the influence of caco3 filler component on thermal decomposition process of pp/ldpe/dap ternary...

Research Article

512

Received: 22 February 2009, Revised: 13 April 2009, Accepted: 18 April 2009, Published online in Wiley InterScience: 17 May 2009

(www.interscience.wiley.com) DOI: 10.1002/pat.1461

The influence of CaCO3 filler component onthermal decomposition process of PP/LDPE/DAP ternary blend

Fatih Dogana*, Kamil Sirinb, Ismet Kayac and Mehmet Balcand

Polypropylene-low density polyethylene (PP-LDPE)

Polym. Adv

blends involving PP-LDPE (90/10wt%.) with (0.06wt%) dialkylperoxide (DAP) and different amounts (5, 10, 20wt%) of calcium carbonate (CaCO3) were prepared by melt-blendingwith a single-screw extruder. The effect of addition of CaCO3 on thermal decomposition process and kineticparameters, such as activation energy and pre-exponential factor of PP-LDPE blend with DAP matrix, was studied.The kinetics of the thermal degradation of composites was investigated by thermogravimetric analysis in dynamicnitrogen atmosphere at different heating rates. TG curves showed that the thermal decomposition of compositesoccurred in one weight-loss stage. The apparent activation energies of thermal decomposition for composites, asdetermined by the Tang method (TM), the Kissinger–Akahira–Sunose method (KAS), the Flynn–Wall–Ozawa method(FWO), and the Coats–Redfern (CR) method were 156.6, 156.0, 159.8, and 167.7 kJ.molS1 for the thermal decompo-sition of composite with 5wt% CaCO3, 191.5, 190.8, 193.1, and 196.8 kJ.molS1 for the thermal decompositionof composite with 10wt% CaCO3, and 206.3, 206.1, 207.5, and 203.8 kJmolS1 for the thermal decomposition ofcomposite with 20wt% CaCO3, respectively. The most likely decomposition process for weight-loss stages ofcomposites with CaCO3 content 5 and 10wt% was an An sigmoidal type. However, the most likely decompositionprocess for composite with CaCO3 content 20wt% was an Rn contracted geometry shape type in terms of the CR andmaster plots results. It was also found that the thermal stability, activation energy, and thermal decompositionprocess were changed with the increase in the CaCO3 filler weight in composite structure. Copyright � 2009 JohnWiley & Sons, Ltd.

Keywords: CaCO3; polypropylene; low density polyethylene; kinetic method; mechanism function

* Correspondence to: F. Dogan, Department of Secondary Science and Mathe-matics Education, Faculty of Education, Canakkale Onsekiz Mart University,17100, Canakkale, Turkey.E-mail: [email protected]

a F. Dogan

Department of Secondary Science and Mathematics Education, Faculty of

Education, Canakkale Onsekiz Mart University, 17100, Canakkale, Turkey

b K. Sirin

Department of Chemistry, Faculty of Science and Arts, Celal Bayar University,

45100, Manisa, Turkey

c I. Kaya

Department of Chemistry, Faculty of Science and Arts, Canakkale Onsekiz

Mart University, 17100, Canakkale, Turkey

d M. Balcan

Department of Chemistry, Faculty of Science, Ege University, 35100, Bornova,

Turkey

INTRODUCTION

Blends of polypropylene (PP) and polyethylene (PE) are amongthose binary systems, which have been attracting a lot ofattention.[1–5] PP has excellent and desirable physical, mechan-ical, and thermal properties when used in room-temperatureapplications. It is relatively stiff and has a high melting point, lowdensity, and relatively good resistance to impact.[6] PP has beenused in a wide range of applications in household goods,packaging, and automobiles. Low density polyethylene (LDPE)has a wide application in industry. Because of the suitableproperties, it can be processed easily and used in differentmaterials. Polyethylene has excellent chemical resistance and isnot affected by acids, bases, or salts.[7] The addition of peroxideto blends of polyolefin-rubber combinations has been used toimprove themechanical properties.[8] Some polyolefins are proneto chain-scission reactions in the presence of free radicals. PP isdegraded due to chain scission in b position to the macroradicalssite, whereas PE is cross-linked due to macroradical recombina-tion.[9] Calcium carbonate (CaCO3) is one of the most commonlyused inorganic fillers in thermoplastics. Importantly, the use ofcalcium carbonate allows the association of a rigid and resistantmaterial, which is cost efficient, with many polymers includingpolyolefines. It is one of the most commonly used inorganic fillersin PP. Many researchers have studied the toughening of PP withCaCO3.

