Browsing by Author "Wijesinghe, H.G.I.M."
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Item Cellulose Whiskers Extracted from Banana Pseudo-Stem as Reinforcing Filler for Natural Rubber Tyre Treads Using Latex Intercalation Method(Uva Wellassa University of Sri Lanka, 2018) Bandara, T.A.R.W.M.M.C.G.; Etampawala, T.N.B.; Kularathne, S.; Wijesinghe, H.G.I.M.; Senevirathna, A.M.W.K.Reinforcing the rubber compounds using cellulose fibre is an emerging trend in rubber industry because of unique physical properties of cellulose fibre. In this study, cellulose fibres were extracted from pseudo-stern of banana using alkali treatments and converted into cellulose whiskers (CW) with high pressure defibrillation followed by acid treatment and bleaching. The CW was characterized using Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffractometry (XRD) and Particle Size Analyzing. Both FTIR and XRD confirm the cellulose structure. XRD studies showed that the percentage crystallinity of bleached fibres is about 69%. The particle size shows a bimodal distribution where approximately 21% of the sample has average size of 110 nm and the rest has the size of 795 nm. The purified CW was intercalated in diluted natural rubber (NR) centrifuged latex in order to prepare CW/NR composites and converted into rubber sheets. Mooney viscosity and stress relaxation coefficient of CW/NR composites were measured. The lowest Mooney viscosity and the highest stress relaxation coefficient were observed in CW/NR composites ensuring higher processability. The compounds were prepared in an internal mixture according to a tyre tread formulation, keeping the sample without CW as the control. Cure characteristics were evaluated at 120 °C and physical properties were evaluated on par with the ASTM standards. The highest cure rate and better scorch time were observed in CW/NR composite. The density, hardness, resilience, cut & chip and tensile strength of the composite were superior while tear strength and abrasion volume loss were inferior to the control. In overall, we observed that cellulose whiskers have a great potential to use as a reinforcing material for natural rubber tyre tread compounds.Item Development of Acrylonitrile Butadiene Rubber Composite with Improved Physico-Mechanical and Oil Resistant Properties by Incorporating Waste Egg Shell Powder as a Filler(Uva Wellassa University of Sri Lanka, 2020) Seneviratne, D.V.M.; Vitharana, V.H.P.; Wijesinghe, H.G.I.M.The present study attempted to develop a high-performance oil-resistant rubber material based on acrylonitrile butadiene rubber (NBR) by incorporating waste eggshell powder (ESP) as a filler to be utilized in automobiles industry while reducing the commercial Carbon Black (CB) content. Since CB is obtained from petroleum resources, its manufacturing process is hazardous and cause environmental pollution. Thus, the use of calcium carbonate (CaCO3) is found as a remarkable way to replace the CB in the rubber compounds due to its non-toxic and environmentally friendly nature. Value addition to waste eggshells was one of the main aspects of this research. The effect of surface modified CaCO3 filler on the cure, mechanical and swelling properties of NBR composites with respect to CB was studied. Filler amount was kept constant at 45 phr. Only the ratio of CB: ESP was changed. Ten ratios of samples were prepared by varying filler amounts by 5 phr. The surface modification of CaCO3 was confirmed using Fourier transform infrared spectroscopy. Particle size having 3.05 μm CaCO3 was successfully obtained from eggshell powder. X-ray diffraction patterns proved that raw eggshell powder was chemically similar to commercial CaCO3. The vulcanizates were evaluated by rheological, physical, and mechanical characteristics. The cure times and scorch times were at an acceptable level. NBR composites with ESP loadings of 0, 5, 10, 15, 20 phr showed tensile strengths of 7-14 MPa, compression sets of 2.38- 5.49 %, hardness of 61 - 72 IRHD. Therefore, it can be deduced that NBR filled with surface modified eggshell powder has competed favorably with the standard CB. Replacing CB from ESP loadings of 5, 10, 15, 20 phr did not show a significant difference in physico-mechanical properties. Hence eggshell CaCO3 can be considered as one of the best conventional fillers suited for automotive applications with a high oil-resistant sealing material. Keywords: Calcium carbonate, Carbon black, Egg shell powder, Filler, Oil resistanceItem A Dual Filler System for Low Speed Tire Base Compound(Uva Wellassa University of Sri Lanka, 2019) Gunasekara, T.D.I.K.; Ranatunga, R.R.M.S.K.; Wijesinghe, H.G.I.M.; Senevirathna, A.M.W.K.The effects of the dual filler system of Carbon Black (CB) and Chopped Tire Cord (CTC) were investigated on the mechanical properties and cure characteristics of low speed tire base compound made out of Natural Rubber (NR) and Reclaim Rubber. Chopped tire cord is a cost effective filling material which is derived from the