Synthesis and Structural analysis of Aluminium-filled Polystyrene Composites from Recycled Wastes

In this study, the effects of powdered Aluminium (Al) as reinforcing fillers for polystyrene-based resin (PBR) matrix has been evaluated based on the analysis of mechanical and structural properties. Samples were prepared by hand lay-out technique enhanced with the usage of single roller. The PBR was reinforced by Aluminium powders (μm) at selected weight fractions of (0, 5, 10, and 15 %) and investigated by X-ray diffraction (XRD) physical and mechanical testing. The study of mechanical properties includes: elongation at break, time to failure and young modulus. The XRD studies confirmed no chemical reaction but rather the introduction of crystalline structure in the polystyrene matrix based on the amount of Aluminium content and the even distribution of aluminium powder in the matrix. The tensile strength increased with increasing filler content; however elongation at break and time to break showed decrement as the weight fraction of aluminium powder is increased in the composites. DOI: http://dx.doi.org/10.5755/j01.erem.74.2.19680


Introduction
Currently, the emerging sophisticated industrial processes and technologies require materials with unusual combinations of properties that cannot be provided by the available and conventional polymers, ceramics, and metal alloys products.These needs can be met through the design and development of composite materials whose constituents synergistically meet the terms of these emerging applications (Jui et al., 2008).In most industrial applications, thermoplastics are used as a matrix for very fine particulates in the production of composite materials when such particles can interact physically and/or chemically with the thermoplastics creating high performance polymeric composites (Alwan et al, 2016).Metallic powders are a special type of particle filler that impart special qualities in plastic composites.These fillers enhance properties such as thermal conductivity, electrical conductivity, response to magnetic fields and heat capacity.
Production of Aluminium/polymer composites has focused on attractive material development exploration due to its associated combination of properties like low density, corrosion resistance, thermal stability, and ease of fabrication.Consequently, studies have been made to investigate the mechanical, thermal, and electrical properties of aluminium powder reinforced polymer composites (David, 2007;Alwan et al., 2016;Hachani and Meghezzi, 2015).However, good particle dispersion and interfacial strength between aluminium powders and the host matrix has been the main issues in the fabrication of aluminium/polymer composites because of the surface properties of Aluminium and the fabrications methods employed being majorly hot pressing and extrusion at elevated temperatures and/or epoxy reinforced technology (Chung et al., 2005;Alwan et al., 2016;Hachani and Meghezzi, 2015).To address this issue, some studies have attempted the surface treatment of aluminium powders before mixing with the host matrix (Jallo et al.2010Chen et al.2010); their results confirm surface treatment as non-effective.
The polystyrene in its virgin state is of poor mechanical properties and of bad resistance to surfactants (Myer, 2002).As a reinforcement method to enhance the properties of the polystyrene, a lot of research works have been focused on polystyrene composites with metal oxides (Jui et al., 2008), carbon nanotubes (Archana et al., 2013) and glass-fibers (Quanyao et al., 2010).The addition of powdered fillers has been demonstrated to be an effective way to improve the mechanical properties of the polymer matrix.However, not much investigation has been carried out on the possibility of reinforcing aluminium powder with polystyrene based resin to improve fracture and tribological properties of aluminium reinforced composites.
Moreover, in its waste state, disposal of polystyrene (PS) has been recognized as a worldwide environmental problem.Reuse of waste PS in composite products development is a greener attempt in product development.In this study, the binding effect of polystyrene based resin on the production of aluminium reinforced composites was investigated.The aim of the present work is to evaluate the effect of powdered aluminium (Al) as reinforcing fillers for Polystyrene based resin (PBR) matrix through the measurement of the mechanical and structural properties.A secondary aim is to study the effect of different loadings (0 -15) % of the investigated fillers on the properties of PBR-Aluminium composites.The present paper discusses the results obtained from the structural study and characterization of the prepared composites for mechanical properties.

