purposes of industrial testing as well as for research and development, DMA is recognized as a highly informative characterisation technique. DMA curves depicts variation of dynamic moduli and damping in glassy or rubbery regions. The current review studies the effect of natural fibres on dynamic mechanical properties of polymer composites. Many results exhibited that inclusion of natural fibres with polymers tends to increase the elastic nature of the polymer matrix.

Impacts of colorants on mechanical properties of epoxy-based fiber composites

Polymer composites are recently being deployed to buildings and vehicles that are required to meet both load-bearing properties and aesthetic needs. Since color is one of the most essential elements of a design, coloring of structural composites is drawing great attention. Despite various attempts of coloration of polymer composites, there is a lack of study on the impact of coloration on mechanical properties of polymer composites. Here, we investigate the influence of colorants (one pigment and three dyes) on mechanical properties of epoxy-based fiber composites. In this study, we found that incorporation of 0.1wt% pigment (Cinquasia® Magenta D4570) enhances mechanical strengths of epoxy-based fiber composites by 10 %, which might be attributed to enhanced T g of epoxy resin matrix where pigment acts as a particle reinforcement. Among three dyes (disperse, acid, and reactive dyes), only disperse dye was dissolved in epoxy resin monomer, but mechanical strengths of resulting composites decreased as the disperse dye reduces T g of epoxy resin matrix, acting like a plasticizer in the matrix. With epoxy-based fiber composites colored with the pigment, we finally suggest implication of coloration that can be applied to early diagnosis of flexure of colored composites.

Carbon Fiber Effect on Structure and Mechanical Properties of Polymer Composites Produced by Additive Manufacturing

Carbon Fiber Effect on Structure and Mechanical Properties of Polymer Composites Produced by Additive Manufacturing

The effect of chemical composition on the biodegradation rate and physical and mechanical properties of polymer composites with lignocellulose fillers

The results of TPLC scientific research, practical experience of their preparation, and application as of 2016 are presented in eight volumes of the “Handbook of Composites from Renewable Materials” (2017, John Wiley & Sons, Inc.). This article provides an analysis of books and articles with open access to the Science Direct (Elsevier) database for the period 2017–2020 to assess the biodegradation rate and physical and mechanical properties of polymer composites with lignocellulosic fillers. The production and use of polymer composites with a thermoplastic polymer matrix and lignocellulosic fillers (TPLC) have significant ecological and eco- nomic prospects since waste biomass from forests, agriculture, and polymers obtained from petroleum raw materials can be used for their production. However, depending on the TPLC application area, there are opposite requirements for the biodegradation rate. For the use in construction and medicine materials and products must have a minimum biodegradation rate. Materials and products for single-use packaging must have the necessary biodegradability potential and have an adjusted biodegradation rate in soil, water, compost environment. Research results show that the properties of TPLC can be significantly influenced not only by the physical but also by the chemical structure of all components of these composites. The chemical properties of polymers, fillers, additives for various purposes can affect their industrial production efficiency.

Enhanced thermal conductivity and mechanical properties of polymeric composites through formation of covalent bonds between boron nitride and rubber chains

AbstractHexagonal boron nitride (BN) platelets, also known as white graphite, are often used to improve the thermal conductivities of polymeric matrices. Due to the poor interfacial compatibility between BN platelets and polymeric matrices, in this study, polyrhodanine (PRd) was used to modify BN platelets and prepared functionalized BN‐PRd platelets, thereby enhancing the interfacial interaction between the thermal conductive filler and polymeric matrix. Then, BN‐PRd platelets were dispersed into the nitrile butadiene rubber (NBR) matrix to yield high thermally conductive composites. The presence of NC═S groups in PRd allowed the combination of PRd and NBR chains containing stable covalent bonds via vulcanization reaction. The thermal conductivity of the as‐prepared 30 vol% BN‐PRd/NBR composite reached 0.40 W/mK, representing an increment of 135% over pure NBR (0.17 W/mK). In addition, the largest tensile strength of NBR composite containing 30 vol% BN‐PRd platelets was 880% times of pure NBR. The 30 vol% BN‐PRd/NBR composite also displayed a relatively high dielectric constant (9.35 at 100 Hz) and a low dielectric loss tangent value (0.07 at 100 Hz), indicating their usefulness as dielectric flexible materials of microelectronics. In sum, the simplicity and good efficiency of formation of covalent bonds between boron nitride and rubber chains look very promising for large‐scale industrial production of high thermally conductive composites.

