BIMS/filler interactions. I. Effects of filler structure

Polymer/filler interactions have been found to affect the performance of tire tread, sidewall, innerliner, or carcass and other industrial rubber products that are all based on filled elastomers. Identification of types of various polymer/filler interactions and ranking of their impacts have been elusive. Isobutylene-based polymers have relatively saturated structures and contain very low concentrations of functional group. Examples are BIMS (a brominated isobutylene/p-methylstyrene copolymer) containing p-bromomethylstyrene and p-methylstyrene; bromobutyl rubber containing  Br and olefin; chlorobutyl rubber containing  Cl and olefin; and butyl rubber containing olefin. On the other hand, high diene rubbers, such as polybutadiene rubber, polyisoprene rubber, and styrene/butadiene rubber, have unsaturated backbones and high olefin contents. Hence, different types and extents of interaction with reinforcing fillers, such as carbon black (CB) or silica, are expected in these two classes of elastomer. This work employs bound rubber (solvent extraction), viscoelasticity, stress–strain measurements, and solid state NMR to identify, differentiate, and scale polymer/filler interactions in unvulcanized BIMS/CB, BIMS/silica, SBR/CB, and SBR/silica composites, where SBR denotes a styrene/butadiene rubber. Four different types of CB and one type of silica have been studied. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4943–4956, 2006     

Norbornylized soybean oil as a sustainable new plasticizer for rubbers with hybrid fillers

Carbon black (CB) and precipitated silica are two major reinforcing fillers in rubbers. CB/silica hybrid filler is also widely used in rubbers to provide balanced properties. CB/silica‐hybrid‐filler‐filled styrene‐butadiene rubber (SBR) containing naphthenic oil (NO), soybean oil (SO) and norbornylized SO (NSO) was investigated. The swelling and curing behavior and rheological, mechanical, thermal, aging and dynamic properties were studied and compared with earlier reported data on CB‐ or silica‐filled SBR. NSO provides better scorch safety and faster cure than SO. Compared with NO, the addition of SO and NSO enhances the thermal stability and aging resistance of SBR vulcanizates. SBR/NSO vulcanizates with hybrid filler exhibit a higher tensile and tear strength than SBR/NO and SBR/SO vulcanizates. A synergistic effect in the abrasion resistance of vulcanizates containing the hybrid filler is observed. An increase of sulfur content in the hybrid‐filler‐filled SBR/NSO vulcanizates provides further improvement in abrasion resistance, wet traction and rolling resistance. © 2017 Society of Chemical Industry     

硅藻土/白炭黑复合填料的补强性研究

为拓展硅藻土在高分子复合材料中的应用,将硅藻土/白炭黑填充到天然橡胶/丁苯橡胶/顺丁橡胶中制备了复合材料。通过RPA2000和扫描电镜分析了复合填料的Payne效应和分散性,考察了硅藻土用量对复合材料工艺性能、力学性能、耐磨耗性能影响。结果表明:少量硅藻土的加入有利于白炭黑在橡胶中的分散,能降低复合材料的门尼粘度和Payne效应,提高复合材料的硫化速度,缩短硫化时间,复合填料的补强效果较好;随着硅藻土用量的增加,复合填料容易聚集,其力学性能呈下降趋势,而磨耗性能变化不大;当硅藻土用量10~20份时,复合材料的综合性能最好。     

Comparative role of Interface in reinforcing mechanisms of Nano silica modified by Silanes and liquid rubber in SBR composites

