Browsing by Author "Liyanage, NMVK"

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item: Conference-Full-text
The Effectiveness of a Watersoluble Synthetic Acrylic Polymer in Enhancing Reinforcing Action of Silica in Carboxylated Acrylonitrile Butadiene Rubber Latex
(2015-08-14) Liyanaarachchi, LADA; Liyanage, NMVK
Carboxylated acrylonitrile butadiene rubber (XNBR) latex was filled with surface modified precipitated silica. Surface modification of silica was affected in an aqueous medium by reacting with a synthetic polymer (SP) containing both hydrophilic and hydrophobic groups. The effectiveness of SP in enhancing reinforcing action of silica in XNBR latex films was evaluated through investigation of mechanical properties of vulcanized latex films cast from XNBR latex compounds filled with modified silica over a range of 5 to 20 phr loadings. Tear strength, which is an important mechanical property in certain latex based products like gloves, of modified silica filled cast films was found to be improved in comparison with that of unmodified silica filled cast films. Tear properties of cast films were continued to increase within the range of filler loadings investigated. An optimization of tensile strength was observed at 15phr filler loading in films containing modified fillers and it exceeds the tensile strength of unmodified filler added films with same loading. Morphological studies performed by scanning electron microscopy illustrated that a better distribution of modified filler particles within the XNBR matrix has occurred which may be a consequence of the discouragement of filler aggregation with surface modification. Surface modification of silica has improved the reinforcement action on XNBR.
item: Conference-Abstract
The Effectiveness of a watersoluble synthetic acrylic polymer in enhancing reinforcing action of Silica in Carboxylated Acrylonitrile Butadiene Rubber Latex
(2015) Liyanaarachchi, LADA; Liyanage, NMVK
Carboxylated acrylonitrile butadiene rubber (XNBR) latex was filled with surface modified precipitated silica. Surface modification of silica was affected in an aqueous medium by reacting with a synthetic polymer (SP) containing both hydrophilic and hydrophobic groups. The effectiveness of SP in enhancing reinforcing action of silica in XNBR latex films was evaluated through investigation of mechanical properties of vulcanized latex films cast from XNBR latex compounds filled with modified silica over a range of 5 to 20 phr loadings. Tear strength, which is an important mechanical property in certain latex based products like gloves, of modified silica filled cast films was found to be improved in comparison with that of unmodified silica filled cast films. Tear properties of cast films were continued to increase within the range of filler loadings investigated. An optimization of tensile strength was observed at 15phr filler loading in films containing modified fillers and it exceeds the tensile strength of unmodified filler added films with same loading. Morphological studies performed by scanning electron microscopy illustrated that a better distribution of modified filler particles within the XNBR matrix has occurred which may be a consequence of the discouragement of filler aggregation with surface modification. Surface modification of silica has improved the reinforcement action on XNBR.
item: Conference-Full-text
Effectiveness of natural polymers as surface modifiers in enhancing reinforcing action of silica in carboxylated nbr latices
(IEEE, 2018-05) Ramasinghe, RLP; Liyanage, NMVK; Chathuranga, D
Reinforcement of Carboxylated Acrylonitrile Butadiene rubber (XNBR) latex using surface modified silica and nanosilica has been investigated in this study. Surface modifiers are special category of substances used to impart better interactions between filler and latex in polymer-latex industry. Modification of both micro silica and nano silica particles’ surface with natural method (NPs) was conferred by an in-situ surface modification process using cellulose, gelatin, chitosan and collagen separately. The reinforcement effect of surface modified silica could be assessed by determining swelling, crosslink density, tensile and tear properties of vulcanized latex films. The distribution of modified silica within the latex films was studied by observing the cross sections of films through a metallurgical microscope. In this study cellulose was found to be the most effective surface modifier probably by discouraging filler/filler interactions while encouraging rubber/filler interactions.
