Ultimate Properties of Stereoregular and Stereoirregular 1,4-Polybutadiene Networks and Their Correlation with Theories

1994 ◽  
Vol 67 (1) ◽  
pp. 88-106
Author(s):  
M. A. Sharaf
Keyword(s):  
Ultimate Strength ◽  
Chemical Structure ◽  
Intrinsic Property ◽  
Primary Role ◽  
Physical Processes ◽  
Ultimate Properties ◽  
Different Temperatures ◽  
Strain Induced Crystallization ◽  
Induced Crystallization ◽  
Maximum Extensibility

Abstract The ultimate properties of stereoregular and stereoirregular 1,4-polybutadiene (PB) networks covering a range in micro-chemical structure (cis-trans-vinyl) have been investigated. The dependence of the ultimate properties, namely the ultimate strength and the maximum extensibility, on sterochemical structure, has been demonstrated at different temperatures. Also, dependence of the ultimate properties on temperature has been apparent. Focusing special attention on the physical processes that culminate in rupture of the network, confirmed and extended the primary role played by strain-induced crystallization. More specifically, strain-induced crystallization enhances attainment of greater values of strength and extensibility. Noncrystallizable elastomers were found to have lower ultimate properties due to the absence of rupture-impeding mechanisms and consequently they become incapable of reaching their maximum extensibility. The frequently observed maximum in plots of the ultimate strength fr vs. the molecular mass Mc has been verified as an intrinsic property of the networks. This property was found to depend on the degree of crosslinking, rather than being time dependent. Values of the ultimate strength fr of both crystallizable and noncrystallizable networks were well reproduced by Bueche's theory of rupture. On the other hand, the Griffith criteria were found to have some success with noncrystallizable networks. Calculated values of the threshold surface free energy G0 were in agreement with those reported in the literature for similar noncrystallizable networks.

scholarly journals Influence of Temperature on Mechanical Properties of P(BAMO-r-THF) Elastomer

Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2507
Author(s):  
Jinxian Zhai ◽  
Hanpeng Zhao ◽  
Xiaoyan Guo ◽  
Xiaodong Li ◽  
Tinglu Song
Keyword(s):  
Mechanical Properties ◽  
X Ray Diffraction ◽  
Polymeric Chains ◽  
Different Temperatures ◽  
Influence Of Temperature On ◽  
Strain Induced Crystallization ◽  
Thermal Histories ◽  
Static Conditions ◽  
The Relationship ◽  
Induced Crystallization

The relationship between temperature and the mechanical properties of an end cross-linked equal molar random copolyether elastomer of 3,3-bis(azidomethyl)oxetane and tetrahydrofuran (P(BAMO-r-THF)) was investigated. During this investigation, the performances of two P(BAMO-r-THF) elastomers with different thermal histories were compared at different temperatures. The elastomer as prepared at 20 °C (denoted as S0) exhibited semi-crystallization morphology. Wide angle X-ray diffraction analysis indicated that the crystal grains within elastomer S0 result from the crystallization of BAMO micro-blocks embedded in P(BAMO-r-THF) polymeric chains, and the crystallinity is temperature irreversible under static conditions. After undergoing a heating-cooling cycle, this elastomer became an amorphous elastomer (denoted as S1). Regarding mechanical properties, at 20 °C, break strains and stresses of 315 ± 22% and 0.46 ± 0.01 MPa were obtained for elastomer S0; corresponding values of 294 ± 6% and 0.32 ± 0.02 MPa were obtained for elastomer S1. At −40 °C, these strains and stresses simultaneously increased to 1085 ± 21% and 8.90 ± 0.72 MPa (S0) and 1181 ± 25% and 10.23 ± 0.44 MPa (S1), respectively, owing to the strain-induced crystallization of BAMO micro-blocks within the P(BAMO-r-THF) polymeric chains.