Materials
The major materials used were obtained from solid waste streams.The polystyrene were sorted and cleaned from University of Ilorin solid waste while the aluminium wastes were obtained from a local fabricator's workshop and were dried in oven for 24 hours at 50 o C to remove free water present in it.The dried sample was graded through No. 100 sieve to obtain the powder of 150µm in size.

Synthesis of Aluminium Filled Polystyrene Composites
Aluminium Filled Polystyrene Composites (AFPC) were prepared by incorporating Aluminium Powder (150µm) of varied content (0, 5, 10, 15 wt %) in Polystyrene based resin (PBR).PBR was obtained as described in Abdulkareem and Adeniyi, 2017.This involved dissolving 59 gram of Polystyrene in 100 mL of petroleum solvent followed by addition of the aluminium filler.The PBR-Aluminium powder mix was thoroughly masticated at room temperature.The final mixture of each formulation was formed by hand layup method enhanced by a single roller before film casting.The cast films were left for 7 days for complete solvent evaporation.The prepared composite films were utilized for characterization.To attain accuracy in performance and results, samples were prepared in triplicates and the average values were reported after characterization.

Structural and Mechanical analyses X-rays diffraction analysis
The phase identification of polystyrene and aluminium, the crystalline state investigation of the PS/aluminium composites, were both studied using X-ray diffraction technique.The XRD diffraction patterns were obtained using Bruker D2 diffractometer within 2θ varies from 10 to 90° with a scanning speed of 2° min -1 .The studied samples were all films.The usage of cobalt anode at ambient temperature was employed.

Tensile testing
Universal testing machine (UTM: M500-50 AT) with tensile test fixture and different types of self-aligning grips were used for holding test specimen in machine.It is fitted with load cell and extensometer to record the test load and elongation accurately.Tensile tests were conducted according to ASTM D638-10.A computerized universal testing machine model was used to conduct a test at a constant cross head speed of the order 4mm/min.Tensile loads were applied till the failure of the sample and load-elongation curves was obtained for all the composite materials produced.All tests were carried out at room temperature (25± 2)˚C.Three specimens were used for all the tests and final results represent the average.

Measurement of Density
The experimental densities of the aluminium powder, solvated polystyrene and composites were gotten using the laboratory-made density setup.Theoretical densities () of the solvated polystyrene/aluminium composites were calculated by the rule of mixture using equation 1 with the assumption of no voids present in the samples and no loss of material during the sample preparation using the density of the solvated polystyrene and aluminium are 0.855 g/cm 3 .and 2.7 g/cm 3 respectively.

41
The experimental densities of the aluminium powder, solvated polystyren 42 using the laboratory-made density setup.Theoretical densities ( �� ) of the sol 43 composites were calculated by the rule of mixture using equation 1 with the assum 44 the samples and no loss of material during the sample preparation using the densit 45 and aluminium are 0.855 g/cm 3 .and 2.7 g/cm 3 respectively.46 47 Where  � and  � are weight fraction of the aluminium filler and PBR matrix resp 50 densities of the aluminium filler and PBR matrix.

51
The void content ( ���� ) in a composite was estimated by comparing th Where  f and  m are weight fraction of the aluminium filler and PBR matrix respectively while  f and  m are densities of the aluminium filler and PBR matrix.
The void content ( void ) in a composite was estimated by comparing the theoretical density with its actual density.
The major materials used were obtained from solid waste streams.The polystyr 9 from University of Ilorin solid waste while the aluminium wastes were obtain 10 workshop and were dried in oven for 24 hours at 50 o C to remove free water presen 11 graded through No. 100 sieve to obtain the powder of 150µm in size.

