Chemical Stress-Relaxation and Other Studies on Styrene-Butadiene Rubber

1974 ◽  
Vol 47 (5) ◽  
pp. 1265-1274 ◽  
Author(s):  
S. H. Kalfayan ◽  
R. Rakutis ◽  
R. H. Silver
Keyword(s):  
Stress Relaxation ◽  
Elevated Temperatures ◽  
Activation Energies ◽  
Hydroxyl Group ◽  
Styrene Butadiene Rubber ◽  
Chemical Stress ◽  
Butadiene Rubber ◽  
Relaxation Rates ◽  
Relaxation Measurements ◽  
Styrene Butadiene

Abstract The aging of styrene—butadiene rubber (SBR) was studied by three methods: stress relaxation, infrared spectroscopy, and swelling measurements, with the purpose of supplying information pertinent to understanding the basic mechanism of its aging. Stress-relaxation measurements in air and nitrogen at elevated temperatures indicated that atmospheric oxygen is the principal cause of chemical stress relaxation of SBR, rather than heat. Intermittent stress-relaxation measurements showed scission and crosslinking occurring simultaneously during network breakdown, and it was concluded that random scission in the backbone is indicated to take place in preference to scission in the crosslinks. Activation energies obtained from relaxation rates at several temperatures was 28 ± 0.5 kcal, comparable to literature values of 30 ± 2 kcals. The rates of carbonyl and hydroxyl group formation in SBR in air at various temperatures were determined by ir spectroscopy, both induction and maximum rates, νm, being measured. Activation energies calculated from these rates showed lower values compared to those obtained from stress-relaxation measurements. This may be due to the possibility that the processes being measured are not the same in each case. The three peaks appearing in the carbonyl region were ascribed to carboxyl, ketone, or aldehyde, and perester. The presence of these groups was confirmed by microanalytical methods. The absorption centered at 3450 cm−1 was attributed to hydrogen-bonded OH groups, i.e., alcohols and hydroperoxides. Positive chemical tests were obtained for hydroperoxide. The number of new network chains formed, νe, obtained from swelling measurements agreed well with those obtained from stress-relaxation measurements. It was found that the rate of the number of new network chains formed increased rapidly during the latter states of oxidation.

Differential Dynamic Shear Moduli of Carbon Black-Filled Styrene-Butadiene Rubber Subjected to Large Shear Strain Histories

1986 ◽  
Vol 59 (2) ◽  
pp. 241-254 ◽  
Author(s):  
Koichi Arai ◽  
John D. Ferry
Keyword(s):  
Stress Relaxation ◽  
Carbon Black ◽  
Shear Strain ◽  
Single Step ◽  
Fourth Power ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Initial Value ◽  
Shear Moduli ◽  
Styrene Butadiene

Abstract Combined measurements of shear-stress relaxation and differential dynamic storage and loss shear moduli G′ and G″ following a single-step shear strain of 0.4, as well as measurements of dynamic moduli in on-off strain and stress histories, have been made on styrene-butadiene rubber (type 1502) filled with carbon black (N299) at loadings of 40, 50, 60, and 70 phr, with 10 phr Sundex 790 oil. Both cured and uncured compounds were studied at temperatures of 25.0° and −0.5°C respectively. The maximum oscillatory shear strain was 0.005, and the frequency was from 0.4 to 1.8 Hz. The storage shear modulus G′(ω, 0) measured without imposition of static strain was approximately proportional to the fourth power of the volume fraction of black. With imposition of single-step strain, the differential storage modulus G′(ω, γ; t) fell 25% to 35% but slowly recovered somewhat while the strain was maintained for 4 to 5 h. During this period, the static stress relaxed continuously. At the highest content of black, the drop in log G′ was the least, and the final recovery was closest to the initial value of G′(ω, 0). In on-off experiments on uncured compounds, when the strain was “on” for 250 s and then “off” (either stress or strain returned to zero), G′ decreased when the strain was imposed as before and decreased further when it was removed. In the “off” state, G′ recovered partially but did not attain the initial value of G′(ω, 0) even after 7 d. In on-off experiments on cured compounds, removal of stress caused G′ to either increase or decrease depending on the content of black; in any case, in the “off” state, G′ recovered completely to its initial value. Other strain histories involved on-off sequences with different “on” periods and multiple on-off sequences with different “on” periods and multiple on-off sequences. The results are interpreted in terms of a network of black particle aggregates whose contacts can slowly rearrange even in the absence of stress as shown by stress relaxation at very small strains in earlier studies. In large strains, it is postulated that some contacts are broken but can partially reform, especially in the stress-free state; the rate of reformation is similar to that of small-strain stress relaxation. Only in cured compounds is the network fully recovered, presumably because in these the particles are imbedded in a crosslinked matrix and have crosslinked bridges that facilitate reestablishment of interparticle contacts, whereas in uncured compounds the matrix has no crosslinks and the bound rubber on adjacent particles may be merely entangled.

