Vinyl Ester Composites Research Articles

Effect of Nanoclay Addition on the Erosion Wear of Glass/vinylester Composites Using Taguchi's Orthogonal Array Technique

Nanoclay dispersed polymer composites possess high specific stiffness and strength measured in-plane. Such composites can withstand out-of plane low-energy impacts, wear, abrasion and erosion. This paper reports the effect of nanoclay addition on particle impact erosion behaviour of glass / vinylester composites using Taguchi's Orthogonal Array technique. Erosion tests were conducted using silica sand particles of size 177 to 595μm. The results showed that addition of nanoclay up to 3wt. % reduced the erosion rate of the composites. Impingement angle, particle size, stand- off-distance and velocity of impact showed decreasing order of significance and the erosion was in the range 292.5 to442.5mg/kg. Morphology of the eroded surface was examined using Scanning Electron Microscopy. Erosion rate was maximum at normal impact angles with crater formation.

Investigation of the machinability characteristics of GFRP/vinyl ester composite using design of experiments

Many glass fibre reinforced polymer (GFRP) composite components made from primary melt processes require additional machining to meet the requirements of assembly and accurate dimensional tolerances. Despite the wide applications of reinforced vinyl ester resin in electrical components, automotive structural applications, mining and chemical process industries, high performance marine applications and sporting goods, very little is known about its machining aspects. Cutting force is treated as one of the primary measures of machinability of materials. In this study, the effect of cutting parameters and tool nose radius on the main cutting force in the turning of vinyl ester and woven fabric-based GFRP composites manufactured by hand lay-up process is investigated. Polycrystalline diamond turning tool inserts are used for machining. The force was measured through longitudinal turning, according to the experimental plan developed based on Taguchi methodology. The signal to noise ratio and analysis of variance were applied to the experimental data in order to determine the effect of the process variables on cutting force.

Comparison of Mechanical Performance of Hybrid Vinybased Composites reinforced with Coir/Sisal and Sisal/Kenaf Fibres

Considerable research in the field of material science has been directed towards the development of new light weight, high performance engineering materials like composite. In many applications, like an aircraft, there is a need for high strength weight ratio. This can be achieved by composite consisting of low density (and soft) matrix reinforced with stiff fibres. Now a day’s attention has been focused in the development of natural fibre composite due to their low cost and easy renewability. In this investigation the mechanical properties of Hybrid fibre reinforced vinyl ester composites were analysed based on volume percentage and length of fibre ,similarly single natural fibre composite were developed to compare the properties .The tensile and impact strength increase with fibre length and fibre content ,on the other hand flexural strength decrease with fibre length and content.

Effect of micron and submicron size cenosphere particulate on mechanical and tribological characteristics of vinylester composites

In the present work, the effects of micron and submicron particle size on the tribological behavior of vinylester composites have been investigated. Three different sizes of cenosphere particles (2 µm, 900 nm, and 400 nm) were used as fillers in the composites. Friction and wear tests were carried out at normal room temperature for sliding speed of 1.9 m/s, 3.2 m/s, 4.4 m/s, and 5.7 m/s and applied normal loads of 10 N, 30 N, 50 N, and 70 N, respectively. The friction and wear behavior of these composites sliding against hardened ground steel EN-32 on a pin-on-disc apparatus has been studied. The tensile, flexural, and compressive strengths of the vinylester composites also have been determined on a universal materials testing machine. It was found that the submicron size particulates as fillers contributed significantly to improve the mechanical properties and wear resistance of the vinylester composites. The results show that the particle size 400 nm was most effective in increasing wear resistance and reducing the coefficient of friction. The morphologies of the worn surface were analyzed by means of scanning electron microscopy.