item: Conference-Abstract
Evaluation of performance of modified graphene based materials in latex films
(Department of Materials Science and Engineering, University of Moratuwa., 2021-12) Dilina, JMA; Gamage, GGUV; Liyanage, NMVK; Abeygunawardana, AAGA
Natural rubber (NR) is one of the main natural materials used in various industrial applications. In order to tailor the natural rubber material according to the end application, natural rubber latex compounding is done, introducing various additives. Fillers are one of the major categories of additive in a latex compound which reduces the cost while catering the final performance of the product. In latex film manufacturing the widely used filler Silica (SiO2) is an inorganic compound which consists of hydroxyls on its surface which impart poor dispersion properties in an organic matrix such as rubber. Surface hydroxyl groups lead to agglomeration of silica particles which directly affects the mechanical properties of NRL thin film products. This issue has been discussed in both academic and industry environments; thus, many studies have introduced different coupling agents such as silane, alkanol amide, polydiallyl dimethylammonium chloride (PDDA) etc. Natural rubber composites filled with Silica, graphite and its derivatives, and modified silica with various forms of graphite have been studied. This research is aimed to improve of filler rubber interaction of silica filled NRL thin films in the presence of exfoliated graphite. Here, Graphite was exfoliated by using a ball milling method assisted with a Naphthalene sulphonic acid derivative (i.e. Tamol) and was used to improve the aqueous dispersion of silica to improve fillerrubber interaction through inter molecular attraction. Optical microscopy, SEM analysis and Raman spectroscopy were used to characterize exfoliated graphite. Properties of vulcanizates were characterized by tensile strength test, tear strength test, swelling test, and SEM analysis. Overall results show that introduction of exfoliated graphite into silica dispersion has enhanced its properties imparting some improvements in physical properties of NRL thin films.
item: Conference-Abstract
Evaluation of performance of modified graphene based materials in tire tread formulations
(Department of Materials Science and Engineering, University of Moratuwa., 2021-12) Kumarasiri, PGA; Madhusanka, JDI; Liyanage, NMVK; Abeygunawardana, AAGA
Tire tread is the outer part of the tire that contacts the road or the ground. To improve its performance, effectiveness of different types of additives has been studied in various researches. Graphene which is considered as the basic structural element of carbon allotropes shows unique properties like excellent thermal conductivity, high strength, and relatively lower density. Therefore, it can be used as an additive in tire tread formulations because enhancing mechanical and thermal properties of tire is an important factor in modern tire industry. In this research, the possibility of synthesizing graphene and/or exfoliated graphite from a ball milling technique has been studied. Also, the properties of the composites of Natural rubber and Exfoliated graphite have been studied. This research is aimed to improve mechanical and thermal properties of tire treads using modified graphene-based materials. Optical microscopy, SEM analysis and Raman spectroscopy were used to characterize exfoliated graphite. Rubber compounds were mixed in a two-roll mill according to a predetermined formulation and were vulcanized using a compression molding machine. Rheological properties of the compounds were characterized by Moving Die Rheography and physical and thermal properties of vulcanizates were obtained using tensile test and Lee’s disk method respectively. Final results show that the exfoliated graphite has enhanced the thermal conductivity and physical properties of tire tread compounds.
item: Conference-Abstract
Evaluation of potential of two natural polymers in enhancing physical properties of silica filled natural rubber latex films
(Society of Materials Engineering Students, Department of Materials Science and Engineering, University of Moratuwa, 2017-03) Rajasekara, RWDHS; Randeepa, HPDK; Liyanage, NMVK; Sivahar, V
The applicability of two natural proteins; zein and soy, extracted from corn and soya respectively, as surface modifiers for silica to be used in natural rubber latex(NRL) compounds was investigated. Two proteins were extracted by affecting some minor modifications to two established processes. Surface modification of silica with the extracted proteins was affected, in-situ, separately in aqueous media while the preparation of silica dispersions. The modified silica was characterized by FTIR spectroscopy. Physical properties of modified silica incorporated NRL films cast from NRL compounds prepared following a standard formula were measured as per the relevant standards. FTIR spectroscopy confirms the surface modification of silica caused by added proteins. The dispersion stability of modified silica dispersions was observed to be better than that of unmodified silica. Distribution of modified fillers in rubber matrix was found to be better than that of unmodified filler. Both types of modified fillers were found to be capable of enhancing tensile properties of NRL films to different extents with marginal effects on tear properties.
