Master of Science in Polymer Technology

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item: Thesis-Abstract
A Study of natural rubber latex - filler interaction
Peris, CN; Gunapala, O; Gunapala, PY
An attempt has been made to evaluate natural rubber latex - filler interaction. 1800- peel test of flexible to rigid joints was performed to determine the peel strength of natural rubber latex -kaolin joints in order to evaluate the interaction of natural rubber latex with standard rubber grade kaolin and activated one by ion exchange reaction with amino -functional derivatives. Experimented natural rubber latex compounds were pre vulcanized with sulphur and ionization radiation. Radiation vulcanization was performed using 60 Co source irradiator, originally designed for sterilization of medical products, with reduced gamma rays dose rate. Its suitability for radiation vulcanization of locally produced natural rubber latex was confirmed experimentally. Obtained results showed that the peel off test device was acceptable for evaluation of natural rubber latex -filler interaction irrespective of the vulcanization system used with latex compound. Peel test results displayed the influence of modified fillers on the peel strength values of tested laminates. Increased peel strength values of the samples containing modified kaolin were attributed to better interaction of the filler with rubber polymer. It was investigated, that facilitated interaction observed with natural rubber latex and modified kaolin resulted in improved properties of filled natural rubber latex compounds of both vulcanization system, and irradiated one was more susceptible within the experiment performed. Preference in mechanical stability time, viscosity factor and tensile was given to radiation vulcanization natural rubber latex (RVNRL). Reinforcing effect of modified filers in natural rubber latex compounds was lower of that observed earlier with dry rubber compounds. The reason for it could be associated with partial deactivation of the active centres initially brought by modification the phenomenon that have to be studied and overcome in the future. However, it is hoped that carried out research positively contributes to the understanding the mechanism of reinforcement of rubber polymers with fillers and development of the technologies upgrading cheap local mineral resources to use them more beneficially in natural rubber formulation technology. Another aspect covered by research related to development of radiation vulcanization technology that gives a definite support for introduction to local latex based manufacturing industries.
item: Thesis-Full-text
A Study on the effect of aeration on mechanical stability of concentrated natural rubber latex upon maturation
Roshanie, LKS
ABSTRACT The ever innovation of rubber products in diversified fields have made it necessary to find suitable quality latex rubberfordifferentproducts.Because,manufacturesofrubberproductsareinsistingoncertain range of mechanical stability ( usually in the range of 500 -1000 seconds), there is a continuous research going on to find suitable test method to asses a such quality of latex It is been found that volatile fatty acid number (VFA No:), Alkalinity and Mechanical Stability Time (MST) test for quality control test proved to be a sui tabl e methods for making quality products. The objective of this research to simply give a alternative mclhod to develop mechanical stability without adding soap because previous studies shows that when soap level is high the quality of the latex was low. Current studies consist of analyzing the MST variation of centrifuged latex with aeration level and maturation. And also analyze the variation of other properties such as Alkalinity, VF A No:, Viscosity , to nductivity and pH. The latex used for this study were obtained from a centrifuged plant, accordingly a special request was made to them to supply latex with minimum addition of soap. Aeration was supplied in different levels to different sample. Following properties was investigated at intervals: MST, Alkalinity, VFA No:, Viscosity, pH and Conductivity Out of the whole investigated properties; response to the aeration level was remarkable in MST, with maturation results suggest that MST is increases with higher the aeration level. Other properties such as a VF A, Alkalinity are not much effect with the air quantity. Therefore supply of air is not destroying the quality of the latex. VF A increment is not much significant. Viscosity is decreases up to some significant level with air quality. pH of the samples show some storage patterns not a trend pattern. Variation in MST is due to the air supplied to the sample; promote hydrolysis of proteins and phospholipids in the latex. Finally former fatty acids anions, phosphate anions are observed at the ... particle interface and enhance the stability of latex Further more results show that the highest aeration level is not the optimum aeration level . so • further studies should be carried out to find an optimum aeration level and how minimize the space of vessel which is required for aeration.
