Papers by Keyword: Ethylene Vinyl Acetate

Abstract: Previous studies on the physical properties of each Polyethylene (PE) or Ethylene Vinyl Acetate (EVA) foam have been widely reported. The current challenge is how to understand the combination of PE and EVA foam in order to obtain appropriate properties in various applications. Therefore, an experimental breakthrough in order to understand the physical mechanism on the PE:EVA mixed foam in order to maintain many appropriate properties due to their applications was studied. The physical properties of a combination of PE and EVA foam with Azodicarbonamide (ADC) as blowing agent and the addition of Zinc Oxide (ZnO) as accelerated agent in foaming process have been investigated in this study. The foams were prepared via two steps. Firstly, the various content of PE and EVA resins with combination of various content of ZnO and the addition of ADC, stearic acids and antioxidants were mixed by a single screw extrusion as the results of pellets. Furthermore, this intermediate product was pressed by compression moulding at the temperature of 175 °C and pressure of 30 bar for 5 minutes, then the pressure was released for the foaming process. The effect of the addition of ZnO were observed on the density and the mechanical properties of the foams. The density decreased with increasing of ZnO content up to 4 per hundred resin (phr) on the foam with PE content maximum of 20 phr. Interestingly the density of the foam increased with the addition of 6 phr of ZnO. Due to the increasing number of ZnO, we found the formation of foams completely. We observed the approval of the hardness, tensile and compression properties of each formulation, respectively. Furthermore, the morphology observation of the foams was conducted by scanning electron microscopy (SEM) to measure the size and homogeneous of the cells. We observed large size of cells at low density of foams, meanwhile uniform of cell was obtained at the high density of foams. Finally, the Fourier transform infrared (FTIR) spectroscopy confirmed that in general the intensity of the absorption peak at around 2216 cm^-1 - 2223 cm^-1 of each formulation decreased with the addition of ZnO up to 4 phr of ZnO and increased again at 6 phr of ZnO.

Abstract: Thermal properties, i.e. melting point and decomposition temperature of polymers, azodicarbonamide (ADC), and other additives mixture, are the most important information to determine the appropriate foaming process parameters. ADC has been widely used as a blowing agent for foam fabrication. Here, ADC will decompose and release gas which will be trapped in the melting polymer to make a foamed product. Originally, ADC has a decomposition temperature at around 220°C. In this study, the effect of Zinc Oxide (ZnO) addition on the thermal properties of intermediate product and Polyethylene/Ethylene Vinyl Acetate (PE/EVA) foam with ADC as the blowing agent was investigated. ZnO addition decreased the decomposition temperature of ADC. The thermal properties were characterized by Differential Scanning Calorimetry (DSC). The result showed that the decomposition temperature of ADC significantly decreased from the temperature of 220°C to 170°C with the increment of the ZnO.

Abstract: In this study, a drop weight testing method was employed to investigate the impact bending behavior of ethylene vinyl acetate (EVA) modified engineered cementitious composite (ECC). The ECC with no EVA was selected as control, and the static and impact bending behavior was compared with the EVA modified ECC. The results showed that the compressive strength of EVA modified ECC decreased by 20%~30% in comparison with control ECC with fly ash substitution ratio variation. The addition of EVA can improve the bending toughness of ECC dramatically under static loading condition. As different from the static bending, the impact bending toughness of EVA modified ECC was smaller than that of control under impact loading condition. However, the degree of damage of EVA modified ECC was lower than control due to small crack width.

Abstract: Ethylene vinyl-acetate copolymer (EVA) composite materials containing multiwall carbon nanotubes (MWCNT), graphene (Gr) and iron (III, IV) oxide (Fe₃O₄) nanoparticles where processed by melt blending. Film specimens were prepared by using compression moulding method. All nanoparticles content in samples was chosen equal to 20 wt.%. The material dielectric spectroscopy was used in a range of 10^-2 Hz to 10⁷ Hz to investigate nanoparticle effect on the dielectric active (ε’) and passive components (ε’’), specific electrical conductivity (σ’) and dielectric loss (tg) for the characterization of the dissipation of electromagnetic energy.

Abstract: The extensive range of fillers used nowadays indicated the major significance of filler in the plastic industry. Although their original purpose was to lower the cost of the molding compounds; prime importance is now attached to selective modification of the properties of a specific plastic. In this study, the examples of LDPE/EVA blends, were put into 0, 3, 6, 9, 12 and 15 wt.% of EVA. The tensile strength, bending strength and impact strength of samples were determined according to ASTM D638, ISO 178 and ISO 179. Results showed that when increasing ratio of EVA in LDPE/ EVA blends, tensile strength decreased from 10.9 MPa to 8.6 MPa. Bending strength decreased linearly from 9.63 MPa to 5.46 MPa. Charpy impact strength decreased from 47.5 kJ/m² to 6.3 kJ/m². On the contrary, elongation in 100% LDPE is 78.3%; with the appearance of EVA, elongation of the LDPE/ EVA blends increased upto 109.1%. In addition, SEM micrographs indicated that, it was more crystal-clear when the EVA content is less; in the highest EVA content with 15%, it can be seen that the specimen after pressing is slightly opaque and darker than the orthers. From that showed the addition of EVA to the polymer leads the tensile strength, bending strength were not affect much, impact strength decreased but elongation experienced an increase.

