Master of Science in Polymer Technology

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item: Thesis-Abstract
Application of polyethylene terephthalate scraps for the manufacturing long oil alkyd resin
(2012-12) Darshana, LAP; Gunapala, O; Premarathna, T
A new aspect of work that covers Polyethylene terephthalate (PET) waste recycling and application in coating industry is presented through this report. It was shown that chemical recycled PET can be used in the manufacturing long oil alkyd resin. In Sri Lanka alone, about 6.5 million polyethylene terephthalate bottles (water bottles, food and other liquid containers, etc) are used monthly. Then large amount of Polyethylene terephthalate scraps are discharged in to the environment. The development of effective recycling technology was based on chemical de-polymerization of post-consumer PET bottles in order to use manufacturing alkyd resin based paint. The depolymerization of PET can be carried out in many ways such as glycolysis, hydrolysis, aminolysis, methanolysis and simultaneous hydrolysis and glycolysis. The useful material terephthalic salt can be synthesis through the hydrolysis process of PET. That could be used to derive terephthalic acid. This terephtalic acid can be used for alkyd resin process. Alkyd resins were any of a large group of thermoplastic resins that were essentially polyester made by heating polyhydric alcohol with polybasic acids or their anhydride and used chiefly in making protective coatings. Originally, alkyd resins were merely the reaction products of phthalic anhydride and glycerine. But these products were too brittle to make satisfactory coatings. The use of oils or unsaturated fatty acids in combination with the brittle alkyds resulted in the air-drying coatings which revolutionized the chemical coating industry. The properties of Terephthalic acid have far same to the phthalic acid. Phthalic anhydride was used as a main material in esterification reaction of alkyd resin process. Then pththalic anhydride could be replaced by Terephthalic acid. This process has been done in two stages. At the first stage, reaction between PET waste and sodium hydroxide were used to produce terepththalic acid. At the second stage, application of terepththalic acid was done in the manufacturing process of long oil alkyd resin. That could be used in industrially. Terephthalic salt could be produced successfully by hydrolysis process using Ethylglycol and sodium hydroxide at the higher temperature (180°C). The reacting mixture was neutralized using strong Acid to take Terephthalic acid. Then terephthalic acid could be applied in alkyd resin process without filtering. This new application of the recycled PET in synthesis of alkyd resin had provided same properties of normal alkyd resins. This method was cost saving method by reducing Rs. 3.00 per one kilogram of resin. As well as this can be used as environmental friendly method to give a better solution for the environment pollution due to plastic waste.
item: Thesis-Full-text
Improving properties of cement based skim coat through controlling water absorption using a vinyl acetate-ethylene copolymer
(2020) Wickramanayaka S; Prasantha MAB; Premachandra J
Improving properties of cement-based skim coat through controlling water absorption using a Vinyl Acetate-Ethylene copolymer This study aims to describe and complement the existing knowledge on the effect of re-dispersible polymer powder (RDP) on water absorption (capillary and surface), application and mechanical properties of cement-based skim coat. The skim coat is a mixture of cement (binder), dolomite powder (filler), cellulose thickener (water retention agent) and re-dispersible polymer powder as a performance-enhancing additive. In this study, commercially available white cement with CEM 42.5 N strength class, Methyl Hydroxyl Ethyl Cellulose (MHEC), Vinyl acetate-ethylene copolymer (RDP) and locally available dolomite powder with particle size below 150 microns have been used. The dosage of RDP was changed from 0% to 2.5 % by the total weight of the formulations. Furthermore, to evaluate the effect of MHEC on the application and final properties of the cement-based skim coat, the MHEC amount was changed from 0 % to 0.4% by the total weight of the formulation. Three white cement-based skim coat products from the market were used to compare the effect of the RDP addition. Water to skim coat mixing ratio was kept constant at 35:100 throughout the experiment. It was found that RDP improved the mechanical properties of the dried skim coat and application properties of the fresh skim coat paste. Adhesive strength and flexural strength were increased with RDP dosage while compressive strength had an optimum RDP level between 1%-1.5%. Open time and setting times were positively affected by RDP dosage and optimum flow properties were achieved at 1.5% of RDP. Both capillary and surface water absorption were reduced with the addition of RDP and reached the lowest at 1.5 % wt. All the application and final performance of the skim coat were improved from 0% to 0.4% with the addition of MHEC.
