Glass Fiber Reinforced Polyester Composites Research Articles

Tamarind Fruit Fiber and Glass Fiber Reinforced Polyester Composites

Polyester-based hybrid composites were developed by combining the tamarind fruit (Tf) and glass fibers into a polyester matrix. Hardness, impact strength, frictional coefficient, and chemical resistance of hybrid composites with and without alkali treatments were studied. Variation of the aforementioned mechanical properties and chemical resistance was studied with different fiber lengths, such as 1, 2, and 3 cm. A 9 vol% of the tamarind and glass fibers was reinforced into the polyester matrix. The aforementioned mechanical properties were optimally improved at 2-cm fiber length when compared with 1- and 3-cm fiber lengths. Chemical resistance was also significantly improved for all chemicals except toluene. A 3°C rise in decomposition temperature while a 2°C rise in glass transition temperature was observed from TGA and DSC micrograms, respectively.

Effect of volume fiber and crack length on interlaminar fracture properties of glass fiber reinforced polyester composites (GF/PO composites)

Double-cantilever beam (DCB) specimens are widely used to measure the mode I critical-energy release rate GIc of glass-fiber reinforced polyester composites (GF/PO composites). It showed GIc varied significantly during crack propagation. GIc of GF/PO composites are higher than that of the pure polyester (PP) resin because of the additional force required to fracture fiber bridging in GF/PO compos-ites. Comparative DCB tests were carried out to demon-strate the occurrence of fiber bridging. GIc varied markedly and were much dispersed, which would induce little varia-tion when initial crack length was 40 mm. The fracture characteristics were analyzed by scanning electron micro-scope. DOI: http://dx.doi.org/10.5755/j01.mech.20.2.6934

Fatigue properties of hemp and glass fiber composites

The fatigue properties of nonwoven randomly oriented short hemp fiber mat and chopped strand mat (CSM) glass fiber reinforced polyester composites have been studied, mainly in tension–tension mode. Despite having poorer absolute fatigue strength, the hemp fiber composites exhibited less fatigue sensitivity as compared with the CSM glass fiber composites in tension–tension fatigue. This could be correlated with the lower stiffness degradation observed during fatigue of the hemp fiber composites as compared with the glass fiber composites at the same normalized peak stress levels. Also, images recorded during fatigue loading showed that the hemp fiber composites were better at resisting crack formation and growth than the glass fiber composites. These results suggest that hemp fiber composites have the potential to replace glass fiber composites in applications where components are subjected to fatigue loads but the stress levels are of moderate value. POLYM. COMPOS., 35:1926–1934, 2014. © 2014 Society of Plastics Engineers

Investigation on Mechanical Property Evaluation of Jute - Glass Fiber Reinforced Polyester

Natural fibers have been investigated for use in polymers including flax, hemp, jute, sisal and banana. Recently there has been a greater leaning towards natural fiber reinforced polymers composites because these are environmental friendly and cost effective to synthetic fiber reinforced composites. In this work hand lay-up process is used to fabricate Jute- glass fiber reinforced polyester composites. Specimen preparation and testing was carried out as per ASTM standards. Composites were prepared using Jute - glass fibers of 50/50, 40/60 and 30/70 Weight fraction ratios and mechanical properties like tensile, impact and flexural strength of Jute - glass fiber reinforced polyester were evaluated. The results shows that tensile strength and impact Strength of 50% Jute-50% glass fiber composition is found to be better than the other two compositions and the flexural strength of 40% Jute-60% glass fiber composition is found to be better than the remaining two compositions. Keywords: Jute, glass fiber, Polyester, Hand Lay-up, Mechanical properties.

Optimizing Multi Characteristics in Drilling of GFRP Composite Using Utility Concept with Taguchi's Approach

In the drilling process of chopped glass fibre reinforced polyester composites; the delamination is a major problem. The delamination reduces the structural integrity of the material, results in poor assembly tolerance and has the potential for long term performance deterioration. Surface roughness is also an important aspect of drilling fibre reinforced polyester which can cause high stress on rivets and bolts, leading to failure. In the modern competitive manufacturing scenario, it is very important to optimize the process parameters to arrive at its full utility. In this present study the utility concept has been applied for multi characteristics optimization and identification of the optimal setting condition of process parameters at various relative weightage values of characteristics. Delamination factor and average surface roughness were taken as the measure of performances for this material and feed rate (f), drill diameter (D), spindle speed (N) and material thickness (t) were chosen as drilling parameters. Experiments were conducted based on Taguchi L9 (34) orthogonal array design. Analysis was performed based on utility method varying the importance of quality characteristics or responses in drilling process. The optimal setting of parameters is expected to be useful for process engineers.

