An Investigation on Mechanical Properties of E-Glass Fiber reinforced Polymer Nanocomposites

An Investigation on Mechanical Properties of E-Glass Fiber reinforced Polymer Nanocomposites

Available online at www.sciencedirect.com ScienceDirect Materials Today: Proceedings 18 (2019) 5454–5463 www.materialstoday.com/proceedings ICMPC-2...

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Available online at www.sciencedirect.com

ScienceDirect Materials Today: Proceedings 18 (2019) 5454–5463

www.materialstoday.com/proceedings

ICMPC-2019

An Investigation on Mechanical Properties of E-Glass Fiber reinforced Polymer Nanocomposites B.VijayKirana, K.Mallikarjuna Raob, D.LingaRajua,b* a

Assistant Professor, Mechanical Engineering Department, B.V.Raju Institute of Technology, Narsapur and 502313, India. b Professor&Assistant Professor, Mechanical Engineering Department, JNTU Kakinada and 533003, India

Abstract Polymer Nanocomposite play a very crucial role in the fields of Engineering nowadays because of rapid industrialization and requirement for the new and innovative materials in the market. Polymer Nanocomposite are having better functional properties, light weight, corrosive resistance, long life, larger surface area e.t.c. It replaces most of the conventional materials in almost all the fields of Engineering. It is because of its tailored material capabilities.In this paper, we have presented the fabrication procedure of E-Glass fiber reinforced Graphene Oxide Nano Platelets (GONP) based polymer nanocomposite material by using hand layup technique. We have conducted the tension, compression, hardness, toughness and flexural tests along with these the tests also conducted like SEM testing, to know how the Nano fillers interact with resin. When compared with neat epoxy laminated coupons, the tailored polymer nanocomposite laminate coupons gives better result and thereby increased Tensile, compressive and flexural properties. As we have observed that the addition of little amount of GONP in the material the properties were improved extensively. We have added four different weight percentages of Nanoparticles in Epoxy material. The considered percentages are 0.5wt%, 1wt%, 1.5wt% and 2wt% of Nanoparticles. From the experimental investigations we found that the tensile strength and compressive strength of material is increased which is expressed in percentages as 10.25, 14.97, 16.26, 18.64 and 1.97, 3.46, 5.65, and 11.56 respectively. Apart from tensile and compressive strength the Flexural strength is also increased by the percentages of 4, 19.92, 26.78, and 28.73 respectively. Very little amount of increment is observed in Hardness. More interestingly we observed that the addition of 4% Nanoparticles make the components very flexible and it takes more time for curing. The developed material based on obtained results proposed to be used as the material in wind turbine blade and tidal Energy extraction rotor blade, where load applied is critical. This material can also be used in Aerospace, Defence, automobile and other fields for structural applications. © 2019 Published by Elsevier Ltd. Selection and peer-review under responsibility of the 9th International Conference of Materials Processing and Characterization, ICMPC-2019 Keywords: Glass Fiber, Graphene Oxide (GO), Nano Platelet, Nanocomposite, Resin

* Corresponding author. E-mail address: [email protected] 2214-7853 © 2019 Published by Elsevier Ltd. Selection and peer-review under responsibility of the 9th International Conference of Materials Processing and Characterization, ICMPC-2019

