properties of luffa ﬁber- reinforced biocompositesthe ASTM E2611-17 standard [42]. s0030 17.3.2...

c0017 Acoustic and mechanicalproperties of luffa fiber-reinforced biocomposites

17Hasan Koruk 1, Garip Genc 21MEF University, Mechanical Engineering Department, Istanbul, Turkey;2Marmara University, Mechatronic Engineering Department, Istanbul, Turkey

s0010 17.1 Introduction

p0015 Composites reinforced by synthetic fibers such as glass, carbon, and aramid are widelyused in practice, including in the aerospace, automotive, sports, and biomedical sectors[1e11]. Although synthetic fibers have superior mechanical properties, such as lowdensity and high strength, the recycling process for these materials takes a long timeand they pollute the environment. Furthermore, burning substances derived from pe-troleum products release enormous amounts of carbon dioxide into the atmosphere.This phenomenon is believed to be the root cause of the greenhouse effect and climatechange. Therefore, finding and developing new materials as alternatives to petroleum-based materials have become a necessity. Because of the biodegradability of naturalfibers, the use of biofibers as reinforcements for composite structures has receivedincreased attention [12e14]. However, the acoustic and mechanical characteristicsof biocomposites and their dynamic behaviors should be fully explored before theyare considered for practical applications.

p0020 Major biomaterials such as flax, jute, hemp, kenaf, sisal, ramie, and Luffa cylindricahave been investigated in many studies [12e36]. Despite challenges such as the culti-vation and continuity of these plant-based materials, their enhanced features havegained immense importance [25]. L. cylindrica has been recognized as a new biode-gradable material and luffa-reinforced composites are being investigated for practicalapplications. Like other natural fibers, luffa fibers do not create a health risk when in-dividuals are exposed to them; in addition, they are inexpensive. In this study, methodsfor identifying the acoustic and mechanical properties of biocomposite structures arebriefly described. Acoustic properties including sound absorption and transmissionloss and mechanical properties including damping and the elasticity of luffa compos-ites are presented. Variations in acoustic and mechanical properties resulting fromdifferent samples and manufacturing processes are also explored to understand theirlimitations in practice.

Mechanical and Physical Testing of Biocomposites, Fibre-Reinforced Composites and Hybrid Compositeshttps://doi.org/10.1016/B978-0-08-102292-4.00017-5Copyright © 2019 Elsevier Ltd. All rights reserved.

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s0015 17.2 Manufacturing, defects, and structural differences

p0025 L. cylindrica is commonly found in South America, Brazil, China, Japan, and Turkeyand in some other countries in Asia. This plant has a type of fruit that is covered with agreen peel on the outside (Fig. 17.1a). The outer green layer starts to dry when thefiber inside the fruit is completely ripe (Fig. 17.1b) and the fibrous structure developsunder the dried outer layer (Fig. 17.1c and d). The size of the luffa plant varies in rela-tion to its location, ranging from 0.15 to 1 m (even more than 1 m in certain areas). Ingeneral, luffa fiber contains cellulose, hemicellulose, and lignin (Table 17.1),although the chemical composition of luffa fibers depends on several factors suchas the plant’s origin, weather conditions (which are changeable annually), and thesoil. For instance, the cellulose content varies from 55% to 90%, the lignin contentis within the range of 10%e23%, the hemicellulose content is around 8%e22%,extractives amount to nearly 3.2%, and ash makes up around 0.4% [26,28,31,37].

(a) (b)(c)

(e) (f) (g)

(d)

Defect Defectsf0010 Figure 17.1 Luffa fibers: (a) green plant, (b) dried plant, (c) fibrous structure, (d) the structure of

luffa fiber with three and four holes, and luffa fibers (e and f) with and (g) without defects.

2 Mechanical and Physical Testing of Biocomposites, Fibre-Reinforced Composites

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p0030 Luffa composites are produced through methods similar to those used to manufacturechemical fiberebased composites. Lignin, the outermost layer of a luffa fiber,reduces adhesion to the matrix. Therefore, the lignin layer could be weakened by varioussurface modifications to increase matrix adhesion [26e30]. Increasing adhesion to theinterface leads to better mechanical properties. Nevertheless, a scanning electron micro-scopy photomicrograph for sample luffa composite structures showed that interfacialcompatibility between luffa fibers and the matrix was acceptable even when a surfacetreatment was not applied to the luffa fibers. Therefore, luffa fibers are used with orwithout a surface treatment in practice and a resin such as epoxy is used as a matrixto manufacture luffa composite structures. In general, luffa fibers are placed betweentwo plates and resin is passed through them. Luffa composite samples are cured atconsiderably high temperatures (50e100�C) under pressure (5e10 bar) for 5e10 h.There have been attempts to use sodium hydroxide [22,26,29,32], alkalization, furfury-lation [36], formic acid, acetic acid [28,33], and dithiothreitol [30] during manufacturingto improve the thermal and mechanical properties of composite structures.