Effect of tribological parameters on scratch behaviour of unidirectional E-glass fibre reinforced polyester composite

Understanding the scratch behaviour of the composite materials is of primary importance. The scratch behaviour of glass fibre reinforced polyester composite was investigated. A new scratch device is designed and developed. Scratch tests at room temperature were carried out, using conical indenter and constant scratching velocity. The main aim of this study is to investigate the effects of tribological parameters on wear mechanisms and friction coefficient. Particularly, the effects of the normal load and the attack angle were presented. The different wear scenario of the composite material during the scratch test was deduced, then supported by an analysis of the glass fibre reinforced polyester composite wear modes using scanning electron microscopy (SEM) observations was performed. The correlation between tribological parameters and wear mechanisms was highlighted through the composite scratch map. Results were compared with those previously published associated with the metallic and the polymeric materials.

Degradation of dynamic mechanical properties of glass fiber reinforced polyester composite pipes after immersion in various temperatures

This paper reports the effect of sulfuric acid solution absorption on the dynamic mechanical properties of glass fiber reinforced polyester composites. An experimental device is presented that allows the effect of changes of environment and temperature on both the diffusion coefficient and the maximum moisture content to be measured. The results indicate that increased temperature raises both the diffusion coefficient and the maximum absorbed moisture of all the composite materials used in this study. Moreover, it has been noted that specimens exposed to higher temperature absorb much more water than those held at low temperature. The dynamic mechanical properties of glass fiber reinforced polyester were found to be highly affected by the presence of absorbed solvents in the specimen and increases in temperature. A fractographic study has been conducted using a scanning electron microscope of the surfaces of specimens broken by tensile testing. Observations indicate that increased immersion time increases the deterioration of the fibre/matrix interface.

Development of Glass/Jute Fibers Reinforced Polyester Composite

Composites play significant role as engineering material and their use has been increasing day by day due to their specific properties such as high strength to weight ratios, high modulus to weight ratio, corrosion resistance, and wear resistance. In present work, an attempt is made to hybridize the material using synthetic (glass) as well as natural fibres (chemically treated jute), such that to reduce the overall use of synthetic reinforcement, to reduce the overall cost, and to enhance the mechanical properties. All composite specimens with different weight percentages of fibres were manufactured using hand lay-up process and testing was done by using ASTM standards. Experimental results revealed that hybridization of composite with natural and synthetic fibres shows enhanced tensile strength, flexural strength, and impact strength. The content of natural reinforcement was found to be in the range of 25–33.3% for best results. The effect of treated jute on flexural properties was more than that on tensile properties, which was due to greater stiffness of jute fibers. Chemical treatment of jute fibers lowers the water absorption and results were comparable to glass fiber reinforced polyester composites. The addition of jute also reduced the overall cost by 22.18%.

Investigations on the effectiveness of cyanoacrylate adhesive for repair of fibre-reinforced polymer laminates under different environmental conditions

This article presents the results of an experimental study on the long-term durability of delaminated glass fibre-reinforced polyester composites that have been repaired using a rubber toughened cyanoacrylate adhesive. While several studies have investigated cyanoacrylate for glass fibre-reinforced polyester repair applications, none has addressed the impact of environmental conditions on bond durability. Glass fibre-reinforced polyester was fabricated in the laboratory and structural damage was induced before application of cyanoacrylate adhesive. Environmental chambers were used to expose the repaired specimens to the following three standard conditions for a duration of 1000 h: dry/wet cycles of salt mist (5% salt), dry/wet non-saline water mist condition (0% salt) and a cold chamber at −20℃. A fourth set were maintained at ambient temperature and pressure and served as the control. Double cantilever beam tests were used to determine the initial peak load for pre- and post-repair specimens. No degradation in the adhesive performance was observed for the specimens exposed to the salt mist and non-saline mist. A decrease in the peak load was observed for those specimens exposed to the cold environment, indicating some reduction in bond strength.

