Entanglements and Networks to Strain-Induced Crystallization and Stress–Strain Relations in Natural Rubber and Synthetic Polyisoprene at Various Temperatures

2013 ◽  
Vol 46 (13) ◽  
pp. 5238-5248 ◽  
Author(s):  
Shigeyuki Toki ◽  
Justin Che ◽  
Lixia Rong ◽  
Benjamin S. Hsiao ◽  
Sureerut Amnuaypornsri ◽  
...  
Keyword(s):  
Natural Rubber ◽  
Stress Strain ◽  
Strain Induced Crystallization ◽  
Induced Crystallization

Influence of Crosslink Characteristics Induced by Aromatic-Based Antioxidants on the Swelling and Stress-Strain Behavior of Natural Rubber Vulcanizates

2003 ◽  
Vol 76 (2) ◽  
pp. 334-347 ◽  
Author(s):  
Tarek M. Madkour ◽  
Rasha A. Azzam
Keyword(s):  
Natural Rubber ◽  
Crosslinking Agent ◽  
Oxidative Degradation ◽  
Thermal Oxidative Degradation ◽  
Stress Strain ◽  
Strain Behavior ◽  
Strain Induced Crystallization ◽  
Elastomeric Chains ◽  
Natural Rubber Vulcanizates ◽  
Induced Crystallization

Abstract Stress-strain measurements were performed on dry and swollen natural rubber vulcanizates prepared using both sulfur as the crosslinking agent and aromatic-based bound antioxidants acting as a second crosslinking agent. The aromatic-based antioxidants were synthesized and analyzed spectroscopically in order to relate the final behavior of the vulcanizates to the nature of the crosslink characteristics. The anomalous upturn in the modulus values of these networks in response to the imposed stress was shown to persist in the dry as well as the swollen state. Since the swollen elastomeric chains cannot undergo a strain-induced crystallization, the abnormal upturns in the modulus values in an absence of a filler were explained on the basis of the limited extensibility of the short chains of networks prepared using two different crosslinking agents in line with earlier modeling predictions. Remarkably, the swelling experiments revealed the increase in the crosslink density of the networks in the early stages of the thermal oxidative degradation procedure indicating a post-cure of the chemically bound antioxidants to the elastomeric chains, which incidentally corresponds to a maximum in the modulus values of the networks. The rheological and other mechanical properties such as the hardness were shown not to have been affected as a result of the incorporation of the chemically bound antioxidants.

DEPENDENCE OF THE ONSET OF STRAIN-INDUCED CRYSTALLIZATION OF NATURAL RUBBER AND ITS SYNTHETIC ANALOGUE ON CROSSLINK AND ENTANGLEMENT BY USING SYNCHROTRON X-RAY

2017 ◽  
Vol 90 (4) ◽  
pp. 728-742 ◽  
Author(s):  
Watcharin Sainumsai ◽  
Shigeyuki Toki ◽  
Sureerut Amnuaypornsri ◽  
Adun Nimpaiboon ◽  
Jitladda Sakdapipanich ◽  
...  
Keyword(s):  
Natural Rubber ◽  
Crosslink Density ◽  
Inhomogeneous Material ◽  
Synthetic Analogue ◽  
Stress Strain ◽  
X Ray ◽  
Stress Strain Relation ◽  
Strain Induced Crystallization ◽  
Induced Crystallization ◽  
Flow Induced Crystallization

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.

Effects of plasticizers on the strain-induced crystallization and mechanical properties of natural rubber and synthetic polyisoprene

RSC Advances ◽  
2015 ◽  
Vol 5 (15) ◽  
pp. 11317-11324 ◽  
Author(s):  
Yueqing Ren ◽  
Suhe Zhao ◽  
Qian Yao ◽  
Qianqian Li ◽  
Xingying Zhang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Natural Rubber ◽  
Stress Strain ◽  
Strain Induced Crystallization ◽  
Induced Crystallization

Effects of different type of plasticizers on the strain-induced crystallization and stress–strain curves of crystallizable rubber.

