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Al-Khwarizmi 

  Engineering  

Journal 
Al-Khwarizmi Engineering Journal,Vol. 13, No. 1, P.P. 42- 49 (2017) 

 

 

Experimental Study to the Effect of Natural Particles Added to 

Unsaturated Polyester Resin of a Polymer Matrix Composite  
 

   Orhan S. Abdullah
 
 

Department of Mechanical Engineering /University of Technology. 

  Email: orhan_sabah@yahoo.com 

 
Received 13 April 2015; accepted 4 August 2016)(  

s://doi.org/10.22153/kej.2017.08.004http  

 

 

Abstract 
 

Experimental investigations had been done in this study to demonstrate the effect of natural particles used as a 

reinforcement material to unsaturated polyester resin. The tensile test and water absorption were investigated according 

to (ASTM D638) and (ASTM D570), respectively. The influence of sunflower husk and pomegranate husk particles, 

used as a reinforcement material, on the tensile strength, Young's modulus and water absorption with different weight 

fraction (3%, 7% and 10%) and particle grain size (50µ m, 100 µ m and 150 µ m), has been investigated. The water 

absorption of polymer composites was studied by measuring the specimen weight before and after immersion in water 

for one hundred days. In the experiments of tensile test, all specimens loading was performed with (50KN) operating at 

a crosshead speed of 10 mm/min. It is observed that the addition of sunflower husk up to 10% and pomegranate husk 

particles up to 7% as reinforcement materials to polyester resin, leads to increase the tensile strength and Young's 

modulus of the composite material prepared and the use of sunflower husk as a reinforcement material increased the 

tensile strength, Young's modulus and water absorption were better  than pomegranate husk at the same percentage of 

addition. The decrease in reinforcement material grain size led to increase the tensile strength, Young's modulus and 

water absorption. Therefore, all the best result seen in composites containing reinforcement material with (50µ m). 

Finally, the best result obtained in tensile strength, Young's modulus and water absorption were with the addition of 

10% sunflower husk as a reinforcement material to polyester resin. 

 

Keywords: Polyester, Polymer composite; Pomegranate husk, Sunflower husk. 

 

   

1. Introduction 
 
    From thousands years, human has tried to 

improve the available materials in their 

surroundings to preferable the life of the people 

around him and the community in overall. These 

attempts had led to different research over the 

years to find alternatives materials. A lot of 

studies had done on composite material to 

investigate this new material specially polymer 

matrix composite which be capable substitute in 

the different industrial applications, when 

compared to old used materials. Also the studies 

show that the using of polymer composite gave a 

better performance than ceramics, polymeric 

materials or alloys
 
[1]. 

There are two main type of polymer will used as 

matrix material, thermoplastic and thermoset. 

Thermoplastic is able to reformed after 

solidification like nylon and polyethylene, while 

thermoset is a material when solidification cannot 

be reformed like epoxy and polyester
 
[2]. 

    The composite material is a result of two 

phases, the first one called the matrix, while the 

second called the reinforcements phase. The 

characteristic of composite materials is dependent 

on the characteristic of the two phase's common in 

the preparation of the composite material
 
[2]. 

     In recent years, many studies have been done 

for natural fillers like coconut shell, pomegranate 

core, pineapple leaf, ginger, palm kernel, etc. as 

fillers in order to substitute the conventional 

fillers by using the natural fillers as a 



  

  

Orhan S. Abdullah                          Al-Khwarizmi Engineering Journal, Vol. 13, No. 1, P.P. 42- 49(2017) 

 

43 

 

reinforcement material in polymer matrix 

composites to decrease the cost, rise productivity 

beside the enhancement of the mechanical 

properties[3]. 

In order to obtain the tensile strength and the 

Young's modulus many researchers modified 

polymers using different natural fillers. N. W. A. 

Razak and A. Kalam
 
[4] studied the effect of oil 

palm empty fruit bunch (OPEFB) on the 

mechanical properties and water absorption 

behaviour of OPEFB /PPnanoclay /PP hybrid 

composites. They observed that the increase of 

OPEFB fibre size has increased it flexural 

strength, modulus and water absorption at smaller 

OPEFB fibre size. 

