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See detailThe effect of interphases created by Al2O3 nanoparticles in styrene butadiene rubber
Sushko, Rymma UL

Doctoral thesis (2014)

Elastomers are key-materials e.g. in tire industry. Nowadays it is common practice to enhance the mechanical performance of elastomers by introducing inorganic nanoparticles into the polymer matrix. Due ... [more ▼]

Elastomers are key-materials e.g. in tire industry. Nowadays it is common practice to enhance the mechanical performance of elastomers by introducing inorganic nanoparticles into the polymer matrix. Due to the extremely small filler size giant interfaces are created between the surfaces of the nanoparticles and the matrix molecules especially when the fillers are homogeneously distributed throughout the host material. Interfacial interactions can lead to the formation of regions with changed molecular mobility and/or morphology (so-called interphases) in the immediate vicinity of the fillers’ surfaces. A challenging task consists in investigating and understanding the effect produced by interphases on the macroscopic properties of the polymer matrix. In the frame of the present PhD research project an uncured styrene-butadiene rubber (SBR) was used as a matrix for three types of nanoparticles: native alumina, alumina coated with γ- mercaptopropyltrimethoxysilane (Mercapto) layers and finally alumina-Mercapto nanoparticles with SBR molecules grafted onto. The thermal and mechanical properties of the three families of nanocomposites were investigated using mechanical spectroscopy (rheometry and dynamical mechanic analysis). Electron microscopy was exploited for structural analysis. Irrespective of the surface treatment of the nanoparticles an unexpected minimum of the glass transition temperature is found at small filler concentrations of about 2 wt.%. At higher filler contents each of the three families of nanocomposites is characterized by its own characteristic evolution of the glass transition temperature as a function of the filler content. Models are suggested to explain the different glass transition behaviors. Furthermore the influence of the surface treatment on the mechanical answer of the nanocomposites especially to low-frequency shear fields is discussed. [less ▲]

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See detailAnomalous glass transition behavior of SBR–Al2O3 nanocomposites at small filler concentrations
Sushko, Rymma UL; Filimon, Marlena UL; Dannert, Rick UL et al

in Nanotechnology (2014), 25(42), 425704

Elastomers filled with hard nanoparticles are of great technical importance for the rubber industry. In general, fillers improve mechanical properties of polymer materials, e.g. elastic moduli, tensile ... [more ▼]

Elastomers filled with hard nanoparticles are of great technical importance for the rubber industry. In general, fillers improve mechanical properties of polymer materials, e.g. elastic moduli, tensile strength etc. The smaller the size of the particles the larger is the interface where interactions between polymer molecules and fillers can generate new properties. Using temperature-modulated differential scanning calorimetry and dynamic mechanical analysis, we investigated the properties of pure styrene-butadiene rubber (SBR) and SBR/alumina nanoparticles. Beside a reinforcement effect seen in the complex elastic moduli, small amounts of nanoparticles of about 2 wt% interestingly lead to an acceleration of the relaxation modes responsible for the thermal glass transition. This leads to a minimum in the glass transition temperature as a function of nanoparticle content in the vicinity of this critical concentration. The frequency dependent elastic moduli are used to discuss the possible reduction of the entanglement of rubber molecules as one cause for this unexpected behavior. [less ▲]

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See detailComparative study of the effect of untreated, silanized and grafted alumina nanoparticles on thermal and dynamic mechanical properties of the styrene-butadiene rubber
Sushko, Rymma UL; Baller, Jörg UL; Filimon, Marlena UL et al

in AIP Conferences Proceedings (2014, May 15), 1599

Elastomers filled with hard nanoparticles are of great technical importance for the rubber industry. In general, fillers improve mechanical properties of polymer materials, e.g. elastic moduli, tensile ... [more ▼]

