18 TH INTERNATIONAL CONFERENCE ON COMPOSITE MATERIALS DEVELOPMENT OF BLENDING SEQUENCE ON CaCO 3 REINFORCED RECYCLED PET/RECYCLED PP BLEND S. Thumsorn 1 *, K. Yamada 2 Y.W. Leong 3 , H. Hamada 2 , 1 Faculty of Engineering, Rajamangala University of Technology Thanyaburi, Thailand 2 Department of Advanced Fibro-Science, Kyoto Institute of Technology, Japan 3 Institute of Materials Research and Engineering, Singapore * Corresponding author (nooh17@yahoo.com) Keywords : Recycled polymer, CaCO 3 , Blending sequence, compatibilizer, morphology 1 Introduction 2 Experimental 2.1 Materials Polyethylene terephthalate (PET) and polypropylene (PP) have been widely used in conventional and Polymers used in this work were RPET and RPP in engineering applications. One kind of the application the form of flakes, which supplied by Yasuda is drinking bottle and constitutes a large portion of Sangyo Co., Ltd., Japan. A finely ground post consumer wastes. The recycling of these commercial grade CaCO 3 (SOFTON 1200) with an materials could be the best way to solve the problem average particle size of 1.8 m was purchased from of land filling. Bihoku Funka Kogyo, Ltd., Japan. A Neoalkoxy Properties of polymer blend are affected by various zirconate (NZ12L) coupling agents was used as the factors such as composition of the blend, impurities, surfactant, which supplied by Kenrich degradation and especially compatibility between Petrochemicals, Inc., at contents of 1.0 wt% to the polymer blends. In the production of multi- weight of filler. A styrene-ethylene-butadiene- component blends, it is known that the blending styrene base compound was used as compatibilizer. sequence will have strong impact on the morphology The ratio of RPET/RPP blend was 95/5. The content and enhanced mechanical properties. Hence of CaCO 3 was fixed at 2.5 wt%. The amount of the properties of polymer blend can achieve by compatibilizer was varied at 0, 1, 3, 5 and 7 phr compatibility, suitable processing technologies and (parts per hundred resins by weight). blending sequence. 2.2 Sample Preparation Calcium carbonate (CaCO 3 ) is a type of mineral that is largely used as filler in plastics for cost reduction, RPET was dried at 120 C for 5 hours in enhance stiffness and induce toughening of filled dehumidifier before compounding. Two different polymer. The incorporation of CaCO 3 with mixing methods were used. The first is all compatibilized recycled PET (RPET) and its PP- compositions were mixed together at the set based cap (RPP) blends, obtain from post consumer conditions in a single screw extruder (one step waste PET bottles, are considered with the aim for mixing), which is referred as “blend_1”. The investigated the effectiveness of compatibilization of extruder barrel temperature was set at 260-285 C RPET/RPP/CaCO 3 blend as well as the mixing and screw speed at 50 rpm. The second is RPP was procedure which present key factors for improving melt mixed with CaCO 3 and coupling agent initially the performances and re-use of these recycle in twin screw extruder and pelletized then mixing materials. with RPET and compatibilizer in single screw This research studies the effect of melt blending extruder (two step mixing), which is referred as sequence on properties of recycled PET and recycled “blend_2”. The blends were dried at 80 C for 5 PP blend filled with CaCO 3 . Compatibilizer was hours in the oven before prepared dumbbell used for reducing interfacial energy between two specimens by injection molding machine (Po Yuen recycled polymers blend. Blending of RPET, RPP, UM50) at barrel temperature of 255-290 C and CaCO 3 and compatibizer was prepared by extrusion injection speed of 100 mm/s. process with two different of mixing sequences. Injection molding specimens were prepared for 2.3 Characterization investigating on morphological, mechanical and Morphology thermal properties of RPET/RPP/CaCO 3 blends.
