effect of filler on talc properties

8/12/2019 Effect of Filler on Talc Properties

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Effect of Talc Fillers Composition on the Properties of

Polypropylene/Talc Composite

Keywords: Polypropylene (PP), Talc, Mechanical properties, Thermal properties, PP/Talc

blends

Abstract

In the present study, the effect of talc content on the mechanical and thermal properties of the polypropylene was investigated. In the experimental study, five different talc concentrations,0, 5, 10, 15 and 20 wt%, were added to polypropylene composites. The mechanical properties

such as tensile strength, modulus elasticity, elongation at break and impact strength for notchtip radius of 1mm were investigated. The mechanical properties of PP/Talc blends does notimproved in terms of tensile strength, impact, modulus elasticity and elongation of break asthe strength decreased with the addition of the talc content increased. For FTIR, it is obviousthat the increased amount of talcum change the functional group of pure PP at certainwavelength. The DSC results for PP/Talc blends show that the degree of degradationincreased and according to TGA results thermal stability was enhanced with the addition oftalc.

1.0 Introduction

Blending has been widely and effectively used to modify or control the properties of polymer by appropriately compounding miscible polymers. Miscible polymer blends cancreate new materials with completely different properties, and fabricated articles may possessgood mechanical properties ( Bajsi et al., 2013). Polypropylene (PP) is well known as anattractive candidate for many engineering applications because of its excellent chemicalresistance, acceptable range of tensile strength and modulus, good impact strength and

processability and low price (Eroglu, 2007). However, the limitation of PP is its pooradhesion to the surface of other phases such as rubber or polar materials. This is primarily aresult of the nonpolar nature of PP. The incorporation of proper filler increase interfacialadhesion between matrix and disperse phase refines blends morphology and therefore leads to

an improvement of processing and application properties of the final material (Varga, 1992).

Various fillers such as graphite, talc and mica are the most often used ingredients thatare added to polypropylene in order to attain cost-effective mechanical properties. The fillertype, content and size, interfacial adhesion and bond strength between matrix and filler andsurface characteristics of the composite can greatly influence the filled system. In a highlyfilled polymer system, non-uniformity of properties can exists because of poor dispersion ofthe filler in the matrix. A good interfacial adhesion between matrix and filler may improvethe mechanical strength (Zhou et al., 2005).

Filled PP containing talc is used extensively because of a combination of stiffness,

dimensional stability, and, importantly, low cost. Talc is a phyllosilicate mineral with tri-octahedral layered structure Mg 3Si4O10(OH) 2 (Shabanat, 2011). The various mechanical


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properties of the final PP compound can be determined in function of the type of talc, talccomposition, particle size, treatment, and on the reinforcement percentage (filler) of the PP.Its foliated structure gives talc has a relatively high L/D or aspect ratio and when added to PPthis produces a greater increase in the rigidity of PP compared to the use of other mineralreinforcements. Talc tend to increase the heat deflection temperature (HDT) and hardness of

PP, but decrease its impact resistance or toughness. Consequently, the material becomes more brittle (Afroze et al., 2012).

Injection process is to ensure the proper development of a good plastic such as smoothfilling and cooling in the setting, in order to meet the requirements to produce quality

products. In the injection process, the most important parameters are temperature (melttemperature, nozzle temperature, mould temperature), pressure (plasticization pressure,injection pressure, cavity pressure ) and the corresponding role of the various time (injectiontime, cooling time) and so on.

Plastic processing temperature is controlled by injection machine barrel. The correct

choice of barrel temperature related to the plastic quality is to ensure a smooth plasticinjection moulding without causing local degradation. In the injection moulding process,mould temperature is the cooling medium control usually water, which used to determine thecooling rate of the plastic melt. The lower mould temperature, the faster the cooling. The melttemperature will decreases more quickly, resulting in melt viscosity injection pressure lossincreases, causing serious and even less filling (Yusoff et al., 2004).

Besides that, injection pressure also can affect the quality of the product produce.Injection pressure is generated in the screw head melt pressure. In the choice of injection

pressure, injection moulding machine should be considered first to allowed injection pressure. If injection pressure is too low only in the back leading to a low pressure cavity, themelt cannot be successfully filled cavity while in the other hand, injection pressure not onlywill result in excess product leakage, deformation will result in products, and even the systemoverload.

