Deformation and orientation in filled rubbers on the nano‐ and microscale studied by X‐ray scattering

Brüning, Karsten; Schneider, Konrad; Heinrich, Gert

doi:10.1002/polb.23148

Cited by 13 publications

(8 citation statements)

References 16 publications

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“…5) suggests reinforcing effect of cellulosic fillers, which may be surprising and confusing. This phenomenon is probably due to the strain inducted crystallization of NR matrix (Brüning et al 2012;Ren et al 2015). During tensile test a part of NR turns the amorphous rubber into a semi-crystalline material.…”

Section: Physico-mechanical Propertiesmentioning

confidence: 99%

Processing and structure–property relationships of natural rubber/wheat bran biocomposites

et al. 2016

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In this work, wheat bran was used as cellulosic filler in biocomposites based on natural rubber. The impact of wheat bran content [ranging from 10 to 50 parts per hundred rubber (phr)] on processing, structure, dynamic mechanical properties, thermal properties, physico-mechanical properties and morphology of resulting biocomposites was investigated. For better characterization of interfacial interactions between natural rubber and wheat bran, achieved results were compared with properties of biocomposites filled with commercially available cellulosic fillers-wood flour and microcellulose. It was observed that wheat bran, unlike commercial cellulosic fillers, contains high amount of proteins, which act like plasticizers having profitable impact on processing, physical, thermo-mechanical and morphological properties of biocomposites. This is due to better dispersion and distribution of wheat bran particles in natural rubber, which results in reduction of stiffness and porosity of the biocomposites. Regardless of cellulosic filler type, Wolff activity coefficient was positive for all studied biocomposites implying reinforcing effect of the applied fillers, while tensile strength and elongation at break decreased with increasing filler content. This phenomenon is related to restricted strain-induced crystallization of NR matrix due to limited mobility of polymer chains in the biocomposites. Furthermore, this explains negligible impact of particle size distribution, chemical composition and crystallinity degree of applied cellulosic filler on static mechanical properties of highlyfilled NR biocomposites. The conducted investigations show that wheat bran presents interesting alternative for commercially available cellulosic fillers and could be successfully applied as a low-cost filler in polymer composites.

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Section: Physico-mechanical Propertiesmentioning

confidence: 99%

Processing and structure–property relationships of natural rubber/wheat bran biocomposites

et al. 2016

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“…NR undergoes strain‐induced crystallization (SIC) that is the rapid development of crystallization under straining. Many aspects of SIC have been reviewed, and further works are continuously appearing, focused on the study of models, crystallite structure, segmental dynamics, local strain response, mechanism of deformation, morphology, orientation and deformation mechanisms, crystallite melting temperature, temperature dependence of the mechanical properties, kinetics and time of crystallization, fatigue behavior, effect of entanglements and endlinking networks, and deproteinization . Some conclusions are widely acknowledged.…”

Section: Introductionmentioning

confidence: 99%

Crystallinity and crystalline phase orientation of poly(1,4-cis-isoprene) fromHevea brasiliensisandTaraxacum kok-saghyz

Musto

Barbera

Maggio

et al. 2016

Polym. Adv. Technol.

