Karnda Sengloyluan - Academia.edu (original) (raw)

Papers by Karnda Sengloyluan

Regional Studies in Marine Science, Dec 31, 2023

Applied Ecology and Environmental Research, Dec 31, 2022

Microplastic is everywhere in the aquatic ecosystem including river sediment. In this study, seve... more Microplastic is everywhere in the aquatic ecosystem including river sediment. In this study, seven sediment sampling stations were selected along the basin, from upstream to downstream (7 stations) of the U-Taphao river for 4 months (February, April, June, and August) in 2022. The total number of microplastic particles found was 1,470 pieces, consisting of 814 fibers (55.37%) and 656 fragment particles (44.63%) from the four sampling months. Station 5 showed the highest concentration of microplastics, followed by station 1. Seven polymers were found throughout the study: PE, PP, PET, rayon, copolymer, PA, and PVA. Polymer analysis from microplastic samples by FTIR polymer analysis showed significant differences in the frequency of polymer types found in each month (p < 0.001).

Applied Ecology and Environmental Research, Dec 31, 2022

Studies around the world show that there is an increasing accumulation of microplastic pollution ... more Studies around the world show that there is an increasing accumulation of microplastic pollution in the sediment. This study concerned the accumulation of microplastics in wetlands (Khuan Khi Sian, southern Thailand) sediment cores that are important to the ecosystem. The results showed significant differences in microplastic accumulation in wetlands in two seasons (p < 0.05), with more microplastic accumulation found in the wet season compared to the dry season. 'Filament' is found to be the most abundant microplastic shape and '500 µm-1 mm' was the most common size among microplastic in wet and dry seasons. Polymer composition analysis with FTIR with dry season microplastics found five types of polymers, with 'polyester' being the most common. Meanwhile, during the wet season, seven types of polymers were recorded, with 'PET' being the most common polymer.

Journal of Marine Science and Engineering

Microplastics have been found to accumulate in freshwater, marine ecosystems, and biological orga... more Microplastics have been found to accumulate in freshwater, marine ecosystems, and biological organisms. The frequency of studies on microplastic contamination in organs has increased recently, although there have been relatively fewer investigations on fish eggs in Thailand. To extract microplastics from catfish samples for laboratory analysis (Osteogeneiosus militaris), we used 10% potassium hydroxide in the digestion process. A needle penetrated the fish eggs to investigate microplastic contamination. We examined microplastics under a stereomicroscope and used Fourier transform infrared spectroscopy to determine the type of polymer. We found microplastic contamination in organs, most commonly in the stomach (0.91 ± 0.13 items/g), followed by tissue (0.53 ± 0.09 items/g), and gills (0.30 ± 0.03 items/g) at the level of significance p < 0.01. We found a total of 349 fish eggs with 27 items of microplastic. The dominant microplastic we found in the stomach, tissue, and gills of th...

PeerJ

Background Microplastics (MPs) are pollutants in rivers and marine environments. Rivers can be so... more Background Microplastics (MPs) are pollutants in rivers and marine environments. Rivers can be sources and sinks of MPs that enter the biota. Previous studies focusing on freshwater species are quite limited, especially for gastropods. Freshwater gastropods are essential to aquatic ecosystems because they are food to other aquatic animals, such as fish, shrimp, and crabs. They are a crucial link in the food chain between water resources and human food. Therefore, this study aimed to investigate MP accumulation in freshwater gastropods, commonly known as snails (Filopaludina sumatrensis speciosa and Pomacea canaliculata), in a river flowing into a shallow coastal lagoon. Method In this study, snail tissue samples were digested with 30% hydrogen peroxide. The mixture was heated at 60 °C for 24 h. MP particles were identified, counted, and characterized (shape, size, and color) by visual identification under a stereomicroscope. Furthermore, polymer-type identification was performed usi...