The objective of the present study is to discuss the role of silica-rubber interfacial interactions on vulcanization kinetics, morphology, mechanical and viscoelastic behavior of silica filled styrene butadiene rubber (SBR) composites. Three types of modifiers, namely mono- and bi-functional silanes as well as hydroxyl-terminated poly butadiene (HTPB) liquid rubber were grafted to silica surface, and composites prepared by these fillers were characterized. Results showed that modified silica, especially grafted by bi-functional silane and liquid rubber, accelerated vulcanization reactions, while pristine silica slowed down vulcanization kinetics of SBR. Morphological studies indicated that all modifications improved dispersion of silica, but HTPB-grafted silica was dispersed to a greater extent in SBR. The observed differences in mechanical and dynamic-mechanical properties of vulcanizates were correlated to the significant differences in silica-rubber and silica-silica interactions. Type of interfacial interactions, i.e. rigid covalent bonds in the bi-functional silane, flexible polymeric bonds in the liquid rubber, and weak energetic bonds in the mono-functional silane, could explain the observed differences. Although all modifications reduced filler networking, rigid covalent bonding by bi-functional silane significantly improved mechanical properties and stabilized the filler network. The mono-functional silane lacks these mechanisms. The soft and flexible interphase of HTPB could create bonds and transfer stresses between the rubber matrix and silica to some extent, however it could not improve the mechanical properties and reduce the Payne effect as much as the bi-functional silane did.     

Guayule natural rubber composites: impact of fillers on their cure characteristics,dynamic and mechanical behavior

Guayule natural rubber (GNR) is an alternative resource of Hevea natural rubber (HNR) with 99.9% cis content in its 1,4-polyisoprene chemical backbone. In this study, compounds were formulated independently with four different reinforcing fillers such as carbon black (HAF), precipitated silica (VN3), fume silica (FUM) and nanofly ash (NFA) for the advancement of GNR based products. The cure characteristic, dynamic-mechanical performance and mechanical properties of GNR composite were studied with the reinforcing effect of different fillers on GNR. The cure characteristic results demonstrated that HAF and FUM silica filled compounds had more processing safety than VN3 and NFA filled compounds. Viscoelastic parameters of the vulcanizates were studied by dynamic mechanical analysis to estimate the glass transition characteristics and dynamic behavior. The higher storage modulus of FUM silica vulcanizate was an indication of superior filler reinforcing nature and improved rolling resistance than other filled systems. Additionally, HRTEM analysis also proved the better filler dispersion ability of FUM silica in GNR matrix. The mechanical properties were studied with a variation of each filler loading of 8, 16, and 32 phr in GNR vulcanizates. The tensile strength of each filled system increased with an increase of filler content from 8 to 32 phr. In comparison, FUM silica GNR vulcanizates exhibited better mechanical properties, therefore, it was considered as a better structure-performance composite than those of HAF, VN3 and NFA filled composites.

     

Effect of fillers on morphological properties in NR/SBR blends for OTR tyres

Abstract

The blends of styrene butadiene rubber (SBR) and natural rubber (NR) are prepared using a two-roll mixing mill in the presence of different types of carbon blacks as reinforcing filler. The effects of fillers on cure characteristics and thermal, dynamic–mechanical, morphological properties of the blends are studied. The ISAF N231 type of carbon black shows a significant effect on tensile, tear and modulus properties by reacting at the interface between SBR/NR matrixes. The dynamic characteristics and storage modulus of SBR/NR with SAF N110 and SRF N774 types of carbon black show distinct characteristics in respect to all other blends in this system. The thermal stability of the rubber vulcanizates containing SAF N110 and SRF N774 types of carbon blacks is higher than other blend types. With the increasing percentage of SBR to NR, the thermal stability of the blend is increased. However, the heat buildup of the blends increases with the increase in SBR percentage.     

Contribution of physico-chemical properties of interfaces on dispersibility, adhesion and flocculation of filler particles in rubber

Reinforcing fillers are added to elastomeric compounds to improve and adjust several mechanical, dynamical, tribological, etc. properties with respect to different applications, i.e. for automotive tires, or technical rubber goods. Carbon black and precipitated silica are widely used as rubber reinforcing fillers; however, some new classes of nanosized substances like organophilic modified clay or carbon nanotubes are presently intensive studied as possible future filler systems in combination with carbon black or silica.An important parameter for the dispersibility and compatibility of the filler in the polymer matrix of rubber compounds is the surface energy and surface polarity of the solid filler particles. Therefore, we systematically measured and compared the dynamic contact angles of a collection of different filler types (carbon blacks, silica, carbon nanotubes and organoclays) using the Wilhelmy method, whereby the particles were fixed as a thin layer at a double-sided adhesive tape. From the contact angle values the polar and disperse part of the surface energies of the filler particles were calculated by fitting Fowkes formula. For an estimation of the compatibility of the fillers with different types of rubber polymers we additionally analyzed the surface energy and polarity of the gum (unfilled) elastomers. From the evaluated surface energies and polarities, thermodynamic predictors for the dispersibility (enthalpy of immersion), the adhesion between filler particles and polymer matrix in the nanocomposite, and for the flocculation behaviour of the particles in a rubber matrix (difference in the works of adhesion) were derived. These thermodynamic predictors improve considerably the compounding process of novel rubber nanocomposites with respect to target-oriented adjustment of rubber properties.     