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1. Introduction In recent days the demand for nano materials is increasing day by day. Because of its unusual properties in several applications. Nanotechnology is creating new manufacturing possibilities and materials. Researchers can use these materials for creating new materials or modify the existing materials based on custom design and requirements of customer or for the particular device. These materials will increase the strength, stiffness, toughness, like other properties which we can tailor based on our requirements. Because of its advantages, it is used in several fields of Engineering and manufacturing sectors. Particularly in Automobile fields, manufacturing units, biomedical applications, packaging, sports equipment..etc. Because of its merits in several fields,, the nanotechnology is also applied nowadays. These nanoparticles concept also used in polymer composites for improving its properties and better functional characteristics. Just by adding the nanoparticles in polymer composites it is observed that its properties were improved. Depends on the type of nanoparticles used particular property will be improved. Polymer composites were also having several applications in the fields of Engineering nowadays. The concept of polymer composites is there from several decades. By adding the nanoparticles in the polymer composites we can form a new material called polymer nanocomposite. This will improve its properties. From the literature, it is revealed that incorporation of different types and different sizes of materials such as layered, nanoparticles, nanotubes, nanofillers like Tio2, Si02, Al203 will improve the mechanical properties. These types of nanoparticles can also be used in coatings and paintings. By adding these nanosized elements in polymer composites it improves High surface to volume ratio of the reinforcing phase, high aspect ratio which make it to improve the upgradition of properties such as toughness, stiffness, hardness, strength, modulus, durability, heat reseistent, fatigue life, etc. Tailoring of polymer-nano composites is increasing day by day, because of the demand for new and innovative materials. There are two alternatives ways to meet the demand for new materials. One way is to modify or tailor the new materials and another one is inventing the new materials. PNCs are prepared by fillers with a size of lessthan 100 nanometers. [1,2] The merits of PNCs are to provide value-added properties to the polymer without sacrificing its original process capability, hidden mechanical properties and light weight. Some authors have done investigations on carbon nanotubes based on PNCs. [2.3] The production cost of graphene can be much lower than that of carbon nanotubes. The availability of carbon nanotubes is limited and high quality of this tubes are not available in the market. If available its cost is very high and limited applications. [4, 5] Graphene, a two-dimensional, single-atom-thick structure of sp2-bonded carbon atoms, has attracted tremendous research attention due to its high specific area and unique mechanical, electrical and thermal properties. [5–8]Significant improvements in strength, fracture toughness and fatigue strength have been reported using graphene as fillers or reinforcements in nanocomposites. To reduce graphene as multilayered graphene sheets earlier several methods were used. i.e CVD, micromechanical exfoliation and chemical reduction are used. But when compared to all these methods chemical reduction is the best to produce a large scale of graphene.[9,10] Graphite flakes are used to produce the GO by using hummers method. In this method, graphite flakes were exposed to strong oxidation and further exfoliation. In addition, mechanical properties of GO are excellent and it has the ultimate stress around 60Gpa and its modulus of elasticity values are around 250Gpa. [11,12,13] fabrication procedure is also important in the preparation of polymer nanocomposite. The following steps are important. The process used to prepare GO, proper dispersion of nanofiller in resin and selection of resin, sonication of Go and resin, an addition of the proper percentage of hardener. Method used to prepare specimens. [14-18] Through there are several techniques available to prepare PNCs, in this study we have used hand layup technique. [19,20] Because of its properties and ease of processing epoxy resin is used for many structural applications. It is one of the widely used epoxy. [21,22] while manufacturing composite, two terms i.e matrix flow and resin cure reaction takes a vital role. Is is because to produce void free perfectly adhered fibers and matrix. It is the key reason for enhancement of mechanical properties. [23-28] the knowledge of cure kinetics and resin flow is also an important factor in fabricating composites. Authors have already mentioned in the literature related to these aspects. [29] just by adding very less amount of weight faction 0.1 wt% of graphene oxide leads to 12% increase in tensile modulus. Flexural which is greater than that of neat epoxy.[30] the addition of 0.25% of Graphene Plateles of size 2-15nm in the epoxy resin leads to 15% enhancement in ultimate tensile strength and 12% enhancement in fracture strength.[31] adding the GNP in different proportions (0.1, 0.25 and 0.5%) flexural fatigue life was improved at a rate of 22.2,27.4 and 17 times. In this paper we have worked on Graphene Oxide polymer