p0035 Inherently, green plants including luffa cannot be identical and structural differ-ences are always expected. For example, the measured masses of 15 dry luffa fiberspecimens with approximately the same dimensions showed that the average massof a luffa plant is 75 g with a standard deviation of 20 g. Whether the number of holesof a luffa plant is three, four, or more (Fig. 17.1d), even for the same harvest, has aneffect on the structure of the fibers. In addition to these structural differences, there aresome defects in the fibrous structure, as is normal for many biofiber plants (Fig. 17.1eand f). Defects are formed during the growth of the plant. Regions with defects havedifferent mechanical properties. It should be noted that luffa fibers in the matrix arerandomly distributed (Fig. 17.1g). In addition, the direction of the press duringmanufacturing may affect the properties of luffa composites.

p0040 The structural differences inherent in the nature of green plants, defects, andthe manufacturing process affect the acoustic and mechanical properties of luffacomposites. Despite this, the structure of luffa fibers consists of a lot of short fibersinterlocking into a mesh. This feature means that luffa composites have small varia-tions in their acoustic and mechanical properties, as presented in Sections 17.3 and17.4. Despite difficulties in homogenizing a batch of L. cylindrica samples for massproduction and manufacturing the luffa composite structures, increasing the use ofthese green materials to minimize the use of chemical based composites is vital for

t0010 Table 17.1 Composition of Luffa cylindrica fibers[26,28,31,37]

Component Content (%)

Cellulose 55e90

Hemicellulose 8e22

Lignin 10e23

Ash 0.4

Extractives 3.2

Acoustic and mechanical properties of luffa fiber-reinforced biocomposites 3

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the environment. In the future, new biocomposite materials based on natural fibers andbioresins are expected to be produced though a chemical matrix, as is currently used tomanufacture biocomposites.

s0020 17.3 Acoustic properties

p0045 Sound absorption and transmission loss are two important acoustic characteristics ofmaterials. Therefore, these characteristics of biocomposites should be explored beforethey can be considered for practical applications. In the following discussion, identi-fication methods for sound absorption and transmission loss are briefly described.Then the acoustic properties of luffa fibers and their composites are presented.

s0025 17.3.1 Identification methods

p0050 The impedance tube method with two microphones (Fig. 17.2) is widely used to iden-tify the frequency-dependent absorption properties of materials [38e41]. In this tech-nique, material samples are inserted into the tube and a sound source in the tube emits aprecisely quantified sound. Using the two microphones, the complex valued acoustictransfer function eH12ðuÞ from p1 to p2 is first measured. The complex valued normalincidence reflection coefficient eRðuÞ based on the measured transfer function is thendetermined by:

eRðuÞ ¼ eH12ðuÞ � e�jks

ejks � eH12ðuÞe2jkðsþLÞ (17.1)

where k ¼ 2pu/c is the wave number, c is the speed of sound in the air, u is thefrequency, and j ¼ ffiffiffiffiffiffiffiffiffiffiffið�1Þp

. Using the reflection coefficient, the sound absorptioncoefficient at normal incidence is calculated by:

aðuÞ ¼ 1� ��eRðuÞ��2 (17.2)

Soundsource

Microphones

Acousticanalyzer

Signalgenerator

RigidplungerTest

sample

Ls

d

1 2

f0015 Figure 17.2 Impedance tube with two microphones used to measure sound pressure inside thetube to determine sound absorption coefficients.


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p0055 Determination of the sound absorption coefficients of materials using an impedancetube is described in ASTM E 1050-12 [38] and ISO 10534-2 [39] standards.

p0060 The transmission loss levels of material samples are determined using a tube withfour microphones (Fig. 17.3). By measuring the sound pressure at four stations andcalculating the complex transfer function using a four-channel acoustic analyzer, thetransmission loss of the material is determined. Measurement of the normal incidencesound transmission of materials based on the transfer matrix method is described inthe ASTM E2611-17 standard [42].

s0030 17.3.2 Sound absorption

p0065 Experimental investigations [32,41,43] showed that luffa fiber samples have consid-erably high sound absorption coefficients (Fig. 17.4). The average sound absorptioncoefficient of a luffa fiber sample with a thickness of 10 mm is around 0.3 for0.5e6.3 kHz. The acoustic absorption properties of luffa fibers compare favorablywith the corresponding properties of acoustic foams used in practice [40]. Luffafiber samples can be used as sound absorption materials in many applicationsthat do not require high load-bearing capabilities. Also, the sound absorption coef-ficients for all luffa fiber and composite samples increase with frequency. Luffacomposites with higher sound absorption coefficients (compared with luffa fibersamples) can be obtained when the correct volume fraction of fiber is determined.The average sound absorption coefficient of a luffa composite sample with a thick-ness of 10 mm and fibereepoxy ratio of 4 is around 0.35 for 0.5e6.3 kHz. Thesound absorption coefficient of a 10-mm glass plate or thicker is around 0.04 for0.5e4 kHz [44]. The hollow lumen structure of fibers and their random distributionis believed to be reason for the superior sound absorption properties of luffastructures [32,41,43].

p0070 Because a luffa composite sample has more elasticity strength compared with aluffa fiber sample, such samples can be used in practical applications where structuralstiffness is required. However, identified sound absorption coefficients of a luffacomposite decrease with an increasing volume fraction of matrix after a specific ratio.It was also reported that the sound absorption coefficient increases when perforatedlinen is used [41]. On the other hand, the treatment (e.g., sodium hydroxide) of

Microphones1 2 3 4

Soundsource

Testsample

Termination

Acousticanalyzer

Signalgenerator

f0020 Figure 17.3 Impedance tube with four microphones used to measure sound pressure inside thetube to determine transmission loss levels.


