Browsing by Author "Edirisinghe, DG"

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item: Article-Abstract
A Novel Reclaiming Agent for Ground Rubber Tyre (GRT). Part 1: Property Evaluation of Virgin Natural Rubber (NR)/Novel Reclaimed GRT Blend Compounds
Premachandra, BAJK; Edirisinghe, DG; De Silva, MIA
Use of reclaimed rubber as a component of a blend with virgin rubber or as a replacement for the virgin material in most rubber applications, especially in tyre components, has increased in the recent past. This is due to the increase in prices of natural and synthetic rubbers and growing concern about environmental issues. This research is aimed at evaluating the properties of rubber compounds produced by blending virgin natural rubber (NR) with ground rubber tyre (GRT), which was modified using a readily available, environmentally friendly, low-cost amino compound. Initially, reclaiming of 40 mesh GRT in the presence of rubber processing oil was studied at four different concentrations of the amino compound and two milling time periods. Mechanochemical reclaiming/devulcanisation was performed at a temperature of 30–70°C, using a laboratory two-roll mill. Properties such as initial plasticity, swelling ratio, crosslink density, and molecular weight between two crosslinks (Mc) of the reclaimed rubber samples were evaluated. Rubber compounds were prepared in the second stage by blending the reclaimed GRT samples with virgin NR in a ratio of 15:85. Mooney viscosity, initial plasticity, cure characteristics, and dynamic properties of the above blend compounds were evaluated and compared with those of the control compounds. This study shows that the amino compound acts as a devulcanising/reclaiming agent for GRT. Rubber compounds prepared by blending virgin NR with novel reclaimed rubber exhibit higher stock viscosity, lower scorch resistance, and lower hysteresis in comparison with the control compounds.
item: Thesis-Abstract
Chemical modification of rubber waste and characterization of their blends with natural rubber
(2014-05-31) Edirisinghe, DG; Premachandra, JK
Ground rubber tyre (GRT) produced by recycling of tyre waste or rejects is used as a filler in the manufacture of tyre components, mainly to reduce the cost. Rubber matrix-GRT compositions generally exhibit poor mechanical properties due to poor matrix-filler adhesion and lack of reactive sites on GRT particle surfaces. Therefore, GRT is modified by employing various types of reclamation processes to enhance mechanical properties. The modified GRT known as reclaimed rubber is widely used as a component in rubber blends in many applications, especially in tyre manufacturing. This study is focused on developing a cost effective, environmental friendly mechano-chemical reclamation process for GRT to produce reclaim rubber using a readily available amino compound. Initially, influence of the amino compound on rubber compound properties was evaluated and results indicate that it acts as an activator for sulphur vulcanization. Properties of GRT modified with the amino compound indicate that the amino compound acts as a reclaiming agent as well. Comparison of properties of natural rubber (NR) / novel reclaimed rubber blend compounds and revulcanisates with those of the controls reveal that the former can be used as alternatives to the latter in the manufacture of tyre treads. Replacement of 30% of virgin NR in the vulcanisates with the novel reclaimed rubber retains about 65-85% of strength properties, elongation at break and resilience. Abrasion volume loss is at an acceptable level and ageing properties are comparable to those of the 100% virgin NR vulcanisate. Further, most of the properties of the virgin NR / novel reclaimed rubber composites are comparable to those of the corresponding composites prepared by blending NR with commercially available reclaimed rubbers. Accordingly, the novel reclaimed rubber could be a suitable component to blend with virgin NR in the manufacture of tyre treads with required properties.
item: Thesis-Abstract
Development of NR/CHR rubber blends with carbon black and silica fillers for tyre inner liners
(2016-06-11) Siriwardana, TAAI; Egodage, S; Edirisinghe, DG
Inner liner of a tubeless tyre is currently constructed using a speciality synthetic rubber called chlorobutyl rubber (CIIR). Blending of CIIR with natural rubber (NR) will enable to achieve improvement in physico-mechanical properties with a reduced compound cost. Also, use of CIIR/NR blends for inner liners are best at retaining air pressure and minimizing the temperature dependence of air permeability. The properly increase is enhanced by addition of a mix of carbon black and silica fillers, which are reinforcing fillers. One reason for carrying out this research is to enhance the market opportunities of NR by developing NR/CIIR blends to reach the end product requirements. In this study, different series of compounds were prepared, one with CIIR alone by varying the carbon black to silica ratio at 10 phr intervals, other with CIIR/NR blends by varying the CIIR to NR blend ratio at 20% intervals. Total filler loading was kept constant at 60 phr. Melt viscosity, hardness, tensile strength, modulus at 300 % and tear strength increased with silica loading, while scorch time, abrasion volume loss and air permeability decreased above silica loading of 30 phr.. Cure time did not show any variation with type of filler. When replacing CIIR with NR, cure rate index increased significantly from 40% NR and hence the cure time decreased. Mechanical properties and air permeability varied significantly. Materials used for the inner liner mainly chlorobutyl rubber are very expensive and hence by using the above mentioned blend with the optimum filler loading, the production cost can be minimized. Results in overall showed optimum properties for the 20:80 CIIR/NR blend at 10:50 carbon black /silica filler ratio.