item: Thesis-Abstract
Development of natural rubber based compounds for manufacture of abrasion resistant gloves
(2020) Ranasinghe PVSK; Gunapala O
Industrial glove industry is a glooming industry which focuses performance enhancement with lowest possible cost. Abrasion resistance is one of the main performance indicators of an industrial glove. Abrasion resistance was improved in the study using reinforcing filler material and a coupling agent with a minimum cost. Surfynol was selected as the best dispersion agent to couple with fume silica and precipitated silica from a range of dispersion agents. Both silica materials were optimized for loading level and fume silica was selected as the filler with most abrasion resistance. The optimized loading level for fume silica was 7 parts per hundred rubber. Silane was used as the coupling agent for the semi-reinforcing filler material and it was optimized as 0.5 parts per hundred rubber for the best abrasion performance. The samples were tested and validated for abrasion resistance, tensile strength, cut resistance, tear resistance, puncture resistance, stiffness, grip and aging. Microscopic view of fume silica loaded glove sample was compared with that of calcium carbonate loaded glove sample and validated for subject of uniformity of coating layers. Abrasion resistance was improved by using reinforcing filler fume silica instead of non-reinforcing filler calcium carbonate. Silane was used as the coupling agent and it was optimized for the best abrasion performance. This newly developed receipt helped to improve the abrasion resistance by 6 times compared to traditionally manufactured gloves out of natural rubber latex filled with non-reinforcing filler calcium carbonate.
item: Thesis-Full-text
The Effect of pre-vulcanization time and vulcanization temperature on inter-layer adhesion and physical properties of middle and tread layers of solid tire
(2020) Kodikara SKNN; Premachandra BAJK
Resilient solid tires are used for industrial vehicles. Three-layer resilient tire composed of heel, middle and tread layers; the integrity of layers is empirical throughout the service life. This thesis investigated inter-layer adhesion capacity between middle and tread layer. The two compounds were pre vulcanized into 6 levels (0%,20%,40%,60%,80%, and 100%) at 100 °C, by changing the Pre-vulcanization time. Primary vulcanized sample was vulcanized secondarily at 150 °C and 170 °C; inter-facial bonding strengths were compared. Increased secondary vulcanization temperature decreased the inter-layer adhesions. Based on adhesion strength, manufacturing limitations and physical properties, the optimum primary vulcanization level selected. To develop acceptable bonding at 0% pre vulcanization of middle layer, the tread layer could pre vulcanized up to 80% at 150 °C secondary vulcanizing temperature and up to 20% at 170 °C. At 20% pre vulcanized middle layer, tread layer could pre vulcanized up to 60% and 20% at secondary vulcanization temperature of 150 °C and 170 °C respectively. At 40% pre vulcanized middle layer, tread layer could pre vulcanized up to 40% at 150 °C secondary temperature; but at secondary temperature of 170 °C, tread layer bonded well only at 0% degree pre vulcanization. In conclusion, 40% of middle and tread layer pre vulcanization levels are suggested as optimum pre vulcanization level at secondary vulcanization temperature of 150 °C, 20% of middle and tread layer pre vulcanization levels was the optimum for secondary vulcanization temperature of 170 °C. Out of two secondary vulcanization temperatures, 170 °C and 20% of middle and tread layer pre vulcanization levels suggested as the optimum pre vulcanization level
item: Thesis-Full-text
Study of the effect of different carbon black combinations on physico-mechanical properties of natural rubber based solid tyre tread compound
(2020) Pathirana KPTC; Egodage S
The performance and the life-time of a solid tyre depend on the properties of the solid tyre tread compound. Abrasion resistance and rebound resilience are the key parameters of the solid tyre tread compound. Carbon black types used in tread compounds and carbon black ratio in the combined filler are the main contributors for the above two properties. But these two properties behave in contradictory ways such that when carbon black particle size is small, the abrasion resistance is high when rebound resilience is low. Hence most suitable carbon black type and ratio should be selected into solid tyre tread compound to have the optimum abrasion resistance and rebound resilience. In this research, the effect of N220 and N330 carbon black grades and their ratio on solid tyre tread compound was studied. N220: N330 ratio was varied in the combined filler from 0:50 pphr to 50:0 pphr to find the optimum ratio, which provides the best abrasion resistance in solid tyre tread compound. N220:N330 optimum ratio was observed as 30:20 at observed maximum tensile properties and abrasion volume loss was at its lowest point. Further, the highest standard deviation of carbon black aggregate size was observed for this ratio and that ratio has shown the highest reinforcement in the solid tyre tread compound.