item: Thesis-Full-text
Evaluation of suitability of 1,4- dimethylpiperazine as a substitute catalyst of polyurethane foam production
(2018) Samarappuli, IP; Liyanage, NMVK
The flexible polyurethane foams have been fabricated from polymeric 4,4’-di-phenylmethane diisocyanate (MDI) and polyols. Catalysts play a major role in polyurethane foam preparation controlling the reaction profile throughout the reaction time. As a substitute catalyst 1,4- dimethylpiperazine promotes gelling reaction as well as blowing reaction as predicted. Effect of 1,4-dimethylpiperazine on polyurethane foam formation was investigated by varying the additive concentration while keeping all the other factors constant. Sample of standard dimensions were prepared from the resultant foam. They were used for density test compression set test, tensile strength and elongation tests. The tests were carried out as per the ASTM -D3574 standards. The reaction profile has moved to slower direction in terms of gelling time, rise time, curing time in the presence of 1,4-dimethylpiperazine compared to the control catalyst. This is due to the less reactivity of the test catalyst. The resultant controlled behavior of the 1,4- dimethylpiperazine could be more useful in applications such as complex molding. Other physical properties such as foam density, hardness, tensile strength, compression set test value lie within the comparable range which could again be useful in molding conditions. It is concluded that 1,4-dimethylpiperazine is a good delayed action catalyst which is found to be better for in-mold flowability and slow cure times with comparable foam properties.
item: Thesis-Abstract
Evaluation of the applicability of natural polymers as coupling agents in imparting reinforcement action of silica fillers in NR latex films
(2014-06-30) Gnanaratna, WDSN; Liyanage, NMVK
The results of an evaluation of the applicability of natural polymers (NPs) as coupling agents in imparting reinforcement action of silica fillers in natural rubber (NR) latex films are described in this research investigation. Three types of NPs namely; chitin, chitosan and cellulose were used for this investigation. Standard extraction processes were used for the extraction of chitin and chitosan. A commercially available grade of cellulose was used for this investigation without purification. Modification of surface of silica particles with NPs was affected by two techniques; in-situ surface modification, and surface modification through a sol-gel process. Coupling action of these NPs was compared with that of the most widely used commercially available coupling agent silane, Si69. A range of stable aqueous colloidal dispersions of precipitated silica were prepared with the use of NPs and Si69. In-situ surface modification performed with NPs and Si69. With NPs, the surface modification was done at four different proportions as 2.5%, 5%, 7.5% and 10% by weight of silica. With Si69, the modification was done at two different proportions as 5% and 10% by weight of silica. Sol-gel surface modification performed with chitosan was done at two different proportions as 5% and 10% by weight of silica. Interactions between polar groups of silica and functional groups of the NP which hinder aggregation of silica particles were confirmed by FTIR spectroscopy. The dispersion stability of the unmodified/modified filler (UMF/MF) dispersions was assessed by observing the phase separation upon standing. Dispersion stability of MF dispersions prepared using both surface modification method is much better than that of UMF dispersions. The particle size distribution of unmodified/ modified filler dispersions was measured by using “Fritsch” particle size analyzer. The particle size of the modified filler with cellulose was found to be lower than that of UMF dispersion. Effectiveness of NPs in enhancing reinforcing action of silica in NR latex was evaluated through investigation of mechanical properties of vulcanized films cast from NR latex compounds containing modified/unmodified fillers in different proportions. Distribution of unmodified/modified fillers within the rubber matrix was investigated through metallurgical microscope and scanning electron microscope by examining micrographs of surfaces of dipped NR latex films and micrographs of cross sections of cast NR latex films containing modified/unmodified fillers respectively. High colloidal stability of modified fillers with NPs indicates that are capable of acting as colloidal stabilizers for silica dispersions. Some of the NPs tested were found to be capable of conferring an appreciable enhancement in reinforcing action of silica in NR latex films. Micrographs graphs of the filled NR latex films revealed that same NPs have conferred uniform distribution of filler particles within the rubber matrix.
item: Conference-Full-text
Evaluation of the suitability of 1,4- dimethylpiperazine as a substitute catalyst in polyurethane foam production
(IEEE, 2018-05) Samarappuli, IP; Liyanage, NMVK; Chathuranga, D
Effect of 1,4–dimethylpiperazine as a catalyst in producing polyether foam was investigated. Reference samples were produced from polyol, methylene di isocyanate (MDI), triethylene diamine (as a control catalyst), distilled water, and silicone oil using laboratory mix formulation based on polyether based polyol system. Standard sample dimensions for density test, tensile strength and elongation tests were produced from the samples. The various tests were carried out on the samples using the ASTM-D3574 standards. It was observed that 1,4- dimethylpiperazine has comparatively low gelling and blowing action compared to triethylene diamine. It is concluded that )1,4- dimethylpiperazine is a good delayed action catalyst which is found to be better for in-mold flowability and slow cure times with comparable foam properties.