Journal of Marine Science and Engineering

Microplastic (MP) contamination in the marine environment has received growing attention. In 2022... more Microplastic (MP) contamination in the marine environment has received growing attention. In 2022, the surface water of the U-Taphao River was sampled four times, in February, April, June, and August. The surface water samples were taken at seven different locations, ranging from upstream to downstream parts of the river. The results reveal that the number of MPs detected at the U-Taphao River in February, April, June, and August were 0.41 ± 0.08, 0.25 ±0.06, 0.24 ± 0.11, and 0.26 ± 0.06 particles/L, respectively. The MPs in the U-Taphao River each month were not statistically different (p = 0.190). The trend of the number of MPs found declined from upstream to downstream. Fibers were the most commonly found MPs in the U-Taphao River in this study and were found at more than 80% of all stations during all sample collection periods. Our results indicate that MP contamination is present in the river water, but it is noted that slightly different polymer types were found during each co...

IOP Conference Series: Materials Science and Engineering, 2020

The effect of acrylonitrile butadiene rubber (NBR) as a compatibilizer in silica-reinforced natur... more The effect of acrylonitrile butadiene rubber (NBR) as a compatibilizer in silica-reinforced natural rubber (NR) is studied. NBR, Emulcril 3380 with 32-34%, was various at 5, 10, 15, 20 and 25 part per hundred parts of rubber (phr) to be used as a compatibilizer for silica-filled NR. The use of NBR as a compatiblizer can improve cure time (T90), cure rate index (CRI), and Mooney viscosity of silica-filled NR compounds, but the re-agglomeration of filler still observes. The use of NBR does not show significantly effect on bound rubber contents. However, tensile strength, reinforcement index and tear strength are increased with increasing amount of NBR contents due to a presence of some rubber-filler interaction through acrylonitrile groups of NBR and silanol groups on the silica surface. It leads to observe more surface roughness on tensile fractured surfaces.

Polymers, 2021

The self-healing composites were prepared from the combination of bromobutyl rubber (BIIR) and na... more The self-healing composites were prepared from the combination of bromobutyl rubber (BIIR) and natural rubber (NR) blends filled with carbon nanotubes (CNT) and carbon black (CB). To reach the optimized self-healing propagation, the BIIR was modified with ionic liquid (IL) and butylimidazole (IM), and blended with NR using the ratios of 70:30 and 80:20 BIIR:NR. Physical and chemical modifications were confirmed from the mixing torque and attenuated total reflection-fourier transform infrared spectroscopy (ATR-FTIR). It was found that the BIIR/NR-CNTCB with IL and IM effectively improved the cure properties with enhanced tensile properties relative to pure BIIR/NR blends. For the healed composites, BIIR/NR-CNTCB-IM exhibited superior mechanical and electrical properties due to the existing ionic linkages in rubber matrix. For the abrasion resistances, puncture stress and electrical recyclability were examined to know the possibility of inner liner applications and Taber abrasion with...