Nonlinear stress relaxation of silica filled solution-polymerized styrene-butadiene rubber compounds

2009 ◽  
Vol 112 (6) ◽  
pp. 3569-3574 ◽  
Author(s):  
Jin Sun ◽  
Hong Li ◽  
Yihu Song ◽  
Qiang Zheng ◽  
Li He ◽  
...  
Keyword(s):  
Stress Relaxation ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Rubber Compounds ◽  
Nonlinear Stress ◽  
Styrene Butadiene

Functionalization of Styrene-Butadiene Rubber and Skim Latex by Photo-Catalytic Reaction Using Nanometric TiO2 Film as a Photocatalyst

2015 ◽  
Vol 659 ◽  
pp. 409-413
Author(s):  
Supinya Nijpanich ◽  
Adun Nimpaiboon ◽  
Jitladda Sakdapipanich
Keyword(s):  
Uv Irradiation ◽  
Catalytic Reaction ◽  
Irradiation Time ◽  
Average Molecular Weight ◽  
Hydroxyl Group ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Rubber Latex ◽  
Styrene Butadiene

Functionalization of rubber latex is used to improve some weak properties. One method of functionalization is chemical modification by a photo-catalytic reaction. In this work, the functionalization of styrene-butadiene rubber (SBR) and skim latex were carried out under UV irradiation in the presence of TiO2 film, which was double spin-coated on a glass petri-dish, followed by calcination at 550°C. The structural characterization of functionalized rubber latex was analyzed by FTIR and NMR techniques. In the case of SBR latex, the hydroxyl group was observed after exposure to 80W of UV irradiation in the presence of H2O2 at concentration of 20% by weight of dry rubber. However, the gel formation derived from cross-linking as a side reaction obstructed the further characterization of microstructure and limited the applications of latex and solid rubber. In the case of skim latex, the effect of pH, H2O2 concentration and UV irradiation time were studied. It was found that the functionalization was successful after exposure to low power of UV irradiation for 1 h in the presence of H2O2 at concentration of 5-10% by weight of dry rubber. The weight-average molecular-weight (Mw) slightly decreased from 2x106 to 1x106 g/mol.

The Thermal and Oxidative Stability of Chlorosulfonated Polyethylene Vulcanizates as Measured by Stress Relaxation

1971 ◽  
Vol 44 (5) ◽  
pp. 1410-1420
Author(s):  
F. Haaf ◽  
P. R. Johnson
Keyword(s):  
Stress Relaxation ◽  
Elevated Temperatures ◽  
Oxidative Degradation ◽  
Activation Energies ◽  
Polymer Chains ◽  
Chlorosulfonated Polyethylene ◽  
Thermal And Oxidative Stability ◽  
Relaxation Measurements ◽  
Accelerator System ◽  
Interchange Reactions

Abstract Stress relaxation measurements of chlorosulfonated polyethylene vulcanizates show that curing with m-phenylene-bis-maleimide gives thermally more stable crosslinks than the conventional metal oxide/sulfur accelerator system. The superior thermal stability of the bis-maleimide cure is based on the covalent nature of the crosslinks. In conventionally cured vulcanizates interchange reactions of the metal sulfonate and polysulfide crosslinks occur at elevated temperatures. The interchange reactions of the crosslinks cause a rapid stress decline at the beginning of the stress relaxation process. Over longer aging periods stress relaxation due to oxidative degradation becomes apparent in vulcanizates of both types. The activation energies of oxidative stress relaxations are very similar for the bis-maleimide and the conventional cure. The similarity of the activation energies indicates that oxidative degradation follows the same path. The site of the oxidative attack is established for bis-maleimide cured vulcanizates. Oxidative degradation is found to occur in the polymer chains rather than in the crosslinks. The effects of fillers and stabilizers are investigated and their mode of action is explained on the basis of the stress relaxation results.