Effect of Coating of Carbon Nanotubes on Mechanical Properties of Polymer Composites: A Review

Abstract Carbon nanotubes (CNTs) possess superior mechanical properties in addition to other functional features. The last decade has seen rapid growth in the usage of CNTs in polymer matrix composites. This has led to the development of novel dispersion and functionalization techniques. Though the CNTs exhibit excellent properties, their use in commercial applications has been restricted by the problem of dispersion in polymers. Perfect bonding of CNTs and polymer interphase with uniform distribution of CNTs are required for fully utilizing the reinforcement effect of the CNTs. In this review, the techniques and principles of CNT dispersion and functionalization/coating have been discussed in depth. The readers will be able to further their understanding of the field of CNT-reinforced polymer composites. Functionalization of CNTs and their dispersion effects are highlighted for polymer-based composites to observe the changes that occur in their mechanical behavior. The issues that require further work include the need to develop the tools and techniques to analyze the extent of dispersion or cluster of CNTs in a matrix of polymer, the need to optimize the process variables, and the need to resolve the inconsistency among the studies involving functionalization of CNTs. Comprehensive studies are needed to determine the association between different variables, such as surface treatment, degree of functionality, conditions of processing, and thermal, mechanical, optical, and electrical properties.

Accelerated weathering performance of injection moulded PP and LDPE composites reinforced with calcium rich waste resources

This study aims to assess and understand the accelerated weathering performance of injection moulded PP and LDPE composites reinforced with calcium rich waste resources for the first time. Two different calcium rich wastes: FGD gypsum and marble waste are incorporated without any chemical treatment in the polymer matrices. Visual appearance, chemical changes, flexural properties (strength, modulus and elongation) and surface morphology are analysed. Weathered surfaces are studied to analyse the structural changes with morphology by FTIR and SEM. LDPE showed higher visual stability by weathering with enhanced flexural properties for FGD gypsum composites. FTIR analysis revealed that the composites prepared with LDPE had a stabilizing effect on photo-degradation (minimum carbonyl index=1.09–1.14), which correlates well with the results of mechanical testing, showing these composites retained remarkable mechanical properties (retention rate>85%.) after weathering. Visual appearances, physical and mechanical properties of polymer composites are affected by the accelerated weathering condition. UV radiation in combination with temperature, humidity and water spray leads to polymer crystallinity with degradation resulting in weaker interfacial bonding and detachment of filler from matrix. Results show that the flexural strength of weathered FGD gypsum-PP, marble waste-PP and marble waste-LDPE composites decreased about 7–38%, 50–59% and 5–6%, respectively. Flexural strength of the weathered FGD gypsum-LDPE composites increased about 7–12%. The present study implies that both the reinforcements can enhance the properties of PP and LDPE composites after accelerated UV weathering exposure with potential for civil engineering applications. FGD gypsum is more prominent while structural and durability performances are taken into account.

High‐strain‐rate mechanical performance of particle‐ and fiber‐reinforced polymer composites measured with split Hopkinson bar: A review

AbstractReinforcing polymers with particles and fibers has been a common strategy for decades, in order to make them suitable for high‐demanding industrial applications. As composites often undergo dynamic loads, it is important to understand their behavior under such conditions. This review first classifies the types of polymer composites and then explains their failure behavior under tension and compression loading, followed by an overview of some of the experimental procedures used to characterize the polymer composites' dynamic mechanical performance. Afterward, the most significant findings in terms of the high‐strain‐rate compressive and tensile strength and modulus of polymer composites are thoroughly discussed. The results, available in the literature, on the mechanical properties of polymer composites under quasi‐static conditions are also presented and compared with the high‐strain‐rate data. The differences are explained by discussing the changes in the structural configurations of polymer matrices under quasi‐static and dynamic loads. Lastly, conclusions and future perspectives are given, with the intent of highlighting the most promising polymer composites that can be used for a wide variety of applications.