Materials Research Innovations

Introduction 1 Chapter 2 Literature overview: reinforcement efficiency of silica-filled rubber wi... more Introduction 1 Chapter 2 Literature overview: reinforcement efficiency of silica-filled rubber with different compatibilizing techniques 7 Chapter 3 Silica-reinforced tire tread compounds compatibilized by using epoxidized natural rubber 45 Chapter 4 Silica-reinforced natural rubber compounds compatibilized by ENR in combination with TESPT and sulfur compensation 73 Chapter 5 Silica-reinforced natural rubber compounds compatibilized by ENR in combination with different silane coupling agent types 97 Chapter 6 Influence of types of silane coupling agents on the reinforcement of silica in natural rubber compounds Chapter 7 Preparation and characterization of silane-grafted natural rubber Chapter 8 Silane-grafted natural rubber as compatibilizer in silicareinforced natural rubber Chapter 9 Compatibilization of silica-filled natural rubber by using silane-grafted-natural rubber with compensation of sulfur Summary Samenvatting Symbols and abbreviations Bibliography Acknowledgements Curriculum vitae colored or transparent articles, e.g., shoe soles. For tire compounds, precipitated silica was first used in small amounts in combination with carbon black to improve adhesion in tire cord-rubber, and to improve cutting and chipping resistances. [8] After a patent of Michelin on the so-called "Green Tire" [9] , silica-silane technology has been increasingly used for passenger car tire treads. Silica is an inorganic filler with hydroxyl, also called silanol groups on its surface that can form hydrogen bonds and thus strong filler-filler interactions to generate silica aggregates and agglomerates. It is therefore difficult to disperse and does not interact with non-polar rubber matrices like natural rubber (NR) and styrene-butadiene rubber (SBR), which are the types of rubbers used in tire compounds. To improve the properties of silica-filled compounds, silane coupling agents are generally added to improve silica-rubber interaction and to decrease the silica-silica interaction. The use of silane coupling agents leads to reduction of compound viscosity, an improvement in cure characteristics and a significant increase of modulus, tensile strength, and abrasion resistance. The first silane coupling agent introduced by Union Carbide, was mercaptopropyl-trimethoxysilane (MPS) under the trade name of A-189. Afterwards, Bis-(triethoxysilylpropyl)tetrasulfide (TESPT) was introduced under the trade name Si-69 by Degussa. [10] The use of the silica/TESPT combination in tire tread compounds improves wet traction and rolling resistance without negative affects on abrasion resistance. Silica technology has been further developed to improve the properties of silica-filled compounds, either in aspects of the silica characteristics or development of new silane coupling agents or compatibilizer systems. 1.2 Background of the thesis Natural rubber (NR) is an important material to produce rubber tires, especially heavy duty truck tires. NR has superior mechanical properties over other synthetic rubbers, due to its high molecular weight, and regular structure of cis-1,4-polyisoprene. NR can crystallize when it is stretched by external force, so called "strain-induced crystallization", which leads to high tensile strength and elongation at break. Despite the good strength of NR, reinforcing fillers such as carbon black and silica are commonly used to enhance the properties of NR further for high performance products such as tires. Due to the strong filler-filler interactions between silica aggregates caused by the large number of silanol groups on the silica surface, the use of silica in NR or other hydrocarbon rubbers requires a silane coupling agent or compatibilizer. The most commonly used silane coupling agent is TESPT, but some drawbacks of the use of this silane in silica-filled compounds have been reported. These are an increase of Mooney viscosity upon storage 1.4 Concept of the thesis This project investigated the use of chemically functionalized natural rubbers as compatibilizers in silica-reinforced natural rubber with emphasis on the improvement of silica-rubber interaction, mechanical properties and tire performance, i.e. wet skid and rolling resistance, in comparison with the use of a conventional silane coupling agent. The thesis is composed of the following chapters; Chapter 1 Introduction: This first chapter shortly reveals the development of tires and filler technology with emphasis on tire compounds. It is then followed by a description of the background and aims of this research. Chapter 2 Literature overview: This part focuses on the use of reinforcing fillers mainly carbon black and silica in rubber compounds. The reinforcing efficiency of silica, factors influencing silica reinforcement and development of silica technology for tire compounds are reviewed. The use of silane coupling agents, some polar materials and chemically modified rubbers to improve silica-rubber interactions and the properties of silica-filled compounds are discussed. This chapter ends by providing motivation and scope of the project. Chapter 3 Silica-reinforced tire tread compounds compatibilized by using epoxidized natural rubber: This chapter first describes the preparation and characterization of epoxidized natural rubber (ENR) with various mole% of epoxide. ENRs with different mole% of epoxide groups are used as compatibilizers to optimize the properties of silica-filled natural rubber compounds compared to compounds with Bis-(triethoxysilylpropyl)tetrasulfide (TESPT) and without compatibilizer. Chapter 4 Silica-reinforced natural rubber compounds compatibilized by ENR in combination with TESPT and sulfur compensation: While a silica-filled natural rubber compound with only ENR as compatibilizer shows overall lower properties than with TESPT silane coupling agent, this section studies the use of an optimized ENR type and content (i.e. 7.5 phr of ENR-51) in combination with TESPT to further enhance the properties of the compounds. The TESPT contents are varied and the effect of extra sulfur to compensate for the sulfur contents in TESPT molecules on the properties of silicareinforced natural rubber is investigated. Chapter 5 Silica-reinforced natural rubber compounds compatibilized by ENR in combination with different silane coupling agent types: The reinforcing CHAPTER 2 Literature Overview: Reinforcement Efficiency of Silica-Filled Rubber with Different Compatibilizing Techniques This Chapter gives an overview of reinforcing fillers which have been used in the rubber industry with particular attention to fillers used in tire compounds, e.g. carbon black and silica. Filler characteristics, such as specific surface area, filler structure and surface activity, that influence the properties of filled rubber are discussed. Filler reinforcement of rubbers in general, and dynamic properties of filled rubber in relation to tire performance are reviewed. Silica-reinforced rubber compounding and its associated difficulties coming from silica-rubber incompatibility are addressed. This leads to the development of silicasilane technology which involves a silanization reaction between alkoxy groups of a silane and silanol groups on the silica surface. Due to the greatly increased interest in silica usage especially for low rolling resistance tire treads, several alternative approaches have been adopted in order to improve silica dispersion and filler-rubber interaction. Some of those approaches are reviewed in this section. Among them the use of polar polymers, such as polychloroprene rubber, acrylonitrile-butadiene rubber, epoxidized rubbers, as compatibilizers for silica-reinforced rubber compounds. Particular attention is given to chemically modified natural rubber which can potentially be used for silica-reinforced natural rubber compounds, as investigated in this thesis. The chapter ends by providing the motivation for this thesis.

