tensile, thermal and dynamic mechanical analysis of sisal

*Correspnding Author: S.Sathees Kumar

Tensile, thermal and dynamic mechanical analysis of sisal, jute and banana fiber bio composites for various

engineering applications 1S.Sudhagar. 2S.Sathees Kumar, 3K.Arun Vasantha Geethan, 4R.Muthalagu

1Assistant Professor, 1,2,3,4Department of Mechanical Engineering,

University College of Engineering, Dindigul, Tamil Nadu, India.

2Professor, CMR Institute of Technology, Hyderabad, Telangana, India. 3Professor, St.Joseph's Institute of Technology, Chennai, Tamil Nadu, India.

4Assistant Professor, B.V. Raju Institute of Technology, Narsapur, Medak District,

Telangana India. [email protected] , 2*[email protected]

Abstract

In this study, tensile, thermal characteristics and dynamic mechanical analysis (DMA)

of fabricated hybrid sisal, jute, and banana fibers reinforced with polyester composites

are described for the first time. The hybrid composite plates are fabricated for different

fiber weights by hand lay-up method. Six different weight compositions and one alkali

treated specimen was utilized to investigate the above properties. The tensile properties

of the bio composites are examined through tensile test. The inclusion of three different

natural fibers reinforced polyester enhanced the ductile properties the composites.

Substantially , the alkali treated fibers achieved maximum tensile strength and tensile

modulus are 203.52 MPa and 7.63 GPa. Scanning Electron Micrographs of tensile

fractured surfaces of the composites revealed stronger adhesion of the natural fibers to

the polyester matrix. Thermal stability and thermal degradation of bio composites are

analyzed by Thermogravimetric analysis (TGA) and Derivative thermo gravimetry

(DTG). In addition of natural fibers reinforced polyester composites confers highest

value of TGA and DTA as compared to other specimens. The dynamic mechanical

analysis of composites in the term of storage modulus(E’), loss modulus (E”) and

damping parameter (Tan ) in a temperature range of 30°C to 300° C was

investigated. The hybrid composite with 50% of sisal, 25% of jute and 25% of banana

reveals the maximum value of storage modulus and loss modulus. These results attained

confirmed the viability of the combination between natural fibers and matrix, thus

opening new perspectives for the use of these natural by products.

Keywords: banana, DMA, jute, polyester, sisal, TGA

1. Introduction Natural fibers have already established a track record as simple filler material in

automobile parts. Natural fibers like sisal, jute, coir, oil palm fiber have all been proved

to be good reinforcement in thermoset and thermoplastic matrices [1–4]. Our earlier

studies have proved banana fibers to be an effective reinforcement in polyester matrix

[5]. Due to increasing environmental awareness, natural fibers have become very popular

among researchers and scientists as reinforcement for polymer matrix in place of

synthetic fibers. Natural fibers have many advantages such as low cost, low density,

Tierärztliche Praxis

ISSN: 0303-6286

Vol 40, 2020

37

mailto:[email protected]

mailto:[email protected]

availability in abundance, environment friendly, non-toxicity, high flexibility,

renewability, biodegradability, high specific strength and modulus, and easy processing

[6–11]. However, natural fibers have high moisture absorption, low impact strength and

low thermal stability as their drawbacks [12–14] Hybridization technique can be used to

overcome these drawbacks of natural fibers. Many researchers used hybridization

technique and found its positive effect as increase in mechanical, thermal and dynamic

mechanical properties. The incorporation of two or more natural fibers into a single

matrix has led to development of hybrid composites. Various researchers have tried

blending of two fibers in order to achieve the best utilization of the positive attributes of

one fiber and to reduce its negative attributes as far as practicable [15]. The behavior of

hybrid composites is a weighed sum of the individual components in which there is more

favorable balance between the inherent advantages and disadvantages. In an interesting

study dynamic mechanical analysis of natural fiber based hybrid composites was

performed and observed that the hybridization of nature fiber improved thermal and

dynamic mechanical properties [16]. Natural fiber composites such as sisal and jute

polymer composites became more attractive due to their high specific strength,

lightweight and biodegradability [17]. Krishna Kumar et al. studied the mechanical

properties on glass-sisal-banana fibers reinforced on epoxy composites. They observed

that the glass-sisal-banana fibers reinforced hybrid composites shows superior properties

and used as an alternate material for synthetic fiber reinforced composite materials [18].

Boopalan et al. investigated and compared the mechanical, thermal and water absorption

properties of raw jute and banana fiber reinforced epoxy hybrid composites. The results

show that the addition of banana fiber in jute/epoxy composites of up to 50% by weight

results in increasing the mechanical and thermal properties and decreasing the moisture

absorption property [19]. Sathish kumar et al. presented the extraction and preparation

methodology of the isophtallic polyester composites using the naturally available fibers

like snake grass, banana and coir fibers. The result showed that the snake grass/banana

and snake grass/coir fiber composites have the maximum tensile and flexural properties

when compared with the snake grass fiber composites [20]. Gupta studied the dynamic

mechanical properties of hybrid jute/sisal fiber reinforced epoxy composite at different

frequencies. The hybrid composites were prepared by hand layup technique keeping

constant 30 wt. % of total fibers content with varying weight percentages of jute and

sisal fibers. The results revealed that storage modulus, loss modulus and glass transition

temperature (Tg) were found to increase with increase in frequencies [21]. The purpose

of this work is to investigate the probable utilization of sisal, banana, and jute fiber areas

reinforcement in polyester matrix composites. Natural fibers reinforced polyester bilayer

hybrid composites fabricated by hand lay-up technique. The aim of this work is to

evaluate the effects of incorporating natural fibers into the polyester at different weight

% of fibers loadings to enhance tensile, thermal stability and viscoelastic properties to

analyze the best and effective filler loading.

