SILICA GRAFTED WITH EPOXIDIZED LIQUID POLYBUTADIENES: EVIDENCE FOR THE MECHANISM OF REINFORCEMENT

ABSTRACT Precipitated silica with backbone epoxidized liquid polybutadiene grafted onto its surface has recently been presented as a new reinforcement material that requires significantly less energy to disperse in comparison wtih the traditional in situ silanization process. This potentially provides better traction and hard-handling performance in car tire treads, without greatly increasing rolling resistance. The purpose of this study was to seek evidence proving the previously proposed reinforcement mechanism, through solid-state 1H low-field nuclear magnetic resonance and equilibrium swelling experiments. The evidence points to an increase in the amount of epoxidized chain segments chemically bonded to the silica surface and to an increase in coating-matrix entanglements with increases in the degree of epoxidation and cure of the coated silica. Such evidence is consistent with the hypothesis of increasing the number of entanglements and/or their progressive loss of mobility with an increase in the degree of epoxidation and decrease in temperature, which is in close agreement with the proposed mechanism.

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Reinforcement from In-Situ Precipitated Silica in Polysiloxane Elastomers under Various Types of Deformation

MRS Proceedings ◽

10.1557/proc-274-77 ◽

1992 ◽

Vol 274 ◽

Cited By ~ 5

Author(s):

James E. Mark ◽

Shuhong Wang ◽

Ping Xu ◽

Jianye Wen

Keyword(s):

Mechanical Properties ◽

Uniaxial Elongation ◽

Compression Set ◽

Precipitated Silica ◽

Equilibrium Swelling ◽

Rupture Energy ◽

End Linking ◽

Reinforcing Effects

ABSTRACTElastomeric networks prepared by tetrafunctionally end linking hydroxyl-terminated poly(dimethylsiloxane) chains (PDMS) were filled by the in-situ precipitation of silica. The resulting networks were investigated under uniaxial elongation, biaxial extension, shear, and torsion in order to characterize the resulting changes in mechanical properties. Compared with the unfilled networks, the silica-filled materials showed large reinforcing effects. Specifically, their values of the modulus, ultimate strength, and rupture energy increased significantly. The results thus indicate that the PDMS networks filled by the in-situ precipitation of silica have very good mechanical properties in several, rather different deformations. Examples of other deformations of interest are equilibrium swelling, and dynamic cycling for characterization of compression set.

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Investigations into the Silica/Silane Reaction System

Rubber Chemistry and Technology ◽

10.5254/1.3538447 ◽

1997 ◽

Vol 70 (4) ◽

pp. 608-623 ◽

Cited By ~ 96

Author(s):

Udo Goerl ◽

Andrea Hunsche ◽

Arndt Mueller ◽

H. G. Koban

Keyword(s):

Silica Surface ◽

Reaction System ◽

Rolling Resistance ◽

Kinetic Studies ◽

Reaction Model ◽

Secondary Reaction ◽

Primary Reaction ◽

Silanol Groups ◽

Precipitated Silica ◽

Low Concentrations

Abstract Silica in combination with organosilanes (e.g. [bis(3-triethoxysilylpropyl)tetrasulfane] = TESPT) has recently become more important in tire applications. Their use in tire treads leads to an improvement in rolling resistance and wet traction. The requirements for the attainment of these properties are, that the triethoxysilyl groups of TESPT react with the silanol groups on the silica surface during compounding, and the polymer active groups react with the polymer during cure. The reaction of precipitated silica with this silane was investigated. The influence of various parameters on the reaction type and the reaction kinetics was considered. The results of the investigation obtained using 29Si-CP/MAS solid state NMR spectroscopy agree well with a horizontal reaction model in which a single siloxane bond is first formed with the silica surface (primary reaction). It is followed by condensation reactions between silanol groups of silane molecules which are already bound to the silica surface (secondary reaction). The kinetic studies data show a clear difference between the fast primary reaction and the slow secondary reaction. Both reactions become more rapid in acidic and alkaline pH ranges. The primary reaction accelerates up to a particular H2O content after which the rate remains constant. The secondary reaction keeps on accelerating with rising H2O content. Modification with different silane concentrations showed a higher rate constant at low concentrations.

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Mixing and Comparative Properties of NR Compounds Filled with Different Types of Reinforcing Fillers

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.266.172 ◽

2017 ◽

Vol 266 ◽

pp. 172-176

Author(s):

Pattarawadee Maijan ◽

Nitinart Saetung ◽

Wisut Kaewsakul

Keyword(s):

Carbon Black ◽

Silica Surface ◽

High Viscosity ◽

Cure Rate ◽

Modified Silica ◽

Reinforcing Fillers ◽

Silane Coupling ◽

Different Types ◽

Cure Time

Mixing behaviors of the compounds filled with different reinforcing fillers were studied in correlation with compound and vulcanizate properties. Four filler systems were used including: 1) silica plus small amount of silane coupling agent; 2) carbon black; 3) pre-modified silica; and 4) silica+silane-carbon black mixed one. The results have shown that silica provides longer optimum cure time and shorter cure rate than carbon black due to accelerator adsorption on silica surface. In addition, owing to highly polar nature on silica surface the silica-based compounds show rather high viscosity, attributed to stronger filler-filler interaction as can be confirmed by Payne effect and reinforcement index. However, the commercial surface treatment or pre-modified form of silica shows superior properties than in-situ modification of silica by silane during mixing, while it gives comparable properties to carbon black-based compound. Tensile properties of vulcanizates show a good correlation with the basic properties of their compounds.

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In-situ monitoring of hydration kinetics of cement pastes by low-field NMR

Journal of Wuhan University of Technology-Mater Sci Ed ◽

10.1007/s11595-010-0072-5 ◽

2010 ◽

Vol 25 (4) ◽

pp. 692-695 ◽

Cited By ~ 4

Author(s):

Anming She ◽

Wu Yao ◽

Yongqi Wei

Keyword(s):

In Situ Monitoring ◽

Hydration Kinetics ◽

Cement Pastes ◽

Low Field ◽

Low Field Nmr ◽

Kinetics Of

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Experimental tests of the impact of selected parameters on the indentation rolling resistances

E3S Web of Conferences ◽

10.1051/e3sconf/20182900002 ◽

2018 ◽

Vol 29 ◽

pp. 00002 ◽

Cited By ~ 1

Author(s):

Dariusz Woźniak ◽

Lech Gładysiewicz ◽

Martyna Konieczna

Keyword(s):

Main Part ◽

Rolling Resistance ◽

Experimental Tests ◽

Conveyor Belt ◽

Significant Component ◽

Different Types ◽

Indentation Rolling Resistance ◽

Belt Conveyors ◽

The Impact

Belt conveyors are main part of transporting systems in mines and in many other branches of industry. During conveyor belt works different types of resistances are generated. Indentation rolling resistance is the most significant component of the resistances from the perspective of energy losses and it cause the biggest costs as well. According to latest state of analyses and measurements it is well known that theoretical rolling resistance were underestimated in comparison with the measured in-situ one. In this paper new method for determination indentation rolling resistance is presented. The authors compared theoretically and experimentally established damping factors. The relation between these two values enabled to obtain more precise equation for damping function. This function is one of the most important component in calculation of the rolling resistance. In new theoretical model value of rolling resistance is nearly twice higher than this used so far.

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