Advanced Materials Research, 2013

Epoxidized natural rubber (ENR) and bis-(3-triethoxysilylpropyl) tetrasulfide (TESPT) were used t... more Epoxidized natural rubber (ENR) and bis-(3-triethoxysilylpropyl) tetrasulfide (TESPT) were used to improve the properties of silica-filled NR. The use of ENR containing 51 mol% epoxide groups (ENR-51) as a compatibilizer without TESPT was optimized at 7.5 phr, based on the results of Payne effect and tensile strength. By using 7.5 phr of ENR-51 with varying amounts of TESPT in a range of 2 to 5 wt% relative to the silica, the properties of compounds were compared to those of the ones with optimum TESPT content (i.e. 8.6 wt% relative to the silica) and without. The addition of TESPT to the ENR-51 compatibilized silica-filled NR compound had no effect on Mooney viscosity but lowered the Payne effect to the same level as that of the silica/TESPT compound, and significantly decreased both scorch and optimum cure times. The silica-filled NR with ENR and the small amount of TESPT combination showed a further increase in tensile strength to match that of the optimized silica/TESPT system, ...

European Polymer Journal, 2014

ABSTRACT Silica-reinforced natural rubber (NR) tire tread compounds with epoxidized natural rubbe... more ABSTRACT Silica-reinforced natural rubber (NR) tire tread compounds with epoxidized natural rubber (ENR) as a compatibilizer are investigated. The ENRs consisting of 10, 38 and 51 mol% epoxide are used in a range of 2.5 to 15.0 parts per hundred parts of rubber (phr). The addition of ENRs, especially ENR-38 and ENR-51, decreases the Mooney viscosity, Payne effect, flocculation rate constant and filler networking factor, which implies an improvement of silica dispersion in the compounds. Chemically bound rubber contents and interaction parameters of the compounds also increase with higher epoxide-contents of the ENRs, indicating more interactions and/or reaction between the epoxide-groups of the ENR and silanol groups on the silica surface. Tensile strength of the vulcanizates is improved with increasing mole% epoxide, and the optimum value is observed at 7.5 phr of ENR-51. The overall results show that silica-reinforced NR can be substantially improved by adding ENR as a compatibilizer, when compared to a compound without ENR, but somewhat less than with using a silane coupling agent.