Low-velocity impact behavior of CNF-filled glass-reinforced polyester composites

A significant improvement in fiber-reinforced polymeric composite materials can be obtained by incorporating a very small amount of nanofillers in the matrix material. In this study, an ultrasonic liquid processor was used to infuse carbon nanofibers into the polyester matrix which was then mixed with a catalyst using a mechanical agitator. Both conventional and carbon nanofibers-filled glass fiber-reinforced polyester composites were fabricated using the vacuum-assisted resin transfer molding process. Low-velocity impact tests was performed at 10 J, 20 J, and 30 J energy levels on conventional as well as 0.1–0.3 wt% carbon nanofibers-filled glass fiber-reinforced polyester composites using Dynatup8210. The morphology of fractured specimens was examined using digital photographs and optical microscopy. There was an increase in the peak load for the nanophased glass fiber-reinforced polyester composites compared with the conventional one. The absorbed energy of nanophased glass fiber-reinforced polyester composites was less than that of conventional one at different energy levels. The extent of damage was more pronounced in the conventional glass fiber-reinforced polyester composites compared to nanophased ones. Failure mechanisms comprised of indentation, debonding, delamination, matrix cracking, and fiber fracture. The extent of damage was pronounced in conventional composite compared to nanophased ones.

Conformal thin film silicon photovoltaic modules

A polymer composite material system and a process for encapsulation of thin film solar cells were developed for profiled roofing elements, in view of building-integrated photovoltaic (PV) applications. Amorphous silicon cells were deposited on a polyethylene naphthalate film and encapsulated with additional polymer layers in the form of a flat laminate using industrial processes. The process technology developed in this work included a pre-forming step of the PV laminate and a moulding step of a glass fibre-reinforced polyester composite. These two steps were optimised using thermo-elastic analyses, with attention paid to laminate designs and process windows compatible with the thermo-mechanical limits of the fragile active PV layers. A demonstrator with standard 1.0 m×1.8 m corrugated roofing profile, a weight of 6.3 kg and 60 W of output power was produced. The long-term endurance of the conformal modules was also validated using humidity-freeze, damp-heat and water immersion tests.

Machinability Study of Hybrid Nanoclay-Glass Fibre Reinforced Polyester Composites

Glass fibre reinforced polyester composites (GRP) and hybrid nanoclay and glass fibre reinforced polyester nanocomposites (CGRP) are fabricated by vacuum assisted resin infusion technique. The optimum mechanical properties are obtained for CGRP with 3 wt.% nanoclay. Three types of drills (carbide twist drill D 5407060, HSS twist drill BS-328, and HSS end mill (4 flutes “N”-type end mill RH-helical flute)) of 6 mm diameters are used to drill holes on GRP and CGRP. Three different speeds (600, 852, and 1260 rpm) and two different feeds (0.045, 0.1 mm/rev) are selected as process parameters. The effect of process parameter on thrust force and delamination during drilling CGRP is analyzed for optimizing the machining parameters. The delamination factor is low for the optimum process parameter (feed = 0.1 mm/rev and speed 852 rpm). Microstructural analysis confirms that at higher feeds, delamination is low for CGRP drilled with carbide tools. In order to analyze the effect of nanoclay in CGRP on tool wear, 200 holes were drilled on CGRP samples with 3 wt.% nanoclay, and the tool wear is analyzed under optimized parametric condition. Tool wear is high in HSS twist drill compared with carbide drill. The presence of nanoclay also accelerates the tool wear.