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nanocomposites. We have taken GONP because of its merits. Currently number of techniques were available to prepare GO nano particles. while preparing GO, it is extracted from Graphine, Graphite is a 3D carbon based material. It is available easily. From this graphite we can make graphene in the form of layers. Graphite is a 3Dcarbon based material, which can be thought of as being made from many layers of graphene. Graphite oxide is slightly different from graphite. If we use strong oxididing agents to oxidize graphite, oxygenated functionalities will introduced in the graphite structure, which makes materials hydrophilic and it expands the layer separation. It will make it possible to exfoliate the GO in the water through sonicaion and it will produce monolayer or the few layer oxygen functionalized graphene, which is called Graphene oxide or GO. The number of layers is the major difference between graphene oxide and graphite oxide. Although graphite oxide is a multilayer system, monolayer flakes and few-layer flakes can be found in a graphene oxide dispersion. Due to the presence of oxygen functionalities, graphene oxide can easily disperse in organic solvents, water, and different matrixes. This is a major benefit when combining the material with polymer or ceramic matrixes is to enhance their mechanical and electrical properties. With respect to electrical conductivity, graphene oxide functions as an electrical insulator, because of the disturbance of its sp2 bonding networks. It is important to reduce the graphene oxide so as to recover the honeycomb hexagonal lattice of graphene, in order to restore electrical conductivity. After a large number of oxygen groups which have been removed, it is not easy to disperse the reduced graphene oxide (rGO), because this material tends to produce aggregates. The properties of graphene can be changed by the fictionalization of graphene oxide. The chemically-altered graphenes obtained by this method could possibly be used in several applications. Depending on the intended application, the graphene oxide can be functionalized in a number of ways. One way to ensure that the chemically-altered graphenes disperse easily in organic solvents is to use amines through organic covalent fictionalization, for instance. This makes the material better suited to production of bio devices and optoelectronics, and for use in drug delivery. Also, it has been shown that it is possible to attach fullerene-functionalized secondary amines and porphyrin-functionalized primary amines to graphene oxide platelets, to enhance the nonlinear optical performance of the material. Graphene oxide could potentially be used as an intermediary in the production of single layer or few-layer graphene sheets. To achieve this, an oxidization and reduction process should be developed that can isolate carbon layers and separate then without changing their structure. In terms of mass production of graphene, the chemical reduction of graphene oxide is considered to be one of the most viable methods. However, scientists have found it challenging to create graphene sheets that have the same quality as those made by mechanical exfoliation on a large scale. Graphene oxide is chosen because among all the other nano particles when GO nanoparticles were added to polymer resin its mechanical properties are increasing extensively for very small quantity of GO. The structure of Graphene odixe if we observe, in the outer edges it contain oxygen atoms, these atoms react with other atoms and the cross linking reactions are good. Which improves the strength of composite. The oxide form is more advantageous in GO. The wrinkeled surgace is also advantageous to form proper bonding with the resin. i.e interlocoking. Literature on reinforcement of E-glass fiber with Graphne oxide based polymer nanocomposites is very limited and based on the books, articles and literature we came to know that graphene has the excellent mechanical properties. Cross linking densities and curing characteristics were not discussed indetail and why mechanical properties were improved was also not clearly discussed in the literate. 2. Methodology Experimental process has shown in the form of a Flowchart as shown in Fig.1. the entire process was done in three stages. In the first stage we have fabricated the specimens in order to fabricate these specimens we have done the calculations based on volume fractions of Fiber and resin in the raio of 60:40, afterwards it is converted into weight fractions. we have dispersed these calculated weight percentages of Nanoparticles in resin and stirred by hand for 20 minutes followed by sonicated for 30 minutes. after the sonication hardner was mixed and in the required ratio and Then poured this mixture in the wooden patterns. In the second stage the specimens were cut as per the ASTM standards and conducted different tests on the test coupons. In the third stage to Evaluate mechanical properties we have conducted the following tests, i.e tensile, compression, flexural, and harndss tests. also we have conducted SEM test to identify the microstructure of the material and to know how the interaction between the resin and fiber as shown in below Fig 1 and Fig 2

B.V. Kiran et al./ Materials Today: Proceedings 18 (2019) 5454–5463

Making of Specimens Preparation of Coupons as per ASTM Standards

Resin and GONP

Tensile, compressive…

Sonication process

Evaluation of Mechanical Properties and micro structure Mechanical Performance

Addition of Hardner

Micro structure Analysis

Specimens as per ASTM Standard Poured into Pattern

Fig.1 : Flow Chart indicating Experimental Procedure

2.1 Materials Required Pattern of the required size Teflonsheet Mould release spray Resin Hardner Sonicator Nanoparticles Portable weighing Machine Hand Glouses Table 1. Resin(LY 556) & Hardner(HY951) Properties. Properties

Resin (t) 0

Hardner (t)

Viscosity at 25 C

10000-12000mpa s

50-100 mPa s

Density at 250C

1.15-1.20 g/cm3

1.20-1.25 g/cm3

Flash Point

>200 0C

195 0C

Table 2. E-Glass Fiber Properties. Properties

Glass Fiber (t)

Specific Gravity

2.5 – 2.62 g/cm3

Density

2.56 g/cm3

Maximum Temp.

380 0C

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2.2 Specimens Preparation:

E-Glass fiber mat

LY 556 Hardner

Weighing Machine

GO NanoPlatelets

Wodden Pattern

release spray

GO layered pattern

Sonicator

GO Layered pattern for Izod test

Neat Epoxy composite after preparation

GNPinserted composite

Specimen with GNP

Fig. 2: Specimens Preparation Procudure

Sequential Steps followed to prepare the specimens After collecting all the materials, we have started preparation and prepapred two types of patterns. One is wooden and another is metallic. The wooden patterns are used for a single purpose and metallic patterns stands for long term usage. Procedure for hand layup: 1. Prepare the pattern as per the dimensions required 2. Take the prepared pattern and apply PVA over it , which avoids the sticking the epoxy to the surface. 3. Make the calculation by considering the resin, fiber volume rations. Along with this also consider the weight percentage of Nanoparitcles. 4. Then take a weighing pan and measure the resin as per the calculation 6. After measuring the resin measure the Nanoparticles and then measure the Hardener. 7. Then mix the resin by addition of Nanoparticles in it for 30 minutes 8. Then used the sonicator for proper dispersion of nanoparticles in the resin for half an hour. 9. Before pouring the resin nanoparticle mixture in the pattern add the Hardner in it. And stir again for few minutes and then pour in the pattern. 10. After pouring the mixture of resin, nanoparticles, harnder in the pattern. Use Vaccum pump to suck the air bubbles present in the resin. Then by using the roller smooth the surface and then cure it for 4-6 Hours under any convenient load.

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Table 3. ASTM Standards to find different Properties. Property

ASTM Std.

Dimensions of specimen(mm3)

Tension Test

D3039

250x25x3

Compression

D3410

155x25x3

Hardness

-

Any Size

Flexural

D790

127x13x3

3. Results and discussion 3.1 Dispersion of Nanoparticles [32] Proper dispersion of nanoparticles is a very important issue in preparation of polymer nanocomposites. It is because the GO nanofillers have the tendency to agglomerate because of Vander Waals forces and its surface area. If we increase the nanofiller concentration in resin the dispersion will become difficult and it won’t be dispersed properly. If it is not dispersed properly the mechanical properties will not be improved. To improve the mechanical properties the dispersion of nanofillers should be uniform. This nanoparticles concentration also effects the curing characteristics. Type, size and dispersion of nanoparticles effects the properties of materials. When lesser the size of nanofiller, it will improve its surface area and gives the better results. Uniform dispersion of Nanofillers improves the mechanical properties of composite as shown in below Fig 3-6. 3.2 Tension Test The test coupons were prepared as per ASTM standard. The percentage variation of Nanofiller effects the tensile properties and found that it has improved the tensile strength and Elastic modulus of the material.

Specimen Without addition of NP

1% addition of GONP

1.5% addition of GONP

2% addition of GONP

0.5 wt%NP specimen Fig 3: Coupons as per ASTM standard to conduct tension test

It is found that when we have added the nanoparticles into the polymer matrix and fibers combination it has improved the tensile and ultimate strength of specimens along with improvement in Elastic modulus. The tensile test was performed on Electronic universal testing machine UTE-60, Neat epoxy specimen values were considered as the reference and found that the ultimate tensile strength of the specimen with 0.5% Nanoparticles improve the tensile strength upto 10.25, for 1% Nanoparticles is increased to 14.97% of the neat specimens., 1.5% Nanoparticles is increased upto 16.26% of the neat specimens. And 2% Nanoparticles is increased to 18.64% of the

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neat specimens. We have tried to add 4% Nanoparticles in the resin but it became difficult and the resin was not cured so fast. We have observed growth in tensile properties from 0.5 to 2wt% . 3.3 Compression test

Neat Epoxy and 0.5 wt%NP specimen

1% addition of GONP

1.5% addition of GONP

2% addition of GONP

0.5 wt% addition of GONP Fig 4: Coupons as per ASTM standard to conduct compression test

In general Composite materials have more strength in the fiber aligned direction and these are weak in compression. For different applications both tensile and compressive strengths are required. Compression test was also carried out on UTE-60. While conductiong the compression test over this specimen the specimen got compressed and less values of the load is sustained by the specimens. At 0.5% addition of Nanoparticles percentage increase in compressive strength is 1.97. at1% Nanoparticles in compressive load is 3.46% of the neat specimens, at 1.5% Nanoparticles the compressive load is increased to 5.65% of the neat specimens. At 2% Nanoparticles the compressive load is increased to 11.56% of the neat specimen. And that the reason for this is because of the alignment of fibers in compression the chopped mat is having the less streangth. But improvement is there in the values when the percentage of Nanoparticles concentration is increased from 0 to 2% of weight of the resin. A rapid growth was observed at 2 wt% addition of NP in the resin. 3.4 Hardness test Hardness is also the property of a material. To conduct hardness test we have taken one of the specimen and conducted the test. There is no particular size needed for this. We have conducted this test on Shore ‘D’ hardness tester and found that there is improve in the values for 1% and 1.5% of Nanoparticles. But very little reduction in hardness value with 2% nanoparticles.Because of increasing the concentration of GONP in the resin its hardness will also improved upto some extent only. The hardness of the material increases because of the increase in the percentage of nanofillers in the resin. 3.5 Flexural test Three point bending test is performed to find modulus of the materials in the beam position. Flexural stress is calculated by using the equation   3 fl / 2bd 2 While conducting the flexural test we found that the flexural strength of the materials was increased and the improvement is also different for different percentages of the nanofillers. It seems that by the addition of nanofillers to the resign it improves the flexural strength. Taking neat resin as the reference, the flexural strength of 0.5% Nanoparticles is found to be 4 and for the addition of 1%, 1.5% and 2% are as following i.e, 19.92, 26.78 and 28.73.