Taguchi method to optimize the micron and submicron size cenosphere particulates filled E‐glass fiber‐reinforced vinylester composites

In this work, the mechanical and tribological characteristics of E‐glass fiber‐reinforced vinylester composites have been investigated experimentally under dry sliding conditions. The E‐glass fiber‐reinforced vinylester composites with uniform micron and submicron size cenosphere particulates of three different sizes (2 µm, 900 nm, and 400 nm) had been prepared in the laboratory. In this work the effect of parameters such as applied normal load, particulate size, sliding speed, sliding distance and roughness on friction and wear behavior have been carried. A plan of experiments, based on the Taguchi design, was performed to acquire data in a controlled way. An orthogonal array L27 (313) and Analysis of variance (ANOVA) have been applied to investigate the influence of process parameters on the coefficient of friction (COF) and sliding wear behavior of these composites. It was found that the submicron size particulates 400 nm as filler contributed significantly to improve the mechanical properties and wear resistance of the composites. The experimental results indicate that the specific wear rate is greatly influenced by applied normal load and particle size. ANOVA results showed that the applied normal load significantly influence the specific wear rate of cenosphere filled glass fiber‐reinforced vinylester composites. Regression analysis is carried to check the suitability of the prediction equation and modeling of the wear parameters and the typical R2 values for COF and specific wear rate are 86.7 and 94.3%, respectively. The scanning electron microscopy are used clarify the experimental in the frictional and wear testing. POLYM. COMPOS., 35:775–787, 2014. © 2013 Society of Plastics Engineers

Friction and sliding wear characteristics study of submicron size cenosphere particles filled vinylester composites using Taguchi design of experimental technique

The friction and wear behavior of vinylester composites filled with uniformly sized micron and submicron cenosphere particles is discussed in this paper. Three distinct uniform size cenosphere particles (2 µm, 900 nm and 400 nm in diameter) were prepared in the laboratory. The experiments have been carried on a pin on disc arrangement at normal room temperature conditions. In this study, a plan of experiments, based on the Taguchi design technique, has been used to acquire data in a controlled way. An orthogonal array L27 (313) and analysis of variance have been applied to investigate the influence of process parameters on the coefficient of friction and sliding wear behavior of these composites under dry sliding condition. It was found that the submicron size particulates as fillers contributed significantly to improve the wear resistance of the vinylester composites. Scanning electron microscopy has been used to investigate the interaction between filler and matrix and various wear mechanisms involved.

Mechanical properties of cellulose fibre reinforced vinyl-ester composites in wet conditions

The effect of prolonged water absorption on the physical and mechanical properties has been investigated for vinyl-ester composites reinforced with natural fibres. The elastic modulus of these composites was measured and the data were validated with various mathematical models. The modelling results revealed that the experimental data matched the data predicted by the Cox–Krenchel model. Prolonged exposure of these composites to water absorption caused a reduction in elastic modulus and strength.

Evaluation of Thermo-Mechanical and Wear Behavior of Short Carbon Fibre Vinyl-Ester Filled Homogenous and Their Functionally Graded Composites

Abstract The paper presents the processing and mechanical characterization of chopped carbon fibre reinforced homogenous and functionally graded vinyl ester composites and also reports on their sliding wear characteristics respectively. The sliding wear characteristics are studied with the help of POD test employing the design of experiments approach based on Taguchi's orthogonal arrays. Dynamic mechanical analysis is carried out of the investigated homogenous/FGMs composites to investigate the overall stiffness/flexibility, so as to improve the specific wear rate. Present study reveals that graded composite possess good mechanical and wear characteristics compared to homogenous composites. SEM confirms the graded dispersion of carbon fibre in the matrix.

