Strain-induced crystallization of peroxide-crosslinked natural rubber

Ikeda, Yuko; Yasuda, Yoritaka; Makino, Shinya; Yamamoto, Shinya; Tosaka, Masatoshi; Senoo, Kazunobu; Kohjiya, Shinzo

doi:10.1016/j.polymer.2007.01.006

Cited by 61 publications

(57 citation statements)

References 25 publications

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“…(The only exception may be the one for NR samples crosslinked with dicumyl peroxide. 49 In this case, the nature of the network structure could be different from the other samples crosslinked by sulfur. Otherwise, the kinetics of crystallization could have influenced because of the relatively high deformation rate adopted for this experiment.)…”

Section: Incipient Strain Of Crystallizationmentioning

confidence: 96%

Strain-Induced Crystallization of Crosslinked Natural Rubber As Revealed by X-ray Diffraction Using Synchrotron Radiation

Tosaka

2007

Polym J

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ABSTRACT:Strain-induced crystallization (SIC) of natural rubber (NR) has been extensively studied even before the advent of macromolecular physics. However, there are still some unsolved basic issues in this field. In this review article, classic studies on SIC of NR are briefly introduced, and then recent results by synchrotron X-ray diffraction studies in separate papers by different authors are categorized and interpreted on the basis of molecular models. Cyclic deformation experiments provided information on partial orientation of the network-chains, on nucleation and morphological changes of crystals and on stress field around the strain-induced crystals. On the other hand, experiments under constant strain provided information on kinetics of SIC, on stress relaxation due to SIC, and so on. The experimental results could be explained under the assumption that the SIC is dominated by strain, and that the crystals are of foldedchain type. However, in order to consistently explain the various experimental results, we have to establish a unified molecular model of the network structure. [doi:10.1295/polymj.PJ2007059] KEY WORDS Network-chain Density / Crosslinking / Supercooling / Entropy / Rubber Elasticity / Crystallite Size / Entanglement / Natural rubber (NR) from Hevea latex is an indispensable material for many industrial and household applications, 1 which is constituted of cis-1,4-polyisoprene (ca. 94%) and non-rubber components such as proteins (ca. 2%) and lipid (ca. 3%).2 The versatility of the plant-derived NR is mainly due to its outstanding tensile properties and the good crack growth resistance. We still cannot reproduce the good performance of the NR products using synthetic cis-1,4-polyisoprene rubber (IR). The superiority of NR has been thought to originate from its ability to crystallize immediately by expansion; by contrast, crystallinity of IR is not as high as NR because of the lower regularity of the main-chain structure. 2,3 In this context, straininduced crystallization (SIC) of NR has been extensively studied even before the advent of macromolecular physics.

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Section: Incipient Strain Of Crystallizationmentioning

confidence: 96%

Strain-Induced Crystallization of Crosslinked Natural Rubber As Revealed by X-ray Diffraction Using Synchrotron Radiation

Tosaka

2007

Polym J

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“…This is determined by acknowledging the fact that each chain has two ends, and therefore, each cross-link unites four ends. 22 This leads to the following equation (2) where 1/2M c is the crosslink density in mol g 21…”

Section: Preparation Of Samplesmentioning

confidence: 99%

α,ω-Alkanedithiol cross-linking of high vinyl 3,4-polyisoprene

Hlangothi

Woolard

Hlangothi

2014

Plastics, Rubber and Composites

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This paper evaluates the ability of a,v-alkanedithiols to cross-link high vinyl 3,4-polyisoprene rubber (represented by Isogrip) through the thiol-ene addition reaction and provides microstructural insights into where cross-linking takes place. The thiol-ene reactions are the hydrothiolation of a C5C bond, which can be initiated in a number of ways. It has been postulated that organic peroxides are very effective in initiating such cross-links and that a,v-alkanedithiolene cross-linking of high vinyl 3,4-polyisoprene primarily takes place on the a-carbon of the unsaturated sites of the rubber chains.

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“…29-31 A custom-made tensile tester (ISUT-2201, Aiesu Giken, Co., Kyoto) was placed on the beam line and WAXD patterns were recorded during stretching at a speed of 100 mm min À1 at room temperature. 31 The wavelength of the X-ray was 0.0832 nm and the camera length was 198 mm. The two-dimensional WAXD patterns were recorded using a CCD camera (HAMAMATSU C4880-50).…”

Section: Dynamic Mechanical Analysis (Dma)mentioning

confidence: 99%

Mechanical characteristics of hydrogenated natural rubber vulcanizates

Ikeda

Phinyocheep

Kittipoom

et al. 2008

Polymers for Advanced Techs

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Mechanical properties of partially hydrogenated natural rubber (HNR) vulcanizates were evaluated regarding their chemical structure and crystallizable nature of HNR, and are reported here, to the best of our knowledge, for the first time. HNRs of three levels of hydrogenation (20.6, 29.0, and 40.6 mol%) were successfully prepared by the chemical modification of natural rubber (NR) latex using N 2 H 4 and H 2 O 2 as reagents, in a sufficient amount for preparing sulfur-crosslinked samples to be subjected to mechanical and structural measurements. The three HNR vulcanizates were found to be crystallizable upon stretching; it is noted that even 40.6 mol% hydrogenation did not prevent HNR vulcanizates from crystallization upon stretching, while their onset strain of crystallization was higher than that of NR vulcanizate. The hysteresis loss and residual strain up to a stretching ratio of 2 for the HNR vulcanizates tended to become larger with the increase in the degree of the hydrogenation. Tensile and dynamic mechanical properties of 20.6 mol% hydrogenated HNR vulcanizate were comparable to those of NR vulcanizate. From differential scanning calorimetry and temperature dispersion of dynamic modulus or loss, the glass transition temperatures of HNR vulcanizates were found to be almost the same as that of NR vulcanizate, which is also notable. The thermal stability of HNR vulcanizates was better than that of NR vulcanizate. Thus, this chemical modification seems to give a promising NR derivative whose properties can be equivalent or even better than the mother polymer.

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Strain-induced crystallization of peroxide-crosslinked natural rubber

Cited by 61 publications

References 25 publications

Strain-Induced Crystallization of Crosslinked Natural Rubber As Revealed by X-ray Diffraction Using Synchrotron Radiation

Strain-Induced Crystallization of Crosslinked Natural Rubber As Revealed by X-ray Diffraction Using Synchrotron Radiation

α,ω-Alkanedithiol cross-linking of high vinyl 3,4-polyisoprene

Mechanical characteristics of hydrogenated natural rubber vulcanizates

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