Elastomers filled with hard nanoparticles are of great technical importance for the rubber industry. In general, fillers improve mechanical properties of polymer materials, e.g. elastic moduli, tensile strength etc. The smaller the size of the particles the larger is the interface where interactions between polymer molecules and fillers can generate new properties. Using Temperature Modulated Differential Scanning Calorimetry (TMDSC) and Dynamic Mechanical Analysis (DMA), we investigated the properties of the pure styrene-butadiene rubber (SBR), SBR/ alumina nanoparticles, SBR/silanized alumina and SBR/alumina grafted to polymer chains. Beside a general reinforcement effect seen in the complex elastic moduli, the studies revealed that: i) small concentrations of nanoparticles (of 1.5-2 wt%) lead to a minimum in the glass transition temperature as a function of nanoparticle content; ii) for the grafted nanocomposites increasing the nanoparticle concentration beyond 4 wt% yields an increase of Tg by 4 K; iii) DMA mastercurves showed that in case of untreated and silanized alumina mechanical behaviour of the composite systems is rather near to the one of the SBR matrix, but the grafting of elastomer molecules to the silanized fillers induces a quasi-solid like response of the system in the low frequency regime. [less ▲]

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See detailAnomaly in thermal and mechanical properties of SBR/alumina nanocomposites
Sushko, Rymma UL; Baller, Jörg UL; Filimon, Marlena UL et al

Scientific Conference (2014, April 03)

Filling elastomers with nanoparticles generally leads to changes in the relaxation behavior of the matrix molecules. Using dynamic mechanical analysis (DMA) and temperature modulated calorimetry (TMDSC ... [more ▼]

Filling elastomers with nanoparticles generally leads to changes in the relaxation behavior of the matrix molecules. Using dynamic mechanical analysis (DMA) and temperature modulated calorimetry (TMDSC), we investigate the influence of different amounts of untreated, hydrophilic alumina nanoparticles on the properties of a model rubber system (SBR). Beside a reinforcement effect seen in the complex elastic moduli, small amounts of nanoparticles of about 2 wt% interestingly lead to an acceleration of the relaxation modes responsible for the thermal glass transition. This leads to a minimum in the glass transition temperature as a function of nanoparticle content in the vicinity of this critical concentration. The frequency dependent elastic moduli are used to discuss the possible reduction of the entanglement of rubber molecules as one cause for this unexpected behavior. [less ▲]

Detailed reference viewed: 59 (7 UL)
See detailEffect of grafted alumina nanoparticles on thermal and dynamic mechanical properties of the styrene-butadiene rubber
Sushko, Rymma UL; Baller, Jörg UL; Filimon, Marlena UL et al

Poster (2013, September)

Elastomers filled with hard nanoparticles are of great technical importance for the rubber industry. In general, fillers improve mechanical properties of polymer materials, e.g. elastic moduli, tensile ... [more ▼]

Elastomers filled with hard nanoparticles are of great technical importance for the rubber industry. In general, fillers improve mechanical properties of polymer materials, e.g. elastic moduli, tensile strength etc. The smaller the size of the particles the larger is the interface where interactions between polymer molecules and fillers can generate new properties. The aim of this contribution is to study the influence of the fillers’ surface treatment on the thermal and mechanical behavior of nanocomposites made of styrene-butadiene rubber (SBR). Three types of nanocomposites are investigated : (i) SBR-unmodified alumina, (ii) SBR – silanized alumina and (iii) SBR – alumina grafted to polymer chains. The surface-modified alumina nanoparticles were prepared using the method described in [1]. The grafting of the SBR chains to the alumina nanoparticles was realized by means of the procedures described in [2] and [3]. Temperature Modulated Differential Scanning Calorimetry (TMDSC) and Dynamic Mechanical Analysis (DMA) are well appropriated tools to investigate the thermal and dynamic glass transition behavior of the different nanocomposites, which is expected to be very sensitive to interfacial interactions between the nanoparticles and matrix molecules. TMDSC experiments reveal that all of the nanocomposites undergo a single glass transition. Thus, interphases induced by interfacial interactions do not manifest themselves by an additional glass transition unless it is hidden by the one of the matrix. Moreover, TMDSC measurements reveal that in general the glass transition temperature Tg depends in a complex manner on the concentration and surface treatment of the nanoparticles. The most important change of Tg is observed for the grafted nanocomposites: increasing the nanoparticle weight concentration beyond 4% yields an increase of Tg by 4 K. The corresponding slowing down of the molecular dynamics goes along with a significant decrease of the relaxator strength. More generally the presented results prove that, at the same filler concentration, the number of degrees of freedom freezing at the glass transition in case of un-grafted systems is practically independent on the chemical nature of the particles surface whereas it changes when there exist covalent bonds between the polymer molecules and the nanoparticles. DMA was used to probe the rheological behaviour of the nanocomposites under oscillatory shear. Isothermal frequency sweeps performed at different temperatures yield the real (G’) and imaginary (G”) parts of the complex shear modulus. Linear response regime conditions were strictly respected. The temperature-frequency equivalence principle was exploited to construct mastercurves for G’ and G” at the reference temperature T=273 K. As usual in polymers, three different behaviors were observed: the dynamic glass transition at high frequencies, the entanglement plateau at intermediary frequencies and viscoelastic “flowing” at very low frequencies. It generally appears that the filling of the SBR matrix with nanoparticles leads to an increase of the storage modulus that is more prominent in the rubbery region than in the glassy segment. While, in the low frequency regime, untreated and silanized alumina yield a mechanical behaviour that is rather near to the one of the neat SBR matrix, the grafting of elastomer molecules to the silanized fillers obviously induces a quasi-solid like response of the system. References: 1. Y.-Ch. Yang, S.-B. Jeong, B.-G. Kim, P.-R. Yoon, Powder Technology, 191, 117–121, 2009. 2. E. Passaglia, F. Donati, Polymer, 48, 35-42, 2007. 3. A. Bhattacharya, B. Misra, Prog. Polym. Sci. 29, 767–814, 2004. [less ▲]