item: Thesis-Full-text
The Effect of incorporation sequence of curative ingredients on cure characteristics of solid tire middle compounds and properties of resultant vulcanizates
(2020) Fernando RPA; Siriwardena S; Egodage S
The purpose of this research is to study the effect of modification of incorporation sequence of accelerator and activators on cure characteristics, physical properties, mechanical properties and dynamic properties of solid tire middle compound. Accelerator-activator masterbatch (MB) was prepared by mixing activators & accelerator in a rubber phase. A series of masterbatches were prepared using different concentrations and maturation periods of accelerator-activator combination and pre-vulcanization inhibitor. They were subsequently used in 1st stage compound mixing of a solid tire middle compound. Cure characteristics and selected properties of these masterbatches incorporated solid tire middle compounds were studied. Economics analysis of the best system among the candidate systems was also carried out. It was found that the cure rate index improved by 52% with the accelerator-activator MB compared to the conventional method of curatives usage when 58.5 pphr accelerator-activator MB is used. No significant effect of the maturation time of MB on the cure characteristics and other properties was found. With the incorporation of activators and accelerators in the MB form, scorch time of the compound showed a slight drop which was overcome by the addition of 0.3 pphr pre-vulcanization inhibitors at the 2nd stage mixing stage. Mechanical properties, dynamic properties, and visco-elastic properties of vulcanizates prepared using accelerator-activator MB and conventional methods were compared. Tensile strength, elongation at the break, blow-out time and storage modulus showed an improvement when MB incorporated vulcanizate with a slight reduction in 300% modulus, heat build-up, crosslink density, and loss modulus. It was found that cure rate index improvement achieved associated with the reduction of curing cycle and energy consumption by around 10% and 12% respectively while maintaining other properties studied within the standard range of the conventionally prepared ones
item: Thesis-Full-text
Enhancing the cushioning effect of solid tire cushion compounds by introducing thermally expandable microspheres
(2020) Rajapakse RASN; Jayasuriya CK; Premachandra J
Solid tire industry is a rapidly growing industry all over the world with a very high demand for different kinds of material handling equipment manufacturing companies. In this case, resilient tires are playing a major role. Resilient tires are widely used in different kinds of applications especially in material handling equipment like forklifts. Mostly this equipment will be used in different environmental conditions like severe sun light, heavy rain, extreme wind, etc. In addition to that, this equipment will be running on different kind of ground conditions like metal yards, concrete pavements, and severely damaged floor conditions etc. When it comes to the tire manufacturer, it is their responsibility to produce tires as per the customer requirement in order to satisfy the basic needs of the customer. In this case, “Resilient tires with good comfort” is one of the key requirements which is coming from the tire users. Base, Cushion & Tread are the three main components of a resilient tire. Base component is the part which is mounted to the vehicle whilst the Tread part will be in contact with the ground surface during motion. Cushion part will act like a bridge between base and tread by delivering perfect comfort to the machine operator. When it comes to the material handling vehicles like forklifts, they are heavy duty machines and operator comfort is very important during running conditions. In order to facilitate a perfect comfort, function of the cushion part plays the major role which can be described technically as “Cushioning Effect”. Even though it is important that the factor cushioning effect of a resilient tire, there are some limitations and challenges to overcome for tire manufacturers to optimize the cushioning effect whilst maintaining other tire properties at the desired levels. Main challenge is to keep the cushioning property at its optimum level and maintain the other physical properties like tensile, hardness, modulus, elongation, tearing, etc. In general, cushioning effect is gained by using a blend of semi-reinforcing carbon black with different particle sizes. Since the use of this blend has many limitations, a serious requirement is there to find a better solution to enhance the cushioning effect of resilient tires whilst maintaining other required properties at the specified levels. This study is an effort of enhancing the cushioning effort of resilient tires by incorporating Thermally Expandable Microspheres (ThEM) into the cushion compound. New compounds were produced by introducing variable ThEM quantities and compared with the regular cushion compound. A series of compound and tire tests were performed in order to identify the perfect formulation with better performance.
