Yamuna Munusamy

EthyleneVinyl Acetate/Natural Rubber/ Organoclay Nanocomposites: Effect of Sulfur and Peroxide Vulcanization:

Ethylene vinyl acetate (EVA)/natural rubber (SMR L)/organoclay thermoplastic elastomer nanocomposites were melt compounded in an internal mixer, Haake Rheometer, at 120°C at a rotor speed of 50 rpm. The thermoplastic elastomer nanocomposites were dynamically vulcanized using sulfur and peroxide systems. In this article we demonstrate the effect of different vulcanizing systems on the processing properties, tensile properties, crosslink density, morphology, thermal degradation and swelling behavior of the EVA/SMR L/organoclay nanocomposites vulcanizates. The peroxide system showed better enhancement in tensile properties and resistance towards swelling compared to the sulfur system. However, the thermal stability of sulfur vulcanizates was better than that for peroxide vulcanizates. Results also indicate that the presence of organoclay increases the crosslink density in sulfur vulcanizates, whereas in peroxide system, crosslink density was not influenced by the organoclay loading. The optimum organoclay loading for both vulcanizing systems were achieved at 2phr loading. Results from scanning electron microscope (SEM) and X-ray diffraction (XRD) studies showed that at 2 phr organoclay loading, nanostructures of individual silicate layers were achieved, whereas, at 8 phr organoclay loading, agglomeration was observed.

Tensile and Morphological Properties of Rice Husk Powder Filled Natural Rubber Latex Foam

Rice husk powder (RHP) is an agricultural by-product, and this research is carried out to incorporate RHP with natural rubber latex (NRL) compound and is foamed to make natural rubber latex foam (NRLF) using the Dunlop method. The tensile properties of modified NRLF is studied and compared with the controlled NRLF (zero RHP loading). The morphology and micro structural characterization has been performed by tabletop microscopy (TM1000). The tensile strength decreases at 2.5 pphr but increases again with increasing filler loading. Elongation at break decreases, whereas modulus at 100% elongation (M 100) and hardness increases with increasing filler loading.

Investigation on the influence of crosslink promoter on the irradiation crosslinking, dynamic mechanical property and thermal stability of ethylene vinyl acetate (EVA)/natural rubber (SMR L)/organoclay nanocomposites

Electron beam crosslinked EVA/SMR L/organoclay nanocomposites had been produced by using a crosslink promoter, TMPTA. The EVA to SMR L ratio was fixed at 50:50 and the organoclay loading used was 2 phr and 8 phr. When the nanocomposites were irradiated up to 200 kGy without TMPTA, the gel fraction was below 55%, but with addition of 3 phr TMPTA the gel fraction increased to 80%. Different level of irradiation dose also was found to form different phase morphology on the nanocomposites as shown in the SEM micrographs. Analysis on FT-IR spectrum proved that the addition of TMPTA improved the crosslinking and grafting, whereas incorporation of organoclay reduces oxidative degradation of the nanocomposites. DMA analysis showed that both storage modulus and glass transition values increased with addition of TMPTA at all irradiation doses. However, the improvement of thermal decomposition temperatures of nanocomposites with TMPTA were lower compared to non-irradiated nanocomposites.

Effect of organoclay loading on the crosslinking and degradation of irradiated ethylene(vinyl acetate) copolymer/natural rubber nanocomposites:

The effects of organoclay loading and electron beam irradiation on the crosslinking and degradation of ethylene(vinyl acetate) copolymer (EVA)/natural rubber, grade Standard Malaysian Natural Rubber (SMR L) nanocomposites was studied. The nanocomposites were prepared through the melt blending technique with the ratio of EVA: SMR L fixed at 50:50 and organoclay loading varied from 0 to10 phr. The samples were irradiated using a 3.0 MeV EB machine with doses ranging from 50 to 200 kGy. At irradiation dose 50–150 kGy organoclay reduces the crosslinking yield significantly as evidenced from the gel fraction results and thus, storage modulus decreases and tan deltamax values increases for the nanocomposites compared to neat EVA/SMR L. However, at 200 kGy the crosslinking yield was not much affected by the organoclay and thus, the storage modulus increased and tan deltamax decreased. Scanning electron micrograph images show that different level of irradiation dose form different phase morphology on the nanocomposites. Analysis on Fourier transform infrared spectrums and carbonyl index values proved that the nanoscale dispersion and barrier effect of organoclay influence the crosslinking and degradation of the nanocomposites thus gives a significant effect on the dynamic mechanical properties.