Moayad A. M. [5]
 
study the effects of rice husk 

fillers on the mechanical properties of rubber 

composite and he discover that the increase in 

volume fraction of reinforcement materials leads 

to increase in young modulus and hardness. 

Mohammed Almamory et.al[6] studied the effects 

of shells powder on mechanical and physical 

properties of nature rubber, and they observed that 

the tensile strength and the hardness of the 

composite material will improved after the 

addition of reinforcement material. 

S. I. Durowaye [7] studied the mechanical 

behaviour of coconut shell and palm fruit 

particulate polyester composites in order to 

develop an engineering material for industrial 

application. The results show the maximum 

strength that the coconut shell and palm fruit 

particulate polyester composites can withstand 

while being stretched or pulled before breaking, 

their weight % (reinforcement) must be kept 

below 10%. 

 Aseel Basim et.al
 
[8] Studied the mechanical 

properties for polymer matrix composite material 

reinforced by nature filler, they used both high 

density polyethylene (HDPE), and low density 

polyethylene (LDPE) as matrix to the composite 

material and used coconut shell particles and fish 

shell particles as reinforced fillers. They observed 

that the addition of nature fillers improve the 

mechanical properties. 

Aseel Basim et.al[9] studied the effects of nature 

material (Rice Husk Ash, Carrot Powder, and 

Sawdust) as filler to fiber glass / epoxy composite 

on mechanical properties; they observed that the 

addition of fillers leads to incremental increase in 

water absorption, hardness, flexural strength and 

shear stress with increasing in volume fraction. 

Jabbar H.[10] study the tensile and compressive 

properties of kaolin reinforced epoxy; he observed 

the tensile and yield strength of the composites 

decreases with rising kaolin content. It is also 

observed that mechanical properties increase with 

decrease in particle size in all cases. 

Shaimaa H. Kamel [11]
 
study the effect of grapes 

and dates particles reinforced polyester matrix 

composite on some of the mechanical properties, 

the results showed that the tensile strength and the 

Young's modulus of filled unsaturated polyester 

increase with the increment of the percentage of 

grapes and dates particles. Also that the 

percentage of (3.5 %) represents the greatest value 

for the modulus of elasticity for unsaturated 

polyester reinforced with dates particle and the 

percentage of (5 %) represents the greatest value 

for the modulus of elasticity for unsaturated 

polyester reinforced with grapes particle. 

    The aim of this research is to investigate the 

effect of adding pomegranate husk and sunflower 

husk in different grain size and weight fraction to 

polyester resin on tensile strength, young's 

modulus and water absorption.  
    
 

2. Experimental details  

2.1 Materials 

2.1.1 Matrix Material 
     

Unsaturated polyester used as a matrix material 

produced by (SIR). It is in liquid state at room 

temperature but after adding the hardener will 

change to solid state. The hardener used to this 

purpose Methyl Ethyl Keton Peroxide with 

mixing ratio 1:50 hardener to polyester resin at 

room temperature. After the adding of hardener to 

the resin the process of mixing will start and keep 

for 10 minutes till the homogenous will completed 

[2]. 

 

2.1.2 Reinforcement Material    
    

The particle were collected and crashed by 

using an electrical mill. The particulates were 

received by vibratory sieve shaker to get a 

suitable size of (150, 100, 50 µ m). 

 

2.2 Specimens Preparation 
 

Hand layup technique was used in this research 

to prepare the specimens. Glass mould used to 

casting the composite material specimens with 

dimension of (200, 150, and 5) mm as shown in 

Figure (1) The inner face of the mould was 

covered with a layer of Vaseline to ensure no-

adhesion between the polymeric material and the 



  

  

Orhan S. Abdullah                          Al-Khwarizmi Engineering Journal, Vol. 13, No. 1, P.P. 42- 49(2017) 

 

44 

 

mould. The specimens were prepared by mixing 

the unsaturated polyester with pomegranate husk 

and sunflower husk powder by using different 

grain size and weight fraction of (3%, 7%, and 

10%) according to roll of mix in term weight 

fraction as shown in equations (1), (2) and (3). 

0
0100×=

c

p

p
w

w
W                                          …(1) 

0
0100×=

c

m
m

w

w
W                                         … (2) 

1=+
mp

WW                                                  … (3) 

Where: 

Wm, Wp: The weight fraction of matrix material 

and particles respectively.  

wc, wm, wp: Weight of composite material, matrix 

material and particles respectively.   