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luffa fibers in composites causes small decreases in the sound absorption coefficientsof the luffa composites [32].

s0035 17.3.3 Transmission loss

p0075 Experimental investigations [41,43,45] showed that luffa composite samples can haveconsiderably high transmission loss levels (Fig. 17.5). For a sample thickness of10 mm, the average transmission loss levels of a luffa sample without epoxy, a luffacomposite sample with a fibereepoxy ratio of 4, and a luffa composite sample witha fibereepoxy ratio of 1.5 are around 3, 6, and 25 dB, respectively. The transmissionloss level increases with an increasing volume fraction of matrix (epoxy) in the com-posite structure. The transmission loss levels of a luffa composite with a fibereepoxy

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f0025 Figure 17.4 Sound absorption coefficients of luffa samples with a thickness of about 10 mm: (a)luffa sample without matrixeepoxy, (b) luffa composite sample with high fibereepoxy ratio(i.e., 4), and (c) luffa composite sample with low fibereepoxy ratio (i.e., 1.5).


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ratio of 1.5 and a thickness of 10 mm compare favorably with the transmission losslevel of a cement or glass panel with a thickness of 10 mm [45,46].

p0080 Luffa composites have the potential to be used in architectural applications such asconcert halls to absorb reverberant noise and provide sound transmission, because

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f0030 Figure 17.5 Transmission loss levels of luffa samples with a thickness of about 10 mm: (a) luffasample without epoxy, (b) luffa composite sample with high fibereepoxy ratio (i.e., 4), and (c)luffa composite sample with low fibereepoxy ratio (i.e., 1.5).


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their sound absorption and isolation capabilities are better than many plant materials[43]. Some linens can be used to prepare acoustic samples using only the luffamaterial in practice; those samples can be used in the acoustic design of halls.However, if a high sound isolation property is also required (in addition to a soundabsorption property), a luffa composite material with an appropriate matrixcomposition can be used.

s0040 17.4 Mechanical properties

p0085 The main characteristics of a material affecting dynamic behavior are density, damping,and elasticity. Therefore, these mechanical properties of biocomposites shouldbe explored before they are considered for practical applications. The density of luffafiber is around 800e900 kg/m3, which is lower than some common natural fiberssuch as sisal (1260e1450 kg/m3), hemp (1480 kg/m3), coir (1250 kg/m3), ramie(1500 kg/m3), and cotton (1510e1600 kg/m3), as seen in Table 17.2 [18,37,47]. Thedensity of the glass fiber widely used in practice is around 2550 kg/m3. In the followingdiscussion, identification methods for elastic and damping properties are brieflydescribed. Then the elastic and damping properties of luffa composites are presented.

s0045 17.4.1 Identification methods

p0090 The static elasticity modulus, ultimate elongation, and tensile strength of materials areeasily determined via tensile testing in practice [48e54]. The dynamic mechanicalproperties such as modal damping levels and the dynamic Young’s moduli of materialsare frequently identified by determining the modal parameters such as the modalfrequencies and loss factors of special test structures (Fig. 17.6). For this purpose,

t0015 Table 17.2 Density of different natural fibers and glass fiber[14,18,37,47]

Fiber Density (kg/m3)

Sisal 1260e1450

Hemp 1480

Coir 1250

Flax 1400

Jute 1460

Ramie 1500

Cotton 1510e1600

Luffa 800e900

Glass 2550


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the frequency response functions using contact or noncontact excitation and responsesensors are first measured [55e57]. The frequency response function for the measuredresponse and excitation can be calculated by:

eHijðuÞ ¼eF�j ðuÞeViðuÞeF�j ðuÞeFjðuÞ

(17.3)

where eFjðuÞ and eViðuÞ are the Fourier transforms of the time domain excitation forcefj(t) applied at point j and the vibration velocity (response) vi(t) measured at point i,respectively; t is time; and superscript * indicates the complex conjugate. A modalanalysis method such as half-power, circle-fit, and line-fit can be used to identifymodal damping and frequencies once the frequency response functions are measured.In the simplest method, the half-power method, the loss factor (hr) for mode r (or modeshape fr), is determined by:

hr ¼u2r;2 � u2

r;1

2u2r

(17.4)

where ur,1 and ur,2 are the frequencies corresponding to half-power points around thenatural frequency ur, which is the peak for that mode.

p0095 Once the modal frequencies and loss factors are determined experimentally, themodal elasticity moduli can be determined using theoretical expressions relatingthe modal parameters to the elastic properties. Simple samples such as beams andplates to identify mechanical properties, are mostly used in experiments. For example,if the test sample is a clamped-free beam, the Young’s modulus for the mode r isdetermined by:

Er ¼ 12rL4u2r

H2C2r

(17.5)

rth mode

Frequency

Modalanalysis:

ηrωrφr

Hij~ν i ν= (x,y,z; t)

fj = f (x,y,z; t)

f0035 Figure 17.6 Frequency response function (eHij) measurements for the identification of modalparameters (hr, ur, and fr) of a test structure.


