Future Carbon Blacks and New Concept of Advanced Filler Dispersion (original) (raw)
Related papers
Effect of curing system on reinforcing efficiency of silane coupling agent
Polymer Testing, 2004
Silane coupling agent has long been used to enhance degree of reinforcement of silica. The mechanical properties of silica-filled vulcanizates are greatly improved in the presence of silane coupling agent, mainly due to an increase in rubber-filler interaction. Recently, various types of silane coupling agent have been developed and commercialized. In the present study, two types of silane coupling agent, i.e. bis-(3-triethoxysilylpropyl) tetrasulfane (Si-69) and 3thiocyanatopropyl triethoxy silane (Si-264) were selected for comparison of their reinforcing action in various curing systems: conventional vulcanization (CV), semi-efficient vulcanization (semi-EV) and efficient vulcanization (EV). The results reveal that the addition of silane coupling agents not only improves compound processability, but also enhances the mechanical properties of the rubber vulcanizates. The effect of silane type on processability is found to be independent of the curing system. Compared with Si-69, Si-264 can react with the silanol groups on the silica surface more readily, due to its less bulky structure and lower viscosity. In other words, Si-264 can reduce the filler-filler interaction to a greater extent than Si-69, leading to better compound processability. The effect of silane type on the vulcanizate properties, on the other hand, depends greatly on the curing system. For CV and semi-EV systems, Si-264 imparts greater degree of reinforcement than Si-69. This might be attributed to the combined effects of better rubber-filler interaction, better filler dispersion and higher state of cure when Si-69 is replaced with Si-264. However, for the EV system, contrary results are obtained, i.e. Si-69 provides better reinforcement than Si-264. Explanation is given to the effect of sulfur contribution of Si-69 which is dominant only in the EV system.
Crosslinking of SBR Compounds for Tire Tread Using Benzocyclobutene Chemistry
Rubber Chemistry and Technology, 2019
This research investigates the potential of benzocyclobutene (BCB) chemistry for crosslinking styrenebutadiene rubber in conjunction with sulfur curatives with the objective of achieving curing at lower temperatures and/or in shorter times compared with entirely sulfur-based cure formulations. The reversible polysulfidic linkages produced in sulfur crosslinking allow self-healing characteristics but suffer from poor heat-aging stability. The CC crosslinks from BCB chemistry are irreversible and offer higher resistance to aging, but they do not present apparent self-healing properties. The hybrid curative package based on CC , C-S, and S-S linkages developed in this work is expected to provide reduced crosslinking time and/or temperature, along with higher crack-growth resistance, the ability to self-heal, higher resistance to fatigue-to-failure, reduced hysteresis, and increased abrasion resistance. The crosslinking performance of 1-substituted BCB-based compounds in conjunction with sulfur is specifically investigated.
2017
Future tire design needs to deliver more challenging performance for cars and customer requirements, revolutionizing tire technologies to be more intelligent and at the same time more safe. Additionally regulations require tire manufacturers to declare fuel efficiency, wet grip rating and external rolling noise performance. The aim is to lead a market transformation towards a more fuel-efficient, safe and low-noise tire, beyond the standards already achieved. Therefore, innovative tire design is very challenging. Synthos provides functionalized S-SBR, which can bring significant benefit for the balance between fuel efficiency by reducing rolling resistance of tires, better surface grip and improved wear resistance by introducing unique functionalization. The presentation will introduce the new look on combination of polymer and different silica-silane systems, and its influence on tire performance. It was confirmed that functionalization gives more possibilities to create a new environmental friendly compounds, and to reduce the silane dosage with no deterioration in compounds properties.
