UNIVERSITI TEKNIKAL MALAYSIA MELAKA
OPTIMIZATION OF MIXING PARAMETERS TO PRODUCE
PP/ENR BLEND VIA RESPONSE SURFACE METHODOLOGY
This report submitted in accordance with requirement of the Universiti Teknikal Malaysia Melaka (UTeM) for the Bachelor Degree of Manufacturing Engineering
(Engineering Material)
by
FAISAL FARIS BIN RAHIM
B050910134
870116565273
UNIVERSITI TEKNIKAL MALAYSIA MELAKA
BORANG PENGESAHAN STATUS LAPORAN PROJEK SARJANA MUDA
TAJUK: Optimization of mixing parameters to produce PP/ENR blend via response surface methodology.
SESI PENGAJIAN: 2011/12 Semester 2
Saya FAISAL FARIS BIN RAHIM
mengaku membenarkan Laporan PSM ini disimpan di Perpustakaan Universiti Teknikal Malaysia Melaka (UTeM) dengan syarat-syarat kegunaan seperti berikut:
1. Laporan PSM adalah hak milik Universiti Teknikal Malaysia Melaka dan penulis. 2. Perpustakaan Universiti Teknikal Malaysia Melaka dibenarkan membuat salinan
untuk tujuan pengajian sahaja dengan izin penulis.
3. Perpustakaan dibenarkan membuat salinan laporan PSM ini sebagai bahan pertukaran antara institusi pengajian tinggi. atau kepentingan Malaysia yang termaktub di dalam AKTA RAHSIA RASMI 1972)
(Mengandungi maklumat TERHAD yang telah ditentukan oleh organisasi/badan di mana penyelidikan dijalankan)
Alamat Tetap:
I hereby, declared this report entitled “Optimizing of mixing parameters to produce PP/ENR blend via response surface methodology” is the results of my own research except as cited in references.
Signature : ……….
Author’s Name : Faisal Faris Bin Rahim Date : 1st June 2012
This report is submitted to the Faculty of Manufacturing Engineering of Universiti Teknikal Malaysia Melaka (UTeM) as a partial fulfillment of the requirements for the degree of Bachelor of Manufacturing Engineering (Engineering Material). The member of the supervisory committee is as follow:
……… (Official Stamp of Principal Supervisor)
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ABSTRAK
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ABSTRACT
Thermoplastic elastomers have become important because they have combination properties of vulcanized rubbers and can be rapidly fabricated as thermoplastic. This research is an effort to explore the potential of polypropylene (PP) when incorporated with ENR. Polypropylene (PP) and epoxidized rubber (ENR) were prepared by melt blending with internal mixer and sulfur curing. Mixer parameter such as the ratio, mixing temperature, mixing time, and rotor speed were optimized with response surface methodology with the assistance of Design Expert 6.0.10
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ACKNOWLEDGEMENT
I would like to offer my unreserved gratitude and praises to Almighty Allah for His generous blessing and the undying strength bestowed upon me during the course of this research.
Special thanks to my supervisor, Dr. Noraiham Mohamad who guide, assist and advice me all the way through this project.