item: Conference-Full-text
Hydrophilic polymers as protein removers for natural rubber latex
(IEEE, 2016-04) Dhanapala, MGV; Liyanage, NMVK; Jayasekara, AGBP; Bandara, HMND; Amarasinghe, YWR
Water soluble hydrophilic polymers (WSHP) in removing extractable proteins in natural rubber latex(NRL) has been investigated. Two WSHPs were synthesised by free radically initiated solution polymerisation technique using two acrylic monomers and these WSHPs were added to field NRL as aqueous solutions at 5 different concentrations separately and matured for 24 hrs. Mixtures were centrifuged and their protein contents were assessed by Modified Lowry method assisted ASTM D 5712-5 and Fourier Transform Infra Red Spectroscopy (FTIR). Performance in reducing proteins by the treatment of latex with a selected concentration from the same tested range, was assessed in vulcanised films too. Both WSHPs are capable of removing extractable proteins in NR latex and this capability is found to be greatly depended on their composition. Protein removing efficiency of homopolymer was found to be increased with the concentration whilst that of copolymer declines after about 0.10 phr. Results of thermal stability studies performed by Thermogravimetric analysis (TGA) on some treated and untreated NRL films complimented observations of FTIR.
item: Conference-Abstract
Investigation of applicability of coconut shell powder as a filler in natural rubber composites
(Society of Materials Engineering Students, Department of Materials Science and Engineering, University of Moratuwa, 2017-03) Athauda, AARS; Chathuranga, G; Liyanage, NMVK; Sivahar, V
Applicability of coconut shell powder(CSP) as a filller in natural rubber(NR) based composites was investigated. Incorporation of CSP into NR composites was done in two different forms; crude CSP, purified CSP, either with or without a coupling agent(silane). Two series of NR compounds containing 80phr of filler were prepared. The compounds of the first series was prepared by varying the carbon black content from 0-80pphr with no CSP present. In the second series the ratio of carbon black/CSP was varied from 80/0 to 20/60. The first series used as the reference series. NR composites filled with different forms CSP separately were compared with equivalent composites filled with carbon black. The processing characteristics and the curing behavior of the composites were determined by Gottfert rheometer. The mechanical performances of the vulcanisates were determined by analyzing their tensile strength, tear strength, hardness, resilience and abrasion resistance. Replacement of carbon black with CSP in NR compounds was found to improve certain properties like hardness, elongation and resilience of resultant vucanisates when present in low concentrations. Overall performance of purified CSP was found to be better than that of crude CSP. The use of silane as a coupling agent slightly improved the properties of the vulcanistes.
item: Thesis-Full-text
Reinforcement of carboxylated acrylonitrile-butadiene rubber latex films by surface modified fillers
Liyanaarachchi, LADA; Liyanage, NMVK
Carboxylated acrylonitrile butadiene rubber (XNBR) latex is a widely used synthetic copolymer of acrylonitrile and butadiene with a small amount of a third monomer containing carboxylic groups. Some of the mechanical properties of XNBR latex are not adequate for certain applications and should be enhanced. Incorporation of reinforcing fillers is most widely used technique for that purpose. Silica filler is used in dry rubber industry as a reinforcement agent, but difficult to use in latex applications due to some problems associated with dispersing silica resulted by its surface chemistry. Surface of silica should be modified in order to use as a reinforcing filler in latex applications. In the present investigation, XNBR latex was filled with a series of surface modified precipitated silica. Surface modification of silica was affected by two methods i.e. non aqueous medium modification and aqueous medium modification, with the use of some synthetic polymers (SP). Three types of SPs, containing hydrophillic and hydrophobic groups that are methacrylic acid and 2-ethyl hexyl acrylate, respectively in different ratios were synthesized and used at a concentration of 3 % by weight of silica for the modification. The effectiveness of the SPs in enhancing reinforcing ability of silica in XNBR latex films was evaluated through investigation of mechanical properties of a range of vulcanized films cast from filled XNBR latex compounds containing modified filler in different concentrations in the range of 5 to 20 phr loadings. One of the well known non-sulphur vulcanization systems of XNBR, crosslinking with zinc oxide was used during the study. Latex films were cast from filled latex by several routes with different process sequences in order to investigate the importance of each step of the process to find out the most suitable step for filler addition. Some of the mechanical properties important for rubber latex applications, such as tear strength, of modified silica filled cast films improved over unmodified silica filled cast films. Optimum tear strength of cast films filled with modified fillers was observed at 20 phr filler loading, while films containing 15 phr filler loading gave optimum tensile properties. Morphological studies done by scanning electron microscopy illustrated improved distribution and lower size of modified filler particles within the XNBR matrix indicating surface modification has reduced filler aggregation. SPs used for the modification are capable of enhancing reinforcing action of silica filller in XNBR latex films. The extent of enhancement of physical properties of filled cast films depends on the hydrophillic/hydrophobic ratio of SPs used for surface modification of silica. Highest physical properties were observed for the vulcanizates containing silica modified with the most hydrophobic SP, which is thought to be the result of better rubber filler interactions created by the entanglement of rubber chains with hydrophobic side groups present in this particular SP.