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-Abstract
Characterization and evaluation of starch xanthide encased powdered natural rubber
Maduwage, S; Amarasinghe, ADUS; Subramaniam, K
Rubber as a free-flowing powder, is essential in order to stream line the manufacturing processes of rubber goods. The previous works noted the importance of using powdered rubber as a competitive raw material for continuous processing in rubber industry. However, in most of these works, the study was continued to the synthetic rubbers and only a few had been reported on the natural rubber. Sri Lanka which is an agricultural based country, has a bulk quantity of natural rubber field latex at a low price. Hence, it is worthwhile to produce a value-added product like powdered rubber using field latex. Encapsulation is a common process in preparing powdered natural rubber. In this process, starch xanthate, SX, which acts as a diluent/reinforcing filler, behaves as an encapsulating agent for latex particles. The level of encapsulation as well as the properties of the resulting powder is highly dependent on the strength and the amount of the SX solution. The present work investigates these effects with varying strength of SX by changing the degrees of substitution, DS, of the SX solution and also the loading of the SX. The lower and the upper limits of DS of SX examined were 0.07 and 0.35 and the results suggested that the intermediate DS levels were more promising. The physical properties of the final vulcanizates were found to be satisfactory and were comparable with the rubbers available in the market. Study on drying techniques established the necessity of water washing step for natural rubber powders to remove non-rubber substances and the applicltion of an anti-cake agent to prevent agglomeration during drying. The effect of different anti-cake agents such as zinc stearate, talc powder and whiting was examined and zinc stearate was found to be the best out of the anti-cake agents used. Highly friable crumbs that ground readily to give powders were obtained with oven drying rather than with sun drying.
item: Thesis-Abstract
Depolymerisation of nr latex and its applications
(2014-07-07) Bopitiya, M; Coomarasamy, A
The controlled molecular weight reduction of NR in latex phase had been carried out by treating NR latex with singlet molecular oxygen generated from inexpensive and nontoxic reagents 'Hydrogen peroxide and sodium hypochlorite' . The extent of degradation was studied by viscosity measurements. The extent to which viscosity is reduced can be controlled to a large extent by the amount of reagents used and the pH of the latex. In acidic medium extent of degradation was higher. The mechanism of scission is investigated. The results obtained are more in favour with the mode of scission proposed by Hock. Potential applications of the process can be grouped in to three general areas corresponding to low, intermediate and high level of treatment. Low level of treatment give rubber of reduced viscosity within the normal range for bulk rubber. Intermediate levels give soft, sticky rubbers pale in colour and showing good pressure sensitive tack and peel strength even without the use of tackyfing resins. High levels of treatment give very viscous liquid rubber.
item: Thesis-Abstract
Design of a technique to study the stress relaxation behaviour of crosslinked rubbers subjected to a constant tensile strain
Jayasinghe, T; Fernando, KP
The objective of this work was to design a technique to study the stress relaxation behaviour of crosnlinked rubbers subjected to a constant tensilestra in, with provision for monitoring two independent parameters namelya. The force on the specimen (under constant strain) at a given timeb. The instantaneous modulus of the specimen at a given time, which is given by the gradient of the force versus deflection curve when the strained specimenis subjected to a further deformation at the time of measurement. The importance of these two parameters lies in the fact that the decay of the force on the specimen under constant strain is a good estimate of the cleave of the chemical bonds on the rubber network with time while the instantaneous modulus is an indication of the influence of the secondary network formed by the cleaved bonds on the rubber. The theories of stress relaxation and the equipment available for stress relaxation Measurements are discussed in detail it: this work in addition to the details of the proposed technique. It should be mentioned that especial emphasis was made here to reduce the cost of equipment when compared with the standard equipments available so that this technique could be made more popular among quality control as well as research workers. In this respect, the proposed equipment was designed in such a way that the load measuring device, which is the most expensive component in the set up could be shared among number of specimens under obesrvations , without disturbing their deformations. Number of specimens prepared under similar conditions were tested using the proposed equipment to study its reproducibility. It was found that the decay of the force on the strained specimen with time was showing excellent reproducibility even though the instantaneous modulus did not show such behavior. A detailed analysis of these results with further modifications recommended is given at the latter part of this work.
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
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-Abstract
Designing of a profile extrusion die
(2014-06-06) Samarawickrama, UDA; Gunapala, PY
Designing of the proposed profile extrusion die had few main tasks. One was to find out the most suitable type of die and the other was to calculate important operating parameters like pressure drop. The next is to calculate the land and calibration dimensions. Due to complex nature of the proposed profile, it was approximated to a slit die for the purposes of calculating pressure drops anddie swell / draw down ef-fects. Based on the thickness calculated for die, product and equilibrated swell state were used to calculate the dimensions of the complex die land and calibrator. When designing the die, due consideration was given to phenomenon like ,melt flow instabilities and shrinkage on cooling.Only top half of the PVC trunking profile was designed in this exercise, as trials are needed to validate the models selected and based on these val-ues only, progress onwards could be envisaged.
