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Effect of Filler Loading and Isophthalic Acid-Maleic Anhydride ( IAMA ) on Properties of Ethylene Vinyl Acetate / Natural Rubber / Potash Feldspar ( EVA / NR / PF ) Composites
| Content Provider | Semantic Scholar |
|---|---|
| Author | Huey, Ho Shuh |
| Copyright Year | 2014 |
| Abstract | The EVA/NR/PF composites with and without IAMA were prepared using Brabender Plasticoder at 160oC with 50rpm rotor speed. The effects of potash feldspar loading and isophathalic acidmaleic anhydride (IAMA) on the tensile properties and morphology analysis of EVA/NR/PF composites were studied. The results indicated that tensile strength for EVA/NR/PF and EVA/NR/PFIAMA composites decreased but M100 increased as the filler loading increased. EVA/NR/PFIAMA composites showed higher value of tensile strength and M100. Introduction Thermoplastic elastomer (TPE) is based on rubber and plastic blends. TPE has the physical properties of conventional elastomers at room and service temperatures, and excellent processing characteristics of thermoplastic materials at high temperature. TPE have economic advantages, good processability and reprocessable [1]. Ethylene vinyl acetate copolymer (EVA) is a random copolymer consists of ethylene and vinyl acetate (VA). The repeating units of EVA are ethylene and vinyl acetate. VA content will affect the properties of EVA such as crystallinity [2]. EVA is easily blended with LLDPE, heat sealability, and provides good processability during extrusion. Due to its excellent whiteness, low density, resistance of color change, low cost and easiness of injection molding, EVA is used widely [3]. Fillers can be classified into three ways: those that reinforce the polymer and improve its mechanical performance; those used to take-up-space and so reduce the amount of resin to produce a part (sometimes referred to extenders); those that dispersed through the polymer to improve its electric conductivity (less common) [4]. The examples of functional filler are carbon black, precipitated silica and calcined clay. Fillers are used due to cost reduction, improved processing, density control, optical effects, thermal conductivity and control of thermal expansion [5]. In this paper, this paper, the effect of potash feldspar loading and IAMA on tensile properties and morphology of ethylene vinyl acetate (EVA)/ natural rubber (NR)/ feldspar (PF) composites were investigated. Materials Ethylene vinyl acetate (EVA) contains 18.1 % VA content was obtained from The Polyolefin Company (Singapore) Pte.Ltd. The natural rubber (SMR-L) was purchased from Rubber Research Institute of Malaysia (RRIM). Potash Feldspar was obtained from Commercial Minerals (M) Sdn. Bhd., Penang, Malaysia. The chemical composition and physical properties of potash feldspar are given in Table 1. Maleic anhydride and isophthalic acid were supplied by Zarm Scientific & Supplier Sdn. Bhd. Penang, Malaysia. Table 1: Chemical and physical properties of potash feldspar Chemical Composition Value (%) SiO 67.0 Al2O3 19.0 CaO 0.11 Na2O 2.3 P2O5 0.18 SO3 0.028 K2O 11.0 Fe2O3 0.12 NiO 0.025 Rb2O 0.28 Ignition loss 0.2 Physical Properties Mean particle size (μm) 13.6 Surface area (m/g) 0.73 Density (g/m) 2.0 The compounding was carried out by melt blending in Brabender Plasticoder. Brabender Plasticorder was set at the temperature of 160 ̊C and rotor speed of 50 rpm. The EVA was loaded into the mixing chamber and preheated for 3 minute before the compounding process started. NR was added after the EVA was melted. The mixing was continued until a constant torque was obtained. Then, the potash feldspar with IA and MA were added. The total mixing time was 10 minutes. The soften blend was pressed into thick round pieces after removed from the chamber. The formulations of EVA/NR/PF composites and EVA/NR/PFIAMA composites are shown in Table 2. Table 2: Formulations of EVA/NR/PF composites and EVA/NR/PFIAMA composites with different filler loading Composite Code EVA/NR (phr) Potash Feldspar (phr) IA-MA (phr) EVA/NR 70/30 EVA/NR/FP-5 70/30 5 EVA/NR/FP -10 70/30 10 EVA/NR/FP -15 70/30 15 EVA/NR/FP -20 70/30 20 EVA/NR/FP -25 70/30 25 EVA/NR/FP-5IAMA 70/30 5 6 EVA/NR/FP-10IAMA 70/30 10 6 EVA/NR/FP-15IAMA 70/30 15 6 EVA/NR/FP-20IAMA 70/30 20 6 EVA/NR/FP-25IAMA 70/30 25 6 IA-MA was added 6 phr in the composites Result and Discussion Figure 1 shows the effect of filler loading on tensile strength of EVA/NR/PF and EVA/NR/PFIAMA composites. From Figure 1, it can be clearly seen that as the filler loading increases, the tensile strength decreases for both EVA/NR/PF and EVA/NR/PFIAMA composites. The causes were poor interaction and incompatibility of the matrixes. Besides, the dispersion of filler was poor. This can be proved by the SEM morphology which shown in Figure 3. Agglomeration of the filler and voids between the matrix and the filler which caused lower tensile strength can be seen in Figure 3(c) and 3(f). EVA/NR/PFIAMA composites showed higher tensile strength than EVA/NR/PF composites. A good interfacial adhesion and homogeneous dispersion have been observed in the feldsfar filled EVA/NR/PF composites which caused the increasing in tensile strength with the addition of IAMA. The–COOH groups from IAMA grafted onto the vinyl group of EVA and NR phases improved the compatibility and interfacial adhesion between the EVA and NR phases. It is proved by the SEM morphology which is shown in Figure 3 (d), (e) and (f). The composites were compatible in the presence of IAMA. El-Sabbagh [6] studied the compatibility study of natural rubber and ethylene-propylene diene rubber blends. The compatibility has been improved with the addition of compatibilizers. Besides, the rheological properties of the blends are improved. Figure 2 shows the effects of filler loading on modulus at 100% elongation (M100) of EVA/NR/PF composites and EVA/NR/PFIAMA composites. The M100 for both the EVA/NR/FP and EVA/NR/PFIAMA composites shows an increasing trend as the increasing of the filler loading. This was due to the addition of feldspar increases the stiffness of the composites. The increasing in the crosslink density and hydrogen bonding the composites caused M100 for EVA/NR/PFIAMA composites indicated higher value compared to EVA/NR/PF composites. Figure 1: Tensile strength vs filler loading of Figure 2: Modulus at 100% elongation vs filler EVA/NR/PF and EVA/NR/PFIAMA composites loading of EVA/NR/PF and EVA/NR/PFIAMA composites (a) EVA/NR/5PF (b) EVA/NR/10PF 0 2 4 6 8 5 10 15 20 25 Te n si le S tr e n gt h ( M P a) Filler Loading (phr) EVA/NR/PF EVA/NR/PF/IAMA |
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