AR T I C L E

Utilization of polyethylene terephthalate waste as a carbonfiller in polypropylene matrix: Investigation of mechanical,rheological, and thermal properties

Anesh Manjaly Poulose1 | Ahmed Yagoub Elnour2 | Nadavala Siva Kumar2 |

Abdullah Alhamidi2 | Justin George3 | Ebrahim H. Al-Ghurabi2 |

Mourad Boumaza2 | Saeed Al-Zahrani1

1Department of Chemical Engineering,Sabic Polymer Research Center, KingSaud University, Riyadh, Saudi Arabia2Department of Chemical Engineering,King Saud University, Riyadh, SaudiArabia3Centre for Advanced CompositeMaterials, The University of Auckland,Auckland, New Zealand

CorrespondenceAnesh Manjaly Poulose, Department ofChemical Engineering, Sabic PolymerResearch Center, King Saud University,P.O. Box 800, Riyadh 11421, Saudi Arabia.Email: apoulose@ksu.edu.sa

Funding informationKing Saud University, Grant/AwardNumber: RG-1441-539

Abstract

Polyethylene terephthalate (PET) waste was converted into carbon and the fea-

sibility of utilizing it as a reinforcing filler material in a polypropylene

(PP) matrix was investigated. The carbon produced by the pyrolysis of waste

PET at 900�C in nitrogen atmosphere contains high carbon content (>70 wt%).

PP/carbon composites were produced by melt blending process at varying

loading concentrations. Scanning electron microscopy images at the fractured

surface revealed that the carbon filler has better compatibility with the PP

matrix. The mechanical, thermal, and rheological properties and surface mor-

phology of the prepared composites were studied. The thermogravimetric anal-

ysis studies showed that the thermal stability of the PP/carbon composites was

enhanced from 300 to 370�C with 20 wt% of carbon. At lower angular fre-

quency (0.01 rad/s), the storage modulus (G0) of PP was 0.27 Pa and those of

PP with 10 and 20 wt% carbon was 4.06 and 7.25 Pa, respectively. Among the

PP/carbon composite prepared, PP with 5 wt% carbon showed the highest ten-

sile strength of 38 MPa, greater than that of neat PP (35 MPa). The tensile

modulus was enhanced from 0.9 to 1.2 GPa when the carbon content was

increased from 0 to 20 wt%.

KEYWORD S

composites, mechanical properties, microscopy, rheology, thermal properties

1 | INTRODUCTION

Environmental pollution is growing at an alarming rateowing to injudicious disposal of solid waste into land andwater, particularly in developing countries. The fastest-growing contributor to such pollution is the accumula-tion of nondegradable plastic waste. Plastic has becomean inevitable part of human life because of its low cost,lightweight, moldability, thermal, and chemical stability.

The most commonly used plastics, such as polyolefins,polyesters, polystyrene, and polyamides, are non-biodegradable and fragmented due to weathering intoparticulate plastics, contaminating the ocean, land andatmosphere. These micro and macrosized waste particlescan accumulate in living organisms and adversely affectthem.1 These plastic wastes are persistent environmentalpollutant and need to convert such plastic waste intovalue-added materials that are not harmful to the

Received: 10 August 2020 Revised: 3 November 2020 Accepted: 5 November 2020

DOI: 10.1002/app.50292

J Appl Polym Sci. 2020;e50292. wileyonlinelibrary.com/journal/app © 2020 Wiley Periodicals LLC 1 of 9

https://doi.org/10.1002/app.50292

ecosystem. In a recent study; the temperature, reactiontime, and catalyst amount was optimized for the produc-tion of oil from the pyrolysis of polystyrene waste,2–4

polypropylene (PP) waste5 and was found to be a greatpromise for replacing the fuel oil. The byproduct of pyrol-ysis of polymeric waste is gas, which can also be utilizedas a fuel.6 Apart from these, there are many methodsreported such as mechanical–chemical recycling,7

thermomechanical degradation,8 biological,9 and soforth. for the plastic waste disposal treatment. Thesemethods often require a special apparatus as well as cata-lysts for the conversion process.