item: Thesis-Full-text
Prediction of thermal conductivity of natural rubber compound filled with carbon black and graphite
(2020) Batuwatte EAPR; Gunapala O
I hereby would like to acknowledge the immense guidance received from my thesis supervisor Dr. Olga Gunapala. Your support and direction to produce quality work is highly appreciated. Also Professor Jagath Premachandra, our course coordinator for the post graduate degree in polymer technology 2016 batch, your encouragement, and support throughout the course was truly encouraging. In addition, the support received from Professor Narayana on the numerical and modelling part was highly acknowledged. Professor Rathanasiri’s insights and comments on the modelling part were very helpful. Furthermore, postgraduate student of the department Mr. Chathuranga Wickramasinghe, your support on the numerical modelling was very useful and productive. I also take this opportunity to thank all the lecturers and staff of the Moratuwa University and all the external lecturers who guided us throughout the postgraduate course. Would like to convey my very special thanks to Mr. Anura Liyanage, Mr. Saliya Gunasekara, Mr.Likitha Lasantha, and all the staff at Bogala mines Sri Lanka for also updating on the existing research project and their valuable insights on the project. In addition, the staff including Mrs. Udara, Mr. Nuwan, and Mr. Asanka in the department of chemical and process that assisted me in various ways during this course. My loving parents, sister, and my wife who supported me all the way through, your presence in my life is a blessing. That level of unconditional love and caring, cannot be quantified yet enable me to be the best version of me. I am very grateful to all of you and your loving kindness.
item: Thesis-Full-text
Study on the cure characteristics of solid tyre middle compound prepared with different technically specified rubber grades
(2020) Ediriweera GJU; Jayasuriya C
Cure characteristics of solid tyre middle compounds are critical as it combines the heel and the tread compounds. Also middle compound is subjected to have high heat build-up due to continuous deflection. In this study cure characteristics of solid tyre middle compound were investigated by preparing the middle compounds with different TSR grades. Three different grades of technically specified rubbers TSR-5L, TSR-10 and TSR-20 were used for the study. All the grades were tested for raw properties such as dirt content, ash content, nitrogen content, plasticity, plasticity retention index and viscosity. Molecular weight and molecular weight distribution of TSR grades were also compared by the frequency sweep test using rubber processing analyzer. Solid tyre middle compounds were mixed using laboratory Banbury mixer and laboratory mill machine in controlled laboratory conditions. The effect of raw rubber properties, molecular weight and molecular weight distribution of three different TSR grades on cure characteristics of solid tyre middle compound were evaluated. It can be concluded that the significant effect can be observed on cure characteristics of middle compound against TSR grades. Also molecular weight of TSR can be positively correlated with middle compound ML value.
item: Thesis-Full-text
Development of a solid tire black tread compound with extremely low polycyclic aromatic hydrocarbon content
(2020) Anthony Pulle VAS; Edirisinghe DG; Premachandra BAJK
The Polycyclic Aromatic Hydrocarbons (PAHs) can be identified as a large group of organic compounds. These organic compounds have two or more fused aromatic rings that contain only carbon and hydrogen atoms. These PAHs are non-polar compounds, lipophilic and insoluble in water. Drinking water can be contaminated with PAHs and PAHs can be available mainly in coal and tar deposits. PAHs are hazardous and the extent to which it is hazardous depends on concentration of PAHs, time duration of exposure to PAHs and the type of PAHs. All PAHs are not hazardous to human health. Human exposure has various methods such as smoking rates, fuel types in cooking, pollution control on power plants, industrial processes and moving vehicles. Two methods are readily available in vehicle, which is emission of incomplete combustion of fuel and worn off parts in tires. Tread compound in tires is a source of PAHs due to the presence of some raw materials used in compounding such as processing oil and carbon black. Tire tread part contains up to 28% of extender oil to provide the required elasticity and stickiness. High aromatic (HA) oil content in car tires is in the range of 6% to 8% of the total tire mass and between 11% to 16% of the tread. These HA oils have a PAH content between 300-700 mg kg-1 and tire has an estimated PAH content in the range of 13.5 mg-112 mg kg-1. Default (tread) compound of industry was selected for this project and a rubber compound was developed with an extremely low PAH level by using alternative raw materials such as PAH free carbon black, glove reclaim (white), vegetable oil derivatives and coconut shell powder. The number of PAHs in the compound reduced to 13.48 mg kg-1 from 51.6 mg kg-1 .