rejected pneumatic tires. To determine the composition of materials, Thermo Gravimetric Analysis (TGA) was carried out for two CTC grades as weight percentages and the grade having high amount of CB (25%) was selected and used during the study. Compounds were prepared keeping CB to CTC ratios at 65:35, 55:45, 45:55 and 35:65 in parts per hundred parts of rubber (pphr) filler loading levels. Then curing and physico-mechanical properties were investigated according to ISO standards. Mooney viscosity of the compounds was within the accepted levels of 60-85 Mooney Units. Scorch time (Ts2) and optimum cure time (T90) have increased due to the reduction of CB content when increasing the CTC content in the compounds. However, it has improved the processing safety of the newly developed base compound. Hardness was within the accepted levels of 87-92 (Shore A) and the tensile strength was greater than 6 MPa. Tear strength and rebound resilience have improved along with the increase of CTC content. In conclusion, it is highly possible to use CTC in Base compounds of low speed tires as a cost effective filler at 65 pphr level with improved properties because the cost of CTC is well below the cost of CB.Item Effect of Ethephon Stimulation on Physico-Mechanical Properties of Carbon Black Filled Natural Rubber Vuleanizates(Uva Wellassa University of Sri Lanka, 2018) Nanayakkara, E.N.N.; Attanayake, A.P.; Wijesinghe, H.G.I.M.; Senevirathna, A.M.W.K.Low intensity harvesting systems (LIH) with ethephon stimulation were introduced to rubber plantations due to the shortage of skilled latex harvesters. The objective of this research study was to identify the effect of ethephon stimulation on physicomechanical properties of the carbon black filled natural rubber vulcanizates. The study was conducted with the RRIC 121 clone using half spiral, once in three-day harvesting system. Experiments were laid out in Randomized Complete Block Design using three blocks with six ethephon treatments (0, 1, 2, 3, 4, 5 %). Each block was composed of 150 trees and each treatment was applied in 25 trees while the non- stimulated (0%) trees were considered as the control. Latex was separately collected from each treatment and processed into unfractioned, unbleached crepe rubber (UFUBCR) and carbon black filled natural rubber vulcanizates were produced according to the general compounding formulation. The vulcanization was carried out at 150 °C for 10 minutes. Initial Plasticity and Mooney Viscosity of UFUBCR reduced with the increase of ethephon concentration, while Plasticity Retention Index showed marked reduction at 4% and 5% ethephon concentrations. Rebound resilience, tensile strength and elongation at break have reduced with high ethephon concentrations. However, hardness, compression set and tear strength has increased with high concentrations of ethephon. Results revealed that elastic properties have reduced and filler reinforcement has increased with high ethephon concentrations. LIH systems with ethephon stimulation does not have any adverse effect on physico-mechanical properties up to 3% ethephon concentrations. However, such properties were negatively affected with the application of higher ethephon concentrations beyond 3%, therefore the application of ethephon up to 3% could be recommended.Item Effect of Mixing Method on Properties of Natural Rubber/Acrylonitrile Butadiene Rubber Blend Composites Reinforced with Silica Extracted from Rice Husk Ash(Uva Wellassa University of Sri Lanka, 2020) Gamlath, G.R.V.S.; Wijesinghe, H.G.I.M.; Senevirathna, A.M.W.K.; Edirisinghe, D.G.Acrylonitrile butadiene rubber (NBR) is used where rubber products require swelling resistance. Natural rubber (NR) can be blended with NBR for synergism of properties using either phase mixing or pre-blending methods. According to literature, the mixing method may have a significant effect on properties of blends and it has not investigated for NR/NBR blends filled with silica extracted from rice husk ash (RHAS). RHAS is used as the filler, an alternative to carbon black which induces high heat built-up in products. The sol-gel method was used to extract RHAS, X-ray diffractogram and Fourier Transform Infrared Spectroscopy proved the amorphous nature and the chemical compatibility of RHAS with commercial silica. Blends filled with 25 parts per hundred parts RHAS were prepared to keep NR to NBR ratio at 0:100, 20:80, 40:60, 60:40, 80:20, and 100:0 using phase mixing and pre-blending methods referring to the control, American Standard Testing Method reference formulation for oil seals. Curing, physical and swelling properties of blends were evaluated. Results revealed that there was no significant difference between mixing methods on properties. Blends with high NBR amounts showed higher crosslinking density while all blends showed acceptable scorch and cure times. Tensile and tear strength showed comparatively lesser values in all blends than the control while elongation properties were compatible with