Magnesium Coated Bioresorbable Phosphate Glass Fibres: Investigation of the Interface between Fibre and Polyester Matrices

Bioresorbable phosphate glass fibre reinforced polyester composites have been investigated as replacement for some traditional metallic orthopaedic implants, such as bone fracture fixation plates. However, composites tested revealed loss of the interfacial integrity after immersion within aqueous media which resulted in rapid loss of mechanical properties. Physical modification of fibres to change fibre surface morphology has been shown to be an effective method to improve fibre and matrix adhesion in composites. In this study, biodegradable magnesium which would gradually degrade to Mg2+ in the human body was deposited via magnetron sputtering onto bioresorbable phosphate glass fibres to obtain roughened fibre surfaces. Fibre surface morphology after coating was observed using scanning electron microscope (SEM). The roughness profile and crystalline texture of the coatings were determined via atomic force microscope (AFM) and X-ray diffraction (XRD) analysis, respectively. The roughness of the coatings was seen to increase from 40 ± 1 nm to 80 ± 1 nm. The mechanical properties (tensile strength and modulus) of fibre with coatings decreased with increased magnesium coating thickness.

Mechanical property evaluation of sisal–jute–glass fiber reinforced polyester composites

The composite materials are replacing the traditional materials, because of its superior properties such as high tensile strength, low thermal expansion, high strength to weight ratio. The developments of new materials are on the anvil and are growing day by day. Natural fiber composites such as sisal and jute polymer composites became more attractive due to their high specific strength, lightweight and biodegradability. Mixing of natural fiber with Glass-Fiber Reinforced Polymers (GFRPs) are finding increased applications. In this study, sisal–jute–glass fiber reinforced polyester composites is developed and their mechanical properties such as tensile strength, flexural strength and impact strength are evaluated. The interfacial properties, internal cracks and internal structure of the fractured surfaces are evaluated by using Scanning Electron Microscope (SEM). The results indicated that the incorporation of sisal–jute fiber with GFRP can improve the properties and used as a alternate material for glass fiber reinforced polymer composites.

Analysis of delamination in drilling glass fiber reinforced polyester composites

Glass fiber reinforced plastic (GFRP) composite materials are finding increased application in aeronautical, automobile and structural applications. Drilling is a complex process, owing to their tendency to delaminate is used to join composite structures. In the present work, an attempt has been made to develop empirical relationships between the drilling parameters such as fiber orientation angle, tool feed rate, rotational speed and tool diameter with respect to delamination in drilling of GFR–polyester composites. The empirical relationship has been developed by using response surface methodology. The developed model can be effectively used to predict the delamination in drilling of GFRP composites within the factors and their limits are studied. The result indicated that the increase in feed rate and drill diameter increases the delamination size whereas there is no clear effect is observed for fiber orientation angle. The spindle speed shows only little effect on delamination in drilling of GFR–Polyester composites.

Finite difference analysis of thermal response and post-fire flexural degradation of glass fiber reinforced composites coated with carbon nanofiber based nanopapers

In this study, a 1D transient finite difference model was developed to predict the thermal response and post-fire flexural modulus degradation of glass fiber reinforced polyester composites subjected to various levels of heat flux. A carbon nanofiber (CNF) based hybrid nanopaper was coated onto the surface of the composites. The protective nanopaper coating was treated as to impose a temperature boundary condition in the model. A temperature dependent post-fire mechanical property model proposed in an earlier study was implemented with the thermal model in which the porosity and permeability of the material were taken into account. By comparing the post-fire residual flexural moduli, the model prediction showed reasonable agreement with the experimental data and expected physical behaviors. The model numerically demonstrates how the coating of nanopaper helps retain the structural integrity of the composite material, namely, the nanopaper coating leads to a reduction in mass loss, reduced cold side temperature, and eventually improved mechanical property. Furthermore, the parametric study of the model suggested that the porosity of the material has profound influence on the residual moduli of the composites.

Effects of carbon nanofibers (CNFs) on thermal and interlaminar shear responses of E-glass/polyester composites

A high intensity ultrasonic liquid processor was used to infuse 0.1–0.4wt.% carbon nanofibers (CNFs) into the polyester matrix which was then mixed with a catalyst using a high speed mechanical agitator. Both conventional and nanophased glass fiber reinforced polyester composites (GRPCs) were fabricated using the vacuum assisted resin transfer molding (VARTM) process. Scanning electron microscope (SEM) revealed best dispersion of CNFs in the 0.2wt.% CNF-loaded resin. Proper resin flow and impregnation of the glass fibers were also seen in the SEM micrographs. DMA studies exhibited about 49.5% increase in the storage modulus and about 3°C increase in the glass transition temperature (Tg) due to the incorporation of CNFs into the GRPC. TMA studies also showed better thermal stability and lower thermal expansion in the CNF-loaded GRPC. CNF-loaded GRPC showed higher ILSS due to better interfacial bonding between the fiber and matrix due to the presence of CNFs. Fracture morphology studied by both optical microscope (OM) and SEM revealed better interfacial bonding in the CNF-loaded GRPC.