Stress-Strain and Stress-Birefringence Studies on Natural Rubber, Isomerized Natural Rubber, and Synthetic Poly(Isoprene)

1974 ◽  
Vol 47 (5) ◽  
pp. 1234-1240 ◽  
Author(s):  
D. P. Mukherjee
Keyword(s):  
Natural Rubber ◽  
Rate Process ◽  
Stress Strain ◽  
Similar Reasoning ◽  
Strain Behavior ◽  
Three Samples ◽  
Strain Induced Crystallization ◽  
High Elongation ◽  
The Difference ◽  
Induced Crystallization

Abstract With respect to stress-birefringence, isomerized natural rubber behaves the same as natural rubber at low elongations, but at high elongation levels the natural rubber sample exhibits higher stress-hysteresis accompanied by higher mechanical loss energy. Therefore, it appears that at low elongation level the viscoelastic rate process governing the stress-strain hysteresis is not sensitive to structural imperfection (within the range of cis-1,4 content studied here), but the crystallization process at higher elongation is strongly dependent on the cis content. This is in agreement with the conclusion made by Scott and co-workers from their dynamic measurements on synthetic poly(isoprene)s. The difference in cis-content between Natsyn and natural rubber and the effect on crystallizability explains the lower hysteresis on the stress-birefringence plot for Natsyn. Similar reasoning explains the stress-birefringence difference between the A.C. rubber and Natsyn. The data, however, shows that Natsyn has the lowest amount of loss energy of the three samples (except at very high input energy >4.5). This difference might be due to effects of physical entanglements or gels which may differ. In addition, the difference in microstructure contributes to the difference in extent of strain-induced crystallization. Since the viscoelastic rate process governing the stress-strain behavior and the strain-induced crystallization are associated with molecular motion, they may not be independent.

The Effect of Temperature on the Stress-Strain Isotherms of Polyisobutylene Networks at High Elongation

1976 ◽  
Vol 49 (1) ◽  
pp. 85-92 ◽  
Author(s):  
M. Kato ◽  
J. E. Mark
Keyword(s):  
Natural Rubber ◽  
Effect Of Temperature ◽  
Stress Strain ◽  
Pronounced Increase ◽  
Strain Induced Crystallization ◽  
High Elongation ◽  
Induced Crystallization

Abstract Three chemically cured, unfilled polyisobutylene networks were studied in elongation to their rupture points at several temperatures in the range 15–80°C. At the lower temperatures, the stress-strain isotherms obtained were similar to those reported for unfilled networks of natural rubber and several other polymers in that they showed an anomalous, marked increase in the modulus or reduced force at high elongations. At intermediate temperatures, this upturn in the force is significantly diminished, however, and the networks rupture at lower elongations. At the higher temperatures, there is no evidence whatever for an upturn in the force, and the elongation at rupture is further reduced. These results on polyisobutylene networks implicate strain-induced crystallization rather than limited chain extensibility as the origin of the pronounced increase in the force at high elongations. The reinforcement provided by the crystallites formed in this manner would account for the increased extensibility of the networks at the lower temperatures. Since natural rubber is very similar to polyisobutylene in its crystallizability, the anomalous stress-strain isotherms widely reported for networks of this polymer are thus probably also due largely, if not entirely, to network crystallization.

Strain-induced crystallization behaviour of natural rubbers from guayule and rubber dandelion revealed by simultaneous time-resolved WAXD/tensile measurements: indispensable function for sustainable resources

RSC Advances ◽  
2016 ◽  
Vol 6 (98) ◽  
pp. 95601-95610 ◽  
Author(s):  
Yuko Ikeda ◽  
Preeyanuch Junkong ◽  
Takumi Ohashi ◽  
Treethip Phakkeeree ◽  
Yuta Sakaki ◽  
...  
Keyword(s):  
Natural Rubber ◽  
Crystallization Behaviour ◽  
Time Resolved ◽  
Sustainable Resources ◽  
Strain Induced Crystallization ◽  
Induced Crystallization

Guayule and rubber dandelion natural rubbers are useful alternatives forHeveanatural rubber in terms of their strain-induced crystallization behaviours.

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