Peroxide and Radiation Cured Compounds Filled with Reinforcing Fine Particle Silica

1961 ◽  
Vol 34 (3) ◽  
pp. 729-734
Author(s):  
J. W. Sellers ◽  
M. P. Wagner ◽  
B. J. DeWitt ◽  
C. C. Stueber ◽  
J. B. Bachmann
Keyword(s):  
Natural Rubber ◽  
Fine Particle ◽  
Crosslink Density ◽  
High Potential ◽  
Bound Rubber ◽  
Curing Systems

Abstract The potential of fine particle silica to reinforce elastomers to an extent comparable with the most efficient furnace blacks has been indicated by the extent and nature of bound rubber formation. This potential has been confirmed in peroxide and radiation cures by the increase in crosslink density of the filled over the unfilled natural rubber mixtures. Confirmation in these curing systems stimulates further research designed to realize this high potential not fully attained in present sulfur cures.

Reinforcing Effect of Silica and Silane Fillers on the Properties of Some Natural Rubber Vulcanizates

2003 ◽  
Vol 76 (5) ◽  
pp. 1290-1310 ◽  
Author(s):  
A. Ansarifar ◽  
R. Nijhawan ◽  
T. Nanapoolsin ◽  
M. Song
Keyword(s):  
Natural Rubber ◽  
Crosslink Density ◽  
Cyclic Fatigue ◽  
Rubber Matrix ◽  
Stored Energy ◽  
Elongation At Break ◽  
Reinforcing Effect ◽  
Bound Rubber ◽  
Technical Properties ◽  
Natural Rubber Vulcanizates

Abstract The reinforcing effect of up to 6 parts per hundred rubber by weight (phr) bis- (3-triethoxysilylpropyl) tetrasulfide (TESPT), a bifunctional organosilane, on the crosslink density, bound rubber, and technical properties of some conventional accelerator/sulfur compounds of natural rubber, containing 30 phr precipitated amorphous white silica was studied. The crosslink density and bound rubber improved as a function of TESPT loading. The tensile strength, elongation at break, stored energy density at rupture, and cohesive tear strength deteriorated at low loading of TESPT, but they subsequently increased after the full amount of TESPT was introduced into the compound. The improved properties of the vulcanizate was due to the better dispersion of the filler in the rubber matrix. However, the cyclic fatigue life was adversely affected, and the hardness hardly changed as a result of adding TESPT to the rubber.

EFFECT OF DEVULCANIZATION ON CROSSLINK DENSITY AND CROSSLINK DISTRIBUTION OF CARBON BLACK FILLED NATURAL RUBBER VULCANIZATES

2016 ◽  
Vol 89 (4) ◽  
pp. 653-670 ◽  
Author(s):  
Anu Mary Joseph ◽  
Benny George ◽  
Madhusoodanan K. N. ◽  
Rosamma Alex
Keyword(s):  
Carbon Black ◽  
Natural Rubber ◽  
Crosslink Density ◽  
Morphological Properties ◽  
Original Sample ◽  
Ambient Conditions ◽  
Absolute Value ◽  
Roll Mill ◽  
Percentage Retention ◽  
The Absolute

ABSTRACTCarbon black filled natural rubber (NR) vulcanizates were devulcanized at ambient temperature in a two roll mill. The effect of cure system, that is, conventional vulcanization (CV), semiefficient vulcanization (semi EV), and efficient vulcanization (EV) systems, used for vulcanization of the original sample, on the efficiency of devulcanization was studied. The efficiency of devulcanization expressed as percentage devulcanization of the samples calculated from residual crosslink density measurements was correlated with the sol fraction of the devulcanized samples based on Horikx analysis. Using chemical probe analysis, we determined (i) the crosslink distribution pattern of the original sample, (ii) the extent to which the different types of crosslinks—that is, polysulfidic, disulfidic, and monosulfidic crosslinks—have been debonded or broken during the shearing process in the two roll mill, and (iii) the pattern of bond formation during revulcanization. Mechanical shearing predominantly breaks the majority crosslink type (polysulfidic crosslinks in CV and semi EV cure systems and disulfidic crosslinks in EV samples). Irrespective of the significant reduction in total crosslink density in all three sets of samples, chain shortening reactions similar to the post-crosslinking chemical reactions at curing temperatures also occur during mechanical shear at ambient conditions, which increased the absolute value of monosulfidic links in CV and semi EV systems. However, in the devulcanized EV system, the absolute value of polysulfidic crosslinks increased, which might be due to the re-crosslinking of the cleaved bonds. All the devulcanized samples were revulcanized, and the mechanical and morphological properties were analyzed. The percentage retention of the vulcanizate properties after revulcanization of the devulcanized samples correlated very well with efficiency of devulcanization.

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.

Effect of vulcanization time on crosslink density and aging performance of natural rubber composites

2020 ◽  
Vol 62