item: Thesis-Abstract
Designing resin-rubber sole compounds for use in local shoe manufacturing industry
Ranatunga, RRMSK; Subramaniam, K; Abeysirigunawardena, W
Natural rubber and Reclaimed rubber based resin- rubber soling sheets compounded with various cheap rubber ingredients were made and evaluated in this work for their use in local shoe manufacturing industry. In the experimental work, natural rubber and reclaimed rubber compounds formulated with different ingredients were prepared and moulded into sheets by compression moulding technique. The surfaces of the sheets were abraded and then crated with different flexible colour-paints. The painted (Coloured) sheets produced were then tested and evaluated for resin- rubber shoe sole sheets. The investigation reveals that the compounds containing the peptised natural rubber (SLR 20) and reclaimed rubber (DSI-Super fine grade) are found to be the most appropriate compounds for the production of resin-rubber soles in the local rubber industry.
item: Thesis-Abstract
Developing a sidewall compound for agricultural tires with improved weather resistance and flexibility by incorporating waste butyl rubber vulcanizates
Kularatne, GS; Prcmachandra, J
Isobutylene ~Isoprene Rubber ( IIR) which is also known as Butyl Rubber is widely used in tire inner tubes & curing membranes due to its unique properties: impermeability to gas & stability at elevated temperatures respectively. Due to comparatively low unsaturation. Butyl Rubber is known to be cure~ incompatible with general purpose rubber. Therefore, preparation of co-vulcanizable blends of Butyl Rubber is not usually recommended.Pneumatic tire sidewall is subjected to cyclic dynamic deformation under various weather conditions. Among pneumatic tires, agricultural tires are supposed to be used under severe weather conditions especially during soil preparation. On top ofthat, sidewalls of agricultural tires do possess larger surface area which will be in contact with severe weather conditions. Being agricultural tires are expensive, those tires are supposed to be re-capped at least three times during the life span. To withstand during the period ofthrce lives oftreads. the sidewall should possess superior 1lexibility and \\ eather resistance.There have been many novel approaches made to achieve weather resistance, in addition to the introduction ofPPDs and Anti-ozonant wax. Introduction of polymers derived from butyl rubber were among the modern attempts. Ter polymer of isobutylene, isoprene and di vinyl benzene acts a "pre-cross linked" butyl derivative which can be directly blended with GPR.The aim of this research project is to enhance weather resistance & 1lexibility of sidewall compound used in agricultural application by incorporating Butyl Rubber vuleanizates while making it cost effective. Resin cured Butyl rubber vulcanizates can be treated as "'pre-cross linked" derivative of Butyl rubber that can be used to improve the performance of sidewall compound.Used tire curing bags were selected as the starting material and an attempt was made to convert it to a usable material by using a cracker mill. Then, compatibility was achieved by means of"grafting'' through carbon black and new side wall compound was developed by blending Butyl rubber curing bag material. Finally, the physical properties and the performance of the sidewall compound were compared against a typical conventional tire side wall compound.The results of the project reveal that the resistance against initiation and propagation of fatigue cracks in tire side wall can be remarkably improved with the introduction of pre cured butyl rubber and thereby it enhances the performance of tire side wall without making any negative effect on other properties.
item: Thesis-Abstract
Development of a model for determining the optimum control parameters on a plastic injection moulding machine
Katugaha, HMCJS; Sivagurunathan, L
Production of plastic items using the injection molding process has become technologically ad-vanced with the advent of both newer technology and newer materials. Setting of machine control parame-ters play a major role in the ultimate product quality and the machine efficiency. Control of machine and mould parameters is complex task, because behavior of the material inside the machine and the mold, is effected by a range of contributing factors. This results in machine control becoming very difficult and one has to overcome this problem either by trial and error procedures, which cost time and material, or employ advanced microprocessor controlled programming methods and advanced automated machines with very high capital costs. In Sri Lanka, injection molding machines with highly advanced features are not very common. Conventional methods are used to determine the appropriate machine settings such as clamping force, charging stroke, barrel and injection pressure. Adjustment of these parameters to correct a fault in the product or to achieve maximum output rates, while manufacturing product quality is done experimentally, often relying on operator experience. This project was aimed at building up some simple mathematical mod-els to determine the optimum settings taking into consideration the basic rheological equations and experi-mental data that are readily available in the literature. The correctness of these models was checked for validity on a medium scale injection molding machine and very encouraging results have been obtained. The applicability of this method for further investigation is critically assessed.