Abstract: The effect of thermoforming on the tear strength of ethylene vinyl acetate (EVA) mouthguard material (Bioplast^®) has not been widely investigated. The present study compared the tear strengths of non-processed and processed EVA specimens in various thicknesses. Two groups of EVA sheet (non-processed and processed) in three different thicknesses of 3, 4 and 5 mm were used in specimen fabrication. The processed EVA sheets were achieved by forming the EVA sheet on the cylindrical stone model with the pressure-molding device (Biostar^®). Twelve of tear strength specimens of non-processed and processed group in each thickness were prepared following the modified ASTM D 624-00 guideline. The tear strength test was conducted using universal testing machine (Lloyd^® 1K series) with the speed of 500 mm/min. The mean thickness and tear strength of the non-processed and processed specimens in each thickness were compared using independent T-test. The differences in the mean tear strength for each thickness of non-processed and process specimens were determined using one-way ANOVA. The mean tear strength and mean thickness of processed EVA specimens was significantly lower than the non-processed EVA specimens for every thickness (P ≤ 0.05). There was no significant difference in the mean tear strength of EVA specimens among each thickness in both non-processed and processed groups. It can be concluded that the thermoforming process has the significant effect on the tear strength of the EVA mouthguard material formed by pressure molding device in every thicknesses. The tear strength of processed specimens were significant lower than the non-processed. Thus, it is more relevant for testing properties of the processed mouthguard material that the mouthguard material before processing.

Abstract: Carbon black and silica have been used as the main reinforcing fillers that increase the usefulness of rubbers. In this work the effect of carbon black (high abrasion furnace)/silica hybrid fillers on the mechanical properties, crosslink density and morphological behaviour of ethylene vinyl acetate (EVA) was investigated. EVA reinforced with 0/50, 10/40, 20/30, 30/20, 40/10 and 50/0 phr of carbon black (CB)/silica hybrid filler. The total hybrid filler is kept constant at 50 phr (parts per hundred rubbers) and six different compounds were prepared. EVA, CB and silica followed by compounding on a two roll mill and molding at 180°C and 20 megapascal (MPa) pressure. The mechanical properties such as tensile & tear strength, elongation at break and 100% modulus have been measured at 23°C on universal testing machine. Abrasion resistance, hardness and rebound resilience are studied using DIN abrader, Shore A durometer and vertical rebound resilience respectively. The tensile strength, modulus, tear strength, abrasion resistance, hardness and crosslink density increased with the CB filler content in hybrid filler, reached the maximum value at 50 phr of high abrasion furnace carbon black. Morphological properties of composites were evaluated by scanning electron microscopy analysis.

Abstract: This paper describes tensile properties, and morphology analysis of different composition of RHDPE and EVA blends were studied. The main goals are to describe the effect of Caprolactam as compatibilizer used to improve the compatibility between RHDPE and EVA. The RHDPE/EVA blends were prepared at 160°C and the rotor speed of 50rpm in an internal mixer. The tensile strength for RHDPE/EVA blends increased, while adding Caprolactam by 6phr in the blend formulation significantly improved the tensile properties. The SEM micrograph show a better interfacial adhesion between RHDPE and EVA phases for RHDEP/EVA/Caprolactam blends than RHDPE/EVA blends.

Abstract: This study was conducted in order to develop the new polymer nanocomposites. In this case, sepiolite was incorporated into Polyamide 6 (PA6) / Ethylene vinyl acetate (EVA) blend. The main aim of this research is to examine the effect of sepiolite concentration on the properties of PA6/EVA/sepiolite nanocomposite. The variations of sepiolite (2 – 10 phr) were added into PA6/EVA blend at the ratio of 80/20 wt%. The nanocomposites were prepared using twin screw extruder and injection moulding. Mechanical properties of PA6/EVA/sepiolite nanocomposite were analyzed by tensile testing and it was revealed that there is no change in stiffness and decrease in strength with more sepiolite content. Meanwhile, the morphology of materials was characterized by field emission scanning electron microscopy (FESEM). The morphology revealed that, the dispersion of sepiolite nanofiller seems to be good and the EVA domain size and distribution was effected by sepiolite content.

Abstract: In this study, ethylene vinyl acetate (EVA) was blended with Polylactic acid (PLA) in order to enhance the mechanical properties of PLA. PLA/EVA blend was melt blended in a twin screw extruder and compression molding with various EVA content (0-20% by weight) and the tensile and morphological properties were examined. The morphological behaviours play an important role in influencing the tensile properties of PLA. The smaller discrete EVA particle in PLA matrix had increased the properties of PLA compared with the one with elongated morphology.