2. Materials and experimental Procedure

Materials In this present investigation Sisal, Jute fibers and banana are used for

fabricating the hybrid composite specimen. The sisal, banana, and jute fibers are

obtained from Ebenezer fiber products, Coimbatore, Tamilnadu, India. Cobalt

Naphthenate as accelerator and Methyl ethyl ketone peroxide (MEKP) as a catalyst is

acquired from M/s. Supreme scientific Ltd., Madurai, India. The polymer used in this

work development was unsaturated terephthalic polyester resin in the pre-accelerated


ISSN: 0303-6286

Vol 40, 2020

38

form, produced by Royal Polímeros under the commercial name of Denverpoly 754.The

Cobalt Naphthenate added as 2% with the resin and the catalyst approximately 2 to 3ml.

Purchased natural fibers are shown in Figureure.1.

a) Sisal fiber, b) Jute fiber, and c) Banana fiber

Figureure.1.Natural fibers

2.1 Fabrication of biocomposites

Sisal, Jute and banana fibers are aligned unidirectionally with bi-layer arrangement in

polyester matrix to prepare the hybrid composites. The physical, mechanical and

chemical properties of natural fibers as shown in Table.1 and Table.2 respectively. The

polyester resin and hardener mixed in a ratio of 10:1 by weight to prepare the matrix.

The mixture is stirred manually to disperse the resin and the hardener in the matrix. The

composite laminates are made by hand-layup technique followed by light compression

moulding technique. A stainless steel mould having dimensions of 300 mm x 300mm is

used for casting of 3mm thick composite laminates for dynamic mechanical analysis.

Stacking of hybrid fibers was carefully arranged random manner after pouring some

amount of resin against the mould to keep the poor impregnation. The resin gets mixed

with the fibers and may tend to be dried up in the open atmosphere under hot sun for 48

hours. Before the resin gets dried up the second layer must be mounted on it. The process

is repeated for another layer also. The epoxy resin applied is distributed to the entire

surface by means of a roller and the air gaps formed between layers during fabrication

are removed by gently squeezing. The specimen is then pressed at a temperature of 32°C,

under the pressure of 6MPa, and the average relative humidity of 65%.To ensure

complete curing the composite samples were post cured at 70ºC for 1 hour and the test

specimens of the required size were cut out from the sheet. As per the dimensions of

mechanical tests, excess resin and fiber edges of specimen are properly removed.

Preparation process of natural fibers reinforced polyester composite specimen as shown

in Figure.2.

Table 1. Physical properties of natural fibers

Fibers

Physical Properties

References Origin Diameter (µm) Density (g/cm3)


ISSN: 0303-6286

Vol 40, 2020

39

Jute Bast 25 – 250 1.3 – 1.49 [6]

Sisal Leaf 50 – 200 1.34 [13]

Banana Leaf 100 – 250 0.8 [16]

Table 2. Mechanical and Chemical properties of natural fibers

Physical Properties Chemical properties

Fibers Tensile

strength

(MPa)

Tensile

modulus

(GPa)

Elongation

(%) Cellulose

(%) Hemi-

celluloses

(%)

Lignin

(%) References

Jute 393 - 800 13–26.5 1.16–1.5 61–71.5 12.0–20.4 11.8 - 13 [12]

Sisal 610–710 9.4–22 2–3 65.8–78 8–14 10 -14 [13]

Banana 161.8 8.5 2.0 63–64 10–19 5 [16]

2.2Alkali treated composites

The important modification done by alkaline treatment is the disruption of hydrogen

bonding in the network structure, thereby increasing surface roughness. This treatment

removes a certain amount of lignin, wax and oils covering the external surface of the

fiber cell wall, depolymerizes cellulose and exposes the short length crystallites [22].

Addition of aqueous sodium hydroxide (NaOH) to natural fiber promotes the ionization

of the hydroxyl group to the alkoxide [23]. It is reported that alkaline treatment has two

effects on the fiber: (1) it increases surface roughness resulting in better mechanical

interlocking; and (2) it increases the amount of cellulose exposed on the fiber surface,

thus increasing the number of possible reaction sites [24]. Consequently, alkaline

treatment has a lasting effect on the mechanical behavior of flax fibers, especially on

fiber strength and stiffness [25]. The fibers are immersed in 5% NaOH aqueous solution

for 30 min. the fibers are then cleaned several times with distilled water followed by

immersing the fibers in very dilute HCl in order to remove the NaOH adhering to the

surface of the fibers. Finally the fibers are again washed several times with distilled

water and then dried in an oven maintained at 80°C. Notation of the Fabricated specimen

and weight % of natural fiber composition for hybrid composites as shown in Table.3.