iv 2.1.2.3 Current Development of Thermoplastic Elastomer 12
2.2 Compounding Process 14
2.2.1 Melt Blending 15
2.2.1.1 Internal Mixer 15
2.2.1.2 Twin-Screw Extruder 16
2.2.1.3 Two Roll Mill 17
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2.2.2 Compressing Molding 19
2.3 Vulcanization/Curing Process 20
2.3.1 Sulfur Vulcanization 20
2.3.2 Peroxide Vulcanization 23
2.3.3 Mixed Vulcanization 24
2.5.3.1 Scanning Electron Microscopy (SEM) 31
2.5.4 Thermal Analysis 32
2.5.4.1 Differential Scanning Calorimetry 32
2.6 Optimization 32
2.6.1 Response Surface Methodology (SEM) 33
3. METHODOLOGY 38
3.1 Introduction 38
3.2 Raw Material 40
3.3 Characterization of Raw Material 40
3.3.1 Polypropylene 40
3.3.2 Epoxidized Natural Rubber 41
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3.4 Optimization of Internal Mixer Parameter using Response Surface
Methodology (RSM) 44
3.4.1 Design of Experiment 44
3.4.1.1 Screening Factor 44
3.5 Blending of PP/ENR Blends in Internal Mixer 46
3.6 Pelletizing 48
3.8.3.1 Scanning Electron Microscopy (SEM) 59
3.8.4 Thermal Analysis 60
3.8.4.1 Differential Scanning Calorimetry (DSC) 60
4. RESULT AND DISCUSSION 61
4.1 Introduction 61
4.2 Raw Material Characterization 62
4.2.1 Density 62
4.2.2 Melt Flow Index 62
4.3 Optimization of Physical and Mechanical Properties 63
4.3.1 Density Analysis 63
4.3.2 Hardness 70
4.3.3 Melt Flow Index 76
4.3.4 Impact Strength 82
4.3.5 Tensile Properties 89
4.3.5.1 Tensile Strength 90
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4.3.5.3 Young Modulus 101
4.4 Analysis 107
4.4.1 Scanning Electron Microscopy (SEM) 107
4.4.2 Differential Scanning Calorimetry (DSC) 110
4.5 Determination of the optimum formulation of PP/ENR using the Response Surface Methodology (RSM) 111
5. CONCLUSION AND RECOMMENDATION 114
5.1 Conclusion 114
5.2 Recommendation 115
REFERENCES 116
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LIST OF TABLES
Table 2.1: Basic recipe for the sulfur vulcanization system 21
Table 2.2: Sulfur vulcanization system 23
Table 2.3: Compounding formulation for ENR 23 Table 2.4: 23 Factorial Design Matrix Used for the Screening Factors 35
Table 2.5: Levels of Variables Chosen for Trial 36
Table 2.6: Full Factorial Central Composite Design for the Optimization
of Machine Parameters in the ENRAN Composite Preparation 36 Table 2.7: Levels of Variables Chosen for Trial in the
Optimization Experiments 36
Table 3.1 General properties of polypropylene 40
Table 3.2 Thermal properties of polypropylene 41
Table 3.3: Properties of sulfur 43
Table 3.4: Properties of zinc oxide 43
Table 3.5: Properties of stearic acid 44
Table 3.6: Combination of parameters internal mixer machine for 24 factorial
designs for screening factor 45
Table 3.7: Level of variables for the screening factor 45
Table 3.8: Composition of ENR vulcanization 46
Table 3.9: Design matrix of process parameter PP/ENR blends 47
Table 3.10: Level of variables 48
Table 3.11: The standard test conditions sample weight and
testing time for materials. 55
Table 4.1: Density Average of PP and ENR 62
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Calculated from the Models 68
Table 4.7: Hardness with Mixing Parameters and Ratios 70 Table 4.8: ANOVA for the Selected Factorial Models 72 Table 4.9: Observed Responses and Predicted Values 73 Table 4.10: Regression Coefficients and P Values as
Calculated from the Models 74
Table 4.11: Melt flow rate with Mixing Parameters and Ratios 77 Table 4.12: ANOVA for the Selected Factorial Models 79 Table 4.13: Observed Responses and Predicted Values 80 Table 4.14: Regression Coefficients and P Values as
Calculated from the Models 80
Table 4.15: Impact strength with Mixing Parameters and Ratios 83 Table 4.16: ANOVA for the Selected Factorial Models 85 Table 4.17: Observed Responses and Predicted Values 86 Table 4.18: Regression Coefficients and P Values as
Calculated from the Models 87
Table 4.19: Tensile strength with Mixing Parameters and Ratios 90 Table 4.20: ANOVA for the Selected Factorial Models 91 Table 4.21: Observed Responses and Predicted Values 92 Table 4.22: Regression Coefficients and P Values as
Calculated from the Models 92
Table 4.23: Elongation to break with Mixing Parameters and Ratios 96 Table 4.24: ANOVA for the Selected Factorial Models 98 Table 4.25: Observed Responses and Predicted Values 99 Table 4.26: Regression Coefficients and P Values as
Calculated from the Models 99
Table 4.27: Young Modulus with Mixing Parameters and Ratios 102 Table 4.28: ANOVA for the Selected Factorial Models 104 Table 4.29: Observed Responses and Predicted Values 105 Table 4.30: Regression Coefficients and P Values as
Calculated from the Models 105