DEVELOPMENT OF BLENDING SEQUENCE ON CaCO 3 REINFORCED RECYCLED RPET/RECYCLED PP BLEND Morphology of the blends was characterized from 0 phr 0 phr cryogenic fractured surface of the specimens by using a scanning electron microscope (JEOL, JSM5200). Gold coating was sputtered onto the specimens for electron conductivity. The image J program was used to measure the sizes of the 1 phr 1 phr disperse phase by the following equation: 4 area (1) Particlesi ze diameter ( d ) i N d 3 phr 3 phr i i (2) Number average diameter ( d ) n N i 4 N d i i (3) Volume average diameter ( d ) v 3 N d i i d 5 phr 5 phr (4) ( ) v Polydisper sity P d d n Where N i is number of particle, which having diameter d i . 7 phr 7 phr Mechanical properties Tensile test were performed by using an Instron 4206 universal testing machine according to standard ASTM D638. The gauge length was 115 (a) (b) mm at an extension rate of 10 mm/min. Fig.1. SEM photographs of (a) blend_1 (b) blend_2 Izod impact strength was determined for 2 mm- at various compatibilizer. deep notched specimens. The tests were conducted by using a Toyo Seiki Izod impact tester. 5.0 RPP disperse phase size ( m) Volume average diameter Thermal stability 4.0 blend_1 Thermal stability of the composites was blend_2 investigated by thermogravimetric analyzer 3.0 (TGA2950, TA Instruments) with Hi-Res mode at heating rate of 30 C/min from 30 C to 600 C 2.0 under air atmosphere. 3 1.0 Results and Discussion Fig.1. presents the effect of blending sequence and 0.0 compatibilizer on morphology of CaCO 3 filled 0 1 2 3 4 5 6 7 8 RPET/RPP blend at various content of Compatibilizer content (phr) compatibilizers. The results show RPP dispersed phase on RPET matrix. It can see that RPP dispersed Fig.2. Effect of blending sequence on RPP dispersed phase in compatibilized blends are smaller than phase size of CaCO 3 filled RPET/RPP blends. without compatibilizer. A reduction in RPP disperse revealed finer sizes and better dispersion of RPP phase sizes was evident with incorporation of disperse phase than blend_1. Fig.2. shows volume compatibilizer. A better dispersion and improved average diameters of RPP dispersed phase in the adhesion at the RPP-RPET interface was also noted. blends. These results revealed a reduction in The difference of RPP dispersed size should be disperse phase sizes when incorporated with considered due to the difference of interfacial compatibilizer, which the average RPP dispersed tension between RPET/RPP and compatibilizer. It phase sizes in blend_2 are smaller than blend_1. could be noted that in 2 steps mixing of blend_2
DEVELOPMENT OF BLENDING SEQUENCE ON CaCO 3 REINFORCED RECYCLED RPET/RECYCLED PP BLEND 5.0 2.2 blend_1 (a) blend_1 Tensile modulus (GPa) 2.0 blend_2 4.0 blend_2 Polydispersity 1.8 3.0 1.6 2.0 1.4 1.0 1.2 0.0 1.0 0 1 2 3 4 5 6 7 8 0 1 3 5 7 Compatibilizer content (phr) Compatibilizer content (phr) Fig.3. Effect of blending sequence on polydispersity of RPP dispersed phase size of CaCO 3 filled 70 RPET/RPP blends. blend_1 (b) Yield strength (MPa) 60 blend_2 Fig.3. presents polydispersity of RPP dispersed 50 phase in the blends. The polydispersity exhibits distribution of RPP dispersed phase in the blends. 40 The polydispersity of blend_2 is lower than blend_1, which indicated that RPP in blend_2 is narrower 30 distribution of RPP dispersed phase sizes and more homogeneity as compared to 1 step mixing than 20 blend_1 [1-2]. 10 0 1 3 5 7 Fig.4. (a) to (c) shows the effect of blending Compatibilizer content (phr) sequence on mechanical properties of CaCO 3 filled RPET/RPP blends. The addition of compatibilizer Notched impact strength (kJ/m 2 ) 5.0 revealed the reduction of tensile modulus and yield (c) blend_1 strength of the blends as presents in Fig.4 (a) and (b), respectively. These results were due to the low blend_2 4.0 stiffness and strength of the compatibilizer. However, the effect of blending sequence is no significant change in tensile modulus and yield strength of blend_1 and 3.0 blend_2. Fig.4. (c) shows notched impact strength of CaCO 3 filled RPET/RPP blends. The incorporation 2.0 of compatibilizer yields higher impact strength. This result was related to the size of RPP dispersed phase in the blends. It is interesting to note that blend_2 1.0 exhibits superior improvement in impact strength 0 1 3 5 7 than blend_1. The smaller dispersed phase size Compatibilizer content (phr) indicated good interfacial interaction between RPP and RPET, which enabled efficient transfer of energy especially during impact loading. Therefore, Fig.4. Effect of compatibilizer and blending premixing of RPP/CaCO 3 initially and later mixing sequence on (a) tensile modulus (b) yield strength with RPET and compatibilizer is the preferred and (c) impact properties of CaCO 3 filled blending sequence to maximize the impact strength. RPET/RPP blends. 3
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