Stress Relaxation and Differential Dynamic Modulus of Carbon Black-Filled Styrene-Butadiene Rubber in Large Shearing Deformations

1984 ◽  
Vol 57 (5) ◽  
pp. 925-943 ◽  
Author(s):  
Yoshinobu Isono ◽  
John D. Ferry
Keyword(s):  
Stress Relaxation ◽  
Carbon Black ◽  
Styrene Butadiene Rubber ◽  
Large Strains ◽  
Butadiene Rubber ◽  
Initial Value ◽  
Static Strain ◽  
Polymer Molecules ◽  
Styrene Butadiene ◽  
Strain Dependent

Abstract Combined measurements of shear stress relaxation and differential dynamic storage and loss shear moduli G′ and G″ have been made on styrene-butadiene rubber (type 1502) containing 50 phr N299 carbon black and 10 phr Sundex 790 oil, both cured and uncured, and compared with similar measurements on the cured and uncured gum rubber. The range of temperature was −22.5° to 63°C, and of static shear strain 0.01 to 0.40; the maximum oscillatory shear strain was about 0.005 and the frequency was usually 0.64 Hz. Dynamic measurements of G′ and G″ with no superposed static strain and stress relaxation measurements at small strains on the filled samples could be reduced by frequency-temperature superposition with αT shift factors that were somewhat larger than those that applied to the raw or crosslinked gum. At about 0.6 Hz, the filler increased the storage modulus by about a factor of 5 for the cured sample and about 10 for the uncured; the moduli for the cured and uncured filled samples were almost identical. The order of rates of relaxation was unfilled uncured > filled uncured > filled cured > unfilled cured. At small static strains, the stress relaxation of the filled samples (both uncured and cured) was substantial, but the differential dynamic moduli G′ and G″ remained nearly equal to their values with zero static strain throughout the relaxation process. With increasing static strain γ, the strain-dependent relaxation modulus G(γ;t) decreased by as much as a factor of 3 for the filled, cured sample and 4 for the filled, uncured sample. The modulus G(γ;t) could not be factored into a strain-dependent and a time-dependent function. During stress relaxation of the filled samples (both cured and uncured) at large strains, the differential storage modulus G′(ω,γ;t) experienced a drop followed by slow recovery toward its initial value at 25°C; the loss modulus G″(ω,γ;t) was unchanged. For the filled, cured sample, complete recovery to the initial value G′(ω,0) (where 0 refers to zero static strain) was accomplished by removing the shearing stress and heating for one day at 63° followed by return of the temperature to 25°C. The results are interpreted in terms of a structure which combines a crosslinked (or, in the case of uncured, an entangled) polymer network and a network of carbon black particles. At small strains, stress relaxation is thought to be accomplished primarily by rearrangements of carbon particles and/or polymer molecules bridging them, without structural damage in the sense that the rearranged structure has the same properties as the original. These rearrangements are impeded by crosslinking in the cured vis-a-vis the uncured filled rubber. The kinetics of rearrangement may be governed by configurational changes of the polymer molecules since the temperature shift factors do not differ greatly from those for the gum rubber. At large strains, the particle network can be damaged but can regain its structure by a healing process which is accelerated at higher temperatures. The conclusions apply to the particular compound studied here and not necessarily to other rubber-black compounds, which according to the literature show great diversity of properties.

Effects of White Rot Fungus Physisporinus sp., Isolated in Japan, on Styrene-butadiene Rubber

2020 ◽  
Vol 93 (9) ◽  
pp. 289-292
Author(s):  
Yumi SHIMIZU ◽  
Shuma SATHO ◽  
Taro NAKAJIMA ◽  
Hiroaki KOUZAI ◽  
Kiminori SHIMIZU
Keyword(s):  
White Rot ◽  
White Rot Fungus ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Styrene Butadiene
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