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where r, L, and H are the density, length, and the thickness of the beam, respectively.Cr is the coefficient for mode r of the clamped-free beam, which is C1 ¼ 0.55959,C2 ¼ 3.5069, C3 ¼ 9.8194, and Cn ¼ (p/2) (r�0.5)2 for r > 3. If the test sample is acircular plate with rigid boundary conditions, the Young’s modulus for the mode r canbe determined by:

l2r ¼ 2purR2

ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi12ð1� y2Þ rh

Erh3

r(17.6)

where R and h are the radius and thickness of the plate, y is Poisson’s ratio, and l2r is afrequency parameter given in the literature for different h/r values [58].

p0100 Numerical methods such as finite elements can be used to model the test structureand extract mechanical properties when the test structure is complicated. Furthermore,more parameters such as frequency-dependent damping levels can be included in thefinite element model for more accurate material properties. Overall, once the systemmatrices of the test structure are determined, the eigenvalue problem given by:

�K� � l2M

�f ¼ 0 (17.7)

is solved to determine the eigenvalues and mode shapes fr of the structure. Here, K*andM are the system stiffness and mass matrices, respectively [59,60]. In general, K*is complex and natural frequencies and loss factors are determined by u2

r ¼ Real�l2r�

and hr ¼ Imag�l2r��

Real�l2r�. In the beginning, some elastic properties for the

materials to be identified can be assumed and modal analyses can be performed.The predicted modal parameters are compared with experimentally determined values,and analyses are repeated until the experimental and theoretical modal parameters arematched.

s0050 17.4.2 Damping and elastic properties

p0105 In many studies, the static elasticity modulus, ultimate elongation, and tensile strength ofdifferent natural fibers are determined via tensile testing [13,15,17,22,23,48,61e70].Results showed that the elasticity modulus of luffa fiber (0.9e1.8 GPa) was lowcompared with other typical natural fibers such as sisal (9.4e22 GPa) and jute(26.5e32 GPa), as seen in Table 17.3. Similarly, the tensile strength of luffa fiber(1.7e20.5 MPa) was low compared with other typical natural fibers such as sisal(500e635 MPa) and jute (393e773 MPa). The elasticity modulus and tensile strengthof the widely used glass fiber in practice are around 73 GPa and 2400 MPa, respectively.One reason for the low strength of luffa is the random distribution of short fibers inthe plant. Coir also has low strength compared with other natural fibers. The lowstrength of coir was reported to be the result of its low cellulose content and reasonablyhigh microfibrillar angle (i.e., the angle between the fiber axis and the fibril of thefiber) [14,71]. Fiber mechanical properties such as the elasticity modulus and ultimatetensile stress are related not only to the chemical composition of the fiber but also to


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its internal structure. It is reported in the literature that the treatment (e.g., sodiumhydroxide) of luffa fibers in the composites increases tensile and yield strength [32].

p0110 The dynamic (modal) elastic moduli of luffa composite structures (determined byanalyzing frequency response functions), even for a volume fraction of matrix of0.5 � 0.1, are acceptable (i.e., 2.5 � 0.1 GPa) [35,45]. The elastic properties of luffacomposites do not have large variation with respect to frequency for 100e1000 Hz(Fig. 17.7). The elasticity modulus of luffa composite structures for a low volumefraction of matrix are comparable to elastomers and plastics [73]. Improving themechanical properties of luffa composites is possible via surface treatment.

p0115 The modal damping levels of luffa composite structures for a volume fraction ofresin of 0.5 � 0.1 can be high (i.e., 2.6 � 0.05%), as seen in Fig. 17.8 [35,45]. Themodal loss factors of luffa composite samples are higher than those of conventionalmaterials, such as glass composites commonly used in practice, as well as aluminum

0

5

4

3

2

1200 400 600 800 1000

Frequency, Hz

Ela

stic

ity m

odul

us, G

pa

1200

f0040 Figure 17.7 Elasticity modulus of various luffa composites (volume fraction of fiber is0.5 � 0.1) as a function of frequency.

t0020 Table 17.3 Static elasticity modulus, ultimate elongation, and tensile strength of differentnatural fibers and glass fiber determined via tensile testing

FiberElasticity modulus(GPa)

Ultimateelongation (%)

Tensile strength(MPa)

Flax[13,17,48,63,64]

12e85 1e4 600e2000

Jute [15,61,65,66] 26.5e32 1.5e1.8 393e773

Kenaf [15,22,67] 21e53 1.6e3.5 350e930

Coir [14,72] 2.5e6 15e25 180e220

Sisal [15,23,61,62] 9.4e22 1.6e2.5 500e635

Hemp [15,22,64] 44.5e70 1.6e1.8 690e788

Luffa [68e70] 0.9e1.8 1.1e2.2 1.7e20.5

Glass 73 3 2400


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and steel [55,74,75], although the modal loss factors of the luffa composite samples areless than those of conventional viscoelastic damping materials [76].