Polyethylene terephthalate (PET) get much attentionowing to its broad range of applications in packaging,manufacturing bottles, fibers, and films; and as an engi-neering thermoplastic.10 PET bottles are the second-mostpopular type of consumer packaging in the global mar-ket, and its market share is expected to grow by 3.9% overthe coming years.11 Worldwide production of PET wasreported to be 41.56 million metric tons (MMT) in 2014and is estimated to reach 73.39 MMT by 2020. Owing tothe lack of proper waste management systems in manycountries, alarming amounts of solid waste are directedto landfills and incineration. According to a survey con-ducted in 2015, out of 6300 million tons (Mt) of plasticwaste, only 9% was recycled; 12% and 79% were inciner-ated and landfilled, respectively. If the current trendscontinue, by 2050, 12,000 Mt of waste plastic will pile upin landfills.12 The incineration of plastic waste releaseslarge amounts of toxic greenhouse gases such as CO2 andCO, which may accelerate global warming and climaticchanges.13–16 This motivated us to develop an efficientand ecofriendly method to recycle plastic waste or con-vert it into value-added products that would mitigate theaccumulation of waste and reduce the toxic gas emissionsto the environment. The recycling process is one of theeffective methods to control plastic waste accumula-tion.10,17,18 Among the different recycling methods, thechemical recycling process can break the polymers intotheir respective monomers via depolymerization. Thedecomposition of PET into its monomers in the presenceof reagents such as acids (acidolysis)19 or methanol(alcoholysis),20,21 or by glycols (glycolysis)22 is anestablished process. The starting monomers of PET canbe recovered and reused.23 Additionally, the polymerwaste has been converted into valuable products, such ascarbon nanotubes,24–26 polymer carbon dots withphotoluminescence,27,28 and plastic-derived oils.29

Numerous processes have been reported for the synthesisof carbon, such as arc discharge,30 chemical vapordeposition,25 and thermal oxidation to obtain graphiticcarbon.31 The easiest and sustainable method of utilizingPET waste is converting it into carbon via pyrolysis

process under an inert atmosphere. In contrast torecycling, the pyrolysis process can be considered as agreen technology, even though it generates gaseous prod-ucts that can be used for satisfying the energy needs forthe pyrolysis plant.14,32,33 Since pyrolysis is performed inan inert atmosphere, it produces less gaseous pollutantsthan incineration. Furthermore, the pyrolysis processdoes not require the sorting of polymers; hence, it is lesslabor-intensive than incineration. Hence, these pyrolysisprocess has many advantages such as ease of operationwith no pretreatment, cost-effective way to reduce envi-ronmental waste and is counted as an energy efficientprocess for the conversion of waste to carbon.33

The PET has more carbon in the molecular chain(above 60%), and its pyrolysis yields a higher amount ofcarbon as a residue.34 It is reported that the activated car-bon from waste PET finds application as an adsorbent innatural gas storage,35 CO2 capture,

36,37 and so forth. Thecarbon procured after pyrolysis has various characteris-tics, such as a large surface area, less functional groupsand low concentration of impurities than the carbon col-lected from biomass pyrolysis. Thus, PET waste is a suit-able precursor for the carbon production, which can beeffectively utilized as a filler material to enrich the ther-mal and mechanical characteristics of a polymer matrix.Accordingly, the main objective of this study was to uti-lize PET waste collected from a recycling firm in Riyadh,Saudi Arabia to produce carbon through pyrolysis undercontrolled atmospheric conditions. The carbon producedvia pyrolysis was characterized using various techniquesand its feasibility as a reinforcing filler material in a PPmatrix was investigated.

2 | EXPERIMENTS

2.1 | Materials and characterization

2.1.1 | Synthesis of carbon from PETwaste via pyrolysis

PET waste (raw material) was collected from the SaudiPlastic Factory Co. Riyadh, Saudi Arabia. The chopped(~10 mm) PET collected directly from the company wascleaned with distilled water to remove any dust and keptin an oven for drying at 110�C for 5–7 h. The PET wastewas pyrolyzed at 900�C with a heating ramp of 10�C/min. Using a tube furnace under an inert atmosphere fora residence time of 2 h. After the 2 h holding time, theheater was switched off allowed it to cool down by natu-ral convection. The carbon collected was weighed andground using a ball-milling apparatus (Fritsch Pul-verisette 7 model with zirconia ceramic balls) at 250 rpm

2 of 9 POULOSE ET AL.

for 6 h. The ground carbon collected from the ball millwas used directly without a sieving process.

2.1.2 | Scanning electron microscopy

Morphological and elemental analyses were performedwith the aid of scanning electron microscope (SEM)(JEOL JSM-6360A Japan, with energy-dispersive X-rayspectroscopy (EDS) facility. The gold coating for the sam-ples was done in JFC/1600 auto fine coater for 40s. Thesputter gold coating was conducted to avoid the chargingeffect leading to better image quality.