item: Thesis-Full-text
Investigation of the effect of mold releasing agent and residual calcium nitrate/calcium ion of nitrile higher mil gloves to wet look defect
(2020) Weerakon W M V B; Walpolage S
Two types of latex are used in disposable gloves manufacturing as natural latex and synthetic latex. Calcium nitrate (calcium ion) is used as the coagulant and calcium carbonate or calcium stearate is used as the former releasing agent. In pre leaching of natural latex gloves, protein removal also required other than the calcium nitrate removal and post leaching is necessary to further removal of protein. Effectiveness of leaching depends mainly on - three factors as leaching time, leaching tank condition and leaching temperature. In natural latex gloves, it can be maintained leaching takes place at a higher temperature since natural rubber has a high crystalline temperature. But in synthetic latex gloves manufacturing, it cannot be kept at the leaching tank temperature at higher temperatures since the glove becomes hard since its crystalline temperature is low. If the glove film has high thickness, leaching is difficult. Limitation of water supply and high wastewater treatment costs are the main issues with leaching. Chlorination is used to modify the disposable glove surface by reducing the tackiness which is a characteristic of rubber. Chlorination reduces the friction between the rubber surface and the other surface which come into contact. There are two types of chlorination as online chlorination and offline chlorination. Online chlorination is done by immersing the glove into a chlorine water tank before removing the glove from the former. At online chlorination, the inner surface of the glove gets smoother. If smoothness of the outside surface also requires, offline chlorination is done as a batch process in chlorinators (a machine like a washing machine). Other than that, chlorine water solution can convert calcium carbonate/ calcium stearate which is used as the former releasing agent to calcium salts. There are some disposable gloves which the chlorination is in complete. Chlorination is used to reduce the tackiness resulted from this incomplete chlorination. Calcium ion can absorb moisture from the surrounding. If calcium ion remains on the latex glove surface, it gives a wet look by absorbing the surrounding moisture. In the industry, it is called “Oil marks”. The degree of wet look depends on calcium ion concentration and surrounding moisture content. If the glove surface contains a iv moisture absorbing material like calcium carbonate or corn starch, wet look is not visible even if the glove surface has a significant amount of calcium ions.
item: Thesis-Full-text
Sodium lignosulfonate and sodium polyacrylate mixture as a dispersing agent for calcium carbonate suspensions
(2020) Adhikari U; Premachandra J; Jayaweera JPN
Preparation of low viscous and high filler loaded calcium carbonate suspension in the aqueous medium is an industrial requirement. To minimize disturbance of handling and processing, to reduce transportation costs and to avoid transportation of excess water, calcium carbonate slurries need to be produced in high solid content. The currently available dispersing agent is less efficient. Therefore an investigation was carried out to prepare an efficient dispersing agent. A different percentage of sodium lignosulfonate was used to mix with the sodium salt of poly (acrylate) to prepare combined dispersing agents. Dispersing agent samples were tested in calcium carbonate powder – water mixture at 45% solid content. Viscosity values vs adding dispersing dosage were measured with a Brookfield viscometer in order to select the more efficient dispersing combination. The maximum filler loading percentage was conducted base on the selected dispersing combination. Different shear rates were applied to higher filler loaded calcium carbonate suspension to the optimized most dispersed shear rate at the lowest viscosity. Final calcium carbonate suspension and temporary prepared suspension particle size, polydispersity index and zeta potential values were measured and compared. The findings were then applied to prepare pilot-scale calcium carbonate suspension. The developed combined dispersing agent was more efficient. It was possible to prepare calcium carbonate suspension with high solid loading (75%) at low viscosities.