2.0 Experimental

2.1 Materials

Polypropylene in pellet and talc in the particle size of around 2 m was used as a fillermaterial.

The materials composition were blends manually to produce PP/Talc ternary composites asshown in Table 1.

Table 1: Compositions of blends used to produce PP/Talc ternary composites (wt %).

The specimens for testingwere prepared by injection

FORMULATION PP (wt%) TALC (wt%)

A0 100 0A1 95 5A2 90 10

A3 85 15

A4 80 20


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moulding at temperature range 180-190C in dog bone or dumb bell shape. The effect of talcon the PP were evaluated and characterized through the mechanical, chemical and thermal

properties such as the tensile strengths, Izod impact test, modulus of elasticity, elongation at break, Fourier transform infared (FT-IR) spectroscopy, Differential Scanning Calorimetry(DSC) and thermo gravimetric analysis (TGA). For mechanical test, the testing were carried

out 5 times and the average value is taken.

2.2 Characterization

Tensile strength: Tensile properties are the most common among various measurement ofmechanical properties. The dimension follow as written in standard ASTM D638. A dumb

bell shaped sample was clamped in the jaws of a testing machine and the required load toelongate the sample under constant rate is applied. The elongation was recorded.

Izod Impact Test: The impact test was done according to standard ASTM D256. In ASTMD256, the width and depth of the specimen will be taken into account. The width and depth

of the specimen used in this experiment is approximately 3.0 mm and 10.8 mm. Specimenwere clamped vertically as a cantilever beam. The pendulum hammer was released allowed tostrike the specimen and swing through. Impact strength were calculated by dividing impactvalues obtained from the scale by the area of the specimen.

Fourier transform infared (FT-IR) spectroscopy: For the analysis, the sample has to be pressed on the ATR-crystal which is the measurement interface. From the ATR-crystal, theIR radiation penetrates slightly few microns into the sample surface. The IR detector of theFT-IR spectrometer then measured the absorbance resulting from the sample.

Differential Scanning Calorimetry (DSC): The melting point of PP//Talc blends wasmeasured using a Mettler Toledo differential scanning calorimeter (DSC) using specimensweighing 5 mg. The DSC curve was obtained at a heating rate of 20 C/min and theexperiments were carried out in a N 2 atmosphere.

Thermo gravimetric analysis (TGA): The specimens were powdered and about 15 mg wasused for the analysis using a Mettler Toledo thermo gravimetric analysis (TGA) at a heatingrate of 20 C/min.

3.0 Result and Discussions

3.1 Tensile and impact properties

In the previous study, Eroglu, 2007, has reported that the addition of talc has a slightincrease on the yield and tensile strengths. However, from the Figure 1(a), in general, it isclearly seen that the addition of talc has decrease the tensile strengths from 5 to 20 wt %. Thiscan be related to the low possible crystallization of PP and poor adhesion between filler andmatrix. The tensile strengths of the thermoplastic matrix vary with filler used. It is wellknown that type of filler, distribution of filler and interaction between matrix and filler are themost important factor affecting the mechanical properties of binary (PP/filler). Non-homogenous distribution of filler and weak adhesion between matrix and filler causemechanical strength to decrease.


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29.723 28.363 27.29024.530

0

5

10

15

2025

30

35

0 5 10 15 20

A V E R A G E T E N S I L E

S T R E N G H T

( M P a )

TALC CONTENT (wt%)

TENSILE TEST

4.342

3.191

3.755

2.918

2.744

00.5

11.5

22.5

33.5

44.5

5

0 5 10 15 20 A V E R A G E S T R E N G H T ( k J / m

2 )

TALC CONTENT (wt%)

IMPACT TEST

Figure 1(a): Effect of various PP/talc composition on the tensile properties

The notch impact strength values are given in Figure 1(b). It becomes apparent thatthe impact resistance changed depending on the talc concentration. It can be seen from thefigure that impact strength of PP/Talc blends showed a slight decrease for up to 5 wt % talc,increase at 10 wt% and then a further decrease at higher filler contents. For 0 and 10 wt%contents of filler particles, the dispersed of talc on the PP is more uniformly distributed andthe effect is higher impact strength. According to Qiu et al ., 2013, for higher contents thedecrease in impact strength, may be related to the tendency to form filler agglomerates,resulting in a poor dispersion of the fillers on the PP.