control. The compression set varied from 1-6%, control had 4.3%. Hardness ranged from 45-60 IRHD, control had 73 IRHD. Equilibrium swelling (%) of control in toluene is 82%, but all blends showed values from 80-150%. Equilibrium swelling (%) of control in hydraulic and engine oil was below 2% while high NBR content showed lower swelling. Equilibrium Swelling (%) ranged from 1-16% in hydraulic oil and 1-12% in engine oil. Overall, these blends can be used in the preparation of non-marking stationary sealing articles and there is a potential to use RHAS in NR/NBR blends for reinforcement. Keywords: Natural rubber, Acrylonitrile butadiene rubber, Pre-blending, Phase mixing, Rice husk ash silicaItem Influence of Partial Replacement of Carbon Black with Areca Nut Husk Fiber on Properties of Natural Rubber Composites(Uva Wellassa University of Sri Lanka, 2019) Madushika, K.P.I.; Wijesinghe, H.G.I.M.; Senevirathna, A.M.W.K.; Edirisinghe, D.G.Development of Natural Rubber (NR) composites using natural fibers (NF) such as coconut, bamboo, banana, sisal, etc. has been increased during the recent past due to the growing need for green rubber composites. NF are low density and low cost materials having high recyclability and biodegradability. However, compatibility between NF and NR is not adequate to achieve properties required for various applications. Areca nut husk is one of the good sources of NF which is abundantly present as a waste. One series of composite was prepared with six NR composites using carbon black (N 330) and surface treated (with silane coupling agent) Areca nut husk fibre (SAF) by varying the SAF loading from 0 to 50 phr at 10 phr intervals, whilst maintaining the total filler loading at 60 phr. Another series with six NR composites was also prepared using the same formulation, but with untreated Areca nut husk fibre (UAF). UAF and SAF composites were characterized using Fourier Transform Infrared Spectroscopy (FTIR). Cure characteristics and physico-mechanical properties of these composites were tested to select the best ratio of the two filler materials in terms of properties for low cost applications. Cure rate decreased, however scorch safety improved with the increase of the amount of SAF in the composite. Hardness, tensile strength and tear strength decreased, whilst resilience, abrasion weight loss and compression set increased with the increase of SAF loading. Results indicated that two third of the carbon black in NR composites could be replaced with SAF without a significant effect to the properties.Item A Novel Method to Manufacture Skim Crepe Rubber with Low Nitrogen Content using Pineapple Juice Treated Skim Latex(Uva Wellassa University of Sri Lanka, 2019-02) De Zoysa, D.M.D.A.; Senevirathne, A.M.W. K.; Wijesinghe, H.G.I.M.; Sudusinghe, Y.C.Y.; Siriwadena, S.Skim Natural Rubber Latex (SNRL) is a by-product obtained during the manufacture of centrifuged latex, contains low dry rubber content (<5%). Direct coagulation of SNRL with concentrated sulfuric acid is the conventional method used to manufacture Skim Crepe Rubber (SCR). SCR fetches a low market value due to its inferiority in quality inherited by the presence of higher non-rubber content compared to that in other raw rubber types. This study focused to develop a healthier and environmental friendly manufacturing process for SCR with lower nitrogen content and higher quality through removal of protein. Pineapple juice (PAJ) was initially treated with Potassium oleate before it was mixed with SNRL (15 ml of PAJ was added to 1 L of SNRL) and kept for 48 hrs at room temperature (28 oC). Then a creaming agent was added at 25 phr to PAJ treated SNRL after adjusting pH to 7.5 and creamed for 36 hours. Three different acidic coagulants of 20% (w/w): sulfuric, oxalic and formic acid were employed to coagulate deproteinized creamed fraction. The control sample of SCR was also prepared by adding 20% (w/w) sulfuric acid to fresh SNRL. Raw rubber properties were evaluated according to the ISO standards. All SCR samples prepared by using creaming followed by the PAJ treatment have low nitrogen content (0.300.40% w/w) and Mooney viscosity (7590 MU) along with higher ash content (0.4-0.5% w/w) than the control sample where above parameters were 1.44% (w/w), 91.55 MU and 0.17% (w/w) respectively. It was found that total acid requirement could be reduced by 50% using novel method. Also deproteinized SCR manufactured using oxalic acid as the coagulant has highest Plasticity Retention Index (61.17%) with good initial Plasticity. This method might be a good solution for removal of protein substances and unfavourable metal ions from SNRL enhancing the quality of SCR. Therefore, this novel method would allow to obtain a better competitive commercial value for SCR.Item Optimization of Mixing Parameters using Mooney Viscosity of Top & Bottom Profiles in Off-the-Road Rubber Track Compounds(Uva Wellassa University of Sri Lanka, 2018) Bhagya Malshani, U.D.D.; Gunawardena, S.; Wijesinghe, H.G.I.M.; Kaliyadasa, P.E.Rubber