Regional Studies in Marine Science, Dec 31, 2023

Applied Ecology and Environmental Research, Dec 31, 2022

Microplastic is everywhere in the aquatic ecosystem including river sediment. In this study, seve... more Microplastic is everywhere in the aquatic ecosystem including river sediment. In this study, seven sediment sampling stations were selected along the basin, from upstream to downstream (7 stations) of the U-Taphao river for 4 months (February, April, June, and August) in 2022. The total number of microplastic particles found was 1,470 pieces, consisting of 814 fibers (55.37%) and 656 fragment particles (44.63%) from the four sampling months. Station 5 showed the highest concentration of microplastics, followed by station 1. Seven polymers were found throughout the study: PE, PP, PET, rayon, copolymer, PA, and PVA. Polymer analysis from microplastic samples by FTIR polymer analysis showed significant differences in the frequency of polymer types found in each month (p < 0.001).

Applied Ecology and Environmental Research, Dec 31, 2022

Studies around the world show that there is an increasing accumulation of microplastic pollution ... more Studies around the world show that there is an increasing accumulation of microplastic pollution in the sediment. This study concerned the accumulation of microplastics in wetlands (Khuan Khi Sian, southern Thailand) sediment cores that are important to the ecosystem. The results showed significant differences in microplastic accumulation in wetlands in two seasons (p < 0.05), with more microplastic accumulation found in the wet season compared to the dry season. 'Filament' is found to be the most abundant microplastic shape and '500 µm-1 mm' was the most common size among microplastic in wet and dry seasons. Polymer composition analysis with FTIR with dry season microplastics found five types of polymers, with 'polyester' being the most common. Meanwhile, during the wet season, seven types of polymers were recorded, with 'PET' being the most common polymer.

Journal of Marine Science and Engineering

Microplastics have been found to accumulate in freshwater, marine ecosystems, and biological orga... more Microplastics have been found to accumulate in freshwater, marine ecosystems, and biological organisms. The frequency of studies on microplastic contamination in organs has increased recently, although there have been relatively fewer investigations on fish eggs in Thailand. To extract microplastics from catfish samples for laboratory analysis (Osteogeneiosus militaris), we used 10% potassium hydroxide in the digestion process. A needle penetrated the fish eggs to investigate microplastic contamination. We examined microplastics under a stereomicroscope and used Fourier transform infrared spectroscopy to determine the type of polymer. We found microplastic contamination in organs, most commonly in the stomach (0.91 ± 0.13 items/g), followed by tissue (0.53 ± 0.09 items/g), and gills (0.30 ± 0.03 items/g) at the level of significance p < 0.01. We found a total of 349 fish eggs with 27 items of microplastic. The dominant microplastic we found in the stomach, tissue, and gills of th...

PeerJ

Background Microplastics (MPs) are pollutants in rivers and marine environments. Rivers can be so... more Background Microplastics (MPs) are pollutants in rivers and marine environments. Rivers can be sources and sinks of MPs that enter the biota. Previous studies focusing on freshwater species are quite limited, especially for gastropods. Freshwater gastropods are essential to aquatic ecosystems because they are food to other aquatic animals, such as fish, shrimp, and crabs. They are a crucial link in the food chain between water resources and human food. Therefore, this study aimed to investigate MP accumulation in freshwater gastropods, commonly known as snails (Filopaludina sumatrensis speciosa and Pomacea canaliculata), in a river flowing into a shallow coastal lagoon. Method In this study, snail tissue samples were digested with 30% hydrogen peroxide. The mixture was heated at 60 °C for 24 h. MP particles were identified, counted, and characterized (shape, size, and color) by visual identification under a stereomicroscope. Furthermore, polymer-type identification was performed usi...