[10–13] Heat sealing is the process by which two structurescontaining at least one thermoplastic layer are sealed by the

. Technol. 2010, 21 512–519 Copyright �

action of heat and pressure.[14] PP/LDPE blends were used toinvestigate and solve the heat sealing problems in theform-fill-seal (FFS) packaging systems. Heat sealing is one ofthe most important steps of the FFS packing method in theplastic package applications. It has critical importance forthe wholeness of the package and it has the ability to functionproperly. If heat sealing is applied well, the packaged product’squantity and freshness cannot be saved.[15] The focus of thisstudy is to understand the changes on thermal decomposition

2009 John Wiley & Sons, Ltd.

THE INFLUENCE OF CaCO3 COMPONENT ON PP/LDPE/DAP

mechanism and kinetic parameters of PP/LDPE/DAP (90/10/0.06wt%) ternary blend when 5–10–20wt% CaCO3 are added.Thermogravimetric analysis is used in order to investigate thekinetics of the thermal degradation of these composites. Theactivation energy of the thermal degradation of CaCO3 com-posite with N2 was obtained by the Tang method (TM), theKissinger–Akahira–Sunose method (KAS), the Flynn–Wall–Ozawamethod (FWO), and the Coats–Redfern (CR) method. Thermaldegradation mechanism for CaCO3 composite was investigatedby CR method, master plots method. On the other hand, theblend (PP/LDPE/DAP (90/10/0.06wt%) used in this study wasprepared in terms of heat sealing strength properties by theresults based on our previous work[16] and is optimum as well.[17]

EXPERIMENTAL

Materials

Isotactic polypropylene (PP-MH418) and low-density polyethy-lene (LDPE-I 22–19 T) were supplied as pellets by PetkimPetrochemical Company. The specific gravity of the PP-MH418is 0.905 g cm�3 and that of the LDPE-I 22–19 T is0.919–0.923 g cm�3, with melt flow index of 4–6 g, 10min�1

(2.16 kg, 230� 0.58C) and 21–25 g, 10min�1 (2.16 kg,190� 0.58C), respectively. 2, 5-dimethyl-2, 5-di (tert-butyl peroxy)-hexane (Sinochem, Tinajın/Chine) was used as a dialkly peroxide(DAP). Calcium carbonate filler (AS 0884 PEW) with 20 mmparticlesize was provided by Tosaf Company (Israel).

Preparation of blends

All compounds were prepared by using a single screw extruder(Collin E 30P). The blends were prepared by melting the mixedcomponents in extruder which was set at the extruder diameter:30mm, length to diameter ratio: 20, pressure: 9–10 bar,temperature scale from filing part to head were 190–2508Cand screw operation speed: 30 revmin�1. All compounds wereproduced as 70 mm thick and 10 cm wide films. Composites ratioand their codes are given in Table 1. PP/LDPE/CaCO3 compositeswere prepared with 0.06wt% peroxide. These composites werecalled PC-1, PC-2, and PC-3. All of these composites wereprepared as samples weighing 1000 g while keeping the 90/10PP-LDPE ratio constant.