ISSN: 0303-6286

Vol 40, 2020

40

Figure.2. Preparation process of bio composite specimens

2.3 Tensile strength

The specimen prepared is shaped into required dimension using a hand cutter and the

edges are polished using a salt paper. It is prepared according to the ASTM D638

standard. The tensile test is conducted on a Tinius Olsen 10 KN Universal testing

machine (UTM) with a gauge length of 75 mm and crosshead speed of the machine is set

at 5 mm/min. The specimen size for tensile test is 115 mm x 20 mm x 3 mm according to

ASTM D638.The process involves placing the test specimen in the UTM and applying

tension to it until the fracture of the material. Then the force is recorded as a function of

the increase in gauge length. During the application of tension, the elongation of the

gauge section is recorded against the applied force. The tensile force is documented as a

perform of the expansion in gauge length. The experiments are conducted for four times

in each composition and the average values are taken for the results [26].


ISSN: 0303-6286

Vol 40, 2020

41

Table 3. Designation for bio composite fiber reinforced polyester composites

Designation of

specimen weight % of natural fiber composition

sisal Jute banana Chemical treatment

A 50 45 5 --

B 40 50 10 --

C 50 35 15 --

D 40 40 20 --

E 50 25 25 --

F 40 30 30 --

G 40 40 20 Alkali treated

2.4 Scanning Electron Microscopy (SEM)

The morphology of the natural fiber composites is observed using a on a JEOL

equipment model JSM-5300LV with 10 kV of voltage acceleration. Tensile fracture

specimens are involved to examined the morphological test.

2.5 Thermogravimetric analysis (TGA)

Thermogravimetric analysis is performed by EXSTAR TG/DTA 6300, Hitachi, Japan.

TG instrument with the temperature accuracy ± 5ºC to examine the thermal degradation

behavior of maximum tensile strength achieved specimen (D). Approximately, 10mg of

powdered samples are placed in an alumina crucible with a diameter of 7mm and are

heated under the dynamic linear rate of 10ºC/min., with a 50cm3 /min nitrogen flow from

50 ºC to 600ºC.

2.6 Dynamic mechanical analysis (DMA)

DMA was executed according to ASTM D4065-01 to determine the viscoelastic

behavior (E’, E”, Tan δ) of polyester composites as a function of temperature. DMA test

was performed using TA (DMA Q 800) instrument, operating in a three-point bending

mode at an oscillation frequency of 1 Hz under controlled amplitude. The temperature

was ramped from 25°C to 200°C, under controlled sinusoidal strain with a heating rate of

5°C/min. The samples were in dimension of 60 × 12.5 × 3 mm. The viscoelastic

properties such as storage modulus, loss modulus and damping of specimens are

measured.


ISSN: 0303-6286

Vol 40, 2020

42

3 Results and Discussion

3.1 Tensile properties of bio composites

It can be observed from Figure.3 and Figure.4. that tensile properties of bio composite

increases with natural fiber loading in all cases. The natural fiber composites

A,B,C,D,E,F and G shows good enhancement of tensile strength. The tensile strength

and tensile modulus are gradually increasing upto the maximum load carrying capacity

of the material. From Figure.3. it has been clearly indicated that the 40% sisal, 30% jute

and 30% banana (specimen F) polymer composites are performing better than the other

composite combinations tested. Normally, fibers such as these can improve the strength,

as lignocellulose fibers can support stresses transferred from the polymer [27]. From the

results, maximum weight % of the sisal, jute and banana fiber contents holds the tensile

property of polymer composites. From the results, Other composites A,B,C, D and E are

revealed better tensile strength and tensile modulus. Due to proper dispersion and good

interfacial link between fiber and polyester matrix may be enhanced the tensile

properties. In fiber based natural composites, dispersion of the filler and matrix interface

adhesion makes the advancement in mechanical properties [28]. Alkaline treatment also

significantly improved the mechanical behaviors of fiber-reinforced composites [29, 30,

31]. The alkali treated fibers obtained the high tensile strength value of 203.52. From the

results , Alkali treated fibers content increased the maximum tensile strength and tensile

modulus of the composites in Specimen G. All tensile values of the specimens compared

to specimen G, the values are 17.8%,15.8% , 13.9%, 10.3%, 7.1% and 4.2% of

A,B,C,D.E and F respectively. This may be due to the bonding of the fiber with the

polyester matrix thereby improving the fiber-matrix interaction. The significance of

alkali treatment is the disruption of hydrogen bonding in the fiber surface, thus

increasing surface roughness [32]. The elongation and tensile modulus are shown in

Table.4. In Figure.4, the tensile modulus of the composites gradually increased from

A,B, C, D, E, F and G specimens of 5.26 Gmpa, 5.73 GPa, 6.17 GPa, 6.48 GPa ,6.86

GPa, 7.24 GPa and 7.63 GPa respectively. From this results, the alkali treated specimen

was achieved the maximum tensile modulus of 7.63 GPa. G specimen compared with

other specimens 31% , 24.9% , 19.1%, 15%, 10% and 5.11% of A,B,C,D,E and F

composite specimens respectively. Furthermore, the tensile modulus of the composites also

increased due to enhance of the elongation at break.