2.1.3 | Raman spectroscopy

The Raman spectrum of the carbon was examined usingan NRS-4500 Laser Raman spectrometer(1000–3000 cm−1). The excitation beam was tuned to awavelength of 532 nm. The measurement was carried outby the objective lens with 20× magnification. A 6 mWbeam power and an exposure time of 3 min. Were usedfor the experiment.

2.1.4 | Elemental analysis

An elemental examination (C, H, N, and O) was executedin PerkinElmer 2400 Series II CHNS/O machine(Norwalk) employing acetanilide standard. Roughly,3 mg of carbon was utilized for the analysis and the testwas performed twice.

2.1.5 | Brunauer–Emmett–Teller

The Brunauer–Emmett–Teller (BET) specific surface areaof the carbon was measured by obtaining nitrogenadsorption isotherms using a Tristar-II 3020(Micromeritics) instrument at −196�C. For the BET mea-surements, 0.2–0.3 g of the samples were taken and weresubjected to degassing at 200�C for about 3 h prior to thetesting.

2.1.6 | Preparation of PP/carboncomposites

The PP homopolymer (TASNEE PP H4120) was suppliedby TASNEE, Saudi Arabia. It had a melt flow index of12 g/10 min. (ISO 1133) and a density of 0.9 g/cm.3

Different formulations (2.5, 5, 7.5, 10, 12.5, 15, and 20 wt% wt/wt) of PP/carbon composites were prepared via themelt-mixing process in a micro Compounder (DSMXplore) at a temperature of 220�C with a screw rotationof 100 rpm. The mixing process was carried out for3 min. and after the stipulated blending time, thePP/carbon composites were subjected to microinjectionmolding (DSM Xplore 12 cm3, Netherlands). Dumb-bellshaped standard tensile testing specimen was preparedkeeping the mold at 35�C and 6 bar pressure. Tensile test-ing was done in UTM (Hounsfield H100 KS model) bythe ASTM D638 method. The average of four test resultswas plotted.

2.1.7 | Differential scanning calorimetry

Differential scanning calorimetry (DSC, Shimadzu DSC-60 model) was performed on the composites. The heatingand cooling program was set from 30 to 220�C, with aramp of 10�C/min. and 4 min. Holding time by taking6–10 mg sample in an aluminum pan.

2.1.8 | Thermogravimetric analysis

Thermogravimetric analysis (TGA) was performed usinga Shimadzu DTG-60H in the temperature span of30–600�C. 10 ± 1.5 mg of the sample was kept in an alu-minum pan where it is heated to 600�C (air atmosphere)with a ramp of 20�C and the weight loss was recorded.

2.1.9 | Fourier transform infraredspectroscopy

Attenuated total reflection-Fourier transform infraredspectroscopy (ATR-FTIR) test was performed in aThermo-Scientific Nicolet iN10 FTIR model with germa-nium microtip attachment (400–4000 cm−1).

2.1.10 | Rheology

The melt flow behavior of the prepared samples wasmonitored using TA instruments AR G2 model having aparallel-plate geometry (25 mm diameter). The sampleswere set at an experimental temperature of 190�C wherethe PP composites melt and the plates gap was retainedat 1000 μm for the measurements. The angular frequencysweep measurements were carried out from 0.01 to628.3 rad/s under oscillatory stress of 3.259 Pa.38

POULOSE ET AL. 3 of 9

3 | RESULTS AND DISCUSSION

3.1 | Scanning electron microscopy,elemental composition, and BET analysesof carbon collected from pyrolysis

SEM images of carbon before and after the ball-millingprocess are shown in Figure 1(a,b), respectively. The car-bon collected directly from the furnace was porous andlightweight, with a sheet-like structure, as shown inFigure 1(a). After the ball milling, the carbon particleshad an angular shape with a nonuniform size (<30 μm),as shown in Figure 1(b). According to the SEM-EDSresults, the carbon content was 77 wt% (Figure 2). TheEDS data matched the C, H, N, O analysis data shown inTable 1. The BET analysis shows that the average surfacearea of the carbon particles was 214.5 m2/g (Table 1). Itcan be observed, from Table 1, that the mass percentageof oxygen is relatively high. This is due to the fact thatthe PET repeating unit (C10H8O4) consist of 33.3 wt% ofoxygen, compared to 62.5 wt% of carbon content.