item: Thesis-Full-text
Reinforcement of carboxylated nitrile rubber latex films by surface modified nanosilica
Ramasinghe, RLP; Liyanage, NMVK
Carboxylated acrylonitrile butadiene rubber (XNBR) is synthetic elastomer which inherent number of physical and chemical properties such as comparable barrier protection, good puncture and chemical resistance and high durability under storage. Although that there is a problem associated with synthetic elastomers that they are typically not self-reinforcing elastomers. Therefore, reinforcing fillers are incorporated to improve the properties of the compounds. Silica is extensively used for latex products. Nanofillers can impart more advanced properties to the final nanocomposite than micro fillers. Surface modification has been introduced to avoid the incompatibility between inorganic filler silica and organic XNBR matrix Role of surface modifiers in this study play dual role, as a capping agent: to control the size of nanoparticles & as a coupling agent: to develop compatibility between rubber and filler. Synthetic surface modifiers i.e. Polymethacrylic acid & Polymethacrylic acid ethyl hexyl acrylate and natural surface modifiers i.e. cellulose, collagen, chitosan & gelatin were used in this study. The FTIR analysis confirm that the surface of nanosilica particles has been successfully modified with acrylic polymers, forming ester bonds between carboxylic groups of acrylic polymers and surface silanol groups of nanosilica. TGA confirms the successful surface modification resulting lower weight loss; indicating small number of free surface silanols groups are present on the silica surface. XRD analysis revealed the amorphous nature of unmodified and all modified nanosilica particles. SEM results help to monitor the particle shape, size and agglomerations of synthesized particles. Evaluation of XNBR vulcanizate properties of micro silica, unmodified nanosilica, acrylic polymer modified nanosilica and natural polymer modified nanosilica filled vulcanizates was carried out. The results show that addition of small quantities of nanosilica causes an increase of mechanical properties of XNBR vulcanizates, while high filler loading of nanosilica appear to decrease the mechanical properties due to the aggregation of nanosilica particles. 2% PMAA and 2% cellulose modified nanosilica filled vulcanizates show balance strength with stretch & comfort properties for the glove manufacturing.
item: Conference-Abstract
Reinforcement of carboxylated nitrile rubber latex films by surface modified nanosilica
(Department of Materials Science and Engineering, 2019-01) Ramasinghe, RLP; Liyanage, NMVK; Sivahar, V; Sitinamaluwa, HS
Natural rubber based vulcanizates possess fairly high tensile strength as they show strain induced crystallisation. However, over the years, there has been a growing concern on the potential allergy caused by natural rubber proteins. As a consequence, the demand for products based on synthetic elastomeric materials such as carboxylated acrylonitrile butadiene rubber latex (XNBR) has been increased. Most synthetic elastomers are non-self-reinforcing and consequently they inherent low strength when unfilled. Synthetic elastomer nano-composites reinforced a with low volume of nanofillers exhibit high mechanical, thermal, barrier and flame-retardant properties. The performance of the particulate fillers on elastomeric appHcations intensely relies on filler-rubber interactions. Due to the filler-rubber interactions, polymer chains of the matrix adsorb onto the filler particle surface. Nano-fillers are quite difficult to disperse uniformly in rubber matrix due to their high surface energy resulting in huge agglomerations. The objective of this research was to address this issue by studying the effects of surface modified nanosilica on reinforcement of XNBR latex vulcanizates. The effects of polymethacrylic acid & poly (methacrylic acid & ethylhexyl acrylate) polymers modified nanosilica as reinforcing filler on the properties of XNBR latex vulcanizates at different filler loadings were investigated. Evaluation of XNBR vulcanizate properties of micro silica, unmodified nanosilica and modified nanosilica filled vulcanizates revealed that the addition of small quantities of nanosilica brings about a significant increase in physical properties of XNBR vulcanizates, while higher filler loadings of nanosilica decrease such properties. 2% polymethacrylic acid modified nanosilica filled vulcanizates at 5 phr level of filler addition were found to possess most suitable properties demanded by dipped products such as gloves.