Express Polymer Letters
Natural Rubber (NR) grafted with 3-octanoylthio-1-propyltriethoxysilane (NXT) was prepared by melt mixing using 1,1′-di(tert-butylperoxy)-3,3,5-trimethylcyclohexane as initiator at 140°C with NXT contents of 10 and 20 parts per hundred rubber [phr] and initiator 0.1 phr. The silane grafted on NR molecules was confirmed by Fourier transform infrared (FTIR), proton nuclear magnetic resonance (1 H-NMR) and scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM-EDX). Based on 1 H-NMR, the use of 10 and 20 phr (parts per hundred resin) of silane resulted in grafted NXT onto NR of 0.66 and 1.32 mol%, respectively, or a grafting efficiency of approx.38%. The use of NXT-grafted NR as compatibilizer in silica-filled NR compounds, to give a total amount of NXT in both grafted and non-grafted forms in the range of 0.8-6.1 wt% relative to the silica, decreases the Mooney viscosity and Payne effect of the compounds, improves filler-rubber interaction, and significantly increases the tensile properties of the silica-filled NR-compounds compared to the non-compatibilized one. At the same silane-content, the use of silane-grafted NR gives slightly better properties than the straight use of the same silane. With sulfur compensation, the use of NXT-grafted-NR with about 6 wt% NXT relative to the silica gives technical properties that reach the levels obtained for straight use of bis-(3-triethoxysilyl-propyl)tetrasulfide (TESPT) at 8.6 wt% relative to the silica.
2000
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.
Comparison between SBR Compounds Filled with In-Situ and Ex-Situ Silanized Silica
Polymers
The main advantages of the use of silica instead of carbon black in rubber compounds are based on the use of a silane coupling agent. The use of a coupling agent to modify the silica surface improves the compatibility between the silica and the rubber. There are two different possibilities of modifying the silica surface by silane: ex-situ and in-situ. The present work studies the differences between these processes and how they affect the in-rubber properties of silica filled SBR compounds.
1995
Vulcanization kinetics and crosslink density of styrene-butadiene rubber compounds have been studied with two vulcanization systems, an efficient (EV) and a conventional (CV) one. A surface-modified silica with boron-amine groups (Si-0-B-(NH,),) was employed as filler. Untreated and modified silica with two silanes (y-mercaptopropyl-trimethoxysilane and y-aminopropyl-triethoxysilane) have been used as reference. The best kinetic parameters, such as highest vulcanization rate, longest induction time and lowest activation energy, were obtained for the compound with boronaminated silica. The crosslink density, achieved with this compound, is similar to that with silane-modified silica, probably because of the better surface distribution of boron-amine groups on the silica. These facts lead to important technological improvements: better processing safety, faster vulcanization rate and improved physical properties. ZUSAMMENFASSUNG: Die Kinetik der Vulkanisation sowie die Vernetzungsdichte von Styrol-Butadien-Kautschukmischungen wurden mit zwei Vulkanisationssystemen, einem wirksamen (EV) und einem konventionellen (CV), untersucht. Ein oberflachenmodifiziertes Silikat mit Boramingruppen (Si-0-B-(NH,),) wurde als Fullstoff eingesetzt. Unbehandeltes und mit zwei Silanen (y-Mercaptopropyl-trimethoxysilan und y-Aminopropyl-triethoxysilan) modifiziertes Silikat wurden zum Vergleich eingesetzt. Die besten
Advanced Composites Letters, 2018
Hybridization of silanized CB/PCC filler reinforced NR/SBR blends was prepared on a two roll mill. The si-CB/PCC composites were vulcanized via a conventional sulphur system at 180°C. The primary aims of this research are to scrutinize the effects of different concentration of si treated hybrid CB/PCC fillers ranging from 2 wt. % to 10 wt. % on the NR/SBR blends properties towards the curing characteristics, viscosity and crosslink density. In this work, a positive correlation was found between silane content on the hybrid filler surface and NR/SBR blend properties. It was found that at 6% of Si 69 concentration (F4) provided improvement in crosslink density and mooney viscosity properties. Increment of crosslink density in the blends would increase the viscosity and it may be due to the network formation between the treated fillers and rubber molecules. Moreover, the incorporation of treated fillers accelerates the curing process due to the surface activation and hence leads to tig...