Figure 1(b): Effect of various PP/talc composition on the impact properties


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21.373

18.483

18.462

14.25

0

5

10

15

20

25

0 5 10 15 20 E L O N G A T I O N A T B R E A K ( % )

TALC CONTENT (wt%)

3.380

4.060

2.818

3.250

0.0000.5001.0001.5002.0002.5003.0003.5004.0004.500

0 5 10 15 20 M O D U L U S O F E L A S T I C I T Y

( M p a

)

TALC CONTENT (wt%)

From Figure 1(c) below, in general, the effect of talc composition on the elongation at break from the obtained results are in good agreement with the literature reported by Eroglu,2007. As can be seen from the figure, elongation at break decreased with the increase in talccontent from 0 to 20 wt%. Addition of low talc significantly increase elongation at break,however higher talc contents caused elongation at break to decrease more slowly. According

Zhou et al., 2005, this decrease can be related to the fillers that restrict the mobility of thematrix and the result of the matrix reinforcement. The results indicate that talc particlesstiffen PP at the cost of some loss in ductility of the composites.

Figure 1(c): Effect of various PP/talc composition on the elongation at break properties

Figure 1(d) shows the effect of talc concentration on the elasticity modulus of PP/talccomposite. Based on the figure, elasticity modulus tends to increase for talc contents up to10wt %. Elasticity modulus show significant decrease for talc content between 15wt% andstarted to increase slightly at 20wt % talc. The highest elasticity modulus is at 4.06 Mpawhich is when the composite filled with 10wt% of talc. However, the results obtained are notcompatible with the results reported by Yousfi et al., 2013, as the highest elastic modulusshould be obtained in presence of highly composition of talc. The increase in elasticitymodulus is related to the rigid filler particles that restrict the mobility and deformability ofthe matrix. However, good talc distribution for lower contents is also thought the mosteffective factor on higher elasticity modules.

Figure 1(d): Effect of various PP/talc composition on the modulus of elasticity properties


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3.2 FTIR analysis

Talcum from a chemical point of view is the powdered form of the silicate mineraltalc with the sum formula Mg 3Si4O10(OH) 2. It is mixed with polymers in order to optimizetheir properties like for instance elasticity, impact resistance or colour fastness. Talcum can

be easily identified by using FT-IR spectroscopy. The result of the measurement of fourdifferent polypropylene (PP) samples with different talc contents can be seen in Figure 2. Theupper spectrum is pure PP and pure talc; the spectra below have increasing talcum content upto 20 %. The most prominent features are broad bands around 1000 cm -1 and 670 cm -1 thatresult from the Si-O stretching modes. It is obvious that the amount of talcum directly relatesto the intensity of the named bands, a fact that can be used for a quantitative analysis (Bruker,2010).