The interplay between the fragility and mechanical properties of styrene–butadiene rubber composites with unmodified and modified sago seed shell powder

Reinforcing rubber with natural fillers from agrarian wastes is a new area of interest in developing rubber composite technologies. Lignocellulosic material from sago seed shell is one of the important promising natural fillers having 37% cellulose used to reinforce styrene–butadiene rubber (SBR) for enhancing its mechanical properties. Moreover, chemically or physically modified natural fillers play a significant role in enhancing the properties of SBR like morphological, thermal, and electrical characteristics. In this investigation, the changes encountered in molecular mobility, glassy dynamics, thermal stability, flexibility, and tensile strength of SBR on reinforcing with unmodified and modified sago seed shell powder were studied using broadband dielectric spectroscopy (BDS) in conjunction with thermogravimetric analysis, and mechanical properties. BDS has been successfully employed to investigate the relaxation phenomena and glass/rubbery transition in SBR, as well as its composites with unmodified and modified sago seed shell powder over the frequency (10⁻¹ to 10⁷ Hz) and wide temperature range (−100 to 150°C). Experimental data were analyzed in terms of electric modulus formalism and were suited well with the Havriliak Nigami equation. The incorporation of filler and its nature (unmodified or modified it with polyaniline, PANI) greatly influenced the morphological pattern, miscibility, and mode of interaction with the rubber matrix of SBR, which owed a path to diverse charge transport mechanism in the composites. The mechanical properties of all the composites were in good correlation with the steepness index obtained from BDS. The tensile strength, tear strength, and hardness of SBR increased slightly on loading with unmodified cellulose, whereas with modified cellulose causes substantial enhancement in its tensile strength.     

Properties of silica‐filled styrene‐butadiene rubber compounds containing acrylonitrile‐butadiene rubber: The influence of the acrylonitrile‐butadiene rubber type

Because silica has strong filler‐filler interactions and adsorbs polar materials, a silica‐filled rubber compound exhibits poor dispersion of the filler and poor cure characteristics in comparison with those of a carbon black‐filled rubber compound. Acrylonitrile‐butadiene rubber (NBR) improves filler dispersion in silica‐filled styrene‐butadiene rubber (SBR) compounds. The influence of the NBR type on the properties of silica‐filled SBR compounds containing NBR was studied with NBRs of various acrylonitrile contents. The composition of the bound rubber was different from that of the compounded rubber. The NBR content of the bound rubber was higher than that of the compounded rubber; this became clearer for NBR with a higher acrylonitrile content. The Mooney scorch time and cure rate became faster as the acrylonitrile content in NBR increased. The modulus increased with an increase in the acrylonitrile content of NBR because the crosslink density increased. The experimental results could be explained by interactions of the nitrile group of NBR with silica. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 385–393, 2002     

Structure and properties of hollow carbon black and filled rubber nanocomposites

Abstract

Hollow carbon black (HCB) is introduced in this work. It has a special hollow structure, high specific surface area, high structure and high electric conductivity. Hollow carbon black is used to fill styrene–butadiene rubber (SBR). The bound rubber test results show that the bound rubber of SBR/HCB can be measured when the HCB content reaches 25 phr because a strong filler network is formed, which indicates good electric conductivity of SBR/HCB. In comparison, the bound rubber of SBR/N330 can not be measured even when the N330 content is 40 phr. The mechanical measurements show that HCB has very good reinforcing effect on SBR especially when the filler content is low. The electric conductivity and thermal conductivity increase with the increase in filler content. At the same filler content, the properties of SBR/HCB nanocomposites are better than those of SBR/N330 nanocomposites, which suggests that HCB has good application potential.     