The particles were supplementary to polyester and 

hardener and then they were homogeneously 

mixed at room temperature inside the molud and 

then left 24 hours for solidification completed.  
 

    

3. Mechanical and physical Tests 
 

3.1 Tensile Test 

 
    Tensile test was used to study the effect of 
axial load applied to the specimen by using tensile 

testing machine (Tensile test H50KT (TINIUS 

OLSEN)) England (UK) /mechanical engineering 

department /university of technology shown in 

figure (2). All the specimen have the same test 

conditions, the applied load was (50 KN), and the 

operating speed 10 mm/min. figure (3) shows 

some of the flat specimens was prepared to the 

purpose of tensile testing with different 

reinforcement particles grain size and weight 

fraction according to tensile test equations (4) & 

(5) and the American standard (ASTM D638) 

with thickness (5mm) as shown in figure (4). 

                                                       …(4) 

  =                                    …(5) 

σ: Stress (Pa), F: Applied load (N),               AO: 
Original area (mm

2
), �: strain (unit less), ∆L: 

length change (mm), Lf: final length (mm), Lo: 

original length (mm).  

 

 

 

3.2. Young's Modulus 
     

The Young's modulus can be obtained by 

calculating the slope of the stress- strain curve for 

the tensile test in the proportional limit zone [12]. 

                                                          …(6) 

Where:  

E: Young's modulus (Pa), σ: Stress (Pa), �: strain 
(unit less). 

 
3.3 Water Absorption 
     

Disc specimens were prepared with diameter 

of 40 mm and thickness 5mm in order to obtain 

the water absorption of the composite material. 

The specimens weighted before and after 

immersion in water according to ASTM D 570 

standard as shown in figure (5). The increase in 

the weight of the specimens was calculated by 

using equation (7). 

Water absorption  

                                                                          ..(7) 

The specimens were immersion for one hundred 

days in water and it was weighted every ten days. 

 

 
 

 
 

Fig. 1. The moulds shape. 



  

  

Orhan S. Abdullah                          Al-Khwarizmi Engineering Journal, Vol. 13, No. 1, P.P. 42- 49(2017) 

 

45 

 

 

         
                               

Fig . 2. Tensile test machine.                                               Fig . 3. Tensile test specimens. 

 

                                 
                                

Fig. 4. Tensile test standard                                             Fig. 5. Water absorption specimen. 

 

 

4. Result and Discussion  

4.1 Tensile Test 
 

From Figure (6), it can observe that the 

addition of sunflower husk particles as a 

reinforcement materials leads to increase the 

tensile strength with the increasing in weight 

fraction of the reinforcement material by (11.6%, 

31.5%, and 46.6%) respectively with particle 

grain size (50 µ m) due to the high linkage 

between polyester and sunflower husk particles 

which leads to increase the resistance against the 

applied axial load. Also from the same figure it 

can recognize that the decrease in particles grain 

size leads to raising the tensile strength, because 

of that the decreasing in particles size leads to 

more contact between the matrix material and 

sunflower husk particles. 

 

 
 

Fig. 6. Effect of sunflower husk particles on tensile 

strength. 
 

 

Figure (7) shows the stress- strain curves of 

pure polyester and (3%,7% and 10%) sunflower 

husk (SH) weight fraction respectively with 

(50µm) grain size. 

 



  

  

Orhan S. Abdullah                          Al-Khwarizmi Engineering Journal, Vol. 13, No. 1, P.P. 42- 49(2017) 

 

46 

 

 
 

Fig. 7. Stress-Strain curves of different weight 

fraction of sunflower husk. 

 

 

While Figure (8) show the effects of 

pomegranate husk particles on tensile strength with 

different particle grain size and weight fraction, 

from this figure it can see that the addition of 

particles leads to increasing in tensile strength due 

to increasing of pomegranate husk percentage till 

7% after this percent the tensile strength will be 

decreases with all particle grain size, a similar 

behavior was seen by S. I. Durowaye et.al[7] we 

use coconut shell and palm fruit particles as a 

reinforcement material to polyester resin this may 

be due to increase in discontinuity between the 

particles surface and the matrix as the 

reinforcement concentration increases in the two 

composites. 

