Peroxide Crosslinking of Ethylene-Propylene Rubber

1965 ◽  
Vol 38 (1) ◽  
pp. 22-32 ◽  
Author(s):  
L. D. Loan
Keyword(s):  
Tensile Strength ◽  
Hydrogen Atom ◽  
Stress Relaxation ◽  
Ethylene Propylene ◽  
Permanent Set ◽  
Ethylene Propylene Rubber ◽  
Crosslinking Reactions ◽  
Allyl Compounds ◽  
Sulfur Containing ◽  
Peroxide Molecule

Abstract The crosslinking of ethylene-propylene rubber by means of cumyl peroxide has been followed in detail. The overall crosslinking efficiency has been found to be about 0.4 crosslinks per peroxide molecule, and this result has been shown by stress relaxation and permanent set experiments to result from a mixture of both scission and crosslinking reactions. The results obtained with two different rubbers are consistent with the view that scission results from abstraction of a tertiary hydrogen atom while crosslinking arises from attack at a secondary hydrogen. Such a scheme allows a relative reactivity of tertiary:secondary of 6:1 to be calculated. The action of sulfur in peroxide cures has been shown to be to introduce labile, presumably sulfur-containing, crosslinks. Such labile crosslinks explain the increased tensile strength of such vulcanizates. Allyl compounds are effective in increasing the crosslinking efficiency of the peroxide.

Effect of Sulfur during Radiation Curing of Poly(Vinyl Ethyl Ether) and Ethylene-Propylene Rubber

1963 ◽  
Vol 36 (1) ◽  
pp. 248-258 ◽  
Author(s):  
Joginder Lal ◽  
James E. McGrath
Keyword(s):  
Tensile Strength ◽  
Ethyl Ether ◽  
Triphenyl Phosphine ◽  
Radiation Curing ◽  
Elongation At Break ◽  
Ethylene Propylene ◽  
Maximum Tensile Strength ◽  
Lower Radiation Dose ◽  
Ethylene Propylene Rubber ◽  
Sulfur Containing

Abstract A study was made of the effect of sulfur, during radiation curing, on the physical properties of poly(vinyl ethyl ether) and an ethylene/propylene copolymer containing HAF carbon black. The presence of sulfur enabled the attainment of higher maximum tensile strength and generally higher crosslink density than when sulfur was omitted. Furthermore, the maximum tensile strength of the sulfur-containing samples was obtained at a lower radiation dose than in the corresponding control experiments. For a given swelling ratio, a higher tensile strength was generally obtained for samples irradiated in the presence of sulfur. For a given dose of radiation, the per cent elongation-at-break values of poly(vinyl ethyl ether) samples decreased as the amount of sulfur in the recipe was increased. In contrast, in the ethylene/propylene rubber the presence of sulfur resulted in an increase in the elongation values. The per cent sol values were also quite high for the ethylene/propylene vulcanizates as compared to the corresponding values in poly(vinyl ethyl ether) samples. In both rubbers, lower sol values were obtained in the presence of sulfur. Chemically bound sulfur was found in poly(vinyl ethyl ether) samples irradiated in the presence of elemental sulfur or dicyclopentamethylene thiuram tetrasulfide. The ability of the network to lose a portion of the combined sulfur by reaction with triphenyl phosphine may indicate that some of the crosslinks contain disulfide and/or polysulfide groups.

Finite Element Analysis of HDPE/EPR-CNT Nanocomposite under Tensile Loading

2015 ◽  
Vol 1115 ◽  
pp. 410-413 ◽  
Author(s):  
N.M. Shaffiar ◽  
M.A. Hasnan ◽  
H. Anuar ◽  
Muataz Hazza Faizi Al Hazza
Keyword(s):  
Finite Element ◽  
Tensile Strength ◽  
Carbon Nanotube ◽  
Ultimate Tensile Strength ◽  
Yield Strength ◽  
Tensile Loading ◽  
Nanocomposite Material ◽  
Material Strength ◽  
Ethylene Propylene ◽  
Ethylene Propylene Rubber