tracks are used in off—the-road heavy duty vehicles. The tread of tracks consists of two layers namely top profile and bottom profile. Rubber Compound ATR 6112 (A) & Compound ETR 5271 (B) are used to manufacture top profiles, while Compound TR 5237 (C) is used in bottom profile. The high Mooney viscosity of such compounds leads to reject the batches of compounds. Therefore, compound mixing parameters were optimized during the study using Mooney Viscosity (MV). Also cure time, scorch delay & hardness of compounds were evaluated. Mixing cycle (s) defined as time for pre-mastication & mixing of curatives and number of mill turns were selected as the major parameters and assessed separately for compounds. Number of mill turns was varied as 3, 2 & 1 for all three compounds. Mixing cycles are Compound A (40,60), (20,60), (0,50,50) & (30,70), and Compound B (20,90), (40,60), (0,50,50) & (30,80), while Compound C at (20,80), (30,70), (0,50,60), & (40,60). Complete Randomized Design with 10 replicates were used. Compounds A and B with the mixing cycle of (0,50,50) where mixing of curatives and rubber compound together, used internal mixer without allowing premastication time. The best mixing cycle was achieved at (30,70) for Compound C with a lower MV. The number of mill turns has not significantly affected on MV, scorch delay, curing time and hardness of all three compounds. The scorch delay was affected by mixing cycle only in Compound B. The curing time was affected by mixing cycle in only Compound A and C. The hardness of the compounds has not significantly affected by mixing cycle. Finally, better cure characteristics of the compounds could be obtained along with reduced Mooney Viscosity by adjusting the mixing cycle. Keywords: Mixing cycle, Mooney viscosity, Mill turns, Rubber track compoundsItem Potential of Using Rice Husk Ash Silica as Filler in Acrylonitrile Butadiene Rubber Compounds(Uva Wellassa University of Sri Lanka, 2020) Wadugodapitiya, R.R.W.M.U.G.K.; Wijesinghe, H.G.I.M.; Edirisinghe, D.G.; Senevirathna, A.M.W.K.Rice husk is a most available and reliable natural source which contains more than 90% of silica (SiO2) in its ash. Silica in its amorphous or crystalline forms can easily be derived from rice husk ash (RHA). Replacement of environmentally harmful carbon black (CB) using such a natural source is important. Therefore, this study was conducted to investigate the potential of using RHA silica (RHAS) as filler for Acrylonitrile butadiene rubber (NBR) compounds as partial replacement of CB. Commercial grade silica (CS) was used for the comparison of the performance of RHAS during the study. RHAS was derived by sol-gel technique and X-ray diffractogram proved the amorphous nature of RHAS and Fourier Transform Infrared Spectrophotometric analysis underlined that the chemical nature of RHAS is almost similar to that of CS. NBR compounds (Series 1) were prepared by keeping CB: RHAS ratio as 55:5, 50:10, 45:15, 40:20, and 35:25 parts per hundred parts of rubber by weight (phr). The compounds (Series 2) which contain CB and CS were prepared using the same ratios. Compound with 60 phr of CB was considered as the control. Both series of compounds have shown desirable highest torque, Delta cure, and lowest torque with better-crosslinking density and processability at all loading levels compared to control. Scorch time and Cure time showed extended times. Hardness, compression set, and tensile strength of both series showed acceptable values even though elongation at break and tear strength showed somewhat inferior properties. Swelling resistance is very high in both series with no significant between the series and to the control. Overall, there is a potential to use RHAS as a partial replacement of CB in NBR compounds and can be used to replace CS. Keywords: Acrylonitrile butadiene rubber, Carbon black, Commercial silica, Rice husk ash silicaItem Reduction of Enzymatic Discolouration of Natural Rubber Latex by Using Antioxidant and Moringa oleifera Leaf Extract(Uva Wellassa University of Sri Lanka, 2019-02) Arachchi, N.N.M.; Attanayake, A.P.; Senevirathna, A.M.W.K.; Wijesinghe, H.G.I.M.Natural rubber latex tends to discolour due to enzymatic activity. This should be avoided to maintain the quality of natural rubber latex. Natural rubber latex of RRISL 203 clone shows higher degree of enzymatic discolouration due to the presence of phenolic substances. The objective of this study was to find a solution to reduce the enzymatic discolouration of latex of the above clone using natural and commercial antioxidants. Leaf extract of Moringa oleifera has been evaluated for its antioxidant activity as it contains higher amount of powerful antioxidant quercertin. Three treatments: M. oleifera leaf extract, Vitamin C (a solution made by dissolving vitamin C tablets) and ‘antioxidant G’ (is a natural antioxidant) were used to perform antioxidant activity in latex obtained from RRISL 203 clone. Three replicates were done