41
The experimental densities of the aluminium powder, solvated polystyren 42 using the laboratory-made density setup.Theoretical densities ( �� ) of the sol 43 composites were calculated by the rule of mixture using equation 1 with the assum 44 the samples and no loss of material during the sample preparation using the densit 45 and aluminium are 0.855 g/cm 3 .and 2.7 g/cm 3 respectively.where,  td -theoretical density of the composite material;  ed -Experimental density of the composite materials

Discussion of Results
The images of the PBR film and the composites with 5, 10, and 15 wt % of aluminium powder are shown in Figure 1 (a-d).It is observed that the incorporation of filler played a remarkable role on the structure of the resultant composites.The optical micrographs of respective composites are presented in Figure 2.With the incorporation of lowest filler content (5 wt %), homogenous dispersion of filler is observed in the composites which explained good filler-resin interaction.At 10 wt % the extent of particle-to-particle connectivity increased due to improved filler-resin interactions, which improved throughout the matrix when the filler content is further increased to 15 wt %.The shiny areas in the images in b, c, d indicated the presence and extent of the aluminium powder when contrasted to a.

Density
The interaction of the aluminium powder with the PBR was observed intricately to be influenced by factors like voidage and weight fractions which as a result influenced the density of the resulting composite.The variation in the density of PBR/aluminium composites is shown in Table 1.This table shows that increase in weight fraction of aluminium powder also increase the densities of PBR/aluminium composites formed with corresponding decrease in voidage fraction.
It was also observed that there are some differences between the experimental and the theoretical densities of fabricated composites.This variation in density is due to the presence of voids and pores in fabricated composites.Evidently, greater void percentages are associated with composites of lower percentage The interaction of the aluminium powder with the PBR was observed intricately to be influenced by 20 factors like voidage and weight fractions which as a result influenced the density of the resulting composite.The 21 variation in the density of PBR/aluminium composites is shown in Table 1.This table shows that increase in

22
weight fraction of aluminium powder also increase the densities of PBR/aluminium composites formed with 23 corresponding decrease in voidage fraction.

24
It was also observed that there are some differences between the experimental and the theoretical 31 32

24
It was also observed that there are some differences between the experimental and the theoretical 31 32

24
It was also observed that there are some differences between the experimental and the theoretical 31 32

24
It was also observed that there are some differences between the experimental and the theoretical 31 32

1
The images of the PBR film and the composites with 5, 10, and 15 wt % of aluminium powder are The interaction of the aluminium powder with the PBR was observed intricately to be influenced by 20 factors like voidage and weight fractions which as a result influenced the density of the resulting composite.The 21 variation in the density of PBR/aluminium composites is shown in Table 1.This table shows that increase in 22 weight fraction of aluminium powder also increase the densities of PBR/aluminium composites formed with 23 corresponding decrease in voidage fraction.

24
It was also observed that there are some differences between the experimental and the theoretical 25 densities of fabricated composites.This variation in density is due to the presence of voids and pores in 31 32

1
The images of the PBR film and the composites with 5, 10, and 15 wt % of aluminium powder are The interaction of the aluminium powder with the PBR was observed intricately to be influenced by 20 factors like voidage and weight fractions which as a result influenced the density of the resulting composite.The 21 variation in the density of PBR/aluminium composites is shown in Table 1.This table shows that increase in 22 weight fraction of aluminium powder also increase the densities of PBR/aluminium composites formed with 23 corresponding decrease in voidage fraction.

24
It was also observed that there are some differences between the experimental and the theoretical 25 densities of fabricated composites.This variation in density is due to the presence of voids and pores in 31 32

1
The images of the PBR film and the composites with 5, 10, and 15 wt % of aluminium powder are

24
It was also observed that there are some differences between the experimental and the theoretical 25 densities of fabricated composites.This variation in density is due to the presence of voids and pores in 31 32

1
The images of the PBR film and the composites with 5, 10, and 15 wt % of aluminium powder are The interaction of the aluminium powder with the PBR was observed intricately to be influenced by 20 factors like voidage and weight fractions which as a result influenced the density of the resulting composite.The 21 variation in the density of PBR/aluminium composites is shown in Table 1.This table shows that increase in 22 weight fraction of aluminium powder also increase the densities of PBR/aluminium composites formed with 23 corresponding decrease in voidage fraction.