item: Thesis-Full-text
Effect of replacement of calcium carbonate by fly ash on processability and thermo-mechanical properties of solid tire middle compounds
(2020) Sandaruwan AHWO; Siriwardhana S; Egodage S
In this study, as the first step, the effect of partial replacement of CaCO3 with unmodified fly ash on the curing characteristics of the solid tire middle compound and the properties of its vulcanizate was investigated. Fly ash and CaCO3 were first characterized. A series of solid tyre middle compounds with varying CaCO3 / fly ash loading were prepared in a laboratory-scale internal mixer. The total content of non-reinforcement filler was kept constant. Fly ash loading was increased from 0 to 60 pphr intervals with replacing CaCO3. The dispersion level was evaluated using the α view and SEM studies. Curing characteristics of the compounds were evaluated. Filler dispersion levels of the compounds and mechanical, rheological and physical properties of the respective vulcanizates were then focused. The unmodified fly ash filled rubber compound with optimum filler loading was selected based on the above properties. In the second step of the study, the same studies were carried out with a smaller particle size (modified) fly ash filled NR compounds loaded with the selected filer loading. It was shown that dispersion level was reduced with the addition of fly ash. Dispersion was improved with the incorporation of fly ash with reduced particle size and narrow particle size distribution. SEM studies showed a higher tendency of particle agglomeration with increasing loading of fly ash. It was found that MH and ML values of the rubber compounds were deteriorated with the increase of unmodified fly ash loading and the values were improved when fly ash with smaller particle size was used. However, no impact was observed on curing characteristics either with the replacement of CaCO3 with fly ash, it's loading nor their sizes. The hardness of the vulcanizates of the unmodified fly ash incorporated compounds was increased with the increase of fly ash percentage. Tensile strength, tearing strength, elongation at break and modulus showed a general reduction with the increase of unmodified fly ash except for tear strength, which had reduced only up to 45 pphr and shown a slight increase in 60 pphr of fly ash added sample. When the overall performance was considered, rubber compounds and vulcanizates prepared with 30 pphr fly ash loading showed the most comparable properties. Studies carried out in the second stage, it was found that physical properties were improved with the use of fly ash with smaller particle size and narrow particle size distribution (0-53 μm) compared to unmodified fly ash incorporated compounds. Rebound resilience values were reduced with the increase of the fly ash percentage. Dynamic mechanical properties such as heat build-up and blowout time were deteriorated with the addition of unmodified fly ash and results were improved with the use of small particles of fly ash. Tan delta value which depends on loss modulus and storage modulus shows a neutral role. Based on the study, it was concluded that there is a potential to replace 50% w/w (i.e. 30 pphr) of the CaCO3 loading from the fly ash with smaller size particles without a significant adverse effect on the curing, physical, mechanical and rheological properties.
item: Thesis-Full-text
Design of plastic rim for industrial and commercial light vehicles using modeling and simulation tools
Gunapala, DL; Egodage, SM
The present research was devoted to designing a plastic rim for industrial and commercial light vehicles using modeling and simulation tools. The main objective of the design project was to design a rim structure that would be capable of sustaining the required load and performing under provided conditions. In order to select a suitable thermoplastic composite a series of plastics was experimented. The selection of material was based on several factors, including mechanical strength under dynamic load, resistance to prolonged action of elevated temperatures and ability to be molded with conventional techniques. The materials which were considered for the design included Polyamide 6, Polyamide 6 with 50% long glass fibers, Polyamide 6 with 50% short glass fibers and Polyamide 6 with 30% short glass fibers, out of which Polyamide 6 with 30% short glass fibers was selected due to it being less brittle, that aided the material to withstand service and accidental impact. Another criterion that supported selected material was associated with its ability to be injection molded with conventional type injection molding techniques. Four models were developed based on general plastic product design standards. Each model was simulated in order to identify areas of potential failure. After that model was optimized by changing its structural arrangements so as the stresses in the potential failure areas were reduced. Next step in modification and optimization ofthe model was done for product mold-ability. The model which comprised a solid body of rim portion with a center bore configured to receive axle hub, an inner band, a circumferentially extended outer band that margined the rim portion, a nave ring that extended outwardly and radially ofsaid center bore wherein a plurality of holes were circularly positioned that were configured to receive bolts, a plurality of ribs extending outwardly and radially at right angles from the