for latex samples obtained from three tapping blocks. Each solution of antioxidant was added separately prior to add formic acid to latex. Samples were prepared as unfractioned-unbleached crepe rubber with a control. Samples were analyzed for Mooney viscosity, Plasticity Retention Index, Volatile Matter Content and Ash Content. Further, colour index test was done for the colour comparison which determine the enzymatic discolouration. There was no significant difference (P>0.05) in raw rubber properties among the treatments whereas significant difference (P<0.05) among treatments for the colour index was observed. Lowest colour index values (1, 1.5 and 2.0) were resulted by the ‘antioxidant G’ in three blocks as compared to the other treatments. Crepe samples prepared by treating Vitamin C and leaf extract of M. oleifera were inferior in colour as compared to the ‘antioxidant G’ treated samples. It can be concluded that ‘antioxidant G’ can be used effectively to reduce the discolouration of natural rubber latex while maintaining its properties satisfactorily.Item Root Cause Analysis for Warming Delay of Resilient Solid Tire Heel Compound on Warming Mill During Manufacturing(Uva Wellassa University of Sri Lanka, 2020) Bandara, B.N.S.; Dilrukshi, N.M.D.; Senevirathne, A.M.W.K.; Wijesinghe, H.G.I.M.Solid tires used in heavy-duty applications consist of three distinct parts: heel, cushion, and thread. The heel is the innermost layer which provides the resistance to air permeation while ensuring excellent adhesion to the rim and cushion. More fiber reinforced compounds are used in heel production. But a warming delay for about 8-10 minutes which is more than the specified time limits to warm the compounds before production has been observed when warm the compounds using warming mill. Therefore, this research focused to analyse the root causes of the warming delay of compounds during the warming operation. Minimum torque (ML) and Mooney viscosity (MV) of the heel compound, nip size of the warming mill, thickness, and maturity of the incoming compound sheets were selected as key factors for the warming delay. Multiple regressions analysis and simple linear regression were applied to predict the relationships of these factors with the warming time while using cubic regression to find the effect of nip size on the warming time. According to the results, there is a significant effect of these factors on warming time. Improper mixing of the compounds tends to show high values for MV, ML, and thickness of incoming compounds. The maturity of the compounds and the nip size of the warming mill was selected for further study. According to the two-way ANOVA, there is an interaction between maturity and nip size on warming time. The nip size (mm) was varied from 7 to 10 at 1mm interval and the maturity time of the compounds was varied as 6, 12, 24, and 48 hours. Results revealed that warming time can reduce using 9mm nip size and 48 hours maturity time of compounds at warming mill in the manufacturing process. Keywords: Minimum torque, Mooney viscosity, Nip size, Solid tire heel, Warming delayItem Silica Extracted from Rice Husk Ash as an Effective Reinforcing Filler for Natural Rubber Composites(Uva Wellassa University of Sri Lanka, 2018) Samaraweera, K.C.; Wijesinghe, H.G.I.M.; Etampawala, T.N.B.; Edirisinghe, D.G.; Senevirathna, A.M.W.K.Rice husk is abundantly available in Sri Lanka, which is generated in larger volumes as rice husk ash (RHA) due to combustion. In general, RHA dumped at landfills as a waste. However, RHA is a promising source of silica as it contains more than 90% by weight. This silica can effectively be extracted by Sol-Gel method. In this research such silica was extracted and characterized using Fourier Transform Infrared Spectroscopy (FTIR) and X-ray Diffractometry (XRD). Both FTIR and XRD analysis confirmed the chemical and amorphous nature of the extracted silica. Natural rubber composites were prepared incorporating silica from 0-10 parts per hundred Rubber (phr) at 2.5 phr intervals using two-roll mill. The effect of silica on curing characteristics and the mechanical properties of vulcanizates were studied. The curing characteristics of the compounds revealed an increase in cure rate and thus considerable decrease in cure time and scorch. Tensile strength, modulus at 100% elongation and tear strength has increased significantly compared to control sample. The effect is prominent with increasing the silica loading. The abrasion volume loss has significantly decreased with the increase of silica loading. The lowest abrasion volume loss and the highest tear strength have reached at 7.5 phr of silica loading level. Whilst the resilience has decreased when increase the silica loading. However, silica loading does not show an impact on hardness. In conclusion, preferred curing characteristics and improved mechanical properties have been achieved. Moreover, it is important to emphasize that in this study the effect of extracted silica on