Mechanical Properties Of Polymer Composites Research Articles

Nanoscale Mechanical Properties of Polymer Composites and Their Impact on Bulk Material Performance.

Nanoscale Mechanical Properties of Polymer Composites and Their Impact on Bulk Material Performance.

Some problem questions in studying the properties of dynamically vulcanized polymer systems based on ethylene/1-hexene copolymer and nitrile butadiene rubber

The article presents the results of a study of the influence of the type and concentration of nitrile butadiene rubber on the main physical and mechanical properties of polymer compositions based on compatibilized ethylene/1-hexene copolymer (EHC*). SKN-18, SKN-26, and SKN-40 were used as nitrile butadiene rubber. The compatibilizer – polyethylene-graft-methacrylic acid was used to improve the compatibility of the mixed components of the mixture. At the first stage, the task of the study was to investigate the effect of the concentration of the considered nitrile rubbers on such properties of the compositions as yield strength, tensile strength, elongation at break, flexural strength, melt flow rate and heat resistance. It was found that, regardless of the type of used nitrile butadiene rubber, with an increase in its content in the composition of the ethylene/1-hexene copolymer, a regular decrease in strength parameters, heat resistance, and melt fluidity is observed. It is shown that with the loading of 30 wt% SKN-18 or 40 wt% SKN-26 and SKN-40 into the composition of the ethylene/1-hexene copolymer phase inversion occurs in the composite materials, according to which the dispersed phase becomes a dispersed medium. The thermomechanical properties of the considered samples were studied. It was found that in those samples in which phase inversion occurred, a region of a highly elastic plateau is formed, which increases with an increase in the content of the rubber component. This area indicates the formation of elastomer with rubber properties. The regularities of crystallization of the compositions depending on the content of the amorphous component were studied by the method of stepwise dilatometry. The mechanism of crystal formation was studied depending on the content of the amorphous component. The influence of the crosslinking agent concentration – dicumyl peroxide on the main properties of dynamically vulcanized elastomers has been studied.

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.

Comparative Evaluation of the Selected Mechanical Properties of Polymer Composites Reinforced with Glass and Hemp Fabrics

Comparative Evaluation of the Selected Mechanical Properties of Polymer Composites Reinforced with Glass and Hemp Fabrics

Thermal Conductivity and Mechanical Properties of Polymer Composites with Hexagonal Boron Nitride—A Comparison of Three Processing Methods: Injection Moulding, Powder Bed Fusion and Casting

Materials providing heat dissipation and electrical insulation are required for many electronic and medical devices. Polymer composites with hexagonal boron nitride (hBN) may fulfil such requirements. The focus of this study is to compare composites with hBN fabricated by injection moulding (IM), powder bed fusion (PBF) and casting. The specimens were characterised by measuring thermal conductivity, tensile properties, hardness and hBN particle orientation. A thermoplastic polyurethane (TPU) was selected as the matrix for IM and PBF, and an epoxy was the matrix for casting. The maximum filler weight fractions were 65%, 55% and 40% for IM, casting and PBF, respectively. The highest thermal conductivity (2.1 W/m∙K) was measured for an IM specimen with 65 wt% hBN. However, cast specimens had the highest thermal conductivity for a given hBN fraction. The orientation of hBN platelets in the specimens was characterised by X-ray diffraction and compared with numerical simulations. The measured thermal conductivities were discussed by comparing them with four models from the literature (the effective medium approximation model, the Ordóñez-Miranda model, the Sun model, and the Lewis-Nielsen model). These models predicted quite different thermal conductivities vs. filler fraction. Adding hBN increased the hardness and tensile modulus, and the tensile strength at high hBN fractions. The strength had a minimum as the function of filler fraction, while the strain at break decreased. These trends can be explained by two mechanisms which occur when adding hBN: reinforcement and embrittlement.