item: Article-Abstract
Effect of blend ratio on properties of natural rubber/low density polyethylene blends
Sampath, WDM; Egodage, SM; Edirisinghe, DG
Thermoplastic natural rubber (TPNR) those produced by blending of thermoplastics and natural rubber using traditional internal mixers and plastic extruders, are becoming increasingly accepted in the global polymer market. Natural rubber (NR)/low density polyethylene (LDPE) blend is used as a TPNR in the manufacture of rubber based articles. These blends can best be appreciated as high impact resistant engineering materials and The main objective of this study was to investigate the effect of blend ratio on physical, chemical and mechanical properties of NR/LDPE blends. In this study, a series of simple blends was formulated by varying LDPE loading from 10 to 90 by wt. at 20% intervals. The blends were prepared using a Brabender Plasticorder by melt mixing at a temperature of 130 °C, and at a rotor speed of 60 rpm. Minimum torque of melt blending was investigated by a moving die rheometer while glass-transition temperature (Tg) of blends were measured by differential scanning calorimetry. Swelling behaviour studied by sol/gel analysis using toluene as the solvent, according to ISO standard. Physicomechanical properties were determined according to ISO standards. Minimum torque, which is an indication of the processability and of stock viscosity, decreased with increase in LDPE loading. Tear strength, tensile strength and hardness increased with increase in LDPE loading while elongation at break decreased. Glass-transition temperature, Tg of NR phase of the blends slightly varied with LDPE loading. Solvent resistance increased with increase in LDPE loading. These results indicate a phase change after 30 % by wt. of LDPE loading. Further, the results reveal that the blends with different properties required for different applications could be obtained by varying the blend ratio.
item: Article-Abstract
The effect of coupling agent and mixing methods on properties of natural rubber and low density polyethylene blends
Sampath, WDM; Egodage, SM; Edirisinghe, DG
Coupling agents are molecular bridges at the interface between two substrates, an inorganic filler an organic polymer matrix. When incorporated into polymer systems, they often promote adhesio) improve dispersion, improve impact strength and thus reduce embrittlement. The practical Utility polymer blend is determined by the compatibility of component polymers, which is considered asjtifundamental property. It has been observed that majority of rubber-thermoplastic blends, in 1 natural rubber (NR) and low density polyethylene (LDPE) blends are incompatible thus -prinferior properties. Thermoplastic molecules can be reshaped with heat and pressure since they cross-link. This provides them the property of being easily fabricated by conventional plastics pti^ techniques such as extrusion, injection molding and blow molding. The main of this s investigate the effects of titanate base coupling agent and mixing methods on NR and L composites in terms of their physic-mechanical, chemical properties and phase morphology of 50/50 NR/LDPE filled CaCo3 composites were prepared by using internal mixer (brabend and 60 rpm for 14 minutes. Coupling agent was incorporated into polymer matrix
item: Conference-Abstract
Improvement of physico-mechanical properties of Calcium Carbonate filled Natural Nubber and Low Density Polyethylene blends with titanate coupling agent
Sampath, WDEM; Edirisinghe, DG; Egodage, SM
Nonblack particulate fillers most used with thermoplastic and rubber are calcium carbonate, silica, talc and alumina hydrates. The main characteristics, which control the effectiveness and the dispersion of filler in the polymer, are structure, surface area and chemical activity of filler. The mechanical behavior of rubber-thermoplastic blends depends greatly on interactions and compatibility that develop between the two polymers and the filler. The main objective of this study is to improve physico-mechanical properties of calcium carbonate (CaCO3) filled natural rubber (NR) and low density polyethylene (LDPE) blends using a titanate coupling agent. Two series of NR/LDPE blends, with and without titanate coupling agent, were prepared by varying LDPE loading from 10% to 90% at 10% intervals. 20 parts by weight of CaCO3 per 100 parts of combined polymer was incorporated into every blend composition. The blends were prepared using a Brabender plasticorder by melt mixing at a temperature of 130 oC, and at a rotor speed of 60 rpm. Physico-mechanical properties such as tensile properties, hardness, tear strength and morphology of the blends were studied. These properties were determined according to ISO standards. Morphology of the tensile fracture surface of blends was observed using a transmitted light microscopy. Tensile strength, tear strength and hardness of NR/LDPE blends increase with increase in LDPE loading while elongation at break decreases. NR/LDPE blends with titanate coupling agent exhibited enhanced properties at every LDPE loading. NR/LDPE blends having 30% of LDPE loading showed highest tensile strength. In this blend, NR was dispersed in LDPE matrix with good adhesion between NR and LDPE.