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optimizing the formulation PP/ENR 111 Table 4.33: Optimum formulation with the processing characteristics and
properties generated for PP / ENR based on the degree of
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LIST OF FIGURES
Figure 2.1: Structure of Polypropylene 10
Figure 2.2: Structure of cis-Polyisoprene 11
Figure 2.3: Structure of Epoxidized Natural Rubber (ENR) 12 Figure 2.4: Schematic representation of the two-roll milling method 18 Figure 2.5: Schematic representation of the compressing molding 19 Figure 2.6: Schematic illustration of injection molding 20 Figure 2.7: The mechanism of peroxide vulcanization 24
Figure 2.8: Cold Compression Molding 25
Figure 2.9: Schematic illustration of how a tensile load produces an elongation
and positive linear strain 28
Figure 2.10: SEM micrographs of dynamically cured 60/40 ENR-30/PP
TPVs with sulphur system 31
Figure 3.1: Flow chart of the research project 39
Figure 3.2: Polypropylene 41
Figure 3.3: Epoxidized Natural Rubber 42
Figure 3.4: Stearic Acid (a), Zinc Oxide (b) and Sulfur (c) 43 Figure 3.5: ENR vulcanization; scale: 20cent Malaysia Diameter 23mm 46 Figure 3.6: HAAKE RHEOMIX OS internal mixer machine 48
Figure 3.7: PP/ENR using crusher machine 49
Figure 3.8: Crusher machine 49
Figure 3.9: Pellet compound is placed in the mold. 50 Figure 3.10: Gotech (GT 7014 – A) hot press machine 51 Figure 3.11: Gotech (GT 7016 –H) Specimen cutter machine 51
Figure 3.12: Electronic densimeter. 53
Figure 3.13: Melt Flow Indexer MH-525 equipment 54
Figure 3.14: Autograph AG-IC floor universal testing machine. 56 Figure 3.15: Dog bone type specimen size for ASTM D-638 Type 1 56
Figure 3.16: Shore D Durometer 57
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Figure 3.18: Zeiss EVO-50 ESEM machine 59
Figure 3.19: DSC Perkin Elmer DSC-7 60
Figure 4.1: Half Normal Plot for Density 65
Figure 4.2: Effects of the ENR and temperature on the density
of the PP/ENR blend 68
Figure 4.3: Density of all samples 69
Figure 4.4: Half Normal Plot for Hardness 71
Figure 4.5: Effects of the ENR and temperature on the hardness
of the PP/ENR blend 74
Figure 4.6: Hardness of all samples 75
Figure 4.7: Half Normal Plot for Melt Flow Rate 78
Figure 4.8: Effects of the ENR and temperature on the melt flow rate
of the PP/ENR blend 81
Figure 4.9: Melt flow rate of all samples 82
Figure 4.10: Half Normal Plot for Impact Strength 84 Figure 4.11: Effects of the ENR and temperature on the impact strength
of the PP/ENR blend 87
Figure 4.12: Impact strength of all samples 88
Figure 4.13: (a) Dogbone for PP, (b) Dogbone for PP/ENR 70/30 and
(c) PP/ENR 40/60 89
Figure 4.14: Half Normal Plot for Tensile Strength 91 Figure 4.15: Effects of the ENR and temperature on the tensile strength
of the PP/ENR blend 94
Figure 4.16: Tensile strength of all samples 94
Figure 4.17: Half Normal Plot for Elongation to Break 97 Figure 4.18: Effects of the ENR and temperature on the elongation to break
of the PP/ENR blend 100
Figure 4.19: Elongation to break of all samples 100 Figure 4.20: Half Normal Plot for Hardness 103 Figure 4.21: Effects of the ENR and temperature on the Young modulus
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Figure 4.22: Young modulus of all samples 106 Figure 4.23: (a) Scanning electron micrograph of unfilled PP at magnification
of 500x. (b) Scanning electron micrograph of PP/ENR 70/30 at magnification of 500x. (c) Scanning electron micrograph
of PP/ENR 40/60 at magnification of 500x. 108 Figure 4.24: (a) Scanning electron micrograph of unfilled PP at magnification
of 5000x. (b) Scanning electron micrograph of PP/ENR 70/30 at magnification of 5000x. (c) Scanning electron micrograph
of PP/ENR 40/60 at magnification of 5000x. 109 Figure 4.25: Fractional degrees of desire fulfilled the selection formula
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LIST OF ABBREVIATIONS
ASTM - American Standard Test Method ENR - epoxidized natural rubber DSC - differential scanning calorimetry FTIR - fourier transform infrared IR - synthetic isoprene rubber
BR - polybutadiene rubber
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LIST OF SYMBOLS
oC - Celsius
M/S - meter per second
% - percentage
kW - kilo watt
min - minute
kg - kilogram
mm - millimeter
μm - micrometer
s - second
nm - nanometer
g - gram
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1.1 Background
Polyolefins are the largest group of thermoplastics, the two most important and common types of polyolefins are polyethylene and polypropylene. They are very popular due to their low cost and wide range of applications. Polyolefins are usually processed by extrusion, injection molding, blow molding, and rotational molding methods.