A small amount of nanodispersed filler leads to an improvement in material properties. Carbon Nanotube (CNT) is one type of filler used in nanocomposite material. A high density polyethylene/ethylene propylene rubber – carbon nanotube (HDPE/EPR-CNT) is one of the nanocomposite material that is new to the industry. This paper investigates the strength of HDPE/EPR-CNT nanocomposite under tensile loading. The experimental results of the tensile test on the nanocomposite will be compared with the tensile simulation in the Finite Element (FE) analysis for validation. The results showed that it is validated with relatively low percentage error of 0.14 % for the ultimate tensile strength and 0.05 % for the yield strength. The ultimate tensile strength of HDPE/EPR-CNT is 17.41 MPa and the yield strength is 14.9 MPa. By using CNT as a filler, the material strength is improved. The ultimate tensile strength of HDPE/EPR-CNT is the highest compared to polyethylene/ethylene propylene rubber - montmorillonite HDPE/EPR-MMT and polyethylene/ethylene propylene rubber HDPE/EPR.

Influence of Vulcanizing System on the Properties of Rubbers Based on Ethylenepropylene Rubber

2021 ◽  
Vol 899 ◽  
pp. 239-244
Author(s):  
Larisa Yuryevna Zakirova
Keyword(s):  
Tensile Strength ◽  
High Temperatures ◽  
Organic Peroxide ◽  
Strength Properties ◽  
Maximum Speed ◽  
Elongation At Break ◽  
Ethylene Propylene ◽  
Rubber Compounds ◽  
Ethylene Propylene Rubber ◽  
Aging In Air

The article investigates the effect of vulcanizing systems of different activity on the vulcanization and elastic-strength properties of rubber compounds based on ethylene-propylene rubber Keltan . Were taken vulcanizing systems: a mixture of organic peroxide, sulfur and sulfenamide accelerator (1); a mixture of organic peroxide, sulfur and dithiodimorpholine (2); a mixture of organic peroxide, sulfur and thiuram accelerator (3); sulfur and sulfenamide accelerator (4). The vulcanization characteristics (maximum and minimum torques; times of onset, optimum and reaching the maximum speed of vulcanization) were evaluated. Elastic-strength (conditional tensile strength, elongation at break, hardness) properties of rubber compounds and operational (changes in conditional tensile strength, elongation at break after aging in air) were determined. It was found that the vulcanizing system (3) containing sulfur, peroxide in an amount of 7.0 parts by weight and thiuram accelerator imparts the best elastic and strength properties to rubber compounds and leads to their resistance to high temperatures.

Influence of Sulfur on Stability and Physical Properties of Peroxide Vulcanized Ethylene Propylene Copolymers

1968 ◽  
Vol 41 (2) ◽  
pp. 304-315 ◽  
Author(s):  
J. R. Dunn
Keyword(s):  
Tensile Strength ◽  
Physical Properties ◽  
Sulfur Content ◽  
Antioxidant Effect ◽  
Reaction Products ◽  
Ethylene Propylene ◽  
Breaking Elongation ◽  
Ultimate Elongation ◽  
Ethylene Propylene Rubber ◽  
Second Peak

Abstract In cumyl peroxide sulfur vulcanizates of ethylene propylene copolymers crosslinked with 4 phr of peroxide, polysulfidic crosslinks are present only at sulfur levels in excess of 0.5 phr in gum vulcanizates and 0.3 phr in black filled vulcanizates. Modulus attains a peak in the presence of 0.5 phr of sulfur in gum vulcanizates and 0.3 phr of sulfur in black filled vulcanizates. Modulus decreases when polysulfides are present. Tensile strength in gum vulcanizates increases continually with increasing sulfur content up to 2.5 phr. The increase in tensile strength is related to a rapid increase in ultimate elongation, promoted by mechanically labile polysulfidic crosslinks. Tensile strength in black filled vulcanizates exhibits peaks at 0.3 and 0.75 phr of sulfur. The first peak represents the technological recipe for this type of vulcanizate and arises from a peak in modulus. The second peak arises from increased breaking elongation promoted by polysulfidic crosslinks. Sulfides present in the vulcanizate act as antioxidants at all sulfur levels. When the sulfides contain one or two sulfur atoms, the antioxidant effect is mild but long lived. The polysulfides yield potent long lived antioxidants. The rapid nonoxidative degradation of the polysulfidic crosslinks is not accelerated by dithiocarbamate and proceeds after the reaction products have been removed by extraction. Dithiocarbamates are potent antioxidants in peroxide vulcanized ethylene propylene rubber both in the presence and in the absence of sulfur.

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