Measurements

Thermal data were obtained by using Perkin Elmer Diamondthermal analysis. The TG-DTA measurements were made within15–5508C range, operating in dynamic mode, with the following

Table 1. Nomenclature, components, and composition ofcomposites

Composition wt%

Sample code PP LDPE CaCO3 DAP

PC-1 90 10 5 0.06PC-2 90 10 10 0.06PC-3 90 10 20 0.06

Polym. Adv. Technol. 2010, 21 512–519 Copyright � 2009 John

5

conditions: sample weight �5mg, heating rates 5, 10, 15, and208Cmin�1, atmosphere of nitrogen (10 cm3min�1), and sealedplatinum pan. All the experiments were performed twice forrepeatability and the results showed good reproducibility withsmall variations in the kinetic parameters.

Kinetics methods

The application of dynamic TG methods holds great promise as atool for unraveling the mechanisms of physical and chemicalprocesses that occur during polymer degradation. In this paper,integral isoconversional methods were used to analyze thenon-isothermal kinetics of all the composites PC-1, PC-2, andPC-3.The rate of solid-state non-isothermal decomposition reactions

is expressed as

da

dT¼ A

b

� �exp

�E

RT

� �f ðaÞ (1)

Rearranging eqn (1) and integrating both sides of the equationleads to the following expression:

gðaÞ ¼ A

b

� � ZT

T0

exp�E

RT

� �dT ¼ AE

b R

� �pðuÞ (2)

where pðuÞ ¼Ru1

� e�u

u2

� �du and u ¼ E=RT

Flynn–Wall–Ozawa method[18,19]

This method is derived from the integral method. The techniqueassumes that A, f(a), and E are independent of T, and A and E areindependent of a, then eqn (2) may be integrated to give thefollowing in logarithmic form:

log gðaÞ ¼ logAE

R

� �� log bþ log p

E

RT

� �(3)

Using Doyle’s approximation[20] for the integral which allows forE/RT> 20, eqn (3) now can be simplified as

log b ¼ logAE

R

� �� log gðaÞ � 2:315 � 0:4567

E

RT(4)

Coats–Redfern method[21]

Coats–Redfern method is also an integral method and it involvesthe thermal degradation mechanism. Using an asymptoticapproximation for the resolution of eqn (2), the followingequation can be obtained:

lngðaÞT2

� �¼ ln

AR

Eb1 � 2RT

E

� �� E

RT(5)

The expressions of g(a) for different mechanisms are listed inTable 2[22,23] and activation energy for degradation mechanismcan be obtained from the slope of a plot of ln [g(a)/T2] versus1000/T.

Tang method[24]

Taking the logarithms of both sides and using an approximationformula for resolution of eqn (2), the following equation can

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13

Table 2. Algebraic expression for the most frequently used mechanisms of solid state process

No Mechanisms Symbol Differential form, f(a) Integral form, g(a)

Sigmoidal curves1 N and G (n¼ 1) A1 (1�a) [�ln(1�a)]2 N and G (n¼ 1.5) A1.5 (3/2)(1�a)[� ln(1� a)]1/3 [� ln(1�a)]2/3

3 N and G (n¼ 2) A2 2(1�a)[� ln(1�a)]1/2 [� ln(1�a)]1/2

4 N and G (n¼ 3) A3 3(1�a)[�ln(1�a)]2/3 [�ln(1�a)]1/3

5 N and G (n¼ 4) A4 4(1�a)[� ln(1�a)]3/4 [� ln(1�a)]1/4

Deceleration curves6 Diffusion, 1D D1 1/(2 a) a2

7 Diffusion, 2D D2 1/(ln(1� a)) (1�a)ln(1�a)þa

8 Diffusion, 3D D3 1.5/[(1� a)�1/3 � 1] (1–2a/3)� (1�a)2/3

9 Diffusion, 3D D4 [1.5(1�a)2/3][1� (1�a)1/3]�1 [1�(1�a)1/3]2

10 Diffusion, 3D D5 (3/2)(1þa) 2/3[(1þa) 1/3� 1]�1 [(1þ a)1/3-1]2

11 Diffusion, 3D D6 (3/2)(1�a) 4/3[[1/(1�a) 1/3]� 1]�1 [[1/(1�a)]1/3� 1]2

12 Contracted geometry shape (cylindrical symmetry) R2 3(1�a)2/3 1� (1�a)1/3

13 Contracted geometry shape (sphere symmetry) R3 3(1�a)2/3 1� (1�a)1/3

Acceleration curves14 Mample power law P1 1 A15 Mample power law (n¼ 2) P2 2a1/2 a1/2

