Browsing by Author "Ramasinghe, RLP"

Now showing 1 - 6 of 6

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
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-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
Synthesis of nanosilica using acrylic polymers as surface modifiers
(2017) Ramasinghe, RLP; Liyanage, NMVK
Preparation and characterization of silica nanoparticles through sol-gel processing using sodium silicate as a precursor were carried out. Amorphous silica was synthesized using sodium silicate and hydrochloric acid by precipitation according to Stőber method. A system of chemical reactions has been developed using two different polymeric anionic surfactants, namely poly(methacrylic acid) (PMAA) and a copolymer of methacrylic acid and 2-ethylhexyl acrylate (PMAA-EHA)(60:40). The synthesized silica particles were characterized by using fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The FTIR analysis confirm that the nanosilica particles surface have been modified with acrylic polymers, forming ester bonds between carboxylic groups of acrylicpolymers and surface silanol groups of nanosilica. TGA studies reveal silica particles modified with polymers showed higher weight loss than unmodified nanosilica due to the decomposition of the acrylic polymer adhered to the silica nanoparticles. The SEM images of unmodified and acrylic polymer modified particles show uniform size distribution and spherical shape.
item: Conference-Full-text
Use of acrylic polymer modified hydrophobic nano-silica in reinforcing of xnbr nano- composites
(IEEE, 2020-07) Ramasinghe, RLP; Liyanage, NMVK; Weeraddana, C; Edussooriya, CUS; Abeysooriya, RP
Carboxylated nitrile butadiene rubber (XNBR) latex is enjoying a big share in the glove manufacturing industry as the natural rubber latex gloves been found to contain some natural proteins which cause allergic reactions in certain individuals. The main problem associated with synthetic elastomers like XNBR is that they are typically not selfreinforcing. Therefore, addition of reinforcing fillers is a must in such lattices to meet application specifications. In the present study, poly(methacrylic acid) (PMAA) and poly(methacrylic acid & ethylhexyl acrylate) (60:40) (P(MAA-EHA)) modified nano-silica was used for reinforcement of XNBR. Evaluation of properties of XNBR vulcanizates filled with of micro silica, unmodified nano-silica, acrylic polymer modified nano-silica was carried out separately. The results show that addition of small quantities of nano-silica confers an increase of mechanical properties of XNBR vulcanizates, while high filler loadings of nano-silica decrease the mechanical properties due to the aggregation of nano-silica particles. The XNBR composites based on 5 phr of 2% PMAA and 1.5% P(MAA-EHA) surface modified nano-silica, showed the highest mechanical and swelling properties amongst all the modified fillers tested.
item: Conference-Full-text
Use of surface modified silica in reinforcing carboxylated nitrile rubber latex
(IEEE, 2016-05) Ramasinghe, RLP; Gannoruwa, GKBM; Liyanage, NMVK; Jayasekara, AGBP; Bandara, HMND; Amarasinghe, YWR
Coupling agents are a special category of chemicals used to impart interactions between filler and polymer in polymer industry. Applicability of natural polymers (NPs) as coupling agents for silica filled Carboxylated Actrilonitrile Butadiene rubber (XNBR) latex is evaluated. Cellulose, Gelatin Chitin and Chitosan were used as coupling agents for this investigation. Modification of surface of silica particles with NPs was affected by an in-situ surface modification process. Interactions between polar groups of silica and functional groups of NP which hinder the aggregation of silica particles were confirmed by FTIR spectroscopy. The colloidal stability of the unmodified / modified filler (UMF/MF) dispersions was evaluated by observing the phase separation upon standing. Stability of MF dispersions were found to be better than that of UMF dispersions. The reinforcing ability of silica through the surface modification by NPs was assessed by the evaluation of mechanical properties of XNBR vulcanized latex films filled with modified/unmodified fillers. The filler distribution within the rubber matrix was investigated through a metallurgical microscope by observing the films cross sections. NPs like chitin and gelatin were found to be effective coupling agents for silica probably by discouraging filler/filler interactions while encouraging rubber/filler interactions.