Journal of Marine Science and Engineering

Microplastic (MP) contamination in the marine environment has received growing attention. In 2022... more Microplastic (MP) contamination in the marine environment has received growing attention. In 2022, the surface water of the U-Taphao River was sampled four times, in February, April, June, and August. The surface water samples were taken at seven different locations, ranging from upstream to downstream parts of the river. The results reveal that the number of MPs detected at the U-Taphao River in February, April, June, and August were 0.41 ± 0.08, 0.25 ±0.06, 0.24 ± 0.11, and 0.26 ± 0.06 particles/L, respectively. The MPs in the U-Taphao River each month were not statistically different (p = 0.190). The trend of the number of MPs found declined from upstream to downstream. Fibers were the most commonly found MPs in the U-Taphao River in this study and were found at more than 80% of all stations during all sample collection periods. Our results indicate that MP contamination is present in the river water, but it is noted that slightly different polymer types were found during each co...

IOP Conference Series: Materials Science and Engineering, 2020

The effect of acrylonitrile butadiene rubber (NBR) as a compatibilizer in silica-reinforced natur... more The effect of acrylonitrile butadiene rubber (NBR) as a compatibilizer in silica-reinforced natural rubber (NR) is studied. NBR, Emulcril 3380 with 32-34%, was various at 5, 10, 15, 20 and 25 part per hundred parts of rubber (phr) to be used as a compatibilizer for silica-filled NR. The use of NBR as a compatiblizer can improve cure time (T90), cure rate index (CRI), and Mooney viscosity of silica-filled NR compounds, but the re-agglomeration of filler still observes. The use of NBR does not show significantly effect on bound rubber contents. However, tensile strength, reinforcement index and tear strength are increased with increasing amount of NBR contents due to a presence of some rubber-filler interaction through acrylonitrile groups of NBR and silanol groups on the silica surface. It leads to observe more surface roughness on tensile fractured surfaces.

Polymers, 2021

The self-healing composites were prepared from the combination of bromobutyl rubber (BIIR) and na... more The self-healing composites were prepared from the combination of bromobutyl rubber (BIIR) and natural rubber (NR) blends filled with carbon nanotubes (CNT) and carbon black (CB). To reach the optimized self-healing propagation, the BIIR was modified with ionic liquid (IL) and butylimidazole (IM), and blended with NR using the ratios of 70:30 and 80:20 BIIR:NR. Physical and chemical modifications were confirmed from the mixing torque and attenuated total reflection-fourier transform infrared spectroscopy (ATR-FTIR). It was found that the BIIR/NR-CNTCB with IL and IM effectively improved the cure properties with enhanced tensile properties relative to pure BIIR/NR blends. For the healed composites, BIIR/NR-CNTCB-IM exhibited superior mechanical and electrical properties due to the existing ionic linkages in rubber matrix. For the abrasion resistances, puncture stress and electrical recyclability were examined to know the possibility of inner liner applications and Taber abrasion with...