Effect of Preparation Methods on the Tensile, Morphology and Solar Energy Conversion Efficiency of RGO/PMMA Nanocomposites

In this study, reduced graphene oxide (RGO)/polymethyl methacrylate (PMMA) nanocomposites were prepared by employing in situ polymerization and solution blending methods. In terms of mechanical properties, RGO loading increased the Young’s modulus but decreased the elongation at break for RGO/PMMA nanocomposites. Tensile strength for solution blended RGO/PMMA nanocomposites increased after adding 0.5 wt % RGO, which was attributed to the good dispersion of RGO in the nanocomposites as evidenced from SEM and TEM. Solar energy conversion efficiency measurement results showed that the optimum concentration of RGO in the RGO/PMMA nanocomposites was found to be 1.0 wt % in order to achieve the maximum solar energy conversion efficiency of 25%. In the present study, the solution blended nanocomposites exhibited better overall properties than in situ polymerized nanocomposites owing to the better dispersion of RGO in solution blending. These findings would contribute to future work in search of higher conversion efficiency using nanocomposites.

Effects of chicken eggshell filler size on the processing, mechanical and thermal properties of PVC matrix composite

ABSTRACT The effects of filler particle size of poly(vinyl chloride)/chicken eggshell powder (PVC/ESP) composites on the processing, tensile properties, morphology and thermal degradation were investigated. The mixing of composites was done using Rheomix internal mixer. The processing torque of PVC/ESP composite at a particle of 0.2 μm exhibits lower processing torque compared to that at a particle size of 7 μm due to the dispersive resistance from larger ESP filler particles. Good interfacial adhesion exists between the filler and matrix in composites prepared via a filler particle size of 0.2 μm, which has improved the tensile strength and modulus of PVC/ESP composite compared to a filler particle size of 7 μm as justified from FESEM images on the tensile fracture surface of the composites. Thermogravimetric analysis results show that the filler particle size of 0.2 μm composite exhibits higher thermal stability compared to the filler particle size of 7 μm composite. GRAPHICAL ABSTRACT

Thermal Performance Study of Composite Phase Change Material with Polyacrylicand Conformal Coating

The composite PCM was prepared by blending polymethyl methacrylate (PMMA) and myristic acid (MA) in different weight percentages. The MA and PMMA were selected as PCM and supporting material, respectively. As liquid MA may leak out during the phase transition, this study proposes the use of two coatings, namely a polyacrylic coating and a conformal coating to overcome the leakage problem. Both coatings were studied in terms of the leakage test, chemical compatibility, thermal stability, morphology, and reliability. No leakage was found in the PCMs with coatings compared to those without under the same proportions of MA/PMMA, thus justifying the use of coatings in the present study. The chemically compatibility was confirmed by FTIR spectra: the functional groups of PCMs were in accordance with those of coatings. DSC showed that the coatings did not significantly change the melting and freezing temperatures, however, they improved the thermal stability of composite PCMs as seen in TGA analysis. Furthermore, the composite PCMs demonstrated good thermal reliability after 1000 times thermal cycling. The latent heat of melting reduced by only 0.16% and 1.02% for the PCMs coated with conformal coating and polyacrylic coating, respectively. Therefore, the proposed coatings can be considered in preparing fatty acid/PMMA blends attributed to the good stability, compatibility and leakage prevention.

Thermal performance study of form-stable composite phase change material with polyacrylic

Phase change material (PCM) is one of the most popular and widely used as thermal energy storage material because it is able to absorb and release a large amount of latent heat during a phase change process over a narrow temperature range. In this work, the form-stable composite PCM was prepared by blending of PMMA and myristic acid in different weight percentage. PMMA was used as a supporting material while myristic acid was used as PCM. Theoretically, PCM can be encapsulated in the support material after blending. However, a small amount of liquid PCMs can leak out from supporting material due to the volume change in phase change process. Therefore, a form-stable composite PCM with polyacrylic coating was studied. Leakage test was carried out to determine the leakage percentage of the form-stable composite PCM. Fourier transform infrared spectroscopy (FTIR) was used to characterize the chemical compatibility of the form-stable PCM composite while differential scanning calorimetry (DSC) was used to study...

CHAPTER 17:Clay Reinforcement in Natural Rubber Based Blends: Micro and Nano Length Scales

This chapter will discuss the preparation techniques used for developing natural rubber/vinyl plastic/organoclay composites. The effect of microscale and nanoscale dispersions of organoclay on the mechanical, thermal and crosslinking properties of these composites will be revealed. Effect of organoclay dispersion on irradiation crosslinking is also focused.