mechanical properties of NR composites has not been compared with the commercially available silica and further studies are suggested.Item Study of Mechanical and Physical Properties of Nitrile Butadiene Rubber Glove with Sulfur, Accelerator and Particle Size of the Dispersion(Uva Wellassa University of Sri Lanka, 2020) Mendis, E.D.M.; Hemachandra, K.A.S.K.; Senevirathna, A.M.W.K.; Wijesinghe, H.G.I.M.Sludge formation in the latex dipping tanks is the most destructive matter in the glove industry. This problem can cause quality defects of the glove and hence, high cost of production. This study was carried out to reduce the sludge quantity while the physical properties of the nitrile butadiene rubber glove by reducing the particle size of the dispersion. The particle size of the dispersion was reduced by increasing milling cycles in the pearl mill. Two milling cycles were considered in this study. Particle sizes of two samples were 2.5µm and 1µm according to the Dynamic Light Scattering test. Those dispersion samples were used to prepare compounds to measure the sludge quantity and gloves were prepared to investigate the physical properties. Particle size with the milling cycles was studied as a preliminary study. Further improvements of the physical properties of the glove were investigated using different sulfur/accelerator ratios within three sulfur vulcanizing systems. Two levels of sulfur/accelerator ratios in each system were used to determine the best ratio with better properties. Dispersion with 1 µm particle size was given at least sludge quantity than the dispersion with 2.5µm particle size while improving the properties. Standard property levels in nitrile butadiene glove were considered as the control in this study. 3.5/1 sulfur/accelerator ratio was given better properties than the 2.5/0.5, 0.4/0.5, 0.8/3, 1/1, 1.5/1.5 ratios. This is because vulcanizate with a high proportion of polysulfidic bonds obtained high mechanical strength. Therefore, it is effective to use dispersions made from 1µm particle size with 3.5/1 sulfur/ accelerator ratio in the production of a nitrile glove. Keywords: Particle size, Physical properties, Sludge, Sulfur/accelerator ratioItem Surface Modification of Cellulose Micro Fibrils Extracted from Banana Pseudo-Stem Using Bis-[3-(triethoxysilyl) propyl] tetrasulfide(Uva Wellassa University of Sri Lanka, 2019-02) Bandara, T.A.R.W.M.M.C.G.; Wijesinghe, H.G.I.M.; Alakolanga, A.G.A.W.; Senavirathna, A.M.W.K.Cellulose as the most abundant biomolecule on the earth, it is on investigations to be used in several applications as a remedy for the exploitation of non-renewable resources and mismanagement of agro-industrial wastes. Banana (Musa sapientum) fibre is a promising source of cellulose which can be derived after harvesting while the majority of the pseudostems are used as a low-cost feedstock for the preparation of compost. However, the cellulose itself is not compatible with most of the materials especially, with non-polar matrices. Therefore, the extracted cellulose has to be surface modified. In this study, micro-fibrillated cellulose was prepared following an alkali treatment coupled with highpressure defibrillation and acid treatments on fibre extracted from pseudo-stem. The resulted micro-fibrillated cellulose was characterized using Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and cellulose structure was confirmed. XRD studies showed 69% crystallinity of micro-fibrillated cellulose. The particle size shows a bimodal distribution where approximately 21% of the sample has an average size of 110 nm and the rest is in averaged 795 nm. The prepared micro-fibrillated cellulose was surface modified using Bis-[3-(triethoxysilyl) propyl] tetrasulfide (TESPT) following rigorous solvent extractions with ethanol and acetone through cellulose membrane. With the surface modification, the percentage crystallinity has increased up to 77.8%. Moreover, the surface modification was confirmed by the results of FTIR spectroscopy showing the stretching vibration of Si-O-C bond at 1031 cm-1 indicating that the surface modification was successful.Item Use of Coir Fibre Waste as an Effective Raw Material for Fibre Boards Reinforced with Natural Rubber Latex Compounds and PhenolFormaldehyde Resin(Uva Wellassa University of Sri Lanka, 2018) Liyanage, W.L.A.M.; Herath, H.M.S.K.; Wijesinghe, H.G.I.M.; Perere, C.R.C.Coir pith is a by-product resulted in extraction of coir from coconut husks. Small fibre particles namely "Kato" mm) are accumulated during coir pith extraction process as a waste material, which has been an issue in the production process. There is a potential to utilize "Kates" as an economically viable raw material to manufacture coir boards (CBs). CBs can be used as alternative source for Hard & Particle Boards and other Synthetic Boards. An effort was made to develop a CB as an alternative to the above boards evaluating the basic parameters. Processing was undertaken using a coir cutter machine and then it was