A Study of Mechanical and Optical Properties of an Alternating NBR and an Emulsion NBR

1973 ◽  
Vol 46 (5) ◽  
pp. 1264-1273 ◽  
Author(s):  
U. P. Mukherjee ◽  
C. Goldstein
Keyword(s):  
Tensile Properties ◽  
Ultimate Strength ◽  
Dynamic Properties ◽  
Dicumyl Peroxide ◽  
Ultimate Elongation ◽  
Alternating Copolymer ◽  
Strain Data ◽  
Strain Induced Crystallization ◽  
Increased Strength ◽  
Induced Crystallization

Abstract At low elongation, over the range of temperatures and frequencies studied, the dynamic properties (elastic modulus and loss factor) and activation energy for the glass-rubber transition are the same for highly alternating and emulsion copolymers of acrylonitrile and butadiene. At higher elongation the stress-birefringence and x-ray data on cured (1.7 phr dicumyl peroxide) highly alternating copolymer show the occurrence of strain-induced crystallization, whereas the emulsion copolymer does not crystallize under strain. The stress-strain data for the highly alternating copolymer cured at 1.7 phr dicumyl peroxide and for the emulsion copolymer cured at 1.7 phr and 0.8 phr show that at 1.7 phr dicumyl peroxide the highly alternating copolymer has higher ultimate strength. However, the emulsion copolymer cured by 0.8 phr dicumyl peroxide shows tensile properties similar to those of the highly alternating copolymer cured by 1.7 phr dicumyl peroxide. Therefore, it may be concluded that the increased strength and ultimate elongation of highly alternating copolymer, as reported by Furukawa, are due to the fact that at the same curative level the emulsion copolymer gets over-cured resulting in lower ultimate strength and elongation. This present study indicates that it is not appropriate to compare the ultimate properties of the emulsion and highly alternating copolymers cured at the same level of dicumyl peroxide. Slight adjustment in curing condition brings highly alternating and emulsion copolymers closer in tensile strength and ultimate elongation. In conclusion, it may be said that this study indicates that highly alternating NBR shows tensile properties similar to those obtained for emulsion NBR already produced commercially.

Synchrotron X-Ray Studies of Vulcanized Rubbers and Thermoplastic Elastomers

2006 ◽  
Vol 79 (3) ◽  
pp. 460-488 ◽  
Author(s):  
Shigeyuki Toki ◽  
Benjamin S. Hsiao ◽  
Shinzo Kohjiya ◽  
Masatoshi Tosaka ◽  
Andy H. Tsou ◽  
...  
Keyword(s):  
Hybrid Structure ◽  
Thermoplastic Elastomers ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
X Ray Diffraction ◽  
X Ray ◽  
Different Temperatures ◽  
Strain Induced Crystallization ◽  
Different Strains ◽  
Induced Crystallization

Abstract Synchrotron X-ray diffraction technique has revealed strain-induced crystallization and molecular orientation in vulcanized rubbers and thermoplastic elastomers (TPE) during deformation in real time. The stress-strain curves and wide angle X-ray diffraction (WAXD) patterns in vulcanized rubbers and TPE were measured simultaneously. In-situ WAXD patterns were taken not only at different strains during uniaxial deformation but also at different temperatures at a constant strain. Results lead to several new insights. (i) Strain-induced crystallization is a common phenomenon in vulcanized rubbers, except SBR (styrene-butadiene rubber), and in TPE (with crystalline hard segments). (ii) Strain-induced crystallization decreases the stress and increases the elongation in the strained rubber. (iii) The hybrid structure of chemical networks and strain-induced crystallites is responsible to the tensile strength and elongation at break for both systems. (iiii) Some original crystal fraction (hard segment domain) in TPE is destroyed. During deformation, strain-induced crystallization increases with strain. Upon retraction even to stress zero, the majority of oriented strain-induced crystallites remains in tack with preferred orientation.

Reconstructing the mechanical response of polybutadiene rubber based on micro-structural evolution in strain-temperature space: entropic elasticity and strain-induced crystallization as the bridges

Soft Matter ◽  
2020 ◽  
Vol 16 (2) ◽  
pp. 447-455 ◽  
Author(s):  
Pinzhang Chen ◽  
Yuanfei Lin ◽  
Jingyun Zhao ◽  
Lingpu Meng ◽  
Daoliang Wang ◽  
...  
Keyword(s):  
Mechanical Response ◽  
Structural Evolution ◽  
Entropic Elasticity ◽  
Polybutadiene Rubber ◽  
Strain Induced Crystallization ◽  
Induced Crystallization

Micro-structural evolution of polybutadiene rubber in strain-temperature space, and the reconstruction of the macro-mechanical response.

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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