This change in tensile properties is attributed to interacting factors such as the rupture of

alkali-sensitive bonds existing between the cellulose and hemicellulose (due to removal

of hemicellulose making the fiber more homogeneous), and the stress transfer between

interfibrillar regions [33]. Further, in the case of untreated fibers, hemicellulose remains

dispersed in the interfibrillar region separating cellulose chains from one another and

because of this barrier, these chains are in a state of strain. The fibers tend to get closely

packed owing to the large scale removal of hemicellulose by alkali treatment and

formation of new hydrogen bonds in between the chain of cellulose fibrils. Thereby the

fibrils rearrange themselves in a more compact manner resulting in closer fiber packing

[34]. The fiber tensile properties tend to decrease after 8 h alkali treatment, possibly due

to the degradation of cellulose in longer duration alkali treatment.


ISSN: 0303-6286

Vol 40, 2020

43

Table.4 Elongation and tensile modulus of bio composites

Designation of composite

Specimen

Elongation (mm) Tensile modulus (GPa)

A 6.4 5.26

B 6.8 5.73

C 7.3 6.17

D 7.7 6.48

E 8.1 6.86

F 8.3 7.24

G 8.6 7.63

Figure.3.Tensile strength of bio composites


ISSN: 0303-6286

Vol 40, 2020

44

Figure.4.Elongation and Tensile modulus of bio composites

3.2 Morphological study of bio composites

After tensile test result, the tensile properties increased gradually from A,B,C,D,E,F and

G. Specimen F (sisal 40%, jute 30% and banana 30%) achieved the high tensile

properties compared to other specimens A,B,C,D and E. Furthermore, compared with

specimen F alkali treated specimen G is attained maximum tensile properties. Due to this

maximum results of two specimens, the F and G specimens were involved the

morphological observation. Figure.5 (a) and Figure.5 (b) is clearly revealed the

interaction of natural fibers with resin matrix. In Figure.5.(a). the fiber interactions

occurred one specific area and some of the broken particles are identified at right side top

of the corner. At the same time, fibers were formed at specific area is called cluster

formation. In this cluster formation, bonding between the fibers and polyester matrix are

better but dispersion of fibers are not covered the all area of specimen and the even and

proper distribution of fibers are partially observed. This improper dispersion of fibers

may be reduced the ductile properties of specimen F compared with G. The alkali

treatment improved fiber matrix interaction by the removal of lignin and hemicellulose,

which led to the better incorporation of fiber with the matrix [35].

In alkali treated specimen G Figure.5 (b), the three fibers are highly interlinking

between the polyester matrix. Furthermore, the image displaying the uniform distribution

of three fibers. From this image the broken particles of the fibers also not identified. No

interfacial gaps were observed from the natural fibers and polyester matrix. It is

interesting to note that there is better fiber/matrix bonding in composites with alkali fiber

loading. Whereas fiber/matrix de-bonding is evident in composites with 40% sisal , 30% jute

and 30% banana fiber loading, composites with alkali fiber loading show no gap between the

fiber and the matrix because of the stronger bonding. When the fiber concentration is lower, the

packing of the fibers will not be efficient in the composite. This leads to matrix rich regions and

thereby easier failure of the bonding at the interfacial region. When there is closer packing of the fibers crack propagation will be prevented by the neighboring fibers.


ISSN: 0303-6286

Vol 40, 2020

45

(a) SEM of F - Specimen (b) SEM of G - Specimen

Figure.5. Morphological images of bio composites

3.3 Thermogravimetric Analysis (TGA) of composite specimens

The thermal degradation was determined by the TGA as shown in Figure.6. Three

degradation stages are observed in each case of samples. First stage involves the thermal

degradation of all polyester composites with an initial weight loss about 150 – 200°C due

to moisture loss through dehydration of secondary alcoholic groups and evaporation of

physically weak and loosely bound moisture on the surfaces of the composites [36]. As

expected, the two stages of degradation are evident in all the profiles which correspond

to temperature regions of different constituents like moisture evaporation (upto 200°C)

and degradation of the hybrid composite material (100 - 350°C). The depolymerization

of composites usually occurs between 320 and 400°C. The initial peak of fibers

reinforced polyester composites was found at 85°C which represents the loss of moisture

and other volatiles at the first degradation. It is observed between room temperature and

100°C.

The next peak which is obtained around 405°C which denotes DTA degradation of

natural fibers and the prominent peak appears at the temperature corresponding to the

maximum degradation rate. Moreover, natural fiber reinforced with polyester composites

increases the degradation temperature (340°C to 400°C) due to retaining and improving

the structural order to minimizing the amorphous content. A greater crystalline structure

essentially requires a higher degradation temperature which is evident in optimal natural

fibers with polyester composites.

3.4 Derivative thermogravimetric (DTG) analysis of composite specimens

The thermal degradation was determined by the Differential Thermal Analysis (DTA)

thermogram as shown in Figure.7. It is also obvious from the thermograph that polyester

inflection temperature or (decomposition temperature) shifts from 360°C to relatively

higher temperature (455°C) by the incorporation of natural fibers in polyester

composites, as the peaks of the DTG curves correspond to the decomposition

temperature of each constituent of the composites.


ISSN: 0303-6286

Vol 40, 2020

46

Figure.6.Effect of fiber loadings on TGA of composites.

Figure.7.Effect of fiber loadings on DTG of bio composites.

The DTG curve shows the decomposition temperature of polyester composite material

value which is above 400°C. As high thermal stability is attributed on account of higher

heat resistibility and thermal stability of highly cross linked natural fibers with the

polyester matrix in polyester composites.