Figure 2: Spectra of polypropylene with varying talcum content; 0-20%

4000.0 3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800 600 515.0

78.0

79

80

81

82

83

84

85

86

87

88

89

90

91

92

93

94

95

96

96.9

cm-1

%T

2949.93

2916.76

2837.58

1456.71

1376.06

1015.81

671.11

400 0.0 3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800 600 515.0

20.0

25

30

35

40

45

50

55

60

65

70

75

80

85

90

95.9

cm-1

%T

3676.14

1452.64

1004.14

884.60

748.71

668.91

4000.0 3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800 600 515.0

77.0

78

79

80

81

82

83

84

85

86

87

88

89

90

91

92

93

94

95

96

97

98

99

99.7

cm-1

%T

2950. 11

2916.97

2837.681456.38

1375.96

1166.57

1016.98

973.30

840.69

669.30

4000.0 3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800 600 515.0

73.0

74

75

76

77

78

79

80

81

82

83

84

85

86

87

88

89

90

91

92

93

94

95

96

97

98

99.0

cm-1

%T

3676.07

2950. 06

2917.13

2837.56

1738.36

1455.93

1375.94

1217.26

1015.11

670.03

4000.0 3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800 600 515.0

57.0

58

60

62

64

66

68

70

72

74

76

78

80

82

84

86

88

90

92

94

96

9898.8

cm-1

%T

3675.84

2950. 43

2917.79

2837.60

1454.83

1376.15

1012.76

669.44

4000.0 3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800 600 515.0

64.0

66

68

70

72

74

76

78

80

82

84

86

88

90

92

94

96

98

98.9

cm-1

%T

3676.34

2950. 54

2917.38

2868.012837.53

1455.45

1376.09

1166.19

1015.88

973.44

841.04

669.54534.50

a) Pure PP

e Talc 15 wt%

d) Talc 10 wt%

c Talc 5 wt%

b) Pure talc

f) Talc 20 wt%

1 0 0 0 c

- 1

6 7 0 c m - 1


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dsc group 3 CHE 659_Sample 3, 01.04.2014 10:55:35dsc group 3 CHE 659_Sample 3, 6.0000 mg

dsc group 4 CHE 659_Sample 4, 01.04.2014 11:28:18dsc group 4 CHE 659_Sample 4, 5.8000 mg

dsc CHE 659_PP, 01.04.2014 12:01:38dsc CHE 659_PP, 4.5000 mg

dsc CHE 659_talc , 01.04.2014 12:35:13dsc CHE 659_talc , 6.2000 mg

dsc CHE 659_gp 1 new, 01.04.2014 13:08:49dsc CHE 659_gp 1 new, 5.5000 mg

dsc CHE 659_gp 2 new, 01.04.2014 13:42:25dsc CHE 659_gp 2 new, 7.4000 mg

mW

-70

-60

-50

-40

-30

-20

-10

0

10

20

min

C50 100 150 200 250 300 350 400 450

0 2 4 6 8 10 12 14 16 18 20 22

^ e x o

S T A R e S W 9 3 0

L a b : M E T T L E R

3.3 Differential Scanning Calorimetry (DSC) analysis

It can be observed from Figure 3 that the melting temperatures (T m) of the polypropylene have only a slightly change with the addition of talc from 0 to 20wt% which isat range 160-170C. T m is the point at which the polymer molecules have gained enoughvibrational freedom to break free from the solid binding forces and form a liquid. Meanwhilethe PP/Talc blends with the addition of talc exhibited a much greater exothermic degradation

peak. The peak temperature of the degradation (T d), was increased as the weight of the talcfilled increased. The measurements showed that the degradation temperature of the pure

polypropylene is 454.36C. The addition of filler concentration increases the degradationtemperatures of blends up to about 476.63C at 20wt% of talc filled. The higher values of the

blends degrade temperature for addition of talc filled is due to the improved interface between polymers and filler and that prevents the molecular mobility of segments of the blend (Bajsiet al., 2013).

Figure 3: DSC T m (a) and T d (b) with varying talcum content; 0-20%

3.4 Thermo gravimetric analysis (TGA) analysis

In order to determine the thermal stability of the polymers as talc weight increased inthe PP/Talc blends, thermogravimetric analysis (TGA) was used. From Figure 4, the graphshown that the polypropylene with less talc degrade faster and the greater talc weight degradelater. The PP/Talc blends with 5wt% talc filled start degrade at 475.93C meanwhile for20wt% filled talc, the PP/Talc blends degrade at 481.57C (Appendix). According to TGAresults, the addition of talc enhanced thermal stability and the homogeneity of the talc filledin PP/Talc blends is better as the weight of talc increased (Bajsi et al., 2013). According toQiu et al., 2103, the high barrier of talc filled layer will retard the active molecules totransmit among the layers or retard the degradation products to release and then improve thethermal stability.


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tga group 2_Sample 1, 01.04.2014 10:14:47tga group 2_Sample 1, 18.7000 mg

tga CHE 659 group 1_Sample 2, 01.04.2014 11:14:53tga CHE 659 group 1_Sample 2, 18.6000 mg