Influence of filler type and loading on cure characteristics and vulcanisate properties of SBR compounds with a novel mixed vulcanisation system

In the present work, the influences of filler type and content on cure characteristics, mechanical and dynamic mechanical properties, and heat aging resistance of filled styrene butadiene rubber (SBR) compounds cured with a mixed vulcanisation system were assessed. A new mixed curing system was developed to obtain vulcanisates with excellent mechanical properties and heat aging resistance compared to those with a commercial EV cure system. The results show that filler has stronger effect on scorch time, cure time and cure rate index with the EV system than with the mixed curing system. The torque difference of filled SBR compounds depends on the filler content. With mixed vulcanisation, it is easier to control the conditions during moulding when the formulation is altered, particularly with a change in filler content. The mixed vulcanisation gave overall improved mechanical properties, heat build-up and heat aging resistance compared to the EV system, even though reinforcing fillers were used in the SBR compounds.     

Effect of bis(diisopropyl)thiophosphoryl disulfide on the covulcanization of styrene–butadiene rubber and ethylene–propylene–diene (monomer) blends

Covulcanization of elastomer blends constituting styrene–butadiene rubber (SBR) and ethylene–propylene–diene (monomer) rubber (EPDM) was successfully performed in the presence of reinforcing fillers like carbon black and silica by using a multifunctional rubber additive, bis(diisopropyl)thiophosphoryl disulfide (DIPDIS). The polarity of EPDM rubber was increased by a two‐stage vulcanization technique, which allowed the formation of rubber‐bound intermediates. In this way the migration of both curatives and reinforcing fillers in the EPDM–SBR blend could be controlled and cure rate mismatch could be minimized. The process significantly improved the physical properties of the blend vulcanizates. The phase morphology, as evident from the SEM micrographs, was indicative of the presence of a much more compact and coherent rubber matrix in the two‐stage vulcanizates. Different accelerator systems were studied to understand better the function and effectiveness of DIPDIS in developing homogeneity in the blends of dissimilar elastomers. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1231–1242, 2004     

Effect of carbon‐based nanoparticles on the cure characteristics and network structure of styrene–butadiene rubber vulcanizate

The network structure of styrene–butadiene rubber (SBR) in the presence of carbon black (CB) with two different structures and multi‐walled carbon nanotubes (MWCNTs) was investigated. Swelling behaviour, tensile properties at various strain rates and cure kinetics were characterized. Experimental data were analysed using the Flory–Rehner model as well as the tube model theory. It is found that the network structure of CB‐filled SBR follows a three‐phase composite model including rigid particles, semi‐rigid bound rubber and matrix rubber. This bound rubber is postulated to be critical for the mechanical and deformational properties, development of crosslinking density in matrix rubber and polymer–filler interaction. For MWCNT‐filled SBR, the bound rubber does not show a substantial contribution to the network structure and mechanical performance, and these properties are greatly dominated by the higher aspect ratio and polymer–filler interaction. Additionally it is deduced that the crosslinking density of matrix rubber increases on incorporation of the fillers compared to unfilled matrix rubber. Copyright © 2012 Society of Chemical Industry     

炭黑-白炭黑双相纳米填料及其增强SSBR性能

研究了2种自制炭墨－白炭墨双相纳米填料（CSDPF）的结构及其填充[矣醒苯橡胶（SSBR）胶料的性能，并与炭黑为黑／白炭黑共混填充胶料的性能做对比。结果表明，CSDPF属两相结构，其增强SSBR的物理机械性能与炭黑及炭黑／白炭黑共混填充胶料相当，但加工性能好，Payne效应小，压缩生热低，动态性能优异。     

碱法制备蔗渣纳米纤维素/丁苯橡胶复合材料性能

针对目前硫酸法制备纳米纤维素高污染、高危险、高处理成本的缺点,采用环境友好、低能耗、低成本的碱法从蔗渣中制备纳米纤维素（2-BNC）,补强丁苯橡胶（SBR）,并与硫酸法制备的纳米纤维素（S-BNC）以及白炭黑（silica）补强SBR的性能进行对比,探究2-BNC的加入对复合材料性能的影响。结果表明,2-BNC在基体中的分散性优于silica,与SBR基体有良好的界面结合,在同等填料份数下,SBR/2-BNC硫化胶的储能模量高于SBR/silica硫化胶,损耗因子下降,耐磨耗性能更加突出,且力学性能更佳;2-BNC和S-BNC对SBR的整体补强效果相当。     