ISSN: 0303-6286

Vol 40, 2020

47

3.5 Storage modulus (E’)

Storage modulus is a measure of the stiffness of the material. Influence of natural

fibers reinforcement on dynamic mechanical characteristics are shown in Figureures

8,9 and 10. From Figure. 8. it can be seen that E specimen has a higher storage

modulus compared to other wt.% of natural fibers added composite up to 95°C.

Further, on increasing the temperature the storage modulus decreases suddenly.

From the results, lowest value observed form the specimen B. Specimen B

compared to all specimens (A,C,D,E and F) it has very lowest storage modulus

value. The Specimen E showed highest storage modulus values above the Tg region

in the rubbery plateau, and the fiber matrix interface is not much deteriorated at

higher temperatures.

Figure.8. Effect of fiber loadings on storage modulus of bio composites

In this case the lowest value has been obtained for sisal 40% jute 50% and banana fiber

10% (specimen - B) loading and the highest value for sisal 40% jute 30% and 30%

banana fiber loading (specimen - F). The effectiveness of the filler is the highest at sisal

40% jute 50% and banana fiber 10% fiber loading. It is important to mention that

modulus in the glassy state is determined primarily by the strength of the intermolecular

forces and the way the polymer chains is packed. In alkali treated G specimen lost

stiffness because of the higher molecule movement at higher temperature. In order to

improve the stiffness of the material, the researchers added fibers in the composite which

increases the storage modulus of the material at higher temperature [37]. It also indicates

an increase in the Tg of the material, the addition of fiber in the composite increases the

stiffness of the material even at higher temperature, because it reduces the molecular


ISSN: 0303-6286

Vol 40, 2020

48

mobility of the material in thermal environment. Even though the storage modulus of

A,B,C, D and F composites are less compared to that of specimen E and G at 30 –

90°C, an increase in the storage modulus is observed beyond 85°C in the rubbery region.

This is because of low molecular mobility of polymer chain and good interfacial bonding

between the matrix and fiber [38]. It should be noted that it is difficult to pinpoint a

single glass transition temperature for all formulations because the transition actually

occurs over a range of temperature. Above the Tg, the decrease in the E’ is less marked

in the composites than in pure resin, which means that above the Tg the reinforcing

effect of the fibers is emphasized. This is typical in semicrystalline polymers and as it is

seen, the general trend is quite the same in composites and pure plastic and no significant

change in the location of the transition is observed. Figure.8 shows that the storage

modulus of specimen C has a lower storage modulus in glassy , transition and rubbery

region compared to that of other composite specimens. Due to the non-uniform

arrangement of natural fiber in matrix, the fiber could not transfer the stress uniformly

and looses the stiffness at lower temperature. From the study it is concluded that storage

modulus of the material is significantly influenced by bonding between the natural fibers

and polyester matrix. Specimen F shows low storage modulus compared with specimen

E. When the amount of fibers augmented in hybrid composite, a slight reduction in the

E’ value was observed, probably due to fibers agglomeration. It represents at higher fiber

loading; dispersion becomes poor leading to a decrease in fiber matrix interaction.

3.6 Loss modulus (E”)

Loss modulus defines the viscous responses (or) the damping properties of the material

and it measures the amount of energy dissipation under cyclic loading. Figure.9 shows

the loss modulus variation with temperature for different natural fiber composites. From

E” plot it is apparent that loss modulus also displays very similar trend with the E’

having variation of Natural fiber loadings in polyester composite system. Figure. 9

shows the lowered E” peak height for polyester composites (specimen B,C,D and F) but

the addition of Akali treated fiber (specimen G ) and specimens A and E into the

polyester matrix increases the loss modulus peak values. Interestingly as like E’ plot,

higher E” peak height was observed for specimen E with respect to rest polyester

composites, emphasizing better dispersion, distribution and no visibility of

agglomeration in the polyester matrix.

The agglomeration conferred the non-homogenous dispersion and two phase system in

the polymer leading to reduction in peak height of E”. The glass transition temperature of

specimens E and C have shifted towards higher temperature. At higher concentrations of

jute in specimen B, agglomeration takes place resulting in incompatibility between the

fiber and the matrix. The Tg from tan d shows a positive shift with increase of frequency

and the mechanical damping of the composites is decreased. The shifting of Tg towards

higher temperature can be associated with the decrease in mobility of matrix due to

incorporation of jute fibers. The distinct viscoelastic changes observed with the

incorporation of hybrid fibers in the matrix were attributed to the formation of an

interphase because of strong interactions between the reinforcing fibers and the matrix.

The value of glass transition temperature for polyester reinforced natural fiber

composites obtained from loss modulus curve is given in Table 5. The increase in width

of the loss modulus curve is taken to represent the presence of an increased range of

order.


ISSN: 0303-6286

Vol 40, 2020

49

Figure.9. Effect of fiber loadings on loss modulus of bio composites

The greater constraints on the amorphous phase could give rise to a higher or broader

glass transition behaviour [39]. The data suggest that alkali treated fibers have not provided

significant improvements in the resin properties.It can be seen from the Figureure that the loss

modulus peak values decrease with increase of fiber content at temperatures below the glass

transition. The effect of the filler is prominent above the glass transition temperature in this case

also. The modulus values increase with fiber content above the glass transition temperature.