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-Abstract
Development of a synthetic sports surface for an athletic track
Siriwardene, L; Fernando, K
A synthetic sports surface is a rnulti-layer structure which has become very popular as a substitute tor natural grass. This research project was meant to study the feasibility of developing a natural rubber base top covering for an athletic track for Sri Lanka's tropical environment. Here, the scrap rubber crumbs were used as the aggregate which is bound by natural rubber latex and cement. The latter was used to help in drying the surface quickly and also to impart greater hardness. Two types of rubber crumbs, namely tyre crumbs and microqilular crumbs with two types - of latex recipes were used to prepare the samples. One latex formulation is about 60 per cent cheaper than the other. Together with the above variation the main emphasis was to determine the most suitable type of crumb and its particle size range which resulted in a surface having properties comparable with those of reference samples meant to be used as athletic tracks. The standard tests to evaluate the track performance are stipulated in DIN 18035 Part 6. However, these tests demand a set of specialized apparatus. These were not available and were not possible to turn out locally within the time frame of the project. Thus an attempt was made to compare the results 0 f the test samples with those of the reference samples by carrying out a set of short term standard tests commonly available. These short term tests showed that the proposed formulations give comparable results with the selected reference samples.
item: Thesis-Abstract
Development of extrusion technology of breathable film for industrial applications
Illangarathne, SSKP; Gunapala, O; Gunapala, PY
The present research was pursued to develop breathable plastic packaging suited for desired level of moisture permeable application. The monolayer plastic films differed by resin composition were extruded by blown film equipment and two types of packaging with different architecture were prepared from the films extruded. To evaluate the package quality, the shelf life of fresh mushrooms packed in the packages was studied. Water vapour transmission rate and other performance properties of plastic films were determined. Results demonstrated good breathability of the developed packaging. Preference was given to the filled polyolefin compounds. Importance of filler particle size, treatment and processing conditions, including biaxial orientation were shown .Use of local filler and traditional single layer extrusion equipment did not contribute to the cost significantly, making packaging affordable easily by local consumer.
item: Thesis-Abstract
Development of inner tube using a blend of natural rubber and chlorobutyl rubber
Perera, HAD; Sivagurunathan, L
In order to develop the properties of tubes manufactured by Sri Lanka Tyre Corporation (SLTC), attempts have been made to improve the physical properties specially with respect to cir permeability mentioned in Chapter I -without changing the possessing parameters In this project attempts have been made to improve the properties of tubes manufactured by srilanka tyre Corporation, by modifying the present formulation used. Modification was one in two stages. In first stage, Natural Rubber(NR) was re placed by the blends of Chlorobutyl (ClIIR) and NTR, while keeping accelerator system constant. Blends of C1IIR and NTR were selected as 100/0 (KR/C1IIR), 90/10, 80/20, 70/30, 60/40. After examining physical properties of above vulcanisates as men ioned in Chapter I and cost factor, the blend of 80/20(N3/C1IIR) was selected to carry out the second part. In the second part, accelar at or system was changed from semi efficient vulcanizing to efficient vulcanizing while keeping the blend of SR/C1IIR 80/20 constant. In this study, it was observed that system (I) and (£) (-Table 13) give better test results than other systems investigated. It appears that 80/20(NR/C1IIR) blend is suitable for tube manufacturing either using accelar at or system (1) or (2) (-Table7).
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-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.
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Development of rubber compound for rice hulling roller manufacture
Chandralal, HNKK
The market potential and manufacturing techniques of rice hulling rollers have been briefly examined. Selection of polymer, curatives and compounding methods were discussed. Experimental data on the comparative performance including service trials, of natural rubber based rollers. vis -a - vis synthetic rubber rollers is presented. The special advantages of skim natural rubber in this particular application is emphasised. The use of silane coupling agent and the cashew nutshell liquid based rubber to metal bonding system in rice hulling rollers is also described.
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Development of rubber compound for rice hulling roller manufacture
Chandralal, HNKK
The market potential and manufacturing techniques of rice hulling rollers have been briefly examined. Selection of polymer, curatives and compounding methods were discussed. Experimental data on the comparative performance including service trials, of natural rubber based rollers. vis -a - vis synthetic rubber rollers is presented. The special advantages of skim natural rubber in this particular application is emphasised. The use of silane coupling agent and the cashew nutshell liquid based rubber to metal bonding system in rice hulling rollers is also described.