p0120 Results showed that luffa sponge material exhibits remarkable strength and superiorenergy absorption capabilities; it is comparable to some metallic cellular materialssuch as aluminum foams and NieP microlattices. The strength of luffa sponge is betterthan that of most other available cellular materials with a similar density range, such asexpended polystyrene foams and NieP microlattices [69]. For example, owing to thehigh strength-to-weight ratio of its cellular materials, luffa sponge can be used as apackaging material or an energy dissipation material [69]. It has been reported thatit is possible to produce medium-density fiberboards by using luffa fiber at variouspercentages in a mixture with the wood [37].

s0055 17.5 Conclusion

p0125 This chapter presents an overview of the acoustic and mechanical behaviors of luffafiber-reinforced biocomposites. Problems inherent in green fibers, such as structuraldifferences and defects in L. cylindrica samples, were introduced. Acoustic proper-ties such as sound absorption and transmission loss of luffa fibers and composites,as well as acoustic identification methods, were presented. Mechanical propertiessuch as the damping and elasticity of luffa composites, as well as identificationmethods, were revealed. Finally, the potential use of luffa material in practicalapplications was evaluated.

p0130 There are some variations inherent in green fibers with regard to the structural prop-erties of luffa plants, such as their mass and density. For example, the standard devi-ation between the mass of 15 different luffa plants with the same dimensions is around25%. However, results showed that deviations in the acoustic and elastic properties ofluffa composites are much lower. Thus, luffa composites with similar acousticand elastic properties can be produced without the special selection of L. cylindricasamples to homogenize the batch of fibers. However, a preliminary selection of raw

00

5

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f0045 Figure 17.8 Modal damping levels of various luffa composites (volume fraction of fiber is0.5 � 0.1).


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samples is required if it is desired for the acoustic and mechanical properties of theluffa composites to have only small variations (e.g., less than 5%).

p0135 Accurate sound absorption and transmission loss levels of luffa fibers and compos-ites can be determined using impedance tube experiments:

u0010 • Luffa fibers have superior sound absorption properties. For example, a thin luffa fiber (i.e.,thickness of 10 mm) has an average sound absorption coefficient of 0.3 for 0.5e6 kHz. Thesound absorption coefficient increases when perforated linen is used.

u0015 • Luffa composites with higher sound absorption coefficients compared with luffa fibersamples can be obtained when the correct volume fraction of fiber is determined.However, sound absorption coefficients of a luffa composite decrease with an increasingvolume fraction of resin after a specific ratio.

u0020 • Transmission loss levels of luffa fibers are acceptable and the level generally increases withan increasing volume fraction of matrix. For example, the transmission loss level is 6 and25 dB for a luffa composite with a thickness of 10 mm with a fibereepoxy ratio of 4and 1.5, respectively, for 0.5e6 kHz. The transmission loss level of luffa composite witha volume fraction of matrix at 1.5 is comparable to that of a cement and glass plate commonlyused in practice.

p0155 Mechanical properties such as elasticity and damping levels of luffa composites canbe identified by determining the modal parameters of test samples. For this purpose,frequency response functions using contact or noncontact excitation and responsesensors are measured. Then modal frequencies and loss factors of luffa compositescan be identified by analyzing the measured frequency response functions and employ-ing a modal analysis method. Using the measured modal parameters and a theoreticalformulation of the test structure, elastic properties can be identified:

u0025 • The measured damping levels of luffa composite structures for a considerably low volumefraction of resin can be high. For example, the average loss factor is 2.6% � 0.05% for a vol-ume fraction of fiber at 0.5 � 0.1 and a frequency range of 0.1e1 kHz.

u0030 • The elasticity moduli of luffa composite structures for a low volume fraction of matrix arecomparable to those of elastomers and plastics, and the elastic properties of luffa compositesdo not have a large variation with respect to frequency. For example, the average elasticitymodulus is 2.5 � 0.1 GPa for a volume fraction of fiber at 0.5 � 0.1 and frequency range of0.1e1 kHz.

p0170 That the vibroacoustic properties of luffa fibers and composites will be useful inpractical applications looks promising. The high damping and acceptable elastic prop-erties of luffa composites may allow them to be employed in many sound and vibrationisolation applications including airplanes, automobiles, and yachts to enhance the useof environmentally friendly materials. Luffa composites also have the potential to beused in architectural applications such as concert halls to absorb reverberant noise andprovide sound transmission, because their sound absorption and isolation capabilitiesare better than many green composites. As just a single example, produced compositeplates could prove a suitable material for decorations. Overall, the superior acousticand mechanical features of luffa composites, as well as their low density, low cost,and biodegradability, make luffa composites attractive for various noise andvibration-control engineering applications.


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Acknowledgments

We thank Dr. Caroline Fell Kurban, director of the Center for Excellence in Learning and Teach-ing at MEF University.

References

[1] Baier H. Design of fiber composite aerospace structures under vibration loads.Comprehensive composite materials II. Oxford: Elsevier; 2018. p. 351e66.

[2] Baltopoulos A, Kostopoulos V. Multifunctional carbon nanotube-based nano-compositesfor aerospace applications. Multifunctionality of Polymer Composites. Oxford: WilliamAndrew Publishing; 2015. p. 448e90.

[3] Brooks R, Shanmuga Ramanan SM, Arun S. Composites in automotive applications:design. Reference module in materials science and materials engineering. Elsevier; 2017.