Mechanical Properties and Synergistic Interfacial Interactions of ZnO Nanorod-Reinforced Polyamide–Imide Composites

Metal oxide nanoparticle -reinforced polymers have received considerable attention due to their favorable mechanical properties compared to neat materials. However, the effect of nanoscale reinforcements of the interface on the composites' mechanical properties has not been investigated in-depth to reach their optimal performance in structural applications. Aiming at revealing the effect of synergistic interfacial interactions on the mechanical properties of polymer composites, using a nanoscale reinforcement, herein, a series of zinc oxide nanorod-reinforced polyamide-imide (PAI)/ZnO) composites were fabricated and their mechanical properties and viscoelastic responses were investigated. The composite prepared by reinforcing them with 5 wt % ZnO nanorods resulted in improved elastic modulus, stiffness, and hardness values by 32%, 14% and 35%, respectively, compared to neat polymer thin films. The viscoelastic dynamics of the composites revealed that there was an 11% increase in elastic wave speed in the composite, containing 5 wt % ZnO nanorods, indicating better response to high impacts. Delayed viscoelastic response decreased by 67% spatially and 51% temporally, with a corresponding decrease in the creep rate, for the 5 wt % ZnO nanorod- containing composite, evidencing its potential applicability in high strength lightweight structures. The improved mechanical properties with respect to the filler concentration evidence strong particle-polymer interfacial interactions, creating "chain-bound" clusters, providing clear reinforcement and polymer chain mobility retardation. However, hypervelocity impact testing revealed that all the composites' films were vulnerable to hypervelocity impact, but the spallation region of the composite films reinforced with 2.5 wt % and 5 wt % ZnO nanorods exhibited a cellular-like matrix with shock-induced voids compared to a rather hardened spallation region with cracks in the neat film.

Combined effect of fiber hybridization and matrix modification on mechanical properties of polymer composites

Glass/carbon fiber reinforced hybrid composites are great candidates for wind turbine blade manufacturers to make larger blades. Variation of stacking sequences ensures design freedom to the composite engineers to optimize the composite structure's mechanical performance. On the other hand, matrix modification of polymer composites with nanoparticles is also of interest to introduce multifunctional properties. This research aims to scrutinize the influence of simultaneous fiber hybridization and matrix modification on polymer composites’ tensile, flexural, and low-velocity impact properties. Hybrid glass/carbon epoxy composites and hybrid glass/carbon/multi-walled carbon nanotube (MWCNT) multiscale polymer composites of stacking sequences [GCGCGC]S, [CGCGCG]S, and [G6C6] were manufactured. Fiber hybridization dramatically improved tensile strength between 51% and 76% compared to glass fiber composite. Depending on the stacking sequence, the flexural strength of the hybrid composites was improved between 10% and 16% concerning carbon fiber composite. With the introduction of MWCNTs, a slight increase in the tensile strength for unsymmetrical hybrid composites by around 5% and decreases by 7% for symmetrical ones were observed. Similar behavior was seen for bending characteristics. Additionally, low-velocity impact tests showed that it is achievable to bring greater impact peak forces up to 70% for hybrid composites than carbon fiber epoxy composites. MWCNTs modification of the matrix restrained the impact damage propagation, as proved by C-scan analysis.

Modified Halpin–Tsai model for predicting the mechanical properties of polymer composites reinforced with different cross-sectional fibers

Electrospinning of fibers is a one-of-a-kind method for producing fibers with various cross-sectional shapes by forcing the fibers through a spinneret using an electric field. In this study, the effect of various natural fiber cross-sections on different volume fractions has been investigated. The representative volume element (RVE) model in the finite element method is a standard homogenization-based multi-scale method for evaluating fibers’ micromechanical and thermal properties. This work employs variously shaped fibers, including Round (R), Triangular, Square, Rectangular, X-shape, Y-shape, and C-shape. With the derived mechanical properties, the modified Halpin-Tsai model was used to adjust the shape factor for various cross-sectional shapes.

Effect of Fly Ash Fraction and Mixing Process Variables On Mechanical Properties of Polymer Composites

The development of material technology continues to be carried out to meet the needs of engineering materials which are increasing day by day and are environmentally friendly or green. In this study, the process of making epoxy resin composites with fly ash was carried out from the combustion process of a power plant. This study aims to determine the strength of the mechanical properties between the epoxy resin and fly ash weight fraction by stirring treatment in the mixing process using tensile, flexural, and impact tests, microscopic examination, FTIR, and X-RD analysis. The treatments were mixing epoxy resin and fly ash with a weight fraction of 10%, 20%, and 30%, stirring speeds of 100 rpm, 150 rpm, and 200 rpm, for 10 minutes, 20 minutes, and 30 minutes. The results showed that the F2S3T3 composite had a greater tensile strength of 31,94 MPa, while the other composites had a tensile strength above 22-30 MPa, and the lowest was 13,07 MPa in the F1S2T3 composite. The maximum modulus of elasticity is found in the F3S3T1 composite with a value of 11,12 MPa, and the lowest is found in the F1S2T3 composite at 2,06 MPa. The F3S2T2 composite has a maximum flexural strength of 33,32 MPa, and the lowest composite F2S2T1 is 17,40 MPa with a flexural modulus of 270,41 MPa. The maximum flexural modulus in the F1S1T1 composite with a value of 382,76 MPa with a flexural strength value of 28,82 MPa. TheF2S1T2 composite has an impact energy of 6,94 Joules with an impact strength of 203,47 MPa, and there are 2 composites that have the same impact energy value of 5,20 Joules, namely F3S2T2, and F3S1T3. From SEM observations, the fracture surface of the composite has a concave and prominent surface, but a lot of dust is trapped so it affects the bond in the matrix and reinforcement.