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Crystallization is studied for poly(isoprene-1,4-cis) from Hevea brasiliensis (natural rubber [NR]) and from taraxacum kok-saghyz, mainly by collecting wide-angle X-ray diffraction patterns after processing and stretching. Although rubber samples before stretching are generally fully amorphous, crystallization can be induced in NR samples by processing at room temperature under moderate pressure. This phenomenon is possibly associated with nucleation by saturated fatty acid components. For rubber samples being fully amorphous in the undeformed state, straininduced crystallization occurs only at high strain ratios (α > 4), leading to high degrees of crystalline phase orientation (f c > 0.9 for α = 5). Rubber samples presenting some crystallinity already in the unstretched state, on the contrary, reach much lower degrees of axial orientation, even for high strain ratios (f c < 0.7 for α = 5). These differences in crystallinity and in crystalline phase orientations produce large differences in stress-strain behavior of the rubber. By room temperature processing, the considered NR samples can also develop an unreported disordered crystalline modification, with low intensity of 120 and 121 reflections. This disordered crystalline modification, which is also maintained after axial stretching procedures, can rationalized by a structural disorder along the b axis, possibly associated with statistical sequences of A + TA À or A À T A + conformations for poly(isoprene-1,4-cis) chains. Copyright © 2016 John Wiley & Sons, Ltd.Keywords: poly(isoprene-1,4-cis); crystallinity; strain-induced crystallization INTRODUCTIONNatural rubber (NR) is the regular head-to-tail polymer essentially made by isoprene-1,4-cis units. [1][2][3][4] It is the most important rubber, with increasing worldwide consumption, that amounts at present to more than 12 million t/year.[5] At the origin of such a large commercial success are the NR outstanding properties: great strength [6,7] and tack [8][9][10] in the uncrosslinked state and in the crosslinked state, very high tensile strength [11,12] and crack growth resistance, both in static [13][14][15][16][17] and in fatigue [18][19][20][21][22][23][24] loading conditions. Beneficial for such NR properties is definitely the great mobility of the polymer chains that are usually amorphous at rest. However, also the ability of NR to crystallize plays a fundamental role. NR undergoes strain-induced crystallization (SIC) that is the rapid development of crystallization under straining. Many aspects of SIC have been reviewed, [25][26][27] and further works are continuously appearing, focused on the study of models, [28,29] crystallite structure, [30,31] segmental dynamics, [32] local strain response, [33] mechanism of deformation, [34] morphology, [35] orientation and deformation mechanisms, [36] crystallite melting temperature, [37] temperature dependence of the mechanical properties, [38] kinetics [36,39,40] and time [41] of crystallization, fatigue behavior, [42,43] effect of entanglements and endlinking n...

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“…These results show that cavities do indeed form in front of crack tips propagating in fatigue conditions in elastomers filled with so‐called reinforcing CB nanoparticles (N347). More generally, the threshold of appearance of the nanocavitation mechanism in uniaxial extension has been shown to depend on the filler volume fraction and certainly on the nature of the filler . At the crack tip, this will result in a different size of the cavitated zone for the same macroscopic loading conditions.…”

Section: Resultsmentioning

confidence: 99%

“…More generally, the threshold of appearance of the nanocavitation mechanism in uniaxial extension has been shown to depend on the filler volume fraction 33,34 and certainly on the nature of the filler. 35,46,47 At the crack tip, this will result in a different size of the cavitated zone for the same macroscopic loading conditions. However, our evidence strongly suggests that elastomers filled with nanoparticles will form nanocavities in a region close to the crack tip and any physically based damage models should take this feature into account.…”

Section: Effect Of Energy Release Rate Gmentioning

confidence: 96%

Nanocavitation around a crack tip in a soft nanocomposite: A scanning microbeam small angle X-ray scattering study

Zhang

Scholz

Crevoisier

et al. 2014

J. Polym. Sci. Part B: Polym. Phys.

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We explore nanocavitation around the crack tip region in a styrene-butadiene random copolymer filled with typical carbon black (CB) particles used in the rubber industry for toughening the rubber. Using quasistatic loading conditions and a highly collimated X-ray microbeam scanned around the crack tip, we demonstrate the existence of a damage zone consisting of nanovoids in a filled elastomer matrix. The existence of voids near the crack tip is demonstrated by a significant increase of the scattering invariant Q/Q 0 in front of both fatigued and fresh cracks. The size of the zone where cavities are present critically depends on the macroscopic strain e m , the loading history, and the maximum energy release rate G applied to accommodate the crack. Our findings show that nanovoiding occurs before fracture in typical CB-filled elastomers and that realistic crack propagation models for such elastomers should take into account a certain level of compressibility near the crack tip.

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Deformation and orientation in filled rubbers on the nano‐ and microscale studied by X‐ray scattering

Cited by 13 publications

References 16 publications

Processing and structure–property relationships of natural rubber/wheat bran biocomposites

Processing and structure–property relationships of natural rubber/wheat bran biocomposites

Crystallinity and crystalline phase orientation of poly(1,4-cis-isoprene) fromHevea brasiliensisandTaraxacum kok-saghyz

Nanocavitation around a crack tip in a soft nanocomposite: A scanning microbeam small angle X-ray scattering study

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