3.2 | Raman spectrum analysis of waste-derived carbon

Raman spectrum of carbon collected from the pyrolysis ofPET waste is shown in Figure 3. The spectrum exhibited Gand D bands with excitation in the visible region. The peakat 1593 cm−1 is due to the sp2 hybridized carbon which cor-responds to the G band. The G band is attributed to thebond stretching of sp2 carbon. The peak at 1341 cm−1

relates to the D band associated with the breathing mode ofthe aromatic ring.39 In the case of crystalline graphite, theG mode of vibrations appears at 1589 cm−1 and can beshifted to the higher or lower frequencies when thenanostructures are disordered. According to the position ofthe G band in the spectrum, the graphene stacking in thecarbon had a less strained geometry. The second prominent

band of the carbon was the D band at 1341 cm−1, which isdue to the lattice breathing mode. The D band is not pre-sent for a graphitic crystal and is very weak for graphenesheets but appears for disordered graphitic structures.40,41

The ratio of intensities of D and G band provide theamount of disorder in the carbon. The ID/IG is the ratio ofthe disordered to ordered carbon (disorder density). The ID/IG ratio of the PET waste carbon is ~0.88, which is lowerthan carbon produced at lower pyrolysis temperatures butsimilar to KOH activated graphene aerogel.41,42 Since theID/IG is low, the quantity of sp2 hybridized carbon in thePET waste carbon is high. The increase in the graphitic car-bon in the PET waste is due to the pyrolysis of waste at ele-vated temperature, which removes all volatile componentsand leaving behind porous carbon.41

3.3 | Thermal characterization of PP/carbon composites

The DSC results indicated that the PP homopolymer hada temperature of melting (Tm) at 166�C and

FIGURE 1 Scanning

electron microscopy images of

carbon (a) before and (b) after

ball-milling

FIGURE 2 Energy-dispersive X-ray spectroscopy point scan of

carbon collected from the pyrolysis of polyethylene terephthalate

waste [Color figure can be viewed at wileyonlinelibrary.com]

4 of 9 POULOSE ET AL.

crystallization temperature (Tc) of 121�C. The DSC analy-sis of the composites revealed that the incorporated car-bon, has no influence on the temperature of melting ofPP. This is due the fact that the PP has no chemical modi-fication due to carbon filler as the mixing process ispurely physical and the melting point of the studied com-posites remains the same as that of PP. However, thecrystallization temperature was found to increase withthe carbon addition; in other words; the incorporation ofcarbon shifted the crystallization temperature slightlytoward higher values. This is an indication of enhancednucleation efficiency due to the addition of the carbonfiller such nucleation efficiency is observed for othertypes of carbon-based fillers.43 On the other hand; theenthalpy of melting (ΔHm) for the PP-carbon compositesand this reduction is proportional to the carbon loadingpercentage, reaching its lowest value of (67 J/g) in PPfilled with 20 wt% compared (89 J/g) for neat PP, asshown in Table 2. This is due to the reduction in the PPweight percentage with increased loading of carbon.

The overall crystallinity (Xc) of the prepared sampleswas determined as follows:

Xc %ð Þ= ΔHm

1−Φð ÞΔHοm× 100 ð1Þ

where (Φ) represents the weight fraction of carbon in thecomposites, ΔHm represents the melting enthalpy, and

ΔH0m represents melting enthalpy of fully crystalline PP

(207 J/g).44

It can be seen from Table 2 that the overall crystallin-ity (Xc) of the PP-carbon composites is decreased whencompared to PP. When only 2.5 wt% of carbon is addedto PP, the overall crystallinity of the composite was foundto be reduced from 43 (for neat PP) to 35.8 (for 2.5 wt%).Although the incorporation of carbon into PP developedthe formation of a greater number of nuclei, as indicatedpreviously by the shifted crystallization temperature,however; the crystallization rate of the PP the crystalgrowth rate is decreased due to the restricted motion ofthe PP chain in the presence of the carbon particles. Thecarbon particles occupied the interstitial positions of thePP chains, which hindered the orderly packing of the PPchains and reduced the total crystallinity of thePP/carbon system.45