item: Thesis-Abstract
Reinforcement of natural rubber lates films with fine particle fillers
(2015-03-01) Somarathne, MCW; Liyanage, NMVK
Reinforcement of natural rubber latex (NRL) is essential for NRL based thin film products manufacture. Silica is one of the most important reinforcing fillers used in dry rubber industry. However, the surface bound silanol groups that are polar and considerably chemically active, make silica less compatible with NRL. In the present study, surface of precipitated silica (Ultrasil VN3) is modified with macromolecular coupling agents (MCAs) consisting of both hydrophilic and hydrophobic groups and the surface modified silica is incorporated into NRL in order to reinforce NRL films which is a novel concept introduced to confer interactions between silica-MCA complex and rubber particles. The MCAs are synthesized in the laboratory by a solution polymerization technique using hydrophilic and hydrophobic monomers. Surface modification of precipitated silica particles with the MCAs is carried out in two reaction mediums; aqueous and non-aqueous, separately. Unmodified/ modified silica is added as aqueous dispersions at neutral pH to compounded and uncompounded NRL in four different levels of loadings from 5 phr to 20 phr in 5 increments. Thin latex films are cast from compounded/uncompounded NRL filled with unmodified and modified fillers. Formation of H-bonds and/or covalent bonds between carboxylic groups of MCA and hydroxyl groups of silica is studied via FTIR spectroscopy and contribution of newly formed bonds in enhancing filler-rubber interactions is emphasized through mechanical, thermal and swelling properties. Microstructures of film cross sections of filler added NRL obtained from SEM and optical microscope confirm the uniform dispersion of modified filler particles throughout the rubber matrix. Tear strength and tensile strength are found to be increased by 50 % and 35 % respectively at 5-10 phr of filler loading of vulcanized films filled with filler modified by the most hydrophilic MCA compared with those of UM filler added vulcanizates. Keywords: Reinforcement, natural rubber latex, silica, surface modification, macromolecular coupling agents
item: Conference-Abstract
Reinforcement of natural rubber latex film using silica filler modified with a commercially available co-polymer solution
Ariyarathne, AATK; Somaratne, C; Walpalage, S; Liyanage, NMVK; Karunanayake, L
Reinforcement of natural rubber (NR) latex films is one of the most difficult tasks in latex industry. Among the others, the best reinforcing filler is silica that steers for improvement of mechanical properties such as tear and tensile strengths of rubber matrix. However, surface of the silica particle is surrounded by hydrophilic silanol groups which are less compatible with natural rubber molecules. Hence, silica is not easy to be used as reinforcing filler for NR latex films without any surface modification. A study of modification of silica surface was successfully done by using an acrylic polymer synthesized in the laboratory. However, synthesis of polymers in this regard is not economically sound for latex industry. Therefore, a commercially available sodium salt of acrylic co-polymer solution is consumed for the modification of surface of silica particles. Modification is accomplished by the establishment of hydrogen bonds between silanol groups of silica and hydrophilic groups of co-polymer and that is confirmed by FTIR spectroscopy. Stability of modified filler dispersion is optimum at neutral pH and particle size reduction of modified filler particles is compatible with the size of rubber particles. The improved physical properties of modified filler added NR latex films are confirmed by testing tear strength, tensile strength and elongation at break. The preferred level of flexibility through interactions formed between modified filler and rubber matrix is shown by reduced glass transition temperature of modified filler added NR films that tested using differential scanning calorimeter (DSC).