 

 
 

Fig. 8. Effect of pomegranate husk particles on 

tensile strength. 

 

 
4.2 Young's Modulus 
      

The relationship between the Young's modulus 

and sunflower husk particles percentage was 
shown in Figure (9). It can notice that the 

increasing in Young's modulus causing be the 

addition of reinforcement particles which added to 

unsaturated polyester resin. Sunflower husk 

particles work to prevent the polyester chains 

from slipping and this leads to increase the 

Young's modulus. The addition of 10 % sunflower 

husk particles with grain size (50 µm)   gives the 

highest Young's modulus with increasing by 

27.2% better than unsaturated polyester resin 

specimen. Analogous demeanor was seen by 

Shaimaa H. Kamel [11]
 

with the addition of 

grapes particles to unsaturated polyester up to 5% 

these quantities of grapes particles strengthen the 

polyester specimen and increase the young's 

modulus. 
 

 
 

Fig. 9. Effect of sunflower husk particles on Young's 

modulus.  

 

Figure (10) appears the behavior of Young's 

modulus after adding pomegranate husk particles 

with different weight fraction and particles grain 

size to unsaturated polyester resin. It can be 

observed that the addition of pomegranate husk 

particles with any particle size was used increase 

the Young's modulus up to 7% percent, while 

after this percent the  Young's modulus values 

starting decrease. 

 

 
 

Fig. 10. Effect of pomegranate husk particles on 

young's modulus. 

 



  

  

Orhan S. Abdullah                          Al-Khwarizmi Engineering Journal, Vol. 13, No. 1, P.P. 42- 49(2017) 

 

47 

 

4.3. Water Absorption 

 
    Water absorption behaviors of the composite in 

water immersion against the time in (days) are 

shown in Figures (11) and (12). The addition of 

sunflower husk and pomegranate husk particles 

leads to increase the water absorption with the 

increasing in immersion time. A similar behavior 

was seen by and N. W. A. Razak and A. Kalam
 

[4] Aseel Basim et.al
 
[8] with the addition of 

natural fiber or particles the water absorption 

increase with the increasing in immersion time 

which leads to increase the humidity and decrease 

the adhesion between the matrix material and the 

reinforcement material made the composite 

material may be containing voids and porosity. 

  

 
 

Fig. 11. Effect of sunflower husk particles on water 

absorption. 

 

 
 

Fig. 12. Effect of pomegranate husk particles on 

water absorption. 

 

     

    Figure (13) show the difference in water 

absorption values at using varies particles grain 

size as a reinforcement material. The results show 

that the decrease in particle grain size leads to 

increase the water absorption and the use of 

sunflower husk have water absorption high than 

pomegranate husk. In the same filled Alaa 

A.Mohammed
 
[13] and Hussein .A.Ali [14] have 

similar result where using different particles grain 

size the lowest particle size have the highest water 

absorption due to the decrease in contact area with 

the matrix. 

 

 
 

Fig. 13. Effect of sunflower husk and pomegranate 

husk grain size particles on water absorption. 

 

*All abbreviations and symbols shown in Table (1) 

 
 

5. Conclusions 

  
From the up results it can conclude the 

following: 

1- The addition of sunflower husk up to 10% and 
pomegranate husk particles up to 7% as 

reinforcement materials to polyester resin leads 

to increase the tensile strength and Young's 

modulus of the composite material prepared.  

2- Using of sunflower husk as a reinforcement 
material increase the tensile strength and 

Young's modulus better than pomegranate 

husk at the same percentage of addition.   

3- The water absorption of composite material 
prepared in this research increase with the 

increasing of reinforcement material weight 

fraction.  

4- The addition of 10% sunflower husk as a 
reinforcement material to polyester resin give 

the best result in tensile strength and young's 

modulus, where the tensile strength and 

young's modulus increasing by (46.6%,27.2%) 

respectively.  

5- The decreasing in reinforcement material grain 
size leads to increase the tensile strength, 

Young's modulus and water absorption. There 

for all the best result seen in composites 

containing reinforcement material with 

(50µ m). 