Effects of particle size, particle loading and sliding distance on the friction and wear properties of cenosphere particulate filled vinylester composites

The present investigations evaluate the effects of particle size, particle loading and sliding distance on the friction and wear behavior of vinylester composites sliding against hardened ground steel on a pin-on-disc wear testing machine. The emphasis are given on the wear rate and coefficient of friction as a function of parameters such as sliding distance (5000–25,000m) at two different applied normal loads of 10N, 70N and at sliding speeds of 1.9m/s and 5.7m/s. Three distinct sizes of cenosphere particles (2μm, 900nm and 400nm) were prepared in the laboratory for preparing the particulates filled vinylester composites. The tensile strength, flexural and compressive strength of the cenosphere particulate filled vinylester composites were determined on a universal materials testing machine. It was found that the submicron size cenosphere particles as fillers contributed significantly to improve the mechanical properties. It was also found that the specific wear rate for all the vinylester composites decreases with sliding distance and after certain duration attains approximately a steady state value. It was observed that in the steady state region, the specific wear rates of vinylester composites vary only marginally. Scanning Electron Microscopy (SEM) analysis also has been carried to identify the wear mechanisms for the worn surfaces of vinylester composites.

Mechanical and wear behavior of vinyl ester-carbon/cement by-pass dust particulate filled homogeneous and their functionally graded composites

Abstract The paper presents the processing, mechanical and sliding wear characterization of particulate filled cement by-pass dust and carbon fiber (fixed) reinforced homogeneous and functionally graded vinyl ester composites. Homogeneous and graded composites are fabricated by simple mechanical stirring and vertical centrifugal casting technique, respectively. Among the physical and mechanical properties, void content, hardness and impact strength are found to increase with increase in filler content in case of functionally graded materials (FGMs), whereas tensile strength and flexural strength are found to deteriorate for both FGMs and homogeneous composites as compared to the neat composites. Sliding wear characteristics are studied with the help of pin-on-disc test employing the design of experiments approach based on Taguchi’s orthogonal arrays. The present study reveals that graded composites exhibit good mechanical and wear characteristics compared to homogeneous composites. Scanning electron microscopy confirms the dispersion of carbon fiber in the matrix in graded composites.

Effect of Microsize Particulates on Tribological Characteristics of Vinylester Composites under Dry and Lubricated Conditions

In this paper the friction wear characteristics of vinylester and vinylester composites have been investigated under dry and water lubricated sliding conditions, under different applied normal load and sliding speed. The experiments have been carried on a pin on disc arrangement at normal temperature conditions. The results showed that with increase in the applied normal load and sliding speed the coefficient of friction and specific wear rate decreases under both dry and water lubricated sliding conditions. It is also found that a thin film formed on the counterface seems to be effective in improving the tribological characteristics. The worm surface examined by SEM showed that more of the fiber exposure and fiber breakage for vinylester composite resulting higher wear rate.

Study on the Effect of Matrix Properties on the Mechanical Performance of Carbon Fabric Composites

Carbon fiber (CF) reinforced compositesusing different types of vinylester (VE)resin includingconventional VE resinhave been prepared. The mechanical performance were characterized by different tests, such as tensile, mode-I interlaminarfracture toughness, tension-tension fatigue and scanning electron microscope (SEM).The experimental results showed that the tensile strength of CF/VE composites changed at a wide range from 22.3% to 37.8% in comparison with the CF/conventional VE composite due to resin type, where the strain at failure was varying. The tensile strength increased with an increase of adhesive strength between carbon fiber and VE resin characterized by the microdroplet test. Namely, a good correlation between the tensile strength of composites and the adhesive strength was found. On the other hand, almost an inverse correlation was found between the tensile strength of composites and the interlaminar fracture toughness of composites obtained by DCB (double cantilever beams) tests. There was no apparent correlation found between the strain at failure for pure resins and the tensile strength of composites.Thefatigue life of CF/VE compositesincreased as well as the tensile strength with an increase of the adhesive strength between carbon fiber and the resin. The samples sometime survived 1000 times longer than that of CF/conventional VE compositewhen the maximum cycle stress was 70% of the tensile strength of the strongest composite.