24
It was also observed that there are some differences between the experimental and the theoretical 25 densities of fabricated composites.This variation in density is due to the presence of voids and pores in 31 32 fillers.The density of the composite sample is sensitive to the volume fraction of voids; as the mass fraction of aluminium fillers with its corresponding volume increased in the mix, it further reduced the free spaces among the PBR molecules and further contributed to an increase in the density of the composites as reported in Anuar & Ismail 2007;Sihama et al., 2015.

XRD
For determining the effect of aluminium powder in the host Polystyrene matrix, XRD spectra of the composites  Another pattern in Figure 3 to 5 gives an idea about the presence of some Aluminium powder reflections.These peaks, in the same diffraction pattern, confirm the formation of properly dispersed Aluminium powder in the composite and development of crystallinity in the Polystyrene matrix.At 5 wt % (Figure 3) aluminium powder loading in aluminium reinforced polystyrene composite, three peaks at 44.4 o , 52.5 o and 77.0 o were observed which is common to loadings at 10 and 15 wt % aluminium (Figures 4 and 5).All of these are attributed to the crystalline nature of aluminium which was similarly observed in the past contributions (Sihama et al., 2015;Özge et al., 2015).However, at 10 and 15 wt % aluminium powder loading, one (42 o ) and two (21.5 o and 81.5 o ) additional peaks were observed respectively, which explained the fact that the composites becomes more crystalline as the percentage of aluminium powder increases.
Furthermore, the comparison among X-ray diffraction patterns of aluminium reinforced polystyrene composites of all aluminium loading between 5 % and 15 % (Figures 3 to 5) confirms the development of crystallinity in the Polystyrene matrix.All the three composites peaks matches with peaks of aluminium, indicating the good dispersion of Aluminium powder in the matrix crystalline composite.Also noticed is the reduction of polystyrene amorphous character and no alteration in crystal structure of aluminium.
It is also seen that no reaction takes place between aluminium powder and Polystyrene during fabrication of composites but rather a development of synergic structural reinforcement in the polystyrene matrix is achieved and their combination brings more rigidity to the studied samples.This position is further confirmed by the mechanical results.

Mechanical
Tensile test of Polystyrene composite reinforced by Aluminium particles showed that the Load-Strain curve behaviour of the composite changed from low strength and brittle at 0% Aluminium powder to increased hardness and strength when the weight fraction of aluminium powder increased to 15 % in the composite materials developed.This is quantitatively explained by the load-strain profile in each of the plots in Figures 6 a-d.
The tensile characteristics which include Young modulus (E) elongation (ε), and time to break, relative to the aluminium content of the composites in the PBR matrix, are equally shown in Figures 7 to 9 respectively.It is shown that there was a decrease in elongation (ε), and Time to break with the increase in the weight fraction of Al powders in the composites until the weight fraction reached 15%.The elongation at break decreased from 47.6% at 0% Aluminium powder to 7.9% at 15% Aluminium powder.Likewise, the time to break decreased from 57.13 sec 0% Aluminium powder to 9.52 sec at 15% Aluminium powder Fig. 6 Load-strain profile of the composite at 0 % (Test 8), 5 % (Test 2), 10 % (Test 3) , 15 % (Test 4) Aluminium filler bonding between the Aluminium filler and Polystyrene matrix prepared in form of PBR.The interfacial 1 adhesion is possible due to the usage of petroleum solvent in the preparation of PBR, which eliminated the 2 adhesion problem mentioned in previous studies (Chung et al., 2005;Alwan et al., 2016;Hachani and 3 Meghezzi, 2015).The increased Young modulus values is related to the effective dispersion of Al micro particles into the

Conclusions
In the present work, the use of aluminium powder and polystyrene from waste streams were used to produce metal filled plastic composites.The following conclusions were drawn: 1. Investigation by optical microscope reveals that the distribution of aluminum particles in the matrix of PBR is uniform and even.2. There is a significant increase in the tensile strength and modulus with an increase in the filler concentration up to15% of mass fraction considered.3. XRD studies showed that there is a good structural interaction between the Aluminium particles and the PBR matrix and no chemical reaction was found.