Modification of isoprene rubber by in situ silica generation

BACKGROUND: The reinforcement of elastomers by the addition of fillers is one of the most important aspects in rubber science and technology. In order to optimise the filler–polymer interface, innovative in situ generation of silica within isoprene rubber was carried out by means of a bottom‐up approach through a sol–gel process starting from tetraethoxysilane as silica precursor. The main aim was the study of the effect of the silica concentration and of the presence of coupling agent on the morphology and the dynamic mechanical behaviour of the composites. RESULTS: The in situ generated silica particles were homogeneously dispersed in the vulcanised rubber with dimensions from a few nanometres to the submicrometre scale. In the presence of coupling agent a good polymer–filler adhesion was observed. The dynamic mechanical behaviour was nonlinear for silica contents higher than 20 wt%. In this range of compositions silica exerted a marked reinforcement on the low‐amplitude storage modulus, which is related to the silica content according to the Huber–Vilgis model. CONCLUSION: Isoprene rubber can be effectively reinforced by the in situ generation of silica for silica contents higher than 20 wt%, and the interaction at the silica–rubber interface can be optimised by using suitable coupling agents. Copyright © 2009 Society of Chemical Industry     

An investigation on the bound rubber and dynamic mechanical properties of polystyrene particles‐filled elastomer

Polymeric nanoparticles have many advantages as the reinforcing filler of rubber. To investigate the mechanism of the reinforcement, nanocomposites of poly(styrene‐butadiene) rubber (SBR) filled with polystyrene (PS) particles as the reinforcing agents was prepared. Morphology and dynamical mechanical properties of PS particles‐filled SBR were investigated. It was found that the polymer chains of the elastomer could be absorbed onto the PS particles, in reminiscent to the concept of bound rubber in inorganic filler‐filled elastomeric system. The adsorbed polymer layer can form up glassy bridges between neighboring filler particles, leading to the agglomeration of the filler particles and the reinforcement of the elastomer. With higher filler content or smaller filler size, the numbers of the glassy bridges increase, and the modulus of the elastomer increases. With higher strain or higher temperature, the filler–filler interaction is disrupted and the material is softened. The study discovered the existence of bound rubber in PS particles‐filled elastomer and illustrated its influence on the dynamic mechanical properties, which could be helpful to design the polymeric nanoparticles for rubber reinforcement. POLYM. COMPOS., 38:1112–1117, 2017. © 2015 Society of Plastics Engineers     

莫来石与沉淀法白炭黑填充丁苯橡胶复合材料的性能比较

在双辊开炼机中将未处理或用质量分数为3%的硅烷偶联剂A-189处理的莫来石粉体加入到丁苯橡胶(SBR)中制成复合材料.研究莫来石的加入量对SBR性能的影响,并与沉淀法白炭黑填充的SBR的性能进行了比较.结果表明,莫来石粉体对SBR表现出半增强特性;与沉淀法白炭黑填充的SBR相比,SBR/莫来石复合材料表现出良好的硫化特...     

Effects of radiation pretreatments on the rubber adsorption power and reinforcing properties of fillers in rubber compounds

Radiation damage to fillers such as carbon black, graphite and silica induced by high doses of γ‐radiation or neutrons dramatically increases their ability to adsorb rubber irreversibly. In fact, the ‘bound rubber’, ie the amount of non‐extractable rubber which remains irreversibly linked to the filler matrix, increases dramatically in radiation‐treated fillers. The increased adsorption power of radiation‐damaged fillers has been attributed to the formation of a higher concentration of surface defects in the form of trapped free radicals, fullerene‐like structures and other kinds of defects. The mechanical properties of rubber compounds filled with radiation‐treated carbon blacks show a significant increase in their reinforcing effects, in line with the increased ability to form ‘bound rubber’. © 2001 Society of Chemical Industry