Influence of halloysite nanotubes on physical and mechanical properties of cellulose fibres reinforced vinyl ester composites

Natural fibres are generally added to polymer matrix composites to produce materials with the desirable mechanical properties of higher specific strength and higher specific modulus while at the same time to maintain a low density and low cost. The physical and mechanical properties of polymer composites can be enhanced through the addition of nanofillers such as halloysite nanotubes. This article describes the fabrication of vinyl ester eco-composites and eco-nanocomposites and characterizes these samples in terms of water absorption, mechanical and thermal properties. Weight gain test and Fourier transform infrared analysis indicated that 5% halloysite nanotube addition gave favourable reduction in the water absorption and increased the fibre–matrix adhesion leading to improved strength properties in the eco-nanocomposites. However, halloysite nanotube addition resulted in reduced toughness but improved thermal stability.

Effect of Micro-Size Cenosphere Content on Friction and Dry Sliding Wear Behavior of Vinylester Composites – A Taguchi Method

In this paper the friction and wear characteristics of vinylester and vinylester composites have been investigated under dry sliding conditions for different applied normal load, sliding speed and sliding distance. The experiments have been carried on a pin on disc arrangement at normal room temperature conditions. The influence of friction and wear parameters like normal load, speed, sliding distance and percentage of filler content on the friction and wear rate has been investigated. In this study, a plan of experiments based on the techniques of Taguchi was performed to acquire data in a controlled way. An orthogonal array L27 (313) and Analysis of variance (ANOVA) were applied to investigate the influence of process parameters on the coefficient of friction and sliding wear behaviour of these composites. The Taguchi design of experiment approach eliminates the need for repeated experiments and thus saves time, material and cost. The results showed that with increase in the applied normal load and sliding speed the coefficient of friction and specific wear rate decreases under dry sliding conditions. It is also found that a thin film formed on the counterface seems to be effective in improving the tribological characteristics. The results showed that the inclusion of cenosphere as filler materials in vinylester composites will increase the wear resistance of the composite significantly.

Thermo-mechanical and sliding wear behaviour of vinyl ester–cement by-pass dust particulate-filled homogenous and their functionally graded composites

In this article, particulate-filled cement by-pass dust and short Kevlar fibre have been utilised to produce homogenous and functionally graded vinyl ester composites. In this study, cement by-pass dust varies from 4 to 12 wt% whereas the Kevlar fibre is kept fixed (i.e. 10 wt%). The physical and mechanical properties like void content and hardness are found to increase with increase in filler content in case of functionally graded materials, whereas tensile strength, impact energy and flexural strength are found to deteriorate for both functionally graded materials and homogeneous composites. Similarly, sliding wear tests are performed over a range of sliding velocities (1.5–4.5 m/s), normal loads (10–25 N), filler contents (4–16 wt%), sliding distance (1–4 km) and abrasive grit size (18–48 µm) using pin on disc test rig. Wear characteristics and their significant factor are successfully analysed using statistics-based Taguchi experimental design and analysis of variance, respectively. Dynamic mechanical analysis is carried out for homogenous and functionally graded materials composites in order to investigate the overall flexibility and interaction of the constituents. Finally, surface morphology of the worn surfaces was studied with the help of scanning electron microscope.

Fluid-structure interaction and its effect on the performance of composite structures under air-blast loading

Three material systems: E-glass Vinyl-Ester (EVE) composites, sandwich composites with EVE facesheet and monolithic foam core (2 different core thicknesses), and monolithic aluminum alloy plates, were subjected to shock wave loading to study their blast response and fluid-structure interaction behaviors. High-speed photography systems were utilized to obtain the real-time side-view and back face deformation images. A 3-D Digital Image Correlation (DIC) technique was used to analyze the real-time back face displacement fields and subsequently obtain the characteristic fluid-structure interaction time. The reflected pressure profiles and the deflection of the back face center point reveal that the areal density plays an important role in the fluid-structure interaction. The predictions from Taylor's model (classical solution, does not consider the compressibility) and model by Wang et al. (considers the compressibility) were compared with the experimental results. These results indicated that the model by Wang et al. can predict the experimental results accurately, especially during the characteristic fluid-structure interaction time. Further study revealed that the fluid-structure interaction between the fluid and the sandwich composites cannot be simplified as the fluid-structure interaction between the fluid and the facesheet. Also, it was observed that the core thickness affects the fluid-structure interaction behavior of sandwich composites.