item: Conference-Full-text
Improvement of Physico-Mechanical Properties of Calcium Carbonate filled Natural Nubber and Low Density Polyethylene Blends with Titanate Coupling Agent
(2015-08-14) Sampath, WDM; Edirisinghe, DG; Egodage, SM
Nonblack particulate fillers most used with thermoplastic and rubber are calcium carbonate, silica, talc and alumina hydrates. The main characteristics, which control the effectiveness and the dispersion of filler in the polymer, are structure, surface area and chemical activity of filler. The mechanical behavior of rubber-thermoplastic blends depends greatly on interactions and compatibility that develop between the two polymers and the filler. The main objective of this study is to improve physico-mechanical properties of calcium carbonate (CaCO3) filled natural rubber (NR) and low density polyethylene (LDPE) blends using a titanate coupling agent. Two series of NR/LDPE blends, with and without titanate coupling agent, were prepared by varying LDPE loading from 10% to 90% at 10% intervals. 20 parts by weight of CaCO3 per 100 parts of combined polymer was incorporated into every blend composition. The blends were prepared using a Brabender plasticorder by melt mixing at a temperature of 130 oC, and at a rotor speed of 60 rpm. Physico-mechanical properties such as tensile properties, hardness, tear strength and morphology of the blends were studied. These properties were determined according to ISO standards. Morphology of the tensile fracture surface of blends was observed using a transmitted light microscopy. Tensile strength, tear strength and hardness of NR/LDPE blends increase with increase in LDPE loading while elongation at break decreases. NR/LDPE blends with titanate coupling agent exhibited enhanced properties at every LDPE loading. NR/LDPE blends having 30% of LDPE loading showed highest tensile strength. In this blend, NR was dispersed in LDPE matrix with good adhesion between NR and LDPE.
item: Article-Abstract
A Novel reclaiming agent for ground rubber tyre (GRT). Part I I: property evaluation of virgin natural rubber (NR)/Novel Reclaimed GRT revulcanisates
Edirisinghe, DG; De Silva, MIA; Premachandra, BAJK
Blending of recycled scrap rubber such as reclaimed rubber with virgin rubber has increased over the last few years, especially in the manufacture of tyre components. The reason for this is the growing concern about the effect of rubber product waste on the environment and the rise in the costs of virgin rubbers. In this study, physicomechanical properties such as tensile properties, tear strength, hardness, resilience, abrasion resistance, ageing performance, and swelling behaviour as well as carbon black dispersion rating of 85/15 virgin NRinovel reclaimed ground rubber tyre (GRT) revulcanisates were evaluated and compared with those of control vulcanisates. Results revealed that the abrasion volume loss of blends of virgin NR and novel reclaimed rubber revulcanisates is lower than that of revulcanisate prepared with a blend of 85/15 virgin NRI reclaimed rubber (Control (Rec)), produced locally, and comparable with that of 100% NR vulcanisate (Control (NR)).Although the tensile strength and elongation at break of the virgin NRinovel reclaimed rubber revulcanisates are lower than those of the Control (NR) vulcanisate, these values are at a level acceptable for tyre treads. Hence, the 85/15 virgin NRinovel reclaimed rubber revulcanisates prepared with the readily available, low-cost, environmentally friendly amino compound can be used as an alternative to the Control (NR) and Control (Rec) vulcanisates in tyre treads.