Conclusions
In the present work, the use of aluminium powder and polystyrene from waste streams were used to produce metal filled plastic composites.The following conclusions were drawn: 1. Investigation by optical microscope reveals that the distribution of aluminum particles in the matrix of PBR is uniform and even.2. There is a significant increase in the tensile strength and modulus with an increase in the filler concentration up to15% of mass fraction considered.3. XRD studies showed that there is a good structural interaction between the Aluminium particles and the PBR matrix and no chemical reaction was found.
Polystyrene matrix to fill the open structure of the crystalline crosslink structure of aluminium powder content in composites samples.It is clear from these plots that the mechanical properties improved with increasing filler content up to 15% Al powder considered in this study.The range is between 335.24MPa for 0% Aluminium to 1972.70 MPa for 15% reinforcement.This can be equally related to the interfacial adhesion and physical bonding between the Aluminium filler and Polystyrene matrix prepared in form of PBR.The interfacial adhesion is possible due to the usage of petroleum solvent in the preparation of PBR, which eliminated the adhesion problem mentioned in previous studies (Chung et al., 2005;Alwan et al., 2016;Hachani and Meghezzi, 2015).

Conclusions
In the present work, the use of aluminium powder and polystyrene from waste streams were used to produce metal filled plastic composites.The following conclusions were drawn: 1 Investigation by optical microscope reveals that the distribution of aluminum particles in the matrix of PBR is uniform and even.
2 There is a significant increase in the tensile strength and modulus with an increase in the filler concentration up to15% of mass fraction considered.
3 XRD studies showed that there is a good structural interaction between the Aluminium particles and the PBR matrix and no chemical reaction was found.
evaporation.The prepared composite films were utilized for characterization.To at 21 and results, samples were prepared in triplicates and the average values were report of polystyrene and aluminium, the crystallin 26 PS/aluminium composites, were both studied using X-ray diffraction technique.T 27 were obtained using Bruker D2 diffractometer within 2θ varies from 10 to 90• with 28 1 .The studied samples were all films.The usage of cobalt anode at ambient tempera (UTM: M500-50 AT) with tensile test fixture 33 aligning grips were used for holding test specimen in machine.It is fitted with l 34 record the test load and elongation accurately.Tensile tests were conducted acco 35 computerized universal testing machine model was used to conduct a test at a con 36 order 4mm/min.Tensile loads were applied till the failure of the sample and 37 obtained for all the composite materials produced.All tests were carried out at r 38 Three specimens were used for all the tests and final results represent the average.
�� -theoretical density of the composite material 57  �� -Experimental density of the composite materials58(1) and  � are weight fraction of the aluminium filler and PBR matrix resp 50 densities of the aluminium filler and PBR matrix.

51
The void content ( ���� ) in a composite was estimated by comparing th 52

25&
densities of fabricated composites.This variation in density is due to the presence of voids and pores in 26 fabricated composites.Evidently, greater void percentages are associated with composites of lower percentage 27 fillers.The density of the composite sample is sensitive to the volume fraction of voids; as the mass fraction of 28 aluminium fillers with its corresponding volume increased in the mix, it further reduced the free spaces among 29 the PBR molecules and further contributed to an increase in the density of the composites as reported inAnuar   30   Ismail 2007;Sihama et al., 2015.

Fig. 1 :Fig. 2 :
Fig. 1: Photographs of the PBR film (a) and the composite with 5, (b) 10, (c) and 15 wt % (d) of Aluminium 25 densities of fabricated composites.This variation in density is due to the presence of voids and pores in 26 fabricated composites.Evidently, greater void percentages are associated with composites of lower percentage 27 fillers.The density of the composite sample is sensitive to the volume fraction of voids; as the mass fraction of 28 aluminium fillers with its corresponding volume increased in the mix, it further reduced the free spaces among 29 the PBR molecules and further contributed to an increase in the density of the composites as reported in Anuar30& Ismail 2007;Sihama et al., 2015.

