Transition of rupture mode of strain crystallizing elastomers in tensile edge-crack tests

Tsunoda, Katsuhiko; Kitamura, Yuji; Urayama, Kenji

doi:10.1039/d3sm00060e

Cited by 7 publications

(4 citation statements)

References 60 publications

(119 reference statements)

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“…Natural rubber (NR) is used in familiar products such as vehicle tires, rubber bands, hoses, gloves, boots, and industrial parts that we do not see in our daily lives. The properties of NR products are distinguished by their exceptional attributes, including elevated toughness, superior tensile strength, and remarkable resistance to crack propagation, and those superior properties are considered to be intimately linked to non-trivial effects of the terminal ends of polyisoprene in NRs. − Hevea NR consists of high-performance properties, namely, malleability, impact resistance, elasticity, resilience, efficient heat dispersion, and abrasion at cold temperature, which not only depends on the high molecular weight of the cis -1,4-polyisoprene chain and amount of cis isoprene but also intimately associated to the structure of the end groups of the polymer chain of NR. − Synthetic rubber cannot mimic the characteristic chemical and mechanical properties of NR despite eight decades of manufacturing research . Hence, owing to its exceptional characteristics, NR continues to find widespread application in various industries, including tire manufacturing, medical devices, and engineering components .…”

Section: Introductionmentioning

confidence: 99%

Role of Terminal Groups of cis-1,4-Polyisoprene Chains in the Formation of Physical Junction Points in Natural Rubber

Dixit

Taniguchi

2023

Biomacromolecules

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The terminal structures of cis-1,4-polyisoprene (PI) chains play a vital role in the excellent comprehensive performance of Hevea natural rubber (NR) with properties such as high toughness, tear-resistance, and wet skid resistance. The cis-1,4polyisoprene chain constituting NR exhibits a distinct composition of terminal groups comprising two distinct types, namely, the ω and α terminal groups. The structures of the ω terminal [dimethyl allyl (DMA)-(trans-1,4-isoprene) 2 ] and six kinds of α end groups of the polymer chain of NR have been explored by utilizing a newly developed 2D NMR method. In the present work, we examine different kinds of PI melt systems, and we choose various combinations of terminal groups: Hydrogen, one DMA unit with two trans isoprene units as ω end groups and ester-terminated isopentene (α1), hydroxy-terminated isopentene (α2), ester-terminated isobutane (α3), hydroxy-terminated isobutane (α4), esterterminated 1,4-cis-isoprene (α5), and hydroxy-terminated 1,4-cis-isoprene (α6), i.e., H PI H (PI 0 )−pure PI (Hydrogen terminal), ω PI α1 (PI I ), ω PI α2 (PI II ), ω PI α3 (PI III ), ω PI α4 (PI IV ), ω PI α5 (PI V ), and ω PI α6 (PI VI ). We evaluated dynamic and static properties of PI chains such as the end-to-end vector autocorrelation function (C(t)), its average relaxation time (τ), end-to-end distance (R ee ), and radius of gyration (R g ). We also estimated the diffusion coefficients of polyisoprene chains and pair correlation functions [radial distribution functions (RDFs)], potentials of mean force (PMFs) in between end residues, and survival probability (P(τ)) of end groups around the end group by analyzing the equilibrated trajectories of full-atom MD simulations. As per the examination of C(t), rotational relaxation time τ, and RDFs, we discovered that the existence of a strong hydrogen bond in α2−α2, α4−α4, and α6−α6 residues makes the dynamics of hydroxy-terminated polyisoprene chains in ω PI α2,α4,α6 melt systems slower. From the analyses of RDFs and PMFs (W(r)), the association between [α2]−[α2], [α4]−[α4], and [α6]−[α6] terminals in ω PI α2,α4,α6 melt systems is significantly stronger than in [ISO]−[ISO] [Hydrogen terminated 1,4-cis-isoprene:(ISO)] in H PI H and ω−ω, [α1]−[α1], [α3]−[α3], and [α5]− [α5] in ω PI α1,α3,α5 systems. We quantified the fraction of cluster formation of terminal groups of a given size in the seven PI melt systems by employing the criteria of PMFs. It is revealed that no stable cluster exists in the H PI H , ω PI α1 , ω PI α3 , and ω PI α5 melt systems. Conversely, in the ω PI α2 , ω PI α4 , and ω PI α6 systems, we perceived stable clusters of [(α2) p ] [(α4) p ] and [(α6) p ] end groups where p (2 ≤ x ≤ 6). These stable clusters validate the presence of physical junction points in between hydroxy-terminated polyisoprene chains through their α2, α4, and α6 terminals. These physical junction points might be crucial for superior properties of NR such as high toughness, crack growth resistance, and strain-induced crystallization.