developed in to CB. Each CB (15 x 15 x 0.5 cm) was prepared using 35 g of "Kcitu" changing the mass of Natural Rubber Latex Compounds (NRLC) and Phenol-Formaldehyde Resin (PFR). Mass of NRLC in CBs varied as 30, 40 and 50 g and the PFR as 5, 10, 15 and 20 g. Having moulded, vulcanization was carried out at 120 °C for 20 min. For the CBs, moisture content (%), density (kg m-3 ), water absorption (%), swelling and physicomechanical properties such as maximum force at break (N) and maximum elongation (%) were evaluated according to ASTM and IS standards. Tests were carried out at 27 °C temperature. CBs were prepared successfully by optimizing the composition. The density of CBs was within the acceptable range: 465.8 - 653.61 kg tn-3 , which is close to the density of 'Hard Boards' and 'Particle Boards'. Moisture content, water absorption and swelling properties were up to the standards. The force at break and maximum elongation showed an increase when the amount of NRLC and PFR was increased. In conclusion, "Katu" can be used as an effective raw material for manufacture of CBs reinforcing with NRCL and PFR for the use of other boards given above. Keywords: Coir fibre board, Natural rubber, Phenol-formaldehydeItem Visco-elastic properties of OMMT filled fractioned bleached crepe rubber(Uva Wellassa University of Sri Lanka, 2015) Wijesinghe, H.G.I.M.; Alakolanga, A.G.A.W.; Withanage, N.S.; Ratnayake, U.N.Natural Rubber (NR) latex tapped from Hevea brasiliensis converts into an important engineering material for different applications. NR latex pale crepe, the purest form of NR produced by Sri Lanka, is mainly used in pharmaceutical and surgical applications, infant toys, food contact rubber articles and adhesives, (Senevirthne and Kumara, 2003). Natural Rubber has a higher greenstrength as but it is soft and has lower dimension stability (Cohan and Spielman, 1948) which is one of the major draw backs in NR for engineering application. Recently, Nanoclays such as montmorillonite clay are attracted as an alternative filler to achieve the reinforcement of rubber compounds by replacing conventional fillers (Ratnayake and Peiris, 2010). Study the effect of Organo-montmorillonite (OMMT) on the visco elastic properties of fractioned bleached crepe rubber will helpful for the advancement of the raw rubber industry as value addition. In this study, OMMT dispersion in the rubber matrix has studied not only by Mooney viscosity and stress relaxation properties but also by the physical properties of vulcanizates. Therefore this study may help to have an advantage for the development of crepe rubber industry and product manufacturing industry in Sri Lanka. Material and Methods NR field latex was obtained from NR processing factory at Rubber Research Institute, Dartonfield, Agalawaththe. Montmorillonite clay modified with quaternary alkyl ammonium salt (OMMT)was used as the nanofiller. Other general chemicals and laboratory equipment were obtained from Rubber Research Institute, Rathmalana. Initially, 5%(w/w) aqueous dispersion of OMMT was prepared using a surface active agent as a dispersing agent. Latex mixing/intercalation method(Gatos and Kocsis, 2010) was carried out to prepare OMMT filled fractioned bleached crepe rubber (OFBCR). Dry rubber content (DRC) of fractionated bleached latex was diluted up to 10% and subsequently OMMT dispersion was incorporated to latex samples at OMMTloading from 0 to 8 phr with an interval of 2 phr, with simultaneous stirring.Standard latex crepe manufacturing procedure was adopted to prepare OFBCR (Senevirthne and Kumara, 2003). Laces were dried in the drying tower at 34°C for three days. Complete randomized design was applied to assign treatments, T 0(0 phr), T2 (2 phr), T4 (4 phr), T6 (6 phr) and T8 (8 phr). The NR was characterized based on DRC and the OMMT was characterized by the ash content. Money viscosity and stress relaxation of OFBCRs were measured according to the [ISO/R 289- 1963] by the Ektron Mooney viscometer. Then the OFBCR samples were compounded according to the pre-determined formulation. Curing characteristics of the OFBCR samples were measured by using MDR 2000 (moving die rheometer, M/S Alpha Technologies, USA) at 150°C according to the ISO 3417:2008 procedure. OFBCR samples were moulded by hydraulic hot press at 150°C temperature and 20MPa pressure for optimum cure time derived from the cure characteristics data.The tensile properties of OFBCR samples were determined by “Instron 3300 Series” material testing machine at a crosshead speed of 500 mm/min as per ISO 37:2011. The hardness of the samples were determined using Elastocon bares digi hardness tester according to the ISO 48:2010. Compression set at constant strain was measured according to ISO 815-1:2008 test method andtear strength of OFBCR samples were determined by “Instron 3300 Series” material testing machine at a crosshead speed of 500 mm/min according to ISO 34- 1:2011. All tests were carried out at 27±2°C and each test was replicated at least 