Materials Research Innovations

Introduction 1 Chapter 2 Literature overview: reinforcement efficiency of silica-filled rubber wi... more Introduction 1 Chapter 2 Literature overview: reinforcement efficiency of silica-filled rubber with different compatibilizing techniques 7 Chapter 3 Silica-reinforced tire tread compounds compatibilized by using epoxidized natural rubber 45 Chapter 4 Silica-reinforced natural rubber compounds compatibilized by ENR in combination with TESPT and sulfur compensation 73 Chapter 5 Silica-reinforced natural rubber compounds compatibilized by ENR in combination with different silane coupling agent types 97 Chapter 6 Influence of types of silane coupling agents on the reinforcement of silica in natural rubber compounds Chapter 7 Preparation and characterization of silane-grafted natural rubber Chapter 8 Silane-grafted natural rubber as compatibilizer in silicareinforced natural rubber Chapter 9 Compatibilization of silica-filled natural rubber by using silane-grafted-natural rubber with compensation of sulfur Summary Samenvatting Symbols and abbreviations Bibliography Acknowledgements Curriculum vitae colored or transparent articles, e.g., shoe soles. For tire compounds, precipitated silica was first used in small amounts in combination with carbon black to improve adhesion in tire cord-rubber, and to improve cutting and chipping resistances. [8] After a patent of Michelin on the so-called "Green Tire" [9] , silica-silane technology has been increasingly used for passenger car tire treads. Silica is an inorganic filler with hydroxyl, also called silanol groups on its surface that can form hydrogen bonds and thus strong filler-filler interactions to generate silica aggregates and agglomerates. It is therefore difficult to disperse and does not interact with non-polar rubber matrices like natural rubber (NR) and styrene-butadiene rubber (SBR), which are the types of rubbers used in tire compounds. To improve the properties of silica-filled compounds, silane coupling agents are generally added to improve silica-rubber interaction and to decrease the silica-silica interaction. The use of silane coupling agents leads to reduction of compound viscosity, an improvement in cure characteristics and a significant increase of modulus, tensile strength, and abrasion resistance. The first silane coupling agent introduced by Union Carbide, was mercaptopropyl-trimethoxysilane (MPS) under the trade name of A-189. Afterwards, Bis-(triethoxysilylpropyl)tetrasulfide (TESPT) was introduced under the trade name Si-69 by Degussa. [10] The use of the silica/TESPT combination in tire tread compounds improves wet traction and rolling resistance without negative affects on abrasion resistance. Silica technology has been further developed to improve the properties of silica-filled compounds, either in aspects of the silica characteristics or development of new silane coupling agents or compatibilizer systems. 1.2 Background of the thesis Natural rubber (NR) is an important material to produce rubber tires, especially heavy duty truck tires. NR has superior mechanical properties over other synthetic rubbers, due to its high molecular weight, and regular structure of cis-1,4-polyisoprene. NR can crystallize when it is stretched by external force, so called "strain-induced crystallization", which leads to high tensile strength and elongation at break. Despite the good strength of NR, reinforcing fillers such as carbon black and silica are commonly used to enhance the properties of NR further for high performance products such as tires. Due to the strong filler-filler interactions between silica aggregates caused by the large number of silanol groups on the silica surface, the use of silica in NR or other hydrocarbon rubbers requires a silane coupling agent or compatibilizer. The most commonly used silane coupling agent is TESPT, but some drawbacks of the use of this silane in silica-filled compounds have been reported. These are an increase of Mooney viscosity upon storage 1.4 Concept of the thesis This project investigated the use of chemically functionalized natural rubbers as compatibilizers in silica-reinforced natural rubber with emphasis on the improvement of silica-rubber interaction, mechanical properties and tire performance, i.e. wet skid and rolling resistance, in comparison with the use of a conventional silane coupling agent. The thesis is composed of the following chapters; Chapter 1 Introduction: This first chapter shortly reveals the development of tires and filler technology with emphasis on tire compounds. It is then followed by a description of the background and aims of this research. Chapter 2 Literature overview: This part focuses on the use of reinforcing fillers mainly carbon black and silica in rubber compounds. The reinforcing efficiency of silica, factors influencing silica reinforcement and development of silica technology for tire compounds are reviewed. The use of silane coupling agents, some polar materials and chemically modified rubbers to improve silica-rubber interactions and the properties of silica-filled compounds are discussed. This chapter ends by providing motivation and scope of the project. Chapter 3 Silica-reinforced tire tread compounds compatibilized by using epoxidized natural rubber: This chapter first describes the preparation and characterization of epoxidized natural rubber (ENR) with various mole% of epoxide. ENRs with different mole% of epoxide groups are used as compatibilizers to optimize the properties of silica-filled natural rubber compounds compared to compounds with Bis-(triethoxysilylpropyl)tetrasulfide (TESPT) and without compatibilizer. Chapter 4 Silica-reinforced natural rubber compounds compatibilized by ENR in combination with TESPT and sulfur compensation: While a silica-filled natural rubber compound with only ENR as compatibilizer shows overall lower properties than with TESPT silane coupling agent, this section studies the use of an optimized ENR type and content (i.e. 7.5 phr of ENR-51) in combination with TESPT to further enhance the properties of the compounds. The TESPT contents are varied and the effect of extra sulfur to compensate for the sulfur contents in TESPT molecules on the properties of silicareinforced natural rubber is investigated. Chapter 5 Silica-reinforced natural rubber compounds compatibilized by ENR in combination with different silane coupling agent types: The reinforcing CHAPTER 2 Literature Overview: Reinforcement Efficiency of Silica-Filled Rubber with Different Compatibilizing Techniques This Chapter gives an overview of reinforcing fillers which have been used in the rubber industry with particular attention to fillers used in tire compounds, e.g. carbon black and silica. Filler characteristics, such as specific surface area, filler structure and surface activity, that influence the properties of filled rubber are discussed. Filler reinforcement of rubbers in general, and dynamic properties of filled rubber in relation to tire performance are reviewed. Silica-reinforced rubber compounding and its associated difficulties coming from silica-rubber incompatibility are addressed. This leads to the development of silicasilane technology which involves a silanization reaction between alkoxy groups of a silane and silanol groups on the silica surface. Due to the greatly increased interest in silica usage especially for low rolling resistance tire treads, several alternative approaches have been adopted in order to improve silica dispersion and filler-rubber interaction. Some of those approaches are reviewed in this section. Among them the use of polar polymers, such as polychloroprene rubber, acrylonitrile-butadiene rubber, epoxidized rubbers, as compatibilizers for silica-reinforced rubber compounds. Particular attention is given to chemically modified natural rubber which can potentially be used for silica-reinforced natural rubber compounds, as investigated in this thesis. The chapter ends by providing the motivation for this thesis.