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Neat Epoxy and 0.5 wt%NP specimen

1% addition of GONP

1.5% addition of GONP

2% addition of GONP

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0.5 wt% addition of GONP Fig 5: Coupons as per ASTM standard to conduct Flexural test

P e rcen tag e inc rease in F lex ura l S tren gth(M p a)

B

35 30

26.78 19.92

20 15 10

4

5 0 0.0

0.5

1.0

1.5

Percentage of Nanoparticles

Tension test

28.73

25

Compression test Hardness test Flexural test Fig.6: Charts indicating variation of properties with variation of Nanoparticles percentages in resin

2.0

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1.

0.5 wt% NP plus Epoxy

2.

1.5 wt% NP in Epoxy

3.

1 wt% NP in Epoxy

4.

1% NP in Epoxy

5.

2% NP in Epoxy

6.

Neat Epoxy

7.

Neat Epoxy

8.

Neat Epoxy

Fig.7 SEM images of Neat Epoxy and different percentages of GONP

3.6 SEM Analysis of Samples Scanning electron microscopy (SEM) is one of the important techniques used to test and characterize the materials. SEM offers high resolution imaging capability. It has been observed that the size and shape of any particles influence the properties of the materials. Generally, most of the materials are size dependent, the physical properties of materials at the nanoscale can differ from the constant physical properties of the same material existing in bulk form. To identify how the particles were dispersed in the resin will be revealed by this. The properties depend on how the nanofillers were dispersed in the material. It affects the mechanical properties of the materials to know how nanoparticles were mixed or whether there were scattrerd or agglomerated at a point are revealed by this technique. The strength of laminate depends on interaction of NP with the resin. The bonding is good.In case of 0.5 and 1% weight of GONP. Where as in the case of 1.5 and 2% the agglomerates were formed because of increase in Nanoparticles percentage. the agglomerates were formed because of the vander Waals forces between the GONP and the dispersion is observed at 20 micron meters level. If the GONP dispersion is uniform the properties will be improved as shown in below Fig 7 and As shown in above Table 1-3 and Below Table 4. 3.7 Table 4: Discussion Tensile Test Compression Test Hardness Test Flexural Test

0.5 Wt% 10.25 1.97 53 4

1Wt% 14.97 3.46 57 19.92

1.5 Wt% 16.26 5.65 57 26.78

2 Wt% 18.64 11.56 56 28.73

4. Conclusions From the present experimental Investigation , we are going to conclude the following points: By adding the Graphene Oxide Nanoparticles to the neat epoxy resin its mechanical properties were improved. The variation in percentage of GONP also effects the mechanical properties when the percentage concentration increases or decreasesTensile, flexural and compressive strengths were improved. Tensile and Flexural Properties were improved extensively when compared to hardness The toughness values are constant for all percentages, even though percentage of GONP increased to 2%

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From SEM characterization we have observed that at 0.5 and 1% weight of Nanoparticles uniform mixing of GONP were observed. at 1.5% and 2% agglomerates were formed because of the cohesive forces between the GONP. If we mix the nanoparticles without the agglomerates we can still improve the properties. References [1] R.A.Vaia and H.D.Wanger, Framework for Nanocomposites, Materials Today, 7(11), 2004, 32-37. [2] R.Verdejo, M.M. Barnal, L.J. Romasanta and M.A. Lopez-Manchado, Graphene Filled Polymer Nanocomposites, Journal of materials chemistry, 21(10), 2011, 3301-3310. [3] J. Liang, et al., Electromagnetic interference Shielding of Graphene/Epoxy Composites, Carbon, 47(3), 2009, 922-925. [4]Huang X, Yin ZY, Wu SX, Qi XY, He QY, Zhang QC et al (2011)Graphene-based materials: synthesis, characterization, properties, and applications. Small 7(14):1876–1902. [5] Rafiee MA, Rafiee J, Srivastava I, Wang Z, Song H, Yu Z-Z et al (2010) Fracture and fatigue in graphene nanocomposites. 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