mg

0

5

10

15

min0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32

\tga group 2_Sample 1tga group 2_Sample 1, 18.7000 mg

\tga CHE 659 group 1_Sample 2

tga CHE 659 group 1_Sample 2, 18.6000 mg

\tga CHE 659 group 3_Sample 3tga CHE 659 group 3_Sample 3, 15.8000 mg

\tga CHE 659 group 4_Sample 4tga CHE 659 group 4_Sample 4, 14.6000 mg

mgmin -1

-10

-5

min0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32

S T A R e SW 9 30

L a b : M E T T L E R

Figure 4: TGA with varying talcum content; 0-20%

4.0 Conclusion

The objective of this experiment was to study the effect of talc content on the mechanical andthermal properties of the polypropylene. From the mechanical properties of PP/Talc blendsdoes not improved in terms of tensile strength, impact and elongation of break as the strengthdecreased with the addition of the talc content increased. The addition of talc has decrease thetensile strengths and elongation at break from 5 to 20 wt %. In the other hand, impactstrength of PP/Talc blends showed a slight decrease for up to 5 wt % talc, increase at 10 wt%and then a further decrease at higher filler contents. For elasticity modulus, the value tends toincrease for talc contents up to 10wt %. Elasticity modulus show significant decrease for talccontent between 15wt% and started to increase slightly at 20wt % talc. The mechanicalstrength between PP/Talc blends decreased as talc filled increased is due to the poorinterfacial adhesion and bond strength between matrix and filler. The surface characteristicsof the composite can greatly influence the filled system. . For FTIR, it is obvious that theincreased amount of talcum change the functional group of pure PP at certain wavelength.The most prominent features are broad bands around 1000 cm -1 and 670 cm -1 that result fromthe Si-O stretching modes. The DSC results for PP/Talc blends show that the degree ofdegradation increased up to 476.63C at 20wt% of talc filled from 454.36C due to theimproved interface between polymers and filler. According to TGA results thermal stabilitywas enhanced as the temperature for the composite to degrade increased from 443.34C at 5wt% filled talc to 452.24C at 20wt% filled talc.


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5.0 Acknowledgement

Thanks to God for giving me the strength and help that finally I manage toaccomplish the technical paper completely. First and foremost, I would like to thanks thelecturer, Pn. Suffiyana Binti Akhbar and members that involve in this project. Thanks for thetime and guiding me through this project from beginning until the end. Finally, I would liketo take this opportunity to thank my family member and all my friends, I would thank youenough for your love and prayers and supporting me throughout my studies.

6.0 References

Afroze S. et al., 2012, Physical, Optical and Thermal Properties of Graphite and Talc FillerReinforced Polypropylene (PP) Composites, Journal of Advanced Scientific and TechnicalResearch, vol. 5, pp. 40-49.

Bajsi E. G., Rek V. and osi, I., 2013, Preparation and Characterization of Talc FilledThermoplastic Polyurethane/Polypropylene Blends, Journal of Polymers, vol. 2014.

Bruker, 2013, IR -Spectroscopic Analysis of Polymer Fillers and Compatibilizers, Retrievedon 18 th April 2014 from http://www.bruker.com/fileadmin/user_upload/8-PDF-Docs/OpticalSpectrospcopy/FT-IR/ALPHA/AN/AN104_Polymer_filler_EN.pdf

Eroglu M., 2007, Effect of Talc and Heat Treatment on the Properties ofPolypropylene/EVA Composite, Journal of Materials Science and Technology, vol. 2, pp.67-73.

Shabanat M., 2011, Study of the Effect of Weathering in Natural Environment onPolypro pylene and Its Composites: Morphological and Mechanical Properties, Journal ofChemistry, vol. 3, pp. 129-132.

Varga J., 1992, Supermolecular structure of isotactic polypropylene , Journal of MaterialsScience, vol. 27, pp. 2557 2579.

Yousfi M., et al., 2013, Use of New Synthetic Talc as Reinforcing Nanofillers forPolypropylene and Polyamide 6 Systems: Thermal and Mechanical Properties , Journal ofColloid and Interface Science, vol. 403, pp. 23-49.

Yusoff S., et al ., 2004, A Plastic Injection Molding Process Characterisation UsingExperimental Design Technique: A Case Study, Journal of Technology, vol. 41, pp. 1-16.

Zhou Y. et al., 2005, Experimental Study on Thermal and Mechanical Behaviour ofPolypropylene, Talc/Polypropylene and Polypropylene/Clay Nanocomposites , Journal ofMaterials Science and Engineering, vol. 402, pp. 109-117.
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effect of filler on talc properties

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