Another interesting result that is observed is the broadening of the loss modulus curve when the

fiber content is increased to sisal 40% jute 30% and 30% banana. Figure. 9 shows the plot of

peak height vs. fiber volume fraction. The peak height shows a regular increase with increase of

fiber content. At a fiber loading of sisal 40% jute 30% and 30% banana, the most pronounced

effect of the filler has been the broadening of the transition region as the fiber concentration increases.

3.7 Material loss factor (Tan δ)

Tan is a damping term that can be related to the impact resistance of a material. Since the

damping peak occurs in the region of the glass transition where the material changes

from a rigid to a more elastic state, it is associated with the movement of small groups

and chains of molecules within the polymer structure, all of which are initially frozen in.

In a composite system, damping is affected through the incorporation of fibers. This is

due mainly to shear stress concentrations at the fiber ends in association with the

additional viscoelastic energy dissipation in the matrix material. Another reason could be

the elastic nature of the fiber.


ISSN: 0303-6286

Vol 40, 2020

50

Table.5 Peak height and Tg from loss modulus and tan delta value of Bio composites

Designation of

composite

Specimen

Peak height of loss

modulus curve,

MPa

Peak height of tan

delta curve Tg , C (from loss

modulus curve) Tg , C (from tan

delta curve)

A 785 0.84 110.7 132.6

B 670 0.66 100.4 116.4

C 690 0.72 117.2 115.1

D 710 0.76 91.8 114.3

E 780 0.88 128.7 141.8

F 580 0.71 90.3 123.5

G 845 0.63 88.8 110.3

The variation of tan with temperature of the composites has been analyzed with respect

to fiber loading and frequency. Incorporation of fibers reduces the tan δ peak height by

restricting the movement of the polymer molecules. Magnitude of the tan peak is

indicative of the nature of the polymer system. Addition of fibers above 40% show the

peaks making the two phases, fiber and matrix distinct. The appearance of peaks can also

be explained as due to a microgel structure cross-linked to a general matrix structure.

Damping curve indicates the level of the interaction between fiber and matrix in a

composite as a function of temperature as shown in Figure.10. Higher interaction

between fiber and matrix means higher energy dissipation of the composite. Damping

parameter is the ratio of loss modulus and storage modulus which shows the impact

properties of material. The peak of Tan δ curve occurs in glass transition region, where

composite changes from rigid to more elastic state due to the movement of molecules in

polymer structure as shown in Figure.10. The value of Tg obtained from tan delta curve

is higher than Tg from loss modulus curve. Specimen B,C,D and F shows low Tg values

compared with specimen A and E. Alkali treated specimen G has very low Tg rate.

However, E has very high Tg value compared with all specimens. The higher value of

Tan δ shows the better impact properties [40]. These results indicated, when the fiber

increasing the Wt. % in the specimens it shows the positive effect of Tan δ. Further

increasing the Wt. % of the specimen it has reduced the Tan δ. The low value obtained

for natural fiber composite was attributed to the poor stress transfer between the fiber

and the matrix. Composite with the bi-layer pattern also revealed the maximum Tan δ

max value and the narrowest peak width, confirming the poor fiber/matrix adhesion

It is known that the incorporation of fibers leads to an increase in the Tg values that can

be attributed to the decreased mobility of the polymer chains. The damping values also


ISSN: 0303-6286

Vol 40, 2020

51

revealed that these composites presented the lowest Tan δ peak height and the broadest

peak, indicating the best fiber- matrix interaction.

Figure.10. Effect of fiber loadings on the tan delta of bio composites

. It is known that the incorporation of fibers leads to an increase in the Tg values that can

be attributed to the decreased mobility of the polymer chains. The damping values also

revealed that these composites presented the lowest Tan δ peak height and the broadest

peak, indicating the best fiber- matrix interaction.

4. CONCLUSIONS

The sisal, jute, and banana natural fibers are reinforced polyester composites on different

weight percentages by hand layup method. Tensile properties of the bio composites are

examined. Maximum tensile values reached the specimen F and alkali treated specimen

G, The tensile values of F and G are 194.92MPa and 203.52 MPa respectively. The G

specimen was attained upto 4.2% and 5.1% enhancement of tensile strength and tensile

modulus respectively compared to specimen F. Morphological images proved the

interlinking between the natural fibers and polyester matrix. Furthermore, thermal

characterizations through TGA, DTG, and Tg, as well as dynamic mechanical analysis

such as storage modulus, loss modulus and Tan delta were performed in this work. The

obtained results explicitly apparent that the incorporation of natural fibers enhanced the

thermal stability and extremely improves E’ and E” dynamic properties of all polymer


ISSN: 0303-6286

Vol 40, 2020

52

composites. However, increase the sisal fiber and equal sharing of jute and banana fiber

loadings in polyester composites enhances the thermal and DMA characteristics.

These effects are attributed to the good reinforcing effects of natural fibers and the

formation of interfacial interaction to the polyester matrix. This type of composite

material can be useful for packaging, light weight automotive parts, shipping industry for

mooring small craft, and construction fields.

C. D. Scott and R. E. Smalley, “Diagnostic Ultrasound: Principles and Instruments”,

Journal of Nanosci. Nanotechnology. vol. 3, no. 2, (2003), pp. 75-80.

References

[1] K.Joseph, S.Thomas and C,Pavithran, “Effect of chemical treatment on the tensile

properties of short sisal fibre-reinforced polyethylene composites”, Polymer. vol.37,

no. 23, (1996) pp.5139-5149.