Figure 4(a,b) present the TGA and DTG results for PPand PP/carbon composites, respectively. The TGA results,Figure 4(a), reveals that the degradation process of neatthe PP and the PP/carbon composites occurs in a singlestep pattern and that thermal steadiness of the PP/carboncomposites is greater than that of neat PP as indicated bythe shift in the onset of degradation temperature towardhigher temperatures. This enhancement of PP thermalsteadiness is due to the higher thermal stability of thecarbon incorporated, which is produced at high tempera-tures with no volatiles to escape.46 When the carbon con-tent is raised from 0 to 20 wt%, the onset of degradationmoved gradually toward the higher temperatures andreaches its highest value, which is shifted by 70�C for PPmatrix filled with 20 wt% carbon. A similar trend of

TABLE 1 Elemental composition

of the sample and BET surface areaSample C (mass %) H (mass %) N (mass %) O (mass %) SSA (m2/g)

Carbon 72.0 0.60 0.2 27.2 214.5

Abbreviations: BET, Brunauer–Emmett–Teller; SSA, specific surface area.

FIGURE 3 Raman spectrum of carbon collected from the

pyrolysis of polyethylene terephthalate waste

TABLE 2 Differential scanning calorimetry results for the

polypropylene (PP)/carbon composites

Material Tc (�C) Tm (�C) ΔHm (J/g) Xc (%)

PP 120.97 165.78 89.00 43.00

PP-2.5C 121.30 166.72 74.20 35.85

PP-5C 122.14 166.24 71.77 34.67

PP-7.5C 122.80 166.00 70.50 34.06

PP-10C 123.10 165.93 68.89 33.28

PP-12.5C 123.00 166.10 67.60 32.66

PP-15C 123.39 166.67 66.89 32.31

PP-20C 123.70 166.50 67.17 32.45

POULOSE ET AL. 5 of 9

enhanced thermal stability has been observed in the liter-ature with other types of carbon-based fillers when addedto the PP matrix.47,48 According to the thermogram(Figure 4), while comparing the residual weight at theend of the curve, it can be noticed that the weight ofresiduals is directly proportional to loading percentage ofPET carbon into PP. The thermal stability of the polymercomposite was improved owing to the dissipation of ther-mal energy by the carbon, which prevented the accumu-lation of energy and the degradation of PP chains.49

3.4 | ATR-FTIR study of PP composites

Figure 5 shows the ATR-FTIR spectra of the PP andPP/carbon composites. The FTIR spectra of the PP andPP/carbon composites had peaks at the same frequencieswith the same intensities, indicating that the melt-blending was a purely physical process; that is, the car-bon filler was not chemically connected to the PP matrixand there was no possibility of a copolymerization reac-tion. The peaks at 2900, 1400, and 1350 cm−1 wereassigned to CH2 bending (asymmetrical), CH3 bending(symmetrical, and asymmetrical) in PP, respectively.50,51

3.5 | Rheological properties of PP/carbon composites

Figure 6 shows the storage moduli (G') of the PP andPP/carbon composites. For the PP/carbon composites,the storage modulus improved with the carbon contentbecause of the possible PP/carbon network formation.52

At lower angular frequency (0.01 rad/s), G0 of PP was0.27 Pa, and those of PP with 10 and 20 wt% carbon was

4.06 and 7.25 Pa, respectively. As shown in Figure 6, withthe highest carbon loading (20 wt%), there was a two-order of magnitude increment in the G' matched withpure PP. The storage modulus was higher than thatreported for PP/biochar composites53 and lower than thatreported for PP/carbon black composites.38,45 Theseresults denote that the interaction between the carbonfrom the PET waste and the PP matrix was better thanthat for biochar/PP composites.

Figure 7 shows the tan δ (G"/G') versus frequencydata for the studied composites. At low frequencies, thePP displayed liquid-like behavior, with G"> > G'. At

FIGURE 4 Thermogravimetric analysis (TGA) results in polypropylene (PP) and PP/carbon composites [Color figure can be viewed at

wileyonlinelibrary.com]

FIGURE 5 Attenuated total reflection-Fourier transform

infrared spectroscopy analysis results for the polypropylene

(PP) and PP/carbon composites [Color figure can be viewed at

wileyonlinelibrary.com]

6 of 9 POULOSE ET AL.

higher frequencies, it exhibited solid-like behavior andthe PP and PP/carbon composites had similar tan δvalues. With the increasing carbon content in the PPmatrix, the storage modulus was increased and the tan δvalues at lower frequencies became equal to those athigher frequencies. The carbon filler concentration atwhich the tan δ versus frequency slope becomes close to0 is the rheological threshold; this was not achieved forthe present system even with a carbon content of20 wt%.54,55