Fire retardant evaluation of carbon nanofiber/graphite nanoplatelets nanopaper-based coating under different heat fluxes

Three types of carbon nanofiber based nanopapers, namely, 1Clay/5CNF/9APP, 1xGnP/5CNF/9APP, and 3xGnP/1CNF/9APP were made and their flame retardant efficiency was compared with thermogravimetric analysis and cone calorimeter test with 50kW/m2 of heat flux. The nanopaper of 3xGnP/1CNF/9APP was selected for experimental study because of its relatively good bonding with underlying structure and flame resistance performance. The fire response of glass fiber reinforced polyester composites with and without the selected nanopaper coating was thoroughly examined with cone calorimeter test using varied heat fluxes. It was found that at higher heat flux, the nanopaper demonstrated better flame retardant efficiency. Specifically, at 100kW/m2 of heat flux, the 1st and 2nd PHRR of the nanopaper-coated sample were more than 32% and 47% lower than the PHRR of control sample, respectively. In order to gain an insight into the pyrolysis process and flame retardation mechanism, the temperature profiles at the middle and back of the samples subjected to different heat fluxes were recorded. At 100kW/m2 of heat flux, the final temperature within the nanopaper-coated sample was roughly 280oC, which is lower than control sample. The degradation rates in flexural moduli of the samples with coupon shape were determined using three-point bending. The three-point bending test results showed when the sample was exposed to 25kW/m2 heat flux for 240 seconds, the flexural modulus of control sample almost reduced to zero, whereas the nanopaper-coated sample still retained a half of its original flexural modulus. Finally, flame retardation mechanism was proposed for the nanopaper-coated composites.

Modelling and Analysis of Thrust Force in Drilling of GFRP Composites Using Response Surface Methodology (RSM)

In recent days, Glass Fiber Reinforced Polyester (GFRP) Composites play important role in aircraft primary structures due to their high strength and low thermal expansion. The drilling process is a traditional cutting process in which hole is made in the material that is being drilled. The drilling process and tool parameters play a major role in deciding the quality of holes. In this paper an attempt has been made to establish an empirical relationship between the thrust force and drilling parameters (tool rotational speed, tool feed rate, drill diameter and fiber orientation angle) in drilling of GFRP Composites. Statistical tools such as design of experiments, analysis of variance, and regression analysis are used to develop the relationships. The developed empirical relationship can be effectively used to predict the thrust force of drilled holes at the 99 per cent confidence level.

Energy Absorption and Strength Evaluation for Compressed Glass Fibre Reinforced Polyester (GRP) for Automobile Components Design in Crash Prevention Scheme

This paper utilized the compressive tests results to establish some critical mechanical properties and crashworthiness parameters that may be required to design GRP composites of polyester matrix in automobile structures. Third order polynomial function was used with numerical methods to establish the elastic properties whish could not be established due to sensitivity of the Monsanto tensometer used to obtain the compression results. This study showed that the finite difference method captured the general trend of experimental solution giving optimum value of compressive stress as 23.78MPa at strain of 0.018 and elastic limit of 12.01MPa at 0.01 strain through finite difference analysis while the solution with third order polynomial interpolation gave optimum compressive stress as 36.57MPa at 0.018 strain and elastic limit of 12.143MPa. Also established with compression data is the compressive or buckling moduli of 1.2GPa. Gauss-Legendre two point rule was used to evaluate the area under the stress-strain curve which measured the amount of energy absorbed per unit volume of sample from where the energy absorbed at ultimate strength of 0.025J/M3- 0.22 J/M3 , energy at fracture of 0.62 J/M3- 1.62 J/M3 and the absorbed specific work 0.001J/Kg are established.