[2] A.C. De Albuquerque, K.Joseph, L.H. de Carvalho and J.R.M. d'Almeida, “Effect of

wettability and ageing conditions on the physical and mechanical properties of

uniaxially oriented jute-roving-reinforced polyester composites”, Composites

Science and Technology. vol.60, no.6, (2000), pp.833-844.

[3] V.G.Geethamma, K.T. Mathew, R.Lakshminarayanan and S.Thomas,“Composite of

short coir fibres and natural rubber: effect of chemical modification, loading and

orientation of fibre”, Polymer, vol.39. no.6-7, (1998), pp.1483-1491.

[4] M.S,Sreekala, M.G.Kumaran and S.Thomas, “Oil palm fibers: Morphology,

chemical composition, surface modification, and mechanical properties”, Journal of

Applied Polymer Science, vol. 66, no.5, pp.821-835.

[5] L.A.Pothan, S.Thomas and N.R. Neelakantan, Journal of Reinf. Plast.

Comp.16,(1997), pp.744.

[6] M.K.Gupta, R.K.Srivastava and H.Bisaria, “Potential of jute fibre reinforced

polymer composites: a review”, International Journal of Fiber and Textile

Research, vol.5, no.3, (2015),pp. 30-38.

[7] M.K.Gupta and R.K.Srivastava, “Mechanical, thermal and dynamic mechanical

analysis of jute fibre reinforced epoxy composite”, Indian Journal of Fibre & Textile

Research ,vol. 42, no.1, (2015), pp.64-71.

[8] B.V.Ramnath, S.J.Kokan, R.N.Raja, R.Sathyanarayanan, C, Elanchezhian, A.R.

Prasad and V.M.Manickavasagam, “Evaluation of mechanical properties of abaca–

jute–glass fibre reinforced epoxy composite”, Materials & Design, vol.51, (2013),

pp.357-366..

[9] I.O. Bakare, F.E. Okieimen, C.Pavithran, H.A.Khalil and M.Brahmakumar,

“Mechanical and thermal properties of sisal fiber-reinforced rubber seed oil-based

polyurethane composites”, Materials & Design, vol.31, no.9,(2010), pp. 4274-4280.

[10] L.Yan,N.Chouw and K.Jayaraman, “Flax fibre and its composites–A

review”, Composites Part B: Engineering, vol.56, (2014), pp. 296-317.


ISSN: 0303-6286

Vol 40, 2020

53

[11] M.S.Huda, L.T. Drzal, A.K.Mohanty and M.Misra, “Effect of fiber surface-

treatments on the properties of laminated biocomposites from poly (lactic

acid)(PLA) and kenaf fibers”, Composites science and technology, vol.68, no.2,

(2008) pp. 424-432.

[12] S.Sathees Kumar,“Dataset on mechanical properties of natural fiber reinforced

polyester composites for engineering applications”, Data in brief, 28, 105054, 2020

[13] O.Faruk, A.K.Bledzki, H.P. Fink, and M. Sain, “Biocomposites reinforced with

natural fibers: 2000–2010”. Progress in polymer science, vol. 37, no.11, (2012)

pp.1552-1596.

[14] M.A.Fuqua, S.Huo and C.A. Ulven, “Natural fiber reinforced composites. Polymer

Reviews”, vol.52, no.3,(2012), pp. 259-320.

[15] M.H.P.S.Jawaid and H.A. Khalil, “Cellulosic/synthetic fibre reinforced polymer

hybrid composites: A review”, Carbohydrate polymers, vol.86, no.1, (2012), pp.1-18.

[16] M.Jacob, Bejoy Francis, Sabu Thomas, K.T.Varughese, “Dynamical Mechanical

Analysis of Sisal/Oil Palm Hybrid Fiber-Reinforced Natural Rubber Composites”,

Polymer Composites, vol.27, no.6, (2006), pp. 671-680.

[17] M.Ramesh, K.Palanikumar, and K. Reddy, “Plant fibre based bio-composites:

Sustainable and renewable green materials”, Renewable and Sustainable Energy

Reviews, vol.79, pp. 558-584.

[18] K.Kumar, K.J.Gokuleshwar, S.Ranganathan and C.Thiagarajan, “Fabrication and

mechanical property study on glass/sisal/banana natural fibres”, International

Journal of Pure and Applied Mathematics, vol. 119, no.12, (2018), pp.15637-15645.

[19] M.Boopalan, M.Niranjanaa and M. J.Umapathy, M. J. “Study on the mechanical

properties and thermal properties of jute and banana fiber reinforced epoxy hybrid

composites”, Composites Part B: Engineering, vol.51,(2013),pp. 54-57.

[20] T.P.Sathishkumar, P.Navaneethakrishnan, S.Shankar and J.Kumar, “Mechanical

properties of randomly oriented snake grass fiber with banana and coir fiber-

reinforced hybrid composites”, Journal of composite materials, vol.47, no.18,

(2013)2181-2191.

[21] M.K.Gupta and A.Bharti, “Natural fibre reinforced polymer composites: a review on

dynamic mechanical properties”, Current Trends Fash. Technol Text. Eng, 1(2014)

pp.1-4.