  

  

Orhan S. Abdullah                          Al-Khwarizmi Engineering Journal, Vol. 13, No. 1, P.P. 42- 49(2017) 

 

48 

 

Table 1, 

 List of abbreviations and symbols 

 
6-  

Abbreviations 

and Symbols 

Meaning Units 

HDPE High Density 

Polyethylene 

- 

LDPE Low Density 

Polyethylene  

- 

OPEFB Oil Palm Empty Fruit 

Bunch 

- 

ASTM American Society of 

Testing and Materials  

- 

SH Sunflower Husk - 

P pomegranate - 

SIR Saudi Industrial Resins - 

 

 

6. References 
  
[1] Sabu Thomas, Kuruvilla Joseph, Sant Kumar 

Malhotra, Koichi Goda, and Meyyarappallil 

Sadasivan Sreekala," Polymer Composites", 

Volume 1, First Edition, Published by Wiley-

VCH Verlag GmbH & Co. KGaA, 2012. 

[2] G.Piatti, "Advanced in Composite 
Materials", Applied Science publishers LTD., 

London, 1987. 

[3] W. Bolten, "Engineering Materials 
Technology", Third edition, A Member of 

reed Elsevier group, 1998. 

[4] N. W. A. Razak, and A. Kalam, " Effect of 
OPEFB Size on the Mechanical Properties 

and Water Absorption Behaviour of 

OPEFB/PPnanoclay/PP Hybrid Composites", 

Procedia Engineering, Vol.41, p.p1593 – 

1599, 2012. 

[5] Moayad A. M., "Effects of Rice Husk Filler 
on the Mechanical and Rheogical properties 

of Rubber Component Based on Natural 

Rubber", The Iraqi Journal for Mechanical 

and Material Engineering, Vol.13, No.2, 

2013. 

[6] Mohammed Almamory et.al, "Effect of 
Shells Powder on Physical Properties of 

Natural Rubber", The Iraqi Journal For 

Mechanical and Material Engineering, 

Vol.13, No.2, 2013. 

[7] S. I. Durowaye1,*, G. I. Lawal, M. A. 
Akande1, V. O. Durowaye, "Mechanical 

Properties of Particulate Coconut Shell and 

Palm Fruit Polyester", International Journal 

of Materials Engineering 2014, 4(4): 141-147 

Composites. 

[8] Aseel Basim Abdul-Hussein, Emad Saadi 
AL-Hassani, and Reem Alaa Mohammed, 

"Effect of Nature Materials Powders on 

Mechanical and Physical Properties of Glass 

Fiber / Epoxy Composite", Engineering and 

Technology Journal, Vol.33, part (A), no.1, 

2015. 

[9] Aseel Basim Abdul-Hussein, Emad Saadi 
AL-Hassani, and Reem Alaa Mohammed, 

"Influence of Coating with Some Natural 

Based Materials on the Erosion Wear 

Behavior of Glass Fiber Reinforced Epoxy 

Resin", Al-Khwarizmi Engineering Journal, 

Vol.11, no.2, 2015. 

[10] Jabbar H. mohmmed, "Tensile and 
Compressive Properties of Kaolin Reinforced 

Epoxy", Al-Khwarizmi engineering journal, 

Vol.11, no.3, 2015. 

[11] Shaimaa H. Kamel, "Studing Some of the 
Mechanical Properties of Unsaturated 

Polyester Reinforced by Re-cycled Natural 

Materials", Al-Qadisiyah Journal for 

Engineering Sciences, Vol. 8, No. 2, 2015. 

[12] Ferdinand L.Singer and Andrew Pytel, 
"Strength of Materials", Third Edition, 

Harper &Row publishers, New York, 1980.   

[13] Alaa A. Mohammed, "Study the Thermal 
Properties and Water Absorption of 

Composite Material Reinforced with Data 

and Olive Seeds", the Iraqi Journal for 

Mechanical and Material Engineering, 

Vol.15, No2, 2015. 

[14] Hussein, A. Ali. , Salim, R. D. & Sultan, A. 
Ali, "Water Absorption and Mechanical 

Properties of High-Density Polyethylene/Egg 

Shell Composite", Journal of Basrah 

Researches (Sciences), Vol. (37), No. 

(3A/15), (2011). 

 

 

 

 
 




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