[4] Grande DH, Greist S, Jessie T, Daniel J. Composites in sports applications. Comprehensivecomposite materials II. Oxford: Elsevier; 2018. p. 469e526.

[5] Ilcewicz L, Ashforth C. Scaling crucial to integrated product development of compositeairframe structures. Comprehensive composite materials II. Oxford: Elsevier; 2018.p. 26e90.

[6] Komus A, Beley N. Composite applications for ground transportation. Comprehensivecomposite materials II. Oxford: Elsevier; 2018. p. 420e38.

[7] Kretsis G, Johnson AF. Conceptual design of composite structures. Comprehensivecomposite materials II. Oxford: Elsevier; 2018. p. 26e46.

[8] Megson THG. Laminated composite structures. Introduction to aircraft structural analysis.3rd ed. Butterworth-Heinemann; 2018. p. 685e735.

[9] Ramanujam BTS, Annamalai PK. Conducting polymeregraphite binary and hybridcomposites: structure, properties, and applications. Hybrid polymer composite materials.Woodhead Publishing; 2017. p. 1e34.

[10] Karmakar B. Glasses and glass-ceramics for biomedical applications. Functional glassesand glass-ceramics. Butterworth-Heinemann; 2017. p. 253e80.

[11] Akkus N, Genc G. Influence of pretension on mechanical properties of carbon fiber in thefilament winding process. Int J Adv Manuf Technol 2017;91(9e12):1e7.

[12] Bodros E, Pillin I,MontrelayN,BaleyC.Could biopolymers reinforced by randomly scatteredflax fibre be used in structural applications? Compos Sci Technol 2007;67(3e4):462e70.

[13] Bos HL, M€ussig J, Oever VD, Martien JA. Mechanical properties of short-flax-fibrereinforced compounds. Compos Appl Sci Manuf 2006;37(10):1591e604.

[14] Wambua P, Ivens J, Verpoest I. Natural fibres: can they replace glass in fibre reinforcedplastics? Compos Sci Technol 2003;63(9):1259e64.

[15] Faruk O, Bledzki AK, Fink H-P, Sain M. Biocomposites reinforced with natural fibers:2000e2010. Prog Polym Sci 2012;37(11):1552e96.

[16] Koronis G, Silva A, Furtado S. Applications of green composite materials. In: Kalia S,editor. John Wiley & Sons; 2016.

[17] Baley C. Analysis of the flax fibres tensile behaviour and analysis of the tensile stiffnessincrease. Compos Appl Sci Manuf 2002;33(7):939e48.

[18] Boynard CA, D’Almeida JRM. Morphological characterization and mechanical behaviorof sponge gourd (Luffa cylindrica) - polyester composite materials. Polym Plast Technol2000;39(3):489e99.


10017-JAWAID-9780081022924






[19] Georgios K, Silva A, Furtado S. Applications of green composite materials. In: Kalia S,editor. Biodegradable green composites. Hoboken, NJ: John Wiley & Sons, Inc; 2016.

[20] Satyanarayana KG, Arizaga GGC, Wypych F. Biodegradable composites based onlignocellulosic fibersdan overview. Prog Polym Sci 2009;34(9):982e1021.

[21] Le Duigou A, Bourmaud A, Gourier C, Baley C. Multi-scale shear properties of flax fibrereinforced polyamide 11 biocomposites. Compos Appl Sci Manuf 2016;85:123e9.

[22] Aziz SH, Ansell MP. The effect of alkalization and fibre alignment on the mechanical andthermal properties of kenaf and hemp bast fibre composites: Part 1 e polyester resinmatrix. Compos Sci Technol 2004;64(9):1219e30.

[23] Murali Mohan Rao K, Mohana Rao K, Ratna Prasad AV. Fabrication and testing of naturalfibre composites: vakka, sisal, bamboo and banana. Mater Des 2010;31(1):508e13.

[24] Liu ZT, Yang YN, Zhang LL, Liu ZW, Xiong HP. Study on the cationic modification anddyeing of ramie fiber. Cellulose 2007;14(4):337e45.

[25] Genc G, El Hafidi A, Gning PB. Comparison of the mechanical properties of flax and glassfiber composite materials. J Vibroeng 2012;14(2):572e81.

[26] Tanobe VOA, Sydenstricker THD, Munaro M, Amico SC. A comprehensive character-ization of chemically treated Brazilian sponge-gourds (Luffa cylindrica). Polym Test 2005;24(4):474e82.

[27] Gassan J, Bledzki AK. Modification methods on nature fibers and their influence on theproperties of the composites. Plastics 1996;42:2552e7.

[28] Kocak D. The study of the effects of different chemical compounds applied on Luffacylindrica fibres with the help of ultrasonic energy. J Polym Eng 2008;28(8):501e15.

[29] Kocak D, Merdan N, Yuksek M, Sancak E. Effects of chemical modifications on me-chanical properties of Luffa cylindrica. Asian J Chem 2013;25(2):637e41.

[30] Singh RC, Alam A, Singh V. Purification, characterization and chemical modificationstudies on a translation inhibitor protein from Luffa cylindrica. Indian J Biochem Biophys2003;40(1):31e9.

