Anisotropy in Molded Nitrile Rubber

Blow, C. M.; Demirli, H. B.; Southwart, D. W.

doi:10.5254/1.3547449

Cited by 2 publications

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“…In a previous work it was observed [44] that CB generally exhibits a reduction of aggregate breadth, or 'flatness', in one direction. Some works [45][46][47][48][49][50][51][52][53] evidenced slightly anisotropic properties in elastomeric systems, in both compression and injection molded rubber parts. The orientation of molecules during the mould-filling operation was identified as the dominating factor, and the presence of CB-MS was found to increase the anisotropy [54].…”

Section: Effect Of Filler Type (At 35 Phr Loading) On Anisotropic Behmentioning

confidence: 99%

Anisotropic properties of elastomeric nanocomposites based on natural rubber and sp2 carbon allotropes

Agnelli¹,

Pandini²,

Torricelli³

et al. 2018

Express Polym. Lett.

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This work provides a comprehensive investigation of the anisotropic mechanical and electrical properties of elastomeric nanocomposites based on natural rubber and sp 2 carbon allotropes. They can be either nanometric and with high shape anisotropy like Carbon Nanotubes (CNT) and lamellar nanographite, or nanostructured and nearly isometric like carbon black. Studies were performed on calendered and compression molded plates. A complete mechanical characterization along all main directions could be performed by a non-standard testing approach. Composites with nanometric, high aspect ratio fillers gave rise to remarkable mechanical anisotropy, revealing an orthotropic and transversally isotropic response: modulus values were very similar in the sheet plane and much larger (almost twice as much) in the orthogonal direction. The electrical anisotropy achieved its maximum at lower CNT content. Composites with carbon black did not reveal mechanical anisotropy, while, quite strikingly, a very large electrical anisotropy was observed for carbon black content close to the percolation threshold. These results provide insights into the anisotropic behavior of nanofilled elastomers, and could pave the way to their exploitation in advanced engineering design and biomimicking biomedical applications.

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Section: Effect Of Filler Type (At 35 Phr Loading) On Anisotropic Behmentioning

confidence: 99%

Anisotropic properties of elastomeric nanocomposites based on natural rubber and sp2 carbon allotropes

Agnelli¹,

Pandini²,

Torricelli³

et al. 2018

Express Polym. Lett.

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“…During sheet rolling processes and injection moulding, the rubber is subjected to a complex set of deformation in the three directions simultaneously, imparting generic anisotropy to the network structure [11,12]. Compression-moulded rubber sheets are somewhat simpler, manifesting in-plane isotropy [13,14] Thus, anisotropy appears to be an intrinsic part of rubber processing despite the lack of a suitable theory to determine cross-link density for anisotropic systems. In this study, we first extend the Flory theory to account for generic anisotropy of swelling and then apply the theory to a series of directional swelling measurements on five different filled elastomers, including compression-moulded and rolled rubber sheets, to examine the nature of the anisotropy, and its influence on the determination of the molecular weight between cross-links.…”

Section: Introductionmentioning

confidence: 99%

Anisotropic swelling of rubber: extension of the Flory theory

Fernandes

Focatiis

2022

J Rubber Res

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The anisotropy of the swelling of rubber is examined both theoretically and experimentally. The Flory theory is extended to account for anisotropic swelling, allowing the determination of the average molecular weight between cross-links for rubber with swelling anisotropy for the first time. In addition, specimens from five commercial rubbers manufactured using either compression-moulding or sheet-rolling processes are swollen in appropriate organic solvents. Their linear dimensions and mass are carefully recorded before swelling, in the swollen state, and after drying, to obtain three linear swelling ratios which can differ by up to 10% within each specimen. Compression-moulded rubbers are shown to be transversely isotropic after moulding, whereas rolled rubbers exhibit full anisotropy, with different swelling ratios in all three directions. None of the rubbers examined were found to be truly isotropic. The new anisotropic swelling theory is applied to the experimental data to determine the average molecular weight between cross-links, which is determined as up to 0.5% larger than the value obtained using the Flory isotropic swelling theory.

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Anisotropy in Molded Nitrile Rubber

Cited by 2 publications

References 0 publications

Anisotropic properties of elastomeric nanocomposites based on natural rubber and sp2 carbon allotropes

Anisotropic properties of elastomeric nanocomposites based on natural rubber and sp2 carbon allotropes

Anisotropic swelling of rubber: extension of the Flory theory

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