16 Mample power law (n¼ 3) P3 (1.5)a2/3 a1/3

17 Mample power law (n¼ 4) P4 4a3/4 a1/4

18 Mample power law (n¼ 2/3) P3/2 2/3(a)�1/2 a3/2

19 Mample power law (n¼ 3/2) P2/3 3/2(a)1/3 a2/3

20 Mample power law (n¼ 4/3) P3/4 4/3(a)�1/3 a3/4

F. DOGAN ET AL.

514

be obtained:

lnb

T1:894661

� �¼ ln

AE

Rg að Þ

� �þ 3:635041

� 1:894661 ln E � 1:001450E

RT

(6)

The plots of ln b

T1:894661

� �versus 1/T give a group of straight lines.

The activation energy E can be obtained from the slope�1.001450 E/R of the regression line.

Kissenger–Akahira–Sunose method[25]

This method is an integral isoconversional method, similar toFWO.

lnb

T2

� �¼ ln

AR

EgðaÞ

� �� E

RT(7)

The dependence of ln (b/T2) on 1/T is calculated for the same avalue at the different heating rates.

Determination of the kinetic model by master plots

Using a reference at point a¼ 0.5 and according to eqn (2), onegets

gðaÞ ¼ AE

bR

� �pðu0:5Þ (8)

where u0.5¼ E/RT. When eqn (2) is divided by eqn (8), thefollowing equation is obtained:

gðaÞgð0:5Þ ¼ pðuÞ

pðu0:5Þ(9)

www.interscience.wiley.com/journal/pat Copyright � 2009

Plots of g(a)/g(0.5) against a correspond to theoretical masterplots of various g(a) functions.[26,27] To draw the experimentalmaster plots of P(u)/P(u0.5) against a from experimental dataobtained under different heating rates, an approximateformula[28] of P(u) with high accuracy is used P(u)¼ exp(�u)/[u(1.00198882uþ 1.87391198)]. Equation (9) indicates that, for agiven a, the experimental value of g(a)/g(a0.5) is equivalent whenan appropriate kinetic model is used. Comparing the exper-imental master plots with theoretical plots, one can complete thekinetic model.[29]

RESULTS AND DISCUSSION

Thermal decomposition process

The thermal decomposition of composites was selected for thekinetic study. The activation energy of the decomposition processwas determined by multiple heating rate kinetics. The typicaldynamic TG thermograms of composites in a dynamic nitrogenatmosphere are shown in Figs 1–3 where the TG curves for thedecomposition of about 5mg composite samples were shownwith heating rates at 5, 10, 15, and 208Cmin�1 under 10mlmin�1

nitrogen gas. All TG curves of composites showed that thethermal decomposition took place mainly in one stage and thecurves shifted to the right-hand side with the heating rate. It wasalso shown that increase in the CaCO3 filler component incomposites increases the residue weight and thermal stability.For example, while the composite PC-1 at heating rate of58Cmin�1 decomposes at 3478C, the initial decomposition ofcomposite PC-3 begins from 3688C with the addition of CaCO3

under the same condition. Parallel results for other heating rateswere shown as well.

John Wiley & Sons, Ltd. Polym. Adv. Technol. 2010, 21 512–519

Figure 1. TG curves of PC-1 composite with CaCO3 content 5wt%.