Vertical alignment of carbon nanotubes in photo-curable polymer for multi-functional hybrid materials

Carbon nanotubes (CNTs) are nanomaterials with excellent mechanical strength, electric conductivity, and low weight. Interestingly, vertically aligned CNTs show much higher mechanical and electrical properties than randomly networked CNTs, because CNTs are much more resistant to axial impacts than lateral impacts; this study suggests an efficient process to produce vertically aligned multi-walled carbon nanotubes (VA-MWNT)-photocurable polymer hybrid materials. VA-MWNTs can fortify the mechanical properties of polymer composites even with very small amounts of MWNTs in the composite. Previous studies have produced VA-MWNT–polymer hybrid materials by coating polymers on MWNT forests synthesized in the vertical direction. However, this method cannot be extended to the large-scale production of hybrid polymers because of the limited area of substrates for the synthesis of the MWNT forests, and because the synthesis requires a complex and expensive process. We arranged MWNTs in the vertical direction in VA-MWNT-polymer mixtures in a short process via electrophoresis. Subsequently, UV irradiation for a few minutes completely cured the photocurable polymer while the MWNTs were fixed in the vertical direction. The VA-MWNT-polymer showed a 17% higher compressive force than the polymer itself and interestingly, a 49% higher compressive force than the polymer with randomly dispersed MWNTs, indicating that the orientation of MWNTs in polymer composites affects their curing behavior as well as mechanical strength. These polymer-MWNT composites can be used as-is or coated on other materials and can be expected to exhibit enhanced mechanical properties in various applications.

Investigating the influence of plasma treated polyethylene powder, carbon fibers in enhancing the mechanical properties of polymer composites using rotomoulding method

AbstractIn this research, rotomoulded samples of polyethylene (PE) were mechanically tested to find better applications. The mold was kept in an oven at 260°C with forced convection. Total fabrication time depended on peak internal air temperature (PIAT) used with 200, 220 and 240°C to confirm the fabrication conditions. The plasma treatment of PE and recycled carbon fiber (CF) was used for the improvement of properties. Maximum tensile strength (TS) of 23.1 MPa was observed in 10 wt% CF/PE composites. Scanning electron microscope (SEM) results revealed good mechanical interlocking with higher chemical interaction of carbon fiber of up to 10 wt% with plasma polyethylene leading to good mechanical properties in the composites. Flexural strength (FS) of 19.98–26.02 MPa in the properties was observed plasma treated in the PE with CF (3–10 wt%) combination. Agglomeration in the carbon fiber lowered flexural properties of 13, 15 wt% filler with both plasma and non‐plasma PE. The CF (3–10 wt%) with plasma PE showed enhanced impact strength (IS) from 6.84 to 8.64 KJ/m2. Maximum TS, FS and IS were observed with peak internal air temperature (PIAT) of 200°C. Surface images showed even distribution of fiber and resin in the plasma treated matrix in 5 wt% CF combinations. The differential scanning calorimetry (DSC) results do not show fluctuations in the melting and crystallization temperatures of the samples after plasma treatment.

Influence of various forms of cellulose on the mechanical properties of polymer composites modified in a constant magnetic field

The paper presents the study of polymer composites on epoxy resin matrix, polymerized in the environment of a constant magnetic field. The composites contained admixtures of various forms of cellulose – microcrystalline cellulose and cellulose from waste hemp straw fibers – in an amount ranging from 10 to 30 wt%. Changes in the mechanical properties due to the effect of a constant magnetic field with a magnetic induction value of B = 0.5 T. The composites additionally contained magnetic particles in the form of carbonyl iron, in the amount of 10 wt%.