item: Conference-Abstract
Reinforcement of Natural Rubber Latex Films through surface modified silica with macromolecular coupling agent
Somaratne, MCW; Liyanage, NMVK; Walpalage, S
The surface of precipitated silica particles was modified by reacting with a macromolecular coupling agent containing both hydrophilic and hydrophobic monomer units. Interfacial interactions between -OH groups of silica and -COOH groups of macromolecule were created through H-bonds and covalent bonds confirmed by Fourier Transform Infrared Spectroscopy. Two different dispersions of unmodified/modified silica were prepared and incorporated to natural Rubber Latex (NRL). Physical properties of NRL films containing modified silica fillers were compared with those of films containing unmodified filler. Even distribution of modified filler was seen in microstructures of film cross sections obtained from Scanning Electron Microscope.
item: Conference-Extended-Abstract
Reinforcement of natural rubber latex films with surface modified silica
(2009) Liyanage, NMVK; Walpalage, S; Somaratne, MCW
The surface of silica particles was modified by treating with a polymer containing both hydrophilic and hydrophobic monomer units. Surface modification involved esterification of the surface hydroxyl groups with the carboxyl groups of the hydrophilic units of the polymer. Conversion of surface -OH groups to surface ester groups was confirmed Fourier Transform Infrared Spectroscopy (FTIR). Tensile properties of natural rubber latex films containing modified silica fillers were compared with those of films containing unmodified filler and the outstanding reinforcing ability surface modified filler was clearly evident.
item: Article-Abstract
Surface modification of silica with a hydrophilic polymer and its influence on reinforcement of natural rubber latex
Somaratne, MCW; Liyanage, NMVK; Walpalage, S
Surface modification of precipitated silica particles was carried out in both aqueous and non aqueous media separately with a polyacrylic based hydrophilic polymer synthesized in the laboratory. FTIR spectroscopy and thermo gravimetric analysis of the modified and unmodified silica particles were performed to confirm successful surface modification. Colloidal stability of the aqueous dispersions of the unmodified/modified silica particles were observed at different pH levels. The dispersions at neutral pH were incorporated in different proportions to un-compounded and compounded natural rubber latex (NRL) separately and thin latex films were produced from them by casting. Dispersability of silica particles within the rubber matrix was examined through microstructure studies of films cast from unmodified/modified silica incorporated un-compounded NRL. The influence of surface modification upon the reinforcement of NRL was investigated through tensile and tear strength properties of vulcanized NRL cast films containing modified silica. The uniform dispersion of silica particles and the improved mechanical properties envisaged better compatibility of modified silica particles with NRL by means of interfacial interactions. A significant improvement in the mechanical properties was observed in the films produced with 5 – 7 phr of modified silica.
item: Conference-Abstract
Synthesis and characterisation of two-roll mill processed natural rubber/graphene oxide modified silica nanocomposits
(Department of Materials Science and Engineering, 2020-02) Jayakody, JACA; Liyanage, NMVK; Abeygunawardane, AAGA
Tyre compounds consist of different additives such as antioxidants, fillers, plasticizing agents, vulcanising agents etc. in addition to natural rubber (NR). Two types of fillers; carbon black and silica, are used in rubber compounding. Carbon black is a powdered form of carbon which is completely miscible with organic rubbers. Nevertheless, silica (SiO2) is an inorganic compound which is not miscible with organic rubber. In addition, silica particles contain surface hydroxyl groups which tend to form hydrogen bonding leading to agglomerations. Coupling agents are used to address these issues when silica is used as a filler in rubber compounding. Different coupling agents, such as silane, alkanolamides, poly (diallyldimethylammonium chloride) (PDDA) etc. are widely used for this purpose. Performance of SiO2 and graphene, epoxidised NR and graphene and, NR and graphene oxide (GO), have been studied by previous researchers. This study was aimed to reduce aggregation of silica and to improve miscibility of silica in NR by modifying silica particles' surfaces with graphene oxide. GO was synthesized by following a modified Hummers' procedure. Silica surface modification was done by simply grinding silica and GO together at a ratio of 100:5. Characterisation of modified silica was performed via FTIR spectroscopy SEM analysis. GO modified silica filled rubber compounds were made on a two-roll mill as per a standard formula. Rheological properties of the compounds were studied by MDR rheography and the mechanical properties such as, tensile strength, tear strength etc. of the vulcanisates were measured following appropriate standards. Overall results indicate that the modification technique used in the study has enhanced the dispersion of silica in rubber imparting some improvements in mechanical properties of NR vulcanisates.