Browsing by Author "Egodage, S"

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item: Conference-Full-text
Biodegradation of natural rubber latex by a novel bacterial species isolated from soil
(IEEE, 2016-05) Hapuarachchi, SNS; Kariyapper, SR; Gunawardana, MBDMD; Egodage, S; Ariyadasa, TU; Jayasekara, AGBP; Bandara, HMND; Amarasinghe, YWR
A natural rubber degrading bacteria Paenibacillus lautus was isolated from soil samples of a rubber plantation in Sri Lanka. The strain was able to decompose natural rubber latex by adhesively growing on its surface using NR latex as the sole carbon source. The staining test performed using Schiff's reagent confirmed the degradation of NR latex. The Fourier Transform Infrared Spectroscopy further verified the result by showing the reduction of C=C double bonds and the presence of carboxylic acids and ketones in the polymer chain. The surface erosion images of the latex overlay surfaces obtained from scanning electron microscopy also validated the degradation process.
item: Conference-Full-text
comparative study on cure, mechanical and dynamic-mechanical properties of natural rubber compounds formulated with dixp, tbztd, zbec and tbbs accelerators
(IEEE, 2021-07) Samarasinghe, H; Walpalage, S; Edirisinghe, D; Egodage, S; Adhikariwatte, W; Rathnayake, M; Hemachandra, K
Today, it is obligatory to replace nitrosamine releasing traditional accelerators owing to the various health, safety and environment regulations and surviving with safe alternative is a one of the key challenges in the rubber industry. In this work four groups of commercially available nitrosamine free/safe accelerators were selected, i,e., diisopropyl xanthogen polysulfide (DIXP), tetrabenzyl thiuramdisulfide (TBzTD), zinc dibenzyl dithiocarbamate (ZBeC) and N-tert-butyl-2-benzothiazole sulfenamide (TBBS). The effect of accelerator type on cure, crosslink density, physico-mechanical and dynamic-mechanical properties of efficient sulfur vulcanized natural rubber (NR) compounds was investigated. Results reveal that accelerator type does not only affect the cure characteristics, but also has a great impact on physical and mechanical properties, DIXP possess the least modulus and strength properties while providing satisfactory optimum cure time for the vulcanization compared to the TBBS accelerator. Improvement in mechanical properties is observed in the order ZBeC, TBzTD, TBBS and corroborates well with the crosslink density. ZBeC and TBzTD show relatively higher hardness, storage modulus and lower hysteresis in the rubbery region indicating different microstructure arrangement compared to commonly use of non-regulated nitrosamine safe TBBS accelerated vulcanizates.
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: Thesis-Full-text
Effect of short fibers on high load bearing press-on tire tread compound
Wattegedara, BMHIB; Egodage, S
This research work was carried out to investigate the effect of short nylon fiber on natural rubber based solid tire tread compound. It was also an objective of this work to find the best fiber loading that would produce short fiber-rubber composites of good physical and mechanical properties of vulcanized rubber. A screening procedure was carried out to identify the best fiber content. Natural Rubber based compound was used and Nylon 6 short fibers were used. Length of fiber was selected as around 5 mm and fiber loadings were varied from 1 to 20 part per hundred rubber. The short fibers were taken from the RFL dip nylon cords but an additional dry bonding system was added to the compound to overcome the bonding failures in cutting edges of the fibers. The Physico-mechanical properties, Dynamic properties and Cure characteristics were studied in detail. There is a positive influence on the tearing strength, cut & chip resistance and compression test (load bearing capability) with the increase in fiber content. The tensile strength and elongation properties were negatively influenced with the loading of short fiber. There was no major influence on Hardness and Specific Gravity of the composites with the increase of fiber content. At the low fiber loading, Abrasion resistance, rolling resistance and hysteretic energy loss (Resilience) of composites had positive influence on properties but beyond the fiber content of 3 parts per hundred rubbers, the properties were negatively influenced. The Minimum torque and Mooney viscosity decreased with the fiber loading up to 5 phr but it increased with the further loading of short fiber. The scorch time increased with the fiber loading but there was no major influence on optimum curing time (t90) As such the general conclusion inferred from this study favor a high potential of using short nylon fiber as reinforcing material for tire tread compounds which are used in high load bearing applications in solid tires.