Simulations for mechanical properties of polymer composites: investigations into suitability of numerical models for TPU-CNT with Mooney–Rivlin ($N = 1$) and friction

Simulations for mechanical properties of polymer composites: investigations into suitability of numerical models for TPU-CNT with Mooney–Rivlin ($N = 1$) and friction

Low density polyethylene composites based on flax fibers modified by a combination of coupling agent

AbstractThis investigation proposes a natural fiber surface modification approach based on the use of a system of coupling agents (CAs) to improve the mechanical properties of polymer composites made of flax fibers and low‐density polyethylene. This system combines the coating of the NaOH treated (mercerized) flax fibers by a CA (Epolene C18 [M‐C18]) in a solution under moderated heat (70°C–80°C), followed by the addition of 1% or 3% wt. of another CA (Epolene E43 [M‐E43]) during the injection molding. The comparison between the solution modified and the neat and mercerized flax fibers using scanning electron micrograph (SEM), thermogravimetric analysis (TGA), and density underscored some differences ascribed to the presence of M‐C18 onto the modified fibers. The mechanical properties showed that the combination of solution modification and direct introduction during the injection‐molding step of 1% of M‐E43 was efficient as the corresponding composites exhibited an improvement of 9.1%, 15.9%, and 11.1% of his tensile, flexural, and impact strengths respectively compared to the neat fiber composite. Due to their good impact and flexural strengths, these composites can be suitable for automotive parts such as keyboard.

Mechanical Properties of Polymer Composites Reinforced with Alkaline-Treated Natural Fibre

The mechanical characteristics of a high impact polyethylene composite (HIPC) reinforced with abaca fibre (AF) are investigated in relation to fibre loading. An alkaline behaviour was used to improve the characteristics of the abaca fibre. With a fibre length of 100 mm, five different fibre loadings of the abaca fibre were used to create the samples of the composite (25, 35, 45, 55, and 65 wt percent). The object was made using compression moulding with unidirectional fibre orientation. The influence of fibre loading was investigated using tensile, hardness, and density tests. In an experiment, it was shown that with 55 percent fibre loading, tensile strength was 312 percent higher than without, and Young’s modulus was 545 percent higher than without. While this was happening, the hardness and density of the AF/PE composites were found to be quite similar, with minor increases from 25 wt percent to 65 wt percent AF loading in comparison to the control sample’s zero wt percent AF loading. 67.42 Shore-D and 1.014 g/cm3 are the highest values. The alkaline treatment of the AF/PE composite had a substantial influence on mechanical characteristics, according to the findings.

Synthesis and mechanical characterization of epoxy hybrid composites containing graphene nanoplatelets

The light-weight and excellent mechanical properties of polymer composites have attributed their use in different structural parts in the aerospace and automobile industries over the past decades. In this research, carbon fiber and Graphene nanoplatelets (GNP) reinforced hybrid composites were fabricated via hand layup followed by compression molding. Effect of different weight percent of GNP (0, 0.25, 0.50, 0.75, and 1 wt%) on mechanical, thermal, and physical properties were analyzed. In comparison to other composites, the 0.5 wt% GNP filled carbon fiber/epoxy composite has improved tensile and flexural strength, inter laminar shear strength, and Vickers hardness. At 0.25 wt% GNP-filled epoxy hybrid composite, impact strength was at its peak. The maximum tensile and flexural strength values were obtained at 0.5 wt% of GNP, 11%, and 8% higher than neat fiber composites. The 0.5 wt% GNP composite has the highest heat deflection temperature and thermal conductivity in terms of thermal characteristics. The morphology of composites was explored by field emission scanning electron microscopy and energy-dispersive X-ray analysis. X-ray diffraction and Fourier transform infrared spectroscopy were also performed for nanocomposite characterization.

Development and optical 3D printing of acrylated epoxidized soybean oil-based composites with functionalized calcium silicate hydrate filler derived from aluminium fluoride production waste

In this study, novel photocurable biobased and biodegradable composites with functionalized fillers from industrial inorganic waste have been developed and applied in optical 3D printing technology. Hydrothermally synthesized calcium silicate hydrates from aluminium fluoride production waste were used as fillers in photoresins based on acrylated epoxidized soybean oil-based. The use of fillers synthesized from industrial waste led to an improvement in the mechanical properties of polymer composites compared to filler synthesized from impurity-free material. The high 3D printing accuracy, perfect layer adhesion, and smooth surface finishing of 3D objects printed with a commercial digital light processing (DLP) 3D printer were shown by the developed composites. The biodegradability of photocured polymer composites reached 19.6% in 60 days. The developed composites have the great potential to be a competitive alternative to conventional petroleum-derived ones and reduce the environmental impact.

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).