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Section: Introductionmentioning

confidence: 99%

Role of Terminal Groups of cis-1,4-Polyisoprene Chains in the Formation of Physical Junction Points in Natural Rubber

Dixit

Taniguchi

2023

Biomacromolecules

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“…The procedure for mixing and curing these ingredients is referenced in a previous publication. 5,20 Table 1 lists the initial Young's modulus (E) for each specimen obtained from uniaxial tensile stress-strain relationship for rectangular strip specimen.…”

Section: Methodsmentioning

confidence: 99%

“…This phenomenon termed strain-induced crystallization (SIC) has been investigated by many researchers. [5][6][7][8][9][10][11][12][13][14] A noteworthy advantage of SIC is the consequent strain hardening, resulting in substantial mechanical reinforcement. Specically, the region proximate to the crack-tip undergoing high strain experiences SIC, thereby forming an effective barrier against further crack propagation.…”

Section: Introductionmentioning

confidence: 99%

Strain hardening in biaxially stretched elastomers undergoing strain-induced crystallization

Hiraiwa,

Mai,

Tsunoda

et al. 2023

RSC Adv.

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“…The reinforcing capability of SIC also substantially contributes to enhancing the tear strength and suppressing the catastrophic crack growth. [ 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 ] In general, the strain near a crack tip in rubber is markedly non‐uniform, while it steeply increases with approaching the crack tip. [ 43 , 44 , 45 , 46 , 47 , 48 , 49 ] In proximity to the crack tip of NR, the localized strain intensifies sufficiently to trigger SIC.…”

Section: Introductionmentioning

confidence: 99%

Unraveling Non‐Uniform Strain‐Induced Crystallization Near a Crack Tip in Natural Rubber

Mai,

Yasui,

Tanaka

et al. 2024

Advanced Science

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Strain‐induced crystallization (SIC) in natural rubber (NR) near crack tips significantly enhances crack growth resistance, but understanding the interplay between local strain field and crystallization remains challenging due to confined and heterogeneous characteristics. Using micro‐scale digital image correlation (DIC) and scanning wide‐angle X‐ray diffraction (WAXD, with a narrow 10 µm square beam), this study maps local strain tensor properties and SIC in the vicinity of the crack tip and its peripheral zone (≈3 mm × 1 mm area). The analysis reveals a significant correlation between these properties. In the peripheral zone, there is a noticeable deviation of both the principal strain axis and the crystal orientation from the crack opening direction. These deviations are linearly correlated, which indicates that shear strain plays a significant role in determining the crystal orientation. Crucially, the maximum tensile component in the tensor of local principal strains predominantly dictates local crystallinity. This simplicity is attributed to the limited variation in types of deformation within the SIC region, with corresponding to deformations falling between planar and uniaxial stretching. These findings pave the way for predicting crystallinity distribution using solely strain field data, offering valuable insights into the role of SIC in enhancing the crack growth resistance of NR.

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Transition of rupture mode of strain crystallizing elastomers in tensile edge-crack tests

Abstract: We revisit the classical results that the fracture energy density (Wb) of strain crystallizing (SC) elastomers exhibits an abrupt change at a characteristic value () of initial notch length (c0) in tensile edge-crack tests.

Cited by 7 publications

References 60 publications

Role of Terminal Groups of cis-1,4-Polyisoprene Chains in the Formation of Physical Junction Points in Natural Rubber

Role of Terminal Groups of cis-1,4-Polyisoprene Chains in the Formation of Physical Junction Points in Natural Rubber

Strain hardening in biaxially stretched elastomers undergoing strain-induced crystallization

Unraveling Non‐Uniform Strain‐Induced Crystallization Near a Crack Tip in Natural Rubber

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