Table 3. Activation energies obtained by Tang, KAS, and FWO me

Alpha

PC-1

Tang KAS FWO Tang

0.05 111.7 111.2 116.0 151.70.1 156.7 156.1 162.4 229.40.2 152.6 152.0 154.2 186.60.3 151.6 151.0 154.7 193.10.4 155.3 154.6 158.4 194.30.5 156.1 155.5 159.3 196.00.6 156.8 156.2 160.0 194.40.7 152.6 151.9 156.4 189.00.8 155.2 154.6 158.6 192.30.9 176.8 176.2 179.1 195.00.95 197.0 196.4 198.4 185.0Mean 156.6 156.0 159.8 191.5



Determination of activation energy Ea, kinetic model g(a),and pre-exponential factor A

Several techniques using different approaches have beendeveloped for solving the integral of eqn (2). The four methodsinvestigated in this work were those of FWO, KAS, Tang, and CRmethod. CR method was based on a single heating rate, whereasthe other methods were based on multiple heating rates.Isoconversional methods were initially employed to analyze theTG data of the composites, because they are independent of anythermodegradationmechanisms. Equation (6) was used to obtainthe activation energy, which can be calculated from the plot of ln(b/T1.894661) versus 1000/T fitting to a straight line. The meanvalues of the activation energies of the thermal decomposition ofcomposites PC-1, PC-2, and PC-3 in N2 were 156.6, 191.5, and206.3 kJ mol�1, respectively. The calculated results are summar-ized in Table 3.Another isoconversion method used in this paper was that of

KAS. Equation (7) was utilized to determine the values ofactivation energy from plots of ln(b/T2) against 1000/T over awide range of conversation. In this case a¼ 0.05, 0.1, 0.2, 0.3, 0.4,0.5, 0.6, 0.7, 0.8, 0.9, 0.95 were chosen to evaluate E values of allthe composites. The determined activation energies are listed inTable 3 and the average values for the thermal degradation ofcomposites were 156.0, 190.8, and 206.1 kJmol�1, respectively,over the range of a given. This result agrees with the mean valueof activation energy obtained by Tang method.FWO method is an integral method, which is also independent

of the degradation mechanism. Equation (4) has been used andthe apparent activation energy of composites can therefore beobtained from a plot of log b against 1000/T for a fixed degree ofconversion since the slope of such a line is given by �0.456E/T.Figure 4 for composite PC-1 illustrates the plots of log b versus1000/T at varying conversion. The activation energies calculatedfrom the slopes are tabulated in Table 3 and the mean values ofactivation energies were determined to be 159.8, 193.1, and207.5 kJmol�1. Comparatively, the obtained E values are veryclose to the values obtained by the previous two methods.Constant mass loss lines were determined by measuring the

temperature at a given mass % for each heating rate. In Fig. 4, theArrhenius type plots of dynamic TG runs related to the thermal

thods of the composites

PC-2 PC-3

KAS FWO Tang KAS FWO

151.1 154.2 254.5 253.9 252.0228.7 233.4 239.3 238.7 242.1185.2 186.1 207.0 208.2 207.3192.4 194.2 207.0 208.6 209.5193.6 195.5 207.0 208.2 209.4195.3 197.2 202.1 201.4 203.0193.7 195.7 204.4 203.8 205.2188.3 190.6 204.0 203.9 205.3191.6 193.9 206.0 203.9 205.3194.4 196.4 182.1 181.4 184.2184.3 187.1 156.1 155.4 159.7190.8 193.1 206.3 206.1 207.5


515

Table 4. Activation energies and pre-exponential factors for decomposition stage of PC-1 obtained by CRmethod in N2 atmosphere