nave ring up to the outer band were positioned both sides ofthe rim configured to improve flexural rigidity of the structure was accepted for fabrication by means ofreinforcement of hub hole area with metal plate. A manufacturing method of plastic rim was selected based on the material processbility, manufacturing cost and efficiency for serial manufacturing and commercialization. Prototype Injection mold was manufactured using cheap and easy to machined steel P-20. Produced standard mold was modified to improve ventilation and to facilitate flow of the plastic melt through the flow path of the injection mold from machine nozzle to cavity The successful prototypes and destructive tests carried out affirmed suitability of the Solidwork Design package and Solidwork Simulation Package for designing, manufacturing and prediction of load bearing capability of the plastic rim. The application of Solidwork Simulation Package during designing stage lead to reduced implementation cost and reduced reproduction numbers of prototypes to evaluate product suitability, thereby making implementation ofthe final product efficient. The main advantages of using plastic composite material for automotive rims included energy efficiency and easy maintenance due to lower weight
item: Thesis-Full-text
Modeling a cylindrical rubber block of tyre tread compound for predicting the temperature profile under heating condition
(2019) Kumara CK; Walpalage S
In the rubber industry, curing is very important parameter. There are many methodologies are used industrially in order to predict the optimum curing time of rubber product. The methodologies are mainly two types as practical and numerical approaches. In the practical approach, it is used a lot of manual activities to collect the temperature distribution within the rubber product. It is time consuming and non-economical method. Therefore, most of the industries are attempting to develop numerical models for the rubber curing. Nowadays the trend is to develop software-based numerical modellings to predict not only the temperature distribution but also state of cure of the rubber product. In this research it was attempted to predict the temperature profile of cylindrical tread rubber block using a well-known software called Solidwork. The accuracy of the model was verified by practically measured data. In order to match practical temperature profile, with the modelled figures, the thermal properties were changed. Even though there are several thermal properties such as thermal conductivity and specific heat capacity, the critical thermal property is the thermal diffusivity. Based on the results, the prediction of temperature profile with the default settings of the software and fixed thermal properties would not be possible.
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.
item: Thesis-Full-text
Standardization of friction cords and its application in rubber formulation technology
Ahugammana, KTPM; Gunapala, O
Dramatic growth in both the use and manufacturing of pneumatic tires including car, bus, truck and airplane tires have led to the accumulation of calendering scraps referred to as unvulcanized rubber friction in junkyards where they pose a fire threat and breeding sites for animals including rodents and insects spreading various diseases. These scraps appeared in bulky nature were subjected to a size reduction process in order to produce friction cords. Since calender scraps cannot undergo natural degradation, piling up of them causes definitely a huge environmental problem. Environment is benefited greatly by reusing these materials as friction cords. Additionally, rubber products manufacturers use friction cords in blends by incorporating them into their rubber compounds. Friction cords are manufactured from leftover materials and as a result they are definitely a cheap product at the market. This results in lowering the final cost of products manufactured by blending friction cords. Six samples of friction cords collected from each bulky material were tested for basic physical properties including specific gravity, hardness, tensile strength, elongation at break, moisture content and rheological properties such as ts2, tc90, ML and MH. Results obtained showed that each and every property of each bulky material varied and that variation occurred from one material to the other. Therefore the main objective of this study was to standardize friction cords by physically mixing one material with the other in different weight proportions. Results obtained for each blend/mixer showed that all tested properties including specific gravity, hardness, tensile strength, elongation at break and moisture content could be controlled within the required range and it was concluded that friction cords can be standardized by mixing them at different weight ratios. In addition, variation in rheological, physical and mechanical properties of fiber filled rubber compounds were studied by replacing nylon flocks partially and completely with friction cords. Results obtained showed that minimum torque, scorch time (t10), optimum cure time (tc90) decreased with the addition of increased quantity of friction cords. However, maximum torque increased with increased loading of friction cords. There was no significant change in specific gravity and elongation at break. But hardness modulus at 100 % elongation, tensile strength gradually increased with the addition of friction cords.