Polyolefin elastomers (POEs) are a relatively new class of polymers that emerged with recent advances in metallocene polymerisation catalysts. Representing one of the fastest growing synthetic polymers, POE’s can be substituted for a number of generic polymers including ethylene propylene rubbers (EPR or EPDM), ethylene vinyl acetate (EVA), styrene-block copolymers (SBCs), and poly vinyl chloride (PVC). Polyolefin elastomers are compatible with most olefinic materials, are an excellent impact modifier for plastics, and offer unique performance capabilities for compounded products.
Thermoplastic elastomers based on natural rubber and thermoplastic blends are classified as thermoplastic natural rubber (TPNR) blends. There are two types of thermoplastic natural rubber. Blending of NR with thermoplastic (i.e., polyolefins) to get co-continuous phase morphology is technologically classified as thermoplastic polyolefin (TPO). The other class is known as thermoplastic vulcanizate (TPV), which is prepared by blending NR with polyolefins and involve vulcanization process. In type two, the rubber phase is vulcanized during the mixing process at
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high temperature, and the process is known as dynamic vulcanization. Dynamic vulcanization of epoxidized natural rubber (ENR) and polypropylene (PP) are also performed by using either a sulfur based system or peroxide. The sulfur cured system showed superior mechanical properties in term of tensile strength, elongation at break and tension set compared to the peroxide system due to the polypropylene degradation during dynamic vulcanization.
1.2 Problem Statement
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1.3 Objective
The main objectives on this research are:
i. To produce PP/ENR blend via melt blending using internal mixer.
ii. To determine the optimum formula and mixer parameter using response surface methodology
iii. To characterize the properties of PP/ENR blend through testing and analysis.
1.4 Scope
This research is focusing on optimization of formulation and mixer parameter to produce PP/ENR blend. Firstly, the experiment was designed using RSM. Then, samples were prepared in different combination of process parameters in an internal mixer followed by various physical and mechanical testing. Some analysis such as thermal and morphology were performed to support the data.
1.5 Chapter Overview
There are five chapters in this report;
i. Chapter 1 is the introduction of the research. That consists of research background, a problem statement, and objectives of the project, scope and chapter overview.
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iii. Chapter 3 is the methodology of this research, response surface methodology and it discuss the raw material specification, equipment and experimental procedures used in this study.
iv. Chapter 4 is the results and discussions of laboratory and field research work described in this study.
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2.1 Polymer Blends
Basic principles of polymer blends are either homogeneous or heterogeneous (He et al., 2004). In homogeneous blends, the final properties are often an arithmetic average of the properties of the blend components. In heterogeneous blends, the properties of all blend components are present. A deficiency in the properties of one component can be camouflaged to a certain extent by strengths of the others (He et al., 2004). Polymer blending is a convenient route for the development of new polymeric materials, able to yield materials with property profiles superior to those of the individual components (He et al., 2004). Blending of polymers is an effective way to obtain materials with specific properties. Most polymers are immiscible, therefore, blending usually leads to heterogeneous morphologies (Willemse et al., 1997). Most polymer pairs are immiscible, and therefore, their blends are not formed spontaneously. Moreover, the phase structure of polymer blends is not equilibrium and depends on the process of their preparation. Five different methods are used for the preparation of polymer blends are melt mixing, solution blending, latex mixing, partial block or graft copolymerization, and preparation of interpenetrating polymer networks (Anonymous, 2005).
Polymer blend constitute of 36 wt% of the total polymer consumption, and their pertinence continues to increase (Utracki, 2002). About 65% of polymer alloy and blend are produced by polymer manufacturer, 25% by compounding companies and the remaining 10% by the transformer (Utracki, 2002).
