Strain-Induced Crystallization of Natural Rubber: Effect of Proteins and Phospholipids

2008 ◽  
Vol 81 (5) ◽  
pp. 753-766 ◽  
Author(s):  
Sureerut Amnuaypornsri ◽  
Jitladda Sakdapipanich ◽  
Shigeyuki Toki ◽  
Benjamin S. Hsiao ◽  
Naoya Ichikawa ◽  
...  

Abstract The effects of proteins and phospholipids in natural rubber (NR) on the strain-induced crystallization behavior during uniaxial deformation were studied by in-situ synchrotron wide-angle X-ray diffraction (WAXD) technique and simultaneous measurements of stress-strain relation. The influences of proteins and phospholipids in NR were evaluated separately by decomposition methods using deproteinization and lipase treatment, respectively. It was found that both components form a naturally occurring network, which is responsible for the strain-induced crystallizability of unvulcanized NR and the corresponding high mechanical property. This network also plays a significant role in strain-induced crystallization of vulcanized natural rubber.

RSC Advances ◽  
2015 ◽  
Vol 5 (32) ◽  
pp. 25171-25182 ◽  
Author(s):  
Xuan Fu ◽  
Guangsu Huang ◽  
Zhengtian Xie ◽  
Wang Xing

The existence of a denser network domain formed by incorporation of filler and its vital role in determining the strain-induced crystallization behavior of nanocomposites is proved by in situ synchrotron X-ray diffraction characterization.


Soft Matter ◽  
2019 ◽  
Vol 15 (4) ◽  
pp. 734-743 ◽  
Author(s):  
Pinzhang Chen ◽  
Jingyun Zhao ◽  
Yuanfei Lin ◽  
Jiarui Chang ◽  
Lingpu Meng ◽  
...  

The structural evolution of NR during stretching at −40 °C and in the strain–temperature space.


2017 ◽  
Vol 90 (4) ◽  
pp. 728-742 ◽  
Author(s):  
Watcharin Sainumsai ◽  
Shigeyuki Toki ◽  
Sureerut Amnuaypornsri ◽  
Adun Nimpaiboon ◽  
Jitladda Sakdapipanich ◽  
...  

ABSTRACT Strain-induced crystallization (SIC) and stress–strain relations of varied crosslink structures and varied crosslink densities of vulcanized natural rubber (NR), vulcanized synthetic polyisoprene rubber (IR), and un-vulcanized natural rubber are compared using a synchrotron X-ray. The onset strain of SIC does not depend on crosslink density and crosslink structures. Un-vulcanized NR shows a smaller onset strain of SIC than that of vulcanized NR. Therefore, entanglements in NR are pivot points to induce SIC, just as entanglements in semi-crystalline plastics induce flow-induced crystallization (FIC). During deformation, complicated phenomena occur simultaneously such as cavitation, crosslink breakdown, SIC with temperature upturn, and limited extensibility of chains between crosslinks, because rubber is a significantly inhomogeneous material. It is still difficult to evaluate the contribution of SIC to stress-upturn of the stress–strain relation of rubber.


Crystals ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 294 ◽  
Author(s):  
Konrad Schneider ◽  
Matthias Schwartzkopf

Vulcanized natural rubber (unfilled and filled with 20 phr carbon black) is strained. We suppress the macroscopic formation of fiber symmetry by choosing strip-shaped samples ("pure-shear geometry") and investigate the orientation of the resulting crystallites by two-dimensional wide-angle X-ray diffraction (WAXD), additionally rotating the sample tape about the straining direction. Indications of a directed reinforcing effect of the strain-induced crystallization (SIC) in the thin strip are found. In the filled material fewer crystallites are oriented and the orientation distribution of the oriented crystallites is less perfect. The results confirm, that it is important for the evaluation of crystallinity under deformation to check, whether fiber symmetry can be assumed. This has consequences in particular on the quantitative interpretation of space-resolved scanning experiments in the vicinity of crack tips. Furthermore it raises the question, whether there is an asymmetric reinforcing effect of the SIC in the vicinity of crack tips inside natural rubber.


2005 ◽  
Vol 38 (16) ◽  
pp. 7064-7073 ◽  
Author(s):  
Shigeyuki Toki ◽  
Igors Sics ◽  
Benjamin S. Hsiao ◽  
Masatoshi Tosaka ◽  
Sirilux Poompradub ◽  
...  

2011 ◽  
Vol 84 (3) ◽  
pp. 425-452 ◽  
Author(s):  
Bertrand Huneau

Abstract Strain-induced crystallization of natural rubber was discovered in 1925 by the means of x-ray diffraction and has been widely investigated by this technique until today. The studies devoted to the structure of the crystalline phase of natural rubber are first reviewed. This structure is strongly anisotropic and can be related to the exceptionally good strength and fatigue properties of this material. The relationships between strain-induced crystallization of natural rubber and its mechanical response, during static or tension-retraction tests, are also reviewed and discussed; in particular, the hysteresis of the stress-strain curve is mainly explained by strain-induced crystallization. The kinetics of crystallization under both static and cyclic deformation is also discussed, as well as the influence of different factors, depending either on material composition (crosslink density, carbon black fillers) or on external parameters (temperature, strain rate…).


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