item: Thesis-Full-text
Effect of lignin base antioxidant on natural rubber base solid tyre tread compound
Gunasekara, HDA; Nilmini, R; De Silva, k
The purpose of this research was to study the feasibility of lignin as an antioxidant for tire tread compounds. Lignin is naturally abundant and cost competitive wood derivatives possessing antioxidant properties and offering reactive functional groups on their surfaces. Further, lignin is a natural, non-hazardous and sufficiently bio degradable material. The present study deals with a natural rubber based tire tread compound containing different antioxidant combinations. Lignin as a bio polymer was combined with commercially available antioxidants (6PPD and SKF) to investigate from the view point of their thermo-oxidative aging. The research specifically focused on producing tire tread compound for industrial applications. Physico-mechanical properties such as tensile properties tear strength, hardness, abrasion and flexing, and cure characteristics, on tire tread compound was investigated before and after thermo-oxidative aging. The results obtained are shown that the lignin exerts a stabilizing effect. Moreover lignin blends with the selected antioxidants increased the stabilization effect. The conclusion extracted from this study demonstrates that the higher potential of using lignin as a natural antioxidant substitute for commercial tire tread compounds
item: Thesis-Full-text
Design of Polyethylene based multilayer extrusion blown film for manufacture of leak free packaging
Hettiarachchi, ND; Gunapala, O
Flexible packaging is a growing market and the majority of flexible package applications are for the food industry. The demand for process optimization and reduced production costs has led to an increase in flexible packaging. And reducing wastage in production line, during storing and transportation is a critical aspect which food product anufacturers are highly concerning.These wastages are higher for liquid products packing flexible materials. That is due to contamination in the seal area. Most of the time liquid products are packing in Vertical-Form-Fill-Seal (VFFS) machines. Therefore seal through contamination is highly occurring while packing of liquid products. The study uses three types of liquid and semi liquid products such as tomato sauce, spicy oil and water based perfume. Since the aggressiveness of these products leak percentage is higher with current material structures.Hence target of this study was to develop a PE based blown film extrusion material which can be used for the laminate structures for these selected products. Newly developed Linear Low Density Polyethylene (LLDPE) was replaced the sealant material of existing structure of those products. Also all the tests were carried out for both existing material structure and new material structure with developed LLDPE. The existing sealant material was blown using 80% LLDPE and 20% Low Density Polyethylene (LDPE) in all 3 layers. But newly developed sealant material was blown incorporating Polyolefin Plastomer (POP) and metallocene LLDPE materials to the inner and middle layers. The study tests a combination of different sealing temperatures and dwell time to determine the optimal sealing condition.Then optimal sealing condition was applied to the production line in order to trial them material structures. Leakages tests were conducted to the packed sachets and final results were determined. Developed blown film extrusion LLDPE film was shown good results compared to the existing material. From new sealant material leak percentage of tomato sauce, spicy oil and water based perfume could be reduced by 20%.
item: Thesis-Full-text
Finding the best level of filler master batch to be accommodated in thin gauged primary packaging products
Farharth, MLM; Gunapala, O
The main aim of this dissertationwas“Finding the best level of filler master batch to be accommodated in thin gauged primary packaging products”, as currently there is only limited information available in the printed media especially for Thermoforming made thin gauged food contact plastic products. Here only the thermoformed thin gauged primary packaging products made out of Polystyrene and Polypropylene materials were studied. To find out best filler level in plastic compounds 2 series of formulations such as Series N1 for Polystyrene based materials and Series N2 for Polypropylene based materials were prepared, where virgin filler load level varied from 0% to 25% were prepared and experimented. And these formulations were based on incremental addition of heavy filler such as Calcium Carbonate in virgin form as Filler Master Batch. Each and every Raw Material batches were tested for MFI (Melt flow Index) against the specification. Thin gauged sheets were extruded according to the decided formulation. Products were turnout via thermoforming process to test for consumer acceptance. Further in order to find out the best level of filler master batch to be accommodated to these products, thermoformed primary packaging was examined for Appearance Test, Specific Gravity test, Drop Test or Impact test, Oil Test and Actual Filler Master Batch test .Those testswere carried out to find out whether physical and aesthetic properties were compromised or not. It was observed during the trials that 25% Virgin FMB based formulated sheets were not suitable for thermoforming process as it tended to crack and torn like a paper. It was concluded through Actual FMB level test, that the accumulated Calcium Carbonate Filler level in the regrind introduced in these formulation had an impact on overall level of fillers in the extruded sheets had caused these cracks and defects. Based on the test results it was concluded that 26% of Filler in Styrene based materials and 40% of Fillers in polypropylene based materials were the optimum level of Filler Master Batch for these thin gauged primary packaging products.