Effect of Bromination on the Properties of Ethylene-Propylene-Diene Rubber in the Presence of Divinylbenzene

1995 ◽  
Vol 68 (5) ◽  
pp. 824-835 ◽  
Author(s):  
J. R. Yoon ◽  
Y. Ikeda ◽  
A. S. Hashim ◽  
S. Kohjiya
Keyword(s):  
Natural Rubber ◽  
Tensile Properties ◽  
Crosslink Density ◽  
Die Swell ◽  
Dicumyl Peroxide ◽  
Peroxide Curing ◽  
Ethylene Propylene Diene Rubber ◽  
Lower Torque ◽  
And Storage ◽  
Diene Rubber

Abstract The curing behavior and vulcanizate properties of EPDM and brominated EPDM (BEPDM) were compared using a dicumyl peroxide curing system. The BEPDM displayed lower torque and crosslink density, but better tensile properties than the EPDM. In the presence of divinylbenzene (DVB) coagent, all vulcanizates, i.e., EPDM, BEPDM, and their blends with natural rubber, had improved tensile properties. At low DVB concentration, the filler effect of DVB on the modulus enhancement was noticed. At high and comparable DVB concentration, both the BEPDM and NR/BEPDM blend showed significantly higher modulus (M100) and tensile strength than their EPDM counterparts. The BEPDM was also found to have higher crosslink density and storage modulus (E′) than the EPDM. This observation could be attributed to the better dispersion of DVB in the BEPDM and NR/BEPDM vulcanizates, as supported by TEM measurements. The TEM data is also consistent with the properties observed on the uncured mixes, in which the NK/BEPDM + DVB mix has favorable viscosity and die swell properties due to the more homogeneous DVB dispersion in the rubber phases. Thus, the bromination of EPDM has resulted in better processing and vulcanizate properties of the rubber and its blend with natural rubber.

Mechanisms Involved in the Recycling of NR and EPDM

1999 ◽  
Vol 72 (4) ◽  
pp. 731-740 ◽  
Author(s):  
M. A. L. Verbruggen ◽  
L. van der Does ◽  
J. W. M. Noordermeer ◽  
M. van Duin ◽  
H. J. Manuel
Keyword(s):  
Natural Rubber ◽  
Crosslink Density ◽  
Main Chain ◽  
Chain Scission ◽  
Ethylene Propylene ◽  
Temperature Range ◽  
Lower Reactivity ◽  
Ethylene Propylene Diene Rubber ◽  
Diene Rubber ◽  
Crosslink Densities

Abstract The thermochemical recycling of natural rubber (NR) and ethylene-propylene-diene rubber (EPDM) vulcanizates with disulfides was studied. NR sulfur vulcanizates were completely plasticized when heated with diphenyldisulfide at 200 °C. It could be concluded that both main chain scission and crosslink scission caused the network breakdown. NR peroxide vulcanizates were less reactive towards disulfide at 200 °C, and only reacted through main chain scission. For EPDM a temperature range of 200–275 °C was studied. In the presence of diphenyldisulfide at 200 °C there was almost no devulcanization of EPDM sulfur vulcanizates, and at 225 and 250 °C there was only slightly more devulcanization. A decrease in crosslink density of 90% was found when 2×10−4 mol diphenyldisulfide/cm3 vulcanizate was added and the EPDM sulfur vulcanizates were heated to 275 °C. EPDM peroxide vulcanizates showed a decrease in crosslink density of ca. 40% under the same conditions. The lower reactivity of EPDM towards disulfide compared with NR is the result of higher crosslink densities, the presence of a higher percentage of more stable monosulfidic crosslinks and the fact that EPDM is less apt to main chain scission relative to NR.

scholarly journals The effects of alkanolamide addition on cure characteristics, swelling behaviour and tensile properties of silica-filled natural rubber (NR) / chloroprene rubber (CR) blends

2018 ◽  
Vol 34 ◽  
pp. 01030 ◽  
Author(s):  
Indra Surya ◽  
Syahrul Fauzi Siregar ◽  
Hanafi Ismail
Keyword(s):  
Tensile Strength ◽  
Natural Rubber ◽  
Tensile Properties ◽  
Crosslink Density ◽  
Tensile Modulus ◽  
Palm Stearin ◽  
Swelling Behaviour ◽  
Elongation At Break ◽  
Cure Characteristics ◽  
Chloroprene Rubber

Effects of alkanolamide (ALK) addition on cure characteristics, swelling behaviour and tensile properties of silica-filled natural rubber (NR)/chloroprene rubber (CR) blends were investigated. The ALK was synthesized from Refined Bleached Deodorized Palm Stearin (RBDPS) and diethanolamine, and incorporated into the silica-filled NR/CR blends as a non-toxic rubber additive. The ALK loadings were 0.0, 1.0, 3.0, 5.0 and 7.0 phr. It was found that the ALK exhibited shorter scorch and cure times and higher elongation at break of the silica-filled NR/CR blends. The ALK also exhibited higher torque differences, tensile modulus and tensile strength at a 1.0 phr of ALK loading and then decreased with further increases in the ALK loading. The swelling measurement proved that the 1.0 phr loading of ALK caused the highest degree in crosslink density of the silica-filled NR/CR blends.

The Dependence of Dielectric Properties on Crosslink Density of Rubbers

1978 ◽  
Vol 51 (1) ◽  
pp. 72-80 ◽  
Author(s):  
R. Bakule ◽  
A. Havránek
Keyword(s):  
Dielectric Properties ◽  
Natural Rubber ◽  
Crosslink Density ◽  
Unit Volume ◽  
Volume Distribution ◽  
Dicumyl Peroxide ◽  
Frequency Range ◽  
Polar Groups ◽  
Main Transition ◽  
Macroscopic Parameters

Abstract The dielectric properties of natural rubber, synthetic polyisoprene, andpolybutadiene samples crosslinked with sulfur and of natural rubber samplescrosslinked simultaneously with sulfur and dicumyl peroxide were studied. Inthe investigated systems, the number of polar groups in unit volume and thecrosslink density may be changed independently over relatively wide ranges.The measurements were performed in the frequency range from 101 to 105 Hzat various temperatures, and macroscopic parameters describing the dielectricproperties of the samples were evaluated. The position and intensity of thedielectric dispersion peak in the main transition zone is only slightly dependenton the crosslink density of the samples. These two values are mainly influencedby the amount of combined sulfur, or more generally, by the number and thedipole moments of polar groups in the sample. The influence of crosslink densityon the width of the absorption curve is very strong; the width increases withincreasing crosslink density. The possibility of explaining this effect in termsof the dependence of the free volume distribution function on crosslink densityis discussed.

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