3 times. Data were analyzed by using the Minitab 16 statistical software with the use of General Liner Model (GLM) with Tukey’s all pair wise comparison tests at 95% confidence interval. Results and Discussion Field latex used for the preparation of nano crepe rubber showed the dry rubber content of 30%. OMMT clay has modified with quaternary alkyl ammonium salts. The ignition weight loss of OMMT is 43%–48%. Ash content of clay is 52%-58%. This ash content represents the amount of silicates and other inorganic metal amount in the clay. Ignition weight loss is correlated to the amount of quaternary ammonium alkyl modifier and adsorbed moisture amount in the clay. Mooney viscometer is an instrument to measure the 'stiffness' of uncured compounds, the result of that viscosity is called as Mooney viscosity at ML 1+4 (100°C). Mooney stress relaxation coefficient is the slope of the power law model when it is in logarithmic scale (log M = a(log t) + log k) where M- torque units from the Mooney stress relaxation test, k- a constant equal to torque 1 s after the rotor has stopped, ‘a’- an exponent that measures the rate of stress relaxation and t- testing time. Also elasticity of rubber material is inversely proportionate to the ‘a’andlower elasticity improves the mixing of rubber and processing, especially extrusion and calendaring. Malac J., (2009). Clay loading level (phr) has significantly affected to the Mooney viscosity expressed as ML (1+4) 100°C of OFBCR samples (p-0.000). Only T6 and T8 has not indicated a significant difference (p-0.0569) between them with respect the Mooney viscosity but all other treatment levels are significantly different among (p-0.000). Mooney viscosities for T0, T2, T4, T6 and T8 are presented in Figure 1. The reason for the reduction of Mooney viscosity is, when increasing the OMMT loading, the plasticization of rubber material by OMMT and may possibly be the chain slippage over the clay platelets (Kader et al., 2010). As reported in Figure 2, the stress relaxation coefficient has increased up to 4 phr and there after it reduces. The maximum stress relaxation coefficient has indicated at the 4 phr clay loading level, therefore, it can be concluded that OFBCR with 4 phr OMMT clay loading has a better processability than other samples. Long relaxation times and high amplitudes of stress relaxation suggest the mechanism of structural relaxation involving large-scale displacements of isolated clusters of nanoparticles within the rubber matrix and vice versa (Dick, 2010).Item Visco-Elastic Properties of Organoclay Filled Nano Crepe Rubber(Uva Wellassa University of Sri Lanka, 2014) Wijesinghe, H.G.I.M.Hevea brasiliensis latex is used to manufacture two crepe rubber types called fractioned bleached (FB) andunfractioned unbleached (UFUB). In rubber manufacturing, conventionally, Carbon Black, CaCO3 and china clay are used as fillers in rubber industry to enhance physical properties and improve the cost performance ratio, but it consumes greater amount of fillers compared to nano fillers. In this study Organoclay/OMMT was used as the nano filler. Most of the time crepe rubber is filled with fillers by melt intercalation method. Literature has indicated that OMMT's latex intercalation method is better than melt intercalation method when considering the nanoclay dispersion in the rubber matrix. Therefore, in the 1St phase, OMMT filled crepe rubber laces were produced by latex intercalation method by adding 5% OMMT dispersion into both FB and UFUB latex as 0,2,4,6 and 8 phr levels and then raw rubber properties were evaluated according to the ISO procedures. In the 2nd phase, the crepe rubber compounds were prepared for each sample and curing and physical properties were evaluated following ISO procedures. The raw rubber properties of nano crepe rubber (NCR) have been indicated reduction of PRI and Mooney viscosity when increase the clay loading level and maximum stress relaxation at 4 phr level of clay loading. Rheological behaviours of NCRs have been indicated an increased cure rate indices and maximum torques but shorter scorch times with the filler loading. Maximum hardness has achieved at the 8 phr loading level for both FB and UFUB nano crepe rubbers, they are 45.4a and 44.8' (IRHD) respectively. Tensile strengths of FB 6, FB 8, UFUB 6 and UFUB8 are 24.35a, 25.38a, 24.38a and 24.42a (MPa) respectively and are the maximum tensile strengths. Moduli at 100% and 300% increase dramatically compared to the gum vulcanizate as a function of clay loading up to 6 phr level for both NCR types and then reduce. Compression set has been maximized at 6 phr (FB 6-15.28% and UFUB 6-15.18%) loading level for both NCR types. Minimum abrasion volume loss has achieved in FB 6 (132.7mm3) and UFUB 4 (146.6mm3). In conclusion, FBNCR has performed better than. UFUBNCR at 4 and 6 phr OMMT loading level because the better dispersion of OMMT in the FB crepe rubber than UFUB crepe rubber. Key words: Natural rubber (NR), Nano crepe rubber (NCR), OMMT