58Cmin�1 108Cmin�1 158Cmin�1 208Cmin�1

E (kJmol�1) ln A E (kJmol�1) ln A E (kJmol�1) ln A E (kJmol�1) ln A

A1 257.5 42.47 286.0 47.22 301.9 47.72 293.5 49.83A1.5 167.7 26.83 186.0 30.19 197.2 30.80 191.6 32.14A2 122.9 18.89 136.6 21.67 144.9 22.24 140.6 23.20A3 78.06 10.86 87.14 12.96 92.66 15.86 89.72 14.07A4 55.62 6.717 62.41 8.498 66.51 9.117 64.24 9.485D1 352.1 57.67 395.7 64.91 419.7 66.04 411.7 68.46D2 396.8 64.99 443.5 72.64 470.2 73.66 460.4 76.54D3 416.7 67.06 464.8 74.87 492.7 75.80 481.8 78.91D4 458.1 74.43 508.9 82.60 539.1 83.32 526.8 86.92D5 316.4 48.98 356.8 55.77 378.5 56.88 371.3 59.03D6 606.4 100.7 666.5 110.1 704.6 109.9 683.6 115.3R2 208.1 5.338 232.4 5.448 246.6 5.484 240.8 5.507R3 223.2 5.408 248.5 5.515 263.5 5.549 257.0 5.574P1 170.2 5.137 191.9 5.257 203.9 5.297 199.7 5.317P2 79.28 4.372 90.08 4.500 95.97 4.541 93.79 4.564P3 48.96 10.79 56.12 4.027 59.99 4.068 58.46 4.094P4 33.80 3.520 39.14 3.667 42.01 3.708 40.80 3.737P3/2 261.1 5.565 29.85 5.683 311.8 5.722 305.7 5.742P2/3 109.5 4.696 124.0 4.820 131.9 4.860 129.1 4.882P3/4 124.7 4.826 141.0 4.948 149.9 4.988 146.7 5.010

F. DOGAN ET AL.

516

decomposition process are shown for masses ranging froma¼ 0.05 to 0.95 in N2. The values of correlation coefficients oflinearization curves related to thermal decomposition processesof composites PC-1, PC-2, and PC-3 were approximately 1.00. Thekinetic data obtained by differentmethods agree with each other.The thermal decomposition of composites in N2 presented

similar behavior for Tang, KAS, and FWO method. The initialactivation energy required for thermal decomposition process ofPC-3 was approximately 254 kJ ol�1, and this mean valueobtained by using the abovemethods is higher than that for PC-1and PC-2. The activation energy values for decomposition ofcomposites in the region of 0.2<a< 0.8 are very narrow (Fig. 5).In order to determine the mechanism of the thermal

decomposition of PC composites, the CR method has beenchosen as it involves the mechanisms of solid-state process.According to eqn (5), activation energy for every g(a) functionlisted in Table 2 can be calculated at constant heating rates from

Figure 4. FWO plots of composite PC-1 for decomposition stage at

varying conversation in N2.


fitting of ln(g(a)/T2) versus 1000/T plots. The activation energiesand the pre-exponential factors at constant heating rates such as5, 10, 15, and 208Cmin�1 were tabulated in Tables 4–6 for thermaldegradation of composites. According to Table 4, the E values ofcomposite PC-1 in N2, corresponding to mechanism A1.5, had bestagreement with the values obtained by Tang, KAS, and FWOmethods. Especially at the heating rate of 58Cmin�1, theactivation energy corresponding to mechanism A1.5 for thermaldecomposition process stage is 167.7 kJmol�1, which was veryclose to the values of 159.8 kJmol�1 obtained by FWO method.The correlation coefficient was also much higher than others.As seen in Table 5, the E values of composite PC-2 obtained by

FWOmethod are also in agreement with the value correspondingto mechanism A1 at the heating rate of 58Cmin�1. According toTable 6, the thermal degradation process of composite PC-3corresponds to the mechanism R3 and the activation energy is203.8 kJmol�1.

Figure 5. Activation energy (E) as a function of conversion degree forthe decomposition processes of composite PC-1, PC-2, and PC-3 calcu-

lated by Tang, KAS, and FWO methods.