25
densities of fabricated composites.This variation in density is due to the presence of voids and pores in 26 fabricated composites.Evidently, greater void percentages are associated with composites of lower percentage 27 fillers.The density of the composite sample is sensitive to the volume fraction of voids; as the mass fraction of 28 aluminium fillers with its corresponding volume increased in the mix, it further reduced the free spaces among 29 the PBR molecules and further contributed to an increase in the density of the composites as reported in Anuar30& Ismail 2007;Sihama et al., 2015.

25
densities of fabricated composites.This variation in density is due to the presence of voids and pores in 26 fabricated composites.Evidently, greater void percentages are associated with composites of lower percentage 27 fillers.The density of the composite sample is sensitive to the volume fraction of voids; as the mass fraction of 28 aluminium fillers with its corresponding volume increased in the mix, it further reduced the free spaces among 29 the PBR molecules and further contributed to an increase in the density of the composites as reported in Anuar30& Ismail 2007;Sihama et al., 2015.

26&
fabricated composites.Evidently, greater void percentages are associated with composites of lower percentage 27 fillers.The density of the composite sample is sensitive to the volume fraction of voids; as the mass fraction of 28 aluminium fillers with its corresponding volume increased in the mix, it further reduced the free spaces among 29 the PBR molecules and further contributed to an increase in the density of the composites as reported in Anuar 30 Ismail 2007; Sihama et al., 2015.

26&
fabricated composites.Evidently, greater void percentages are associated with composites of lower percentage 27 fillers.The density of the composite sample is sensitive to the volume fraction of voids; as the mass fraction of 28 aluminium fillers with its corresponding volume increased in the mix, it further reduced the free spaces among 29 the PBR molecules and further contributed to an increase in the density of the composites as reported in Anuar 30 Ismail 2007; Sihama et al., 2015.

26&
fabricated composites.Evidently, greater void percentages are associated with composites of lower percentage 27 fillers.The density of the composite sample is sensitive to the volume fraction of voids; as the mass fraction of 28 aluminium fillers with its corresponding volume increased in the mix, it further reduced the free spaces among 29 the PBR molecules and further contributed to an increase in the density of the composites as reported in Anuar 30 Ismail 2007; Sihama et al., 2015.

26&
fabricated composites.Evidently, greater void percentages are associated with composites of lower percentage 27 fillers.The density of the composite sample is sensitive to the volume fraction of voids; as the mass fraction of 28 aluminium fillers with its corresponding volume increased in the mix, it further reduced the free spaces among 29 the PBR molecules and further contributed to an increase in the density of the composites as reported in Anuar 30 Ismail 2007; Sihama et al., 2015.

Fig. 8
Fig. 8Elongation (ε) relative to the Aluminium content of the composites

Fig. 9 Fig. 8 :Fig. 9 :
Fig. 9Time to break relative to the Aluminium content of the composites

Structural and Mechanical analyses 24 X-rays diffraction analysis 25
Three specimens were used for all the tests and final results represent the average.

Table 1 :
The variation in the density of PBR/aluminium composites

Table 1
. This table shows that increase in 22 weight fraction of aluminium powder also increase the densities of PBR/aluminium composites formed with 23 corresponding decrease in voidage fraction.

Table 1 :
The variation in the density of PBR/aluminium composites

Table 1
. This table shows that increase in 22 weight fraction of aluminium powder also increase the densities of PBR/aluminium composites formed with 23 corresponding decrease in voidage fraction.

Table 1 :
The variation in the density of PBR/aluminium composites

Table 1
. This table shows that increase in 22 weight fraction of aluminium powder also increase the densities of PBR/aluminium composites formed with 23 corresponding decrease in voidage fraction.

Table 1 :
The variation in the density of PBR/aluminium composites

Table 1 :
The variation in the density of PBR/aluminium composites

Table 1 :
The variation in the density of PBR/aluminium composites

Table 1
. This table shows that increase in 22 weight fraction of aluminium powder also increase the densities of PBR/aluminium composites formed with 23 corresponding decrease in voidage fraction.

Table 1 :
The variation in the density of PBR/aluminium composites

Table 1 :
The variation in the density of PBR/aluminium composites