Influence of Mercerization on the Physical and Mechanical Properties of Polymeric Composites Reinforced with Amazonian Fiber

Natural fiber has been an attractive alternative as reinforcement in polymeric composites. However, their physical properties can be impaired due to the hydrophilic behavior of the vegetal fibers: the weak bonds at the interface fiber/matrix emerge due to the hydrophobic behavior of some polymeric matrices. This paper aims to evaluate the influence of mercerization process in Leopoldinia piassaba fibers on the physical, mechanical, thermal, morphological, and accelerated aging properties of polyurethane (PU)-based composites produced by the thermoforming process. The experimental design (22+1) was applied considering the parameters NaOH Treatment and %(PU)Resin. The NaOH Treatment consisted of 5 % and 10 % NaOH solution for fibers mercerization, and %(PU)Resin consisted of different amounts of PU (15 %, 17.5 % and 20 %). The mercerization process chemically modified the interface fiber/matrix and improved the resistance of the composite to screw withdraw strength, ranging from 573 N to 1019 N, and from 574 N to 1648 N considering Surface and Top, respectively. According to Scanning Electron Microscopy (SEM) analysis, the mercerization process also improved the fiber/matrix adherence and reduced pores, resulting in swelling decreasing and thermal conductivity increasing. Furthermore, the mean thickness swelling (TS) value ranged from 6 to 15 % and was not statistically different after accelerated aging. The developed composites containing untreated fibers showed thermal conductivity values similar to the commercial medium density fiberboard (MDF).

Effect of fly ash and coupling agent on the structural, morphological, thermal, and mechanical properties of polyamide 6/acrylonitrile‐butadiene‐styrene blend

AbstractIn the present study, coal fly ash (FA) was used as a reinforcement in a thermoplastic matrix blend of polyamide 6/acrylonitrile‐butadiene‐styrene (PA/ABS). In the first part of this work, the as‐received FA (raw FA) was sieved with a 25 μm sieve to obtain FA with particle size less than 25 μm (FA). Then, the physicochemical properties of the raw FA and the FA were determined. Afterwards, FA was used to prepare a masterbatch of 20 wt% FA and 80 wt% PA by twin‐screw extrusion. Using this masterbatch, composites with different FA contents (4.5, 9, 14, and 18.5 wt%), with and without styrene‐(ethylene‐butylene)‐styrene grafted with maleic anhydride (SEBS‐g‐MA) (S‐g‐M), were produced by extrusion, which was followed by injection molding. Subsequently, several characterization techniques were performed to investigate the effect of FA loading and the S‐g‐M coupling agent on the structural, morphological, thermal, and mechanical properties of the developed composites. The results showed that incorporating FA particles in the matrix blend improved the thermal stability and crystallinity, the Young's modulus, the tensile strength, and torsional properties of the composites. In contrast, the addition of S‐g‐M coupling agent to the polymer composites improved the interfacial adhesion between FA particles and the matrix blend. This further enhanced the structural, morphological, thermal, and mechanical properties of the polymer composites. Overall, the use of FA as an inorganic filler improves the thermal and mechanical properties of polymer composites and shows a potential for promising applications.

Effects of Hydrothermal Seawater Aging on the Mechanical Properties and Water Absorption of Glass/Aramid/Epoxy Hybrid Composites

Abstract With the increase in the diversity of applications, the effect of environmental conditions on the mechanical properties of polymeric composites have become more valuable due to the sensitivity of polymers to aging. In this study, an experimental investigation was carried out to study the seawater aging effect on the flexural and low-velocity impact behavior of glass/aramid/ epoxy hybrid composites. Four types of composite groups that are [G6]S, [A6]S, [G3A3]S, [A3G3]S manufactured by vacuum infusion method were immersed in seawater at 25 °C and 70°C for 1000 h. Mechanical tests were conducted under three different conditions, namely, dry, wet, re-dried. As temperature increases, the water gain ratio also increases for all composite groups. Flexural strength was significantly reduced with seawater absorption for the wet state tested groups at each temperature. The reductions in flexural strength of the re-dried test groups are less than in the wet state test samples. Charpy test results showed that as the composite groups were exposed to hydrothermal aging, the impact strength of the plain glass/ epoxy, GAG/epoxy, and AGA/epoxy hybrid composite decreased. SEM analysis showed that as temperature increases, delamination and fiber/matrix cracks also increases.