[31] Seki Y, Sever K, Erden S, Sarikanat M, Neser G, Ozes C. Characterization of Luffacylindrica fibers and the effect of water aging on the mechanical properties of its compositewith polyester. J Appl Polym Sci 2012;123(4):2330e7.

[32] Jayamani E, Hamdan S, Rahman MR, Heng SK, Bin Bakri MK. Processing and charac-terization of Epoxy/Luffa composites: investigation on chemical treatment of fibers onmechanical and acoustical properties. Bioresources 2014;9(3):5542e56.

[33] Kocak ED. The influence of ultrasonic energy on chemical treatment of surface propertiesand the properties of composites made of luffa cylindrical fiber-polyester resin. J EngMater Technol 2008;130(4):1e7.

[34] Wang XJ, Shen JH, Zuo ZH, Huang XD, Zhou SW, Xie YM. Numerical investigation ofcompressive behaviour of luffa-filled tubes. Compos B Eng 2015;73:149e57.

[35] Genc G, Koruk H. On the difficulties in manufacturing of luffa fibers reinforced bio-composites and variations in their dynamic properties. In: 45th international congressand exposition on noise control engineering; 2016 August 21-24; Hamburg, Germany;2016. p. 1566e70.

[36] Saw SK, Ghose J, Sarkhel G. Potentiality of Luffa fiber used as reinforcement in polymercomposites. In: Jawaid M, Sapuan SM, Alothman OY, editors. Green biocomposites:manufacturing and properties. Springer International Publishing; 2017. p. 293e310.Cham.

[37] Akgul M, Korkut S, Camlibel O, Ayata U. Some chemical properties of Luffa and itssuitability for medium density fiberboard (MDF) production. Bioresources 2013;8(2):1709e17.


10017-JAWAID-9780081022924






[38] ASTM E 1050e12. Standard test method for impedance and absorption of acousticalmaterials using a tube, two microphones and a digital frequency analysis system. 2012[New York].

[39] ISO 10534-2. Acoustics - determination of sound absorption coefficient and impedance inimpedance tubes, part 2: transfer-function method. 2001.

[40] Koruk H. An assessment of the performance of impedance tube method. Noise ControlEng J 2014;62(4):264e74.

[41] Koruk H, Genc G. Investigation of the acoustic properties of bio luffa fiber and compositematerials. Mater Lett 2015;157(0):166e8.

[42] ASTM E2611. Standard test method for measurement of normal incidence sound trans-mission of acoustical materials based on the transfer matrix method. 2017 [West Con-shohocken, PA].

[43] Genc G, Koruk H. Investigation of the vibro-acoustic behaviors of Luffa bio compositesand assessment of their use for practical applications. In: 23rd international congress onsound and vibration: from ancient to modern acoustics; 2016 July 10-14; Athens, Greece;2016. p. 1e8.

[44] Smith BJ, Peters RJ, Owen S. Acoustics and noise control. 2nd ed. Addison WesleyLongman; 1996.

[45] Genc G, Koruk H. Identification of the dynamic characteristics of Luffa fiber reinforcedbio-composite plates. Bioresources 2017;12(3):5358e68.

[46] Ng CF, Hui CK. Low frequency sound insulation using stiffness control with honeycombpanels. Appl Acoust 2008;69(4):293e301.

[47] Siqueira G, Bras J, Dufresne A. Luffa cylindrica as a lignocellulosic source of fiber,microfibrillated cellulose, and cellulose nanocrystals. Bioresources 2010;5(2):727e40.

[48] Charlet K, Eve S, Jernot JP, Gomina M, Breard J. Tensile deformation of a flax fiber. ProcEng 2009;1(1):233e6.

[49] Bodros E, Baley C. Study of the tensile properties of stinging nettle fibres (Urtica dioica).Mater Lett 2008;62(14):2143e5.

[50] Jumaidin R, Sapuan SM, Jawaid M, Ishak MR, Sahari J. Characteristics of thermoplasticsugar palm Starch/Agar blend: thermal, tensile, and physical properties. Int J Biol Mac-romol 2016;89:575e81.

[51] Paiva MC, Bernardo CA, Edie DD. A comparative analysis of alternative models to predictthe tensile strength of untreated and surface oxidised carbon fibers. Carbon 2001;39(7):1091e101.

[52] Bos HL, Van den Oever MJA, Peters OCJJ. Tensile and compressive properties of flaxfibres for natural fibre reinforced composites. J Mater Sci 2002;37(8):1683e92.

[53] Hu W, Ton-That MT, Denault J. Tensile property characterization of natural fibersapplying single fiber tensile test. Abstr Pap Am Chem Soc 2009:238.

[54] Do TT, Lee DJ. Analysis of tensile properties for composites with wrinkled fabric. J MechSci Technol 2010;24(2):471e9.

[55] Koruk H, Sanliturk KY. Identification and removal of adverse effects of non-contactelectromagnetic excitation in Oberst Beam Test Method. Mech Syst Signal Process2012;30:274e95.

[56] Koruk H. Quantification and minimization of sensor effects on modal parameters oflightweight structures. J Vibroeng 2014;16(4):1952e63.