3.6 | Mechanical behavior of PP/carboncomposites

Figure 8 shows the dependence of the tensile strengthand tensile modulus (secondary axis) of the PP/carboncomposites on the loading percentage of carbon. Theincorporation of carbon improved the tensile strength ofthe PP/carbon composites competed with the PP sample.Among the samples prepared, the composite sample with5 wt% carbon loading exhibited the peak tensile strength(37.94 MPa), which was approximately 7.8% elevatedthan that of PP (35.2 MPa). Further increase in the car-bon content, slightly decreases the tensile strength of thecomposites due to the brittleness imparted by the carbon.The brittleness was indicated by SEM images of the ten-sile fracture surfaces, as shown in Figure 9(a–d). The ten-sile modulus of the PP/carbon composites increased withthe carbon content owing to the PP/carbon network for-mation, which restricted the movement of the PPchains.56 Although the addition of carbon increases thetensile properties with low concentrations, at high carbon

loading, the tensile strength has reduced. The maximumamount of carbon that can be added to the PP matrixwithout diminishing the tensile properties has notstudied.

Figure 10 shows the elongation percentage at thebreak and elongation percentage at yield for the PP andPP/carbon composites. The addition of carbon to the PPmatrix imparted a sudden decrease in the elongation atbreak related to PP. However, the elongation at the yieldof the PP/carbon composites decreased linearly with theincreasing carbon loading. The substantial reduction inthe composite ductility was due to the constrained move-ment of the PP chains in the presence of carbon particles.

FIGURE 6 Rheological analysis (storage modulus

vs. frequency) results for the polypropylene (PP) and PP/carbon

composites [Color figure can be viewed at wileyonlinelibrary.com]

FIGURE 7 Tan δ data for the polypropylene (PP) and

PP/carbon composites [Color figure can be viewed at

wileyonlinelibrary.com]

FIGURE 8 Tensile strength and tensile modulus (secondary

axis) of the polypropylene (PP)/carbon composites (carbon content

ranged from 0 to 20 wt%) [Color figure can be viewed at

wileyonlinelibrary.com]

POULOSE ET AL. 7 of 9

4 | CONCLUSION

The plastics are inevitable in daily life, and accordingly,the plastic waste will grow and need to find out sustain-able methods to convert such wastes into valuable prod-ucts. The researchers are in search of various methods to

convert such plastic waste into useful products. Thepyrolysis of waste plastic under controlled atmosphericconditions is economical and safe for the environment.

In this article, we demonstrated the feasibility of uti-lizing plastic waste-derived carbon as a reinforcing fillerin polymer composites. PET waste-derived carbon withhigh carbon content was produced and utilized as a fillermaterial in a PP matrix. ATR-FTIR characterization rev-ealed that the melt-blending process was purely physicaland Raman spectra indicated that the graphene stackingin the carbon led to a less strained geometry with disor-dered graphitic structures. The thermal stability, the ten-sile modulus and tensile strength of the resultantcomposites were further improved with a decrease inelongation at break. Future work can be oriented towardthe surface functionalization of collected carbon for bet-ter filler-matrix interaction and hence enhancement ofmechanical properties. The effect of carbon particle sizeand different pyrolysis temperatures on the properties ofcarbon and the composites can be done in future.

ACKNOWLEDGMENTSThe King Saud University authors extend their apprecia-tion to the Deanship of Scientific Research at King SaudUniversity for funding this work through research groupno (RG-1441-539).

FIGURE 9 Scanning

electron microscopy images of

the tensile fracture surfaces of

(a) polypropylene (PP)/2.5C,

(b) PP/5C, (c) PP/15C, and

(d) PP/20C

FIGURE 10 Elongation at yield and elongation at break

(secondary axis) of the polypropylene/carbon composites (carbon

content ranged from 0 to 20 wt%) [Color figure can be viewed at

wileyonlinelibrary.com]

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ORCIDAnesh Manjaly Poulose https://orcid.org/0000-0002-0508-865X

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How to cite this article: Poulose AM, Elnour AY,Kumar NS, et al. Utilization of polyethyleneterephthalate waste as a carbon filler inpolypropylene matrix: Investigation of mechanical,rheological, and thermal properties. J Appl PolymSci. 2020;e50292. https://doi.org/10.1002/app.50292

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