[22] A.Mandal, and D.Chakrabarty, “Studies on the mechanical, thermal, morphological

and barrier properties of nanocomposites based on poly (vinyl alcohol) and

nanocellulose from sugarcane bagasse”, Journal of Industrial and Engineering

Chemistry, vol.20. no.2,(2014),pp. 462-473.

[23] A.K.Mohanty, M.Misra and L.T. Drzal, “Surface modifications of natural fibers and

performance of the resulting biocomposites: an overview. Composite

interfaces, vol.8, no.(5), (2001), pp. 313-343.

[24] R.Agrawal, N.S.Saxena, K.B.Sharma, S.Thomas, and M.S.Sreekala, “Activation

energy and crystallization kinetics of untreated and treated oil palm fibre reinforced

phenol formaldehyde composites”, Materials Science and Engineering: A, 277(1-2),

(2000), pp.77-82


ISSN: 0303-6286

Vol 40, 2020

54

[25] A.Valadez-Gonzalez, J.M.Cervantes-Uc, R.J.I.P. Olayo, R. and P.J.Herrera-Franco,

“Effect of fiber surface treatment on the fiber–matrix bond strength of natural fiber

reinforced composites”, Composites Part B: Engineering, vol.30, no.3, (1999),

pp.309-320.

[26] S.Sathees Kumar and G.Kanagaraj, “Investigation of characterization and

mechanical performances of Al2O3 and SiC reinforced PA6 hybrid

composites”, Journal of Inorganic and Organometallic Polymers and

Materials, vol.2, no.4, (2016), pp788-798.

[27] A.Jähn, M.W.Schröder, M.Füting, K.Schenzel and W.Diepenbrock,.

“Characterization of alkali treated flax fibres by means of FT Raman spectroscopy

and environmental scanning electron microscopy. Spectrochimica Acta Part A:

Molecular and Biomolecular Spectroscopy”, vol. 58, no.10, (2002), pp.2271-2279.

[28] A.Burkart, “A monograph of the genus Prosopis (Leguminosae subfam.

Mimosoideae)”, Journal of the Arnold Arboretum, (1976), pp. 450-525.

[29] C.Y. Lai, S.M. Sapuan, M. Ahmad, N. Yahya, and K.Z.H.M. Dahlan, “Mechanical

and electrical properties of coconut coir fiber-reinforced polypropylene

composites”, Polymer-Plastic Technology and Engineering, vol.44, no.4, (2005),

pp.619-632.

[30] K.M.Nair, S.M. Diwan and S.Thomas, “Tensile properties of short sisal fiber

reinforced polystyrene composites. Journal of applied polymer science”, 60(9),

(1996)1483-1497.

[31] B.K.Sarkar and D.Ray, “Effect of the defect concentration on the impact fatigue

endurance of untreated and alkali treated jute–vinylester composites under normal

and liquid nitrogen atmosphere. Composites Science and Technology, 64(13-14),

(2004), pp, 2213-2219.

[32] M. Jacob, S.Thomas and K.T. Varughese, K. T. “Mechanical properties of sisal/oil

palm hybrid fiber reinforced natural rubber composites”, Composites science and

Technology, 64(7-8), (2004), pp. 955-965.

[33] A.Mukherjee, P.K.Ganguly and D.Sur,“Structural mechanics of jute: the effects of

hemicellulose or lignin removal”, Journal of the Textile Institute, vol.84, no.3,pp

(1993), pp.348-353.

[34] Y.S.Wang, W.M. Koo and H.D.Kim, “Preparation and properties of new

regenerated cellulose fibers”,Textile research journal, vol.73, no.11, (2003), pp.998-

1004.

[35] L.Yan, N.Chouw, X.Yuan “Improving the mechanical properties of natural fiber

fabric reinforced epoxy composites by alkali treatment”, Journal of Reinforced

Plastics and Composites, vol.31, (2012), pp.425-437.

[36] I.Nor Azowa, H.Kamarul Arifin, A.Khalina, “Effect of fiber treatment on mechanical

properties of Kenaf fiber-Ecoflex composites”, Journal of Reinforced Plastics and

Composites, 29, (2010), pp.2192-2197, 2010.

[37] P.A.Sreekumar, R.Saiah, J.M. Saiter, N.Leblanc, K.Joseph, G.Unnikrishnan and

S.Thomas, “Effect of chemical treatment on dynamic mechanical properties of sisal

fiber-reinforced polyester composites fabricated by resin transfer

molding”, Composite Interfaces, vol.15, no.(2-3),(2008), pp. 263-279.


ISSN: 0303-6286

Vol 40, 2020

55

[38] S.Dong and R.Gauvin, “Application of dynamic mechanical analysis for the study of

the interfacial region in carbon fiber/epoxy composite materials. Polymer

composites, vol.14, no.5, (1998), pp.414-420.

[39] S.Xu, N.Girouard, G.Schueneman, M.L.Shofner and J.C. Meredith, “Mechanical

and thermal properties of waterborne epoxy composites containing cellulose

nanocrystals”, Polymer, vol.54, no.24, (2013), pp.6589-6598.

[40] L.A.Pothan, Z.Oommen and S. Thomas, Dynamic mechanical analysis of banana

fiber reinforced polyester composites”, Composites Science and Technology, vol. 63,

no.2, (2003), pp.283–293.


ISSN: 0303-6286

Vol 40, 2020

56

tensile, thermal and dynamic mechanical analysis of sisal

Documents