[57] Koruk H, Sanliturk KY. Damping uncertainty due to noise and exponential windowing.J Sound Vib 2011;330(23):5690e706.

[58] Liew KM, Han JB, Xiao ZM. Vibration analysis of circular mindlin plates using thedifferential quadrature method. J Sound Vib 1997;205(5):617e30.


10017-JAWAID-9780081022924






[59] Sanliturk KY, Koruk H. Development and validation of a composite finite element withdamping capability. Compos Struct 2013;97:136e46.

[60] Sanliturk KY, Koruk H. A new triangular composite shell element with damping capa-bility. Compos Struct 2014;118:322e7.

[61] Alves C, Ferr~ao PMC, Silva AJ, Reis LG, Freitas M, Rodrigues LB, et al. Ecodesign ofautomotive components making use of natural jute fiber composites. J Clean Prod 2010;18(4):313e27.

[62] Jacob M, Thomas S, Varughese KT. Mechanical properties of sisal/oil palm hybrid fiberreinforced natural rubber composites. Compos Sci Technol 2004;64(7e8):955e65.

[63] Davies GC, Bruce DM. Effect of environmental relative humidity and damage on thetensile properties of flax and nettle fibers. Text Res J 1998;68(9):623e9.

[64] Duval A, Bourmaud A, Augier L, Baley C. Influence of the sampling area of the stem onthe mechanical properties of hemp fibers. Mater Lett 2011;65(4):797e800.

[65] Liu L, Yu J, Cheng L, Qu W. Mechanical properties of poly(butylene succinate) (PBS)biocomposites reinforced with surface modified jute fibre. Compos Appl Sci Manuf 2009;40(5):669e74.

[66] Vilaseca F, Mendez JA, P�elach A, Llop M, Ca~nigueral N, Giron�es J, et al. Compositematerials derived from biodegradable starch polymer and jute strands. Process Biochem2007;42(3):329e34.

[67] Hao A, Zhao H, Chen JY. Kenaf/polypropylene nonwoven composites: the influence ofmanufacturing conditions on mechanical, thermal, and acoustical performance. Compos BEng 2013;54(0):44e51.

[68] Papanicolaou GC, Psarra E, Anastasiou D. Manufacturing and mechanical responseoptimization of epoxy resin/Luffa Cylindrica composite. J Appl Polym Sci 2015;132(22).

[69] Shen J, Min Xie Y, Huang X, Zhou S, Ruan D. Mechanical properties of luffa sponge.J Mech Behav Biomed Mater 2012;15(0):141e52.

[70] Paglicawan MA, Cabillon MS, Cerbito RP, Santos EO. Loofah fiber as reinforcementmaterial for composite. Philipp J Sci 2005;134(2):113e20.

[71] Mohanty AK, Misra M, Hinrichsen G. Biofibres, biodegradable polymers andbiocomposites: an overview. Macromol Mater Eng 2000;276(3e4):1e24.

[72] Yashwanth MK, Easwara Prasad GL, Akshay KN. Comparative study on properties of coirand sisal fibre reinforced composites. Int J Innovat Res Sci Eng Technol 2016;5(9):922e6.

[73] Nashif AD, Jones DIG, Henderson JP. Vibration damping. 1th ed. New York:Wiley-Interscience; 1985.

[74] Prabhakaran S, Krishnaraj V, kumar MS, Zitoune R. Sound and vibration dampingproperties of flax fiber reinforced composites. Proc Eng 2014;97:573e81.

[75] Koruk H, Dreyer JT, Singh R. Modal analysis of thin cylindrical shells with cardboardliners and estimation of loss factors. Mech Syst Signal Process 2014;45(2):346e59.

[76] Koruk H, Sanliturk KY. Assesment of the complex eigenvalue and the modal strain energymethods for damping predictions. In: 18th international congress on sound and vibration(ICSV 2011); 10-14 July; Rio de Janeiro, Brazil; 2011. p. 2182e9.


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JAWAID: 17

Non-Print Items

Abstract

This chapter presents an overview of the acoustic and mechanical behaviors of luffa fiber-reinforced biocomposites. A

growing number of studies are examining the composites of biodegradable fibers such as flax, hemp, kenaf, and luffa

because of the adverse effects of their chemical materials on nature. Their low cost and the superior acoustic and

acceptable mechanical properties of biocomposites make them attractive for practical applications such as sound and

vibration isolation. However, the acoustic and mechanical characteristics of biocomposites and their dynamic behaviors

should be fully determined before they are considered for practical applications. In this chapter, acoustic properties such

as sound absorption and transmission loss and mechanical properties such as the damping and elasticity of luffa fiber-

reinforced composites are presented. Variations in acoustic and mechanical properties owing to different samples and

manufacturing processes are explored.

Keywords:

Damping properties, Defects, Elastic properties, Finite element modeling, Impedance tube method, Luffa composites, Modal

analysis, Sound absorption, Transmission loss, Young’s modulus.

properties of luffa ﬁber- reinforced biocompositesthe ASTM E2611-17 standard [42]. s0030 17.3.2...

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Transcript of properties of luffa ﬁber- reinforced biocompositesthe ASTM E2611-17 standard [42]. s0030 17.3.2...