Advanced Materials Research, 2013

Epoxidized natural rubber (ENR) and bis-(3-triethoxysilylpropyl) tetrasulfide (TESPT) were used t... more Epoxidized natural rubber (ENR) and bis-(3-triethoxysilylpropyl) tetrasulfide (TESPT) were used to improve the properties of silica-filled NR. The use of ENR containing 51 mol% epoxide groups (ENR-51) as a compatibilizer without TESPT was optimized at 7.5 phr, based on the results of Payne effect and tensile strength. By using 7.5 phr of ENR-51 with varying amounts of TESPT in a range of 2 to 5 wt% relative to the silica, the properties of compounds were compared to those of the ones with optimum TESPT content (i.e. 8.6 wt% relative to the silica) and without. The addition of TESPT to the ENR-51 compatibilized silica-filled NR compound had no effect on Mooney viscosity but lowered the Payne effect to the same level as that of the silica/TESPT compound, and significantly decreased both scorch and optimum cure times. The silica-filled NR with ENR and the small amount of TESPT combination showed a further increase in tensile strength to match that of the optimized silica/TESPT system, ...

European Polymer Journal, 2014

ABSTRACT Silica-reinforced natural rubber (NR) tire tread compounds with epoxidized natural rubbe... more ABSTRACT Silica-reinforced natural rubber (NR) tire tread compounds with epoxidized natural rubber (ENR) as a compatibilizer are investigated. The ENRs consisting of 10, 38 and 51 mol% epoxide are used in a range of 2.5 to 15.0 parts per hundred parts of rubber (phr). The addition of ENRs, especially ENR-38 and ENR-51, decreases the Mooney viscosity, Payne effect, flocculation rate constant and filler networking factor, which implies an improvement of silica dispersion in the compounds. Chemically bound rubber contents and interaction parameters of the compounds also increase with higher epoxide-contents of the ENRs, indicating more interactions and/or reaction between the epoxide-groups of the ENR and silanol groups on the silica surface. Tensile strength of the vulcanizates is improved with increasing mole% epoxide, and the optimum value is observed at 7.5 phr of ENR-51. The overall results show that silica-reinforced NR can be substantially improved by adding ENR as a compatibilizer, when compared to a compound without ENR, but somewhat less than with using a silane coupling agent.