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517

Figure 6. Master plots of theoretical g(a)/g (0,5) against a for variousreaction models (solid curves represent 20 kinds of reaction models given

in Table 2) and experimental data [(*), (~), and (^)] of composites at the

heating rates 5, 10, 15, and 208C min�1.

Table 7. Pre-exponential factors and correlation coefficients obta

b (K mol�1)

PC-1/A1.5

�[ln(1� a)]2/3

ln A (s�1) r ln A

5 26.013 0.998 3210 24.568 0.992 3115 25.567 0.996 3120 25.102 0.996 30mean 25.312 31

Correlation coefficient (r).

Figure 7. Plotting ln [bR/E]� ln[P(u)] against�ln[ln(1�a)]2/3 for PC-1 at

different heating rates.


F. DOGAN ET AL.

518

In order to confirm the conclusions, the experimental masterplots P(u)/P(u0,5) against a constructed from experimental data ofthe thermal degradation of composites under different heatingrates and the theoretical master plots of various kinetic functionsare all shown in Fig. 6. The comparison of the experimentalmaster plots with theoretical ones indicated that the kineticprocess of the thermal decomposition of the composites PC-1,PC-2, and PC-3 agreed with the mechanisms A1.5, A1, and R3master curves very well.By assuming A1.5, A1, and R3 laws, experimental data, the

expression of the An and Rn models, and the average reactionenergies were introduced into eqn (2), the following expressionwas obtained:

lnbR

E

� �� ln½PðuÞ� ¼ lnA � ln½lnð1 � aÞ�2=3 for PC � 1 (10)

lnbR

E

� �� ln½PðuÞ� ¼ lnA � ln½lnð1 � aÞ� for PC � 2 (11)

lnbR

E

� �� ln½PðuÞ� ¼ lnA� ln½1� ð1� aÞ�1=3 for PC� 3 (12)

A group of lines was obtained by plotting ln[bR/E]� ln[P(u)]against�ln[(1� a)]2/3 for PC-1. As shown in Fig. 7 and Table 7, thepre-exponential factors were calculated from the intercepts ofthe lines corresponding to various heating rates.

CONCLUSION

Polypropylene-low density polyethylene (PP-LDPE) blends with0.06wt% dialkylperoxide containing different amounts of CaCO3

filler were prepared by melt-blending with a single-screwextruder. The effect of CaCO3 filler component on thermalstability, thermal decomposition process, and kinetic parameters,such as activation energy, pre-exponential factor of preparedblends with dialkylperoxide matrix were investigated. Theactivation energies of the thermal degradation obtained by

ined by plotting ln[bR/E]� ln[P(u)] against kinetic functions

CompositePC-2/A1 PC-3/R3

Kinetic function, g(a)

�[ln(1� a)] �[[1� (1�a)]1/3]

(s�1) r ln A (s�1) r

.031 0.999 34.925 0.999

.578 0.998 34.292 0.990

.193 0.994 33.594 0.998

.737 0.992 33.946 0.986

.384 34.189



the Tang, KAS, FWO, and Coats-Redfern methods in N2 werefound to be 156.6, 156.0, 159.8, and 167.7 kJmol�1 for compositePC-1, 191.5, 190.8, 193.1, and 196.8 kJ mol�1 for composite PC-2,and 206.3, 206.1, 207.5, and 203.8 kJmol�1 for composite PC-3.The resulting logarithmic values of the pre-exponential factor ln A(s�1) obtained from master plots method were 25.312 for PC-1,31.318 for PC-2, and 34.189 for PC-3. Also, analysis of the resultsobtained by the Coats-Redfern method and master plots methodshows that the degradation mechanism of composites in N2 goesto An and Rn mechanism for all stages of the decomposition. Inconclusion, in terms of the Coats-Redfern method and masterplot results, the decomposition process shows different mech-anisms for blends with different CaCO3 content. With 5 and10wt% CaCO3, an An mechanism is observed while with 20wt%CaCO3, the mechanism is Rn.

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