Detailed reference viewed: 94 (3 UL)
See detailAnomalous behaviour of SBR/Al2O3 nanocomposites at small filler concentrations
Sushko, Rymma UL; Baller, Jörg UL; Filimon, Marlena UL et al

Poster (2013, June)

Elastomers filled with hard nanoparticles are of great importance for the rubber industry. In general, the incorporation of the small particles improves the mechanical properties of polymeric materials, e ... [more ▼]

Elastomers filled with hard nanoparticles are of great importance for the rubber industry. In general, the incorporation of the small particles improves the mechanical properties of polymeric materials, e.g. elastic modulus, tensile strength etc. Nanocomposites made of poly(styrene-co-butadiene) and alumina nanoparticles (unmodified and modified with different silane coupling agents) were investigated by temperature modulated differential scanning calorimetry (TMDSC) and dynamic mechanical analysis (DMA). It has been shown that the glass transition behaviour of SBR/alumina nanocomposites differs when the concentration and surface properties of the Al2O3 nanoparticles are changed. The influence of the fillers on the shear stiffness of the rubber material was also investigated. TMDSC investigations shed light on a surprising behaviour of the glass transition temperature when the nanoparticle concentration is changed: at low filler contents the quasi-static glass transition temperature Tg passes through a minimum. While further increasing the nanoparticle content Tg increases to finally saturate at high concentrations. DMA results showed a quasi-solid-like frequency-independent response of the nanocomposites in the low frequency regime with increasing of the filler concentration. [less ▲]

Detailed reference viewed: 65 (2 UL)
See detailThermal and mechanical properties of styrene butadiene rubber/alumina nanocomposites
Sushko, Rymma UL; Baller, Jörg UL; Sanctuary, Roland UL

Poster (2013, March)

SBR is a rubber material with high technical relevance. In order to enhance the mechanical properties of the rubber one method consists e. g. in dispersing inorganic nanoparticles in the polymer matrix ... [more ▼]

SBR is a rubber material with high technical relevance. In order to enhance the mechanical properties of the rubber one method consists e. g. in dispersing inorganic nanoparticles in the polymer matrix. By doing so, the properties of a given composite can be tuned either by changing the nanoparticle concentration or by modifying the surface properties of the fillers. Both interventions have indeed the potential to take influence on the structure and properties of the interphases emerging between the fillers and the polymer matrix. In this contribution we report on the glass transition behavior of SBR/alumina nanocomposites when the concentration and surface properties of the Al2O3 nanoparticles are changed. We also discuss the influence of the fillers on the shear stiffness of the rubber material. The samples were investigated by temperature modulated differential scanning calorimetry (TMDSC) and dynamic mechanical analysis (DMA). TMDSC investigations shed light on a surprising behavior of the glass transition temperature when the nanoparticle concentration is changed: at low filler contents the quasi-static glass transition temperature Tg passes through a minimum. While further increasing the nanoparticle content Tg increases to finally saturate at high concentrations. One of the main DMA results is that increasing of the Al2O3 concentration induces a quasi-solid-like frequency-independent response of the nanocomposites in the low frequency regime. [less ▲]

Detailed reference viewed: 139 (0 UL)