Crystal Structure of Natural Rubber

Takahashi, Yasuhiro; Kumano, Takeshi

doi:10.1021/ma0305683

Cited by 51 publications

(37 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…45 Later on, Bunn reported a new model of the crystal structure and d Cry 5 1.00 g cm 23 in 1942. 46 Nowadays, the argument of the detailed atomistic arrangement inside the unit cell is still under debate, 47,48 but most of the models result in a value of d Cry between 0.97 and 1.07 g cm 23 . Here, we adopt Bunn's result to estimate the contribution of the crystallites to the XSLD contrast of the system.…”

Section: Appendix: Effect Of Crystallization On the Calculation Of / mentioning

confidence: 99%

Strain induced nanocavitation and crystallization in natural rubber probed by real time small and wide angle X‐ray scattering

Zhang

Scholz

Merckel

et al. 2013

J Polym Sci B Polym Phys

View full text Add to dashboard Cite

The concomitant appearance of crystallites and nanocavities under uniaxial strain is investigated by X‐ray scattering in a model natural rubber system. The nanocavities appear after crystallization and only when the true stress is above a critical cavitation stress σCav. The presence of crystallites alone does not influence the calculation of the void volume fraction ϕvoid. The nanocavities formed are 20–50 nm in size with a constant aspect ratio. The presence of filler shifts the critical crystallization extension ratio λCry, λCav, and σCav to lower values. The clear correlation between σCav and the crystallinity at the onset of cavitation χC(λCav) implies that the crystallites take most of the mechanical loading thus delaying the cavitation in the amorphous phase. Under cyclic loading, nanocavitation is significant only in the first loading and in the successive loadings if the extension ratio is above its maximum historical value. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013, 51, 1125–1138

show abstract

Section: Appendix: Effect Of Crystallization On the Calculation Of / mentioning

confidence: 99%

Strain induced nanocavitation and crystallization in natural rubber probed by real time small and wide angle X‐ray scattering

Zhang

Scholz

Merckel

et al. 2013

J Polym Sci B Polym Phys

View full text Add to dashboard Cite

show abstract

“…(In terms of the discrepancy factor, this crystal structure is not so good and is not necessarily acceptable at present. Recently, Takahashi & Kumano 16 refined the crystal structure of NR using modern techniques. The statistical structure has been approved also in their work.…”

Section: Experimental Studiesmentioning

confidence: 99%

“…The final volume changed with , which was the same order with the mesh size of the network. (Note that L 120 tends to be quite smaller than L 200 because of the statistical crystal structure of NR, 14,16 as discussed by Tosaka et al 51 Accordingly, we have to be careful if we consider the volume of crystallite using L 120 .) These results suggest that the growth of strain-induced crystallites is limited by a certain property of the network structure which deform in the affine manner.…”

Section: Morphological Featuresmentioning

confidence: 99%

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

Tosaka

2007

Polym J

View full text Add to dashboard Cite

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.

show abstract

“…The strain-induced crystallization (SIC) of rubber is classically investigated using X-ray diffraction (XRD). Since the pioneering work by Katz in 1925, [1] which provided the first XRD pattern of a stretched natural rubber (NR), numerous studies on SIC were carried out, dealing with the crystalline phase structure, [2][3][4][5] chain orientation, [6] and kinetics of crystallization, [7,8] nonexhaustively.…”

Section: Introductionmentioning

confidence: 99%

Strain‐induced crystallization in rubber: A new measurement technique

Cam

2017

Strain

View full text Add to dashboard Cite

The crystallinity of stretched crystallizable rubbers is classically investigated using X-ray diffraction. In this study, we propose a new method based on temperature measurement and quantitative calorimetry to determine rubber crystallinity during mechanical tests. For that purpose, heat power density are first determined from temperature variation measurements and the heat diffusion equation. The increase in temperature due to strain-induced crystallization is then deduced from the heat power density by subtracting the part due to elastic couplings. The heat capacity, the density, and the enthalpy of fusion are finally used to calculate the crystallinity from the temperature variations due to strain-induced crystallization. The characterization of the stress-strain relationship and the non-entropic contributions to rubber elasticity is not required.This alternative crystallinity measurement method is therefore a user-friendly measurement technique, which is well adapted in most of the mechanical tests carried out with conventional testing machines. It opens numerous perspectives in terms of high speed and full crystallinity field measurements.

show abstract

Crystal Structure of Natural Rubber

Cited by 51 publications

References 17 publications

Strain induced nanocavitation and crystallization in natural rubber probed by real time small and wide angle X‐ray scattering

Strain induced nanocavitation and crystallization in natural rubber probed by real time small and wide angle X‐ray scattering

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

Strain‐induced crystallization in rubber: A new measurement technique

Contact Info

Product

Resources

About