Fracture Toughness of Vinyl Ester Composites Reinforced with Sawdust and Postcured in Microwaves

A commercial vinyl ester resin supplied by Hetron Chemical Pty. was reinforced with varying percentages by weight of sawdust. The sawdust particles were sieved into 3 different sizes, which were <300 μm, 300–425 μm, and 425–1180 μm, respectively, with a view to increase its fracture toughness for civil and structural applications. The sawdust used varied from 0% w/t to 15% w/t in step of 5% w/t. For higher w/t% of sawdust, the mixture would be too sticky to be mixed and cast. The cast composites were cured in ambient conditions and then postcured in microwave irradiation. They were then tested for fracture toughness using short bar tests. The values of fracture toughness of the composites increased with increasing particulate size, and this is due to the size distribution of the filler. It was found that the optimum amount of sawdust (425–1180 μm) was 15% w/t, with which the increase in fracture toughness was 126% as compared to neat resin and the reduction in cost was 15%. Furthermore, the optimum amount of sawdust (300–425 μm) was also 15% w/t, with which the increase in fracture toughness was 28.3% as compared to neat resin and the reduction in cost was again 15%.

Thermal properties of calcium carbonate powder reinforced vinyl ester composites: Pilot study

AbstractThe viscoelastic properties of vinyl ester (VE) composites filled with calcium carbonate (CC) (CaCO3) powder have been evaluated using the dynamic mechanical analysis (DMA) technique. It was found that irrespective of the percentage by weight of CaCO3 powder, the VE composites postcured in an oven up to 60°C have higher glass transition temperatures (Tg) and storage modulus than their counterparts cured at ambient conditions. However, the loss moduli were lower for composites postcured in an oven than their ambient cured counterparts. It was also found that the crosslinking density of the composites slightly increased with particulate (CaCO3) loading and composites postcured in an oven have higher crosslinking density than their counterparts cured at ambient conditions. These results confirmed an increase in stiffness for composites with postcuring treatment. Micrographs by SEM were obtained and confirmed a close inter phase adhesion of the CC filler with the VE resin matrix in the composites. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Effective property estimates for composites containing multiple nanoheterogeneities: Part II nanofibers and voids

The Effective Continuum Micromechanics Analysis Code was used to predict effective elastic moduli of vinyl ester composites containing a combination of solid/hollow carbon nanofibers with varying degrees of fiber waviness, voids, and traditional E-glass fibers. The predicted effective elastic moduli for nanofiber-reinforced composites matched well with experimental results from the literature. In addition, single- and multiple-step homogenization procedures were both used to determine effective properties for hybrid composites containing reinforcements of disparate sizes (i.e., nanofibers combined with traditional E-glass fibers). This work aims to facilitate the development of engineered multiscale materials design by providing insight into relationships between nanomaterial physical characteristics, interactions, and structure across disparate spatial scales that lead to improved macroscale performance.

Mode‐I intralaminar fracture toughness of silica particles‐filled glass woven fabric‐reinforced vinyl ester composites

AbstractGlass woven fabric reinforced vinyl ester (GV) composites filled with different weight proportions of silica particles were fabricated by hand lay up technique followed by oven curing. The plane strain Mode‐I Intralaminar fracture toughness, KIC of the silica filled GV composites has been studied and the experimental results were compared with those of unfilled GV composites. The findings of the experiments showed that the fracture toughness has improved by the addition of silica particles up to 6 weight % with marginal increase of tensile properties. The silica filled and unfilled GV composites showed brittle fracture, with maximum toughness for 6 weight % silica particles. The morphology of fracture surfaces was examined by using SEM. Pulled and fractured fibers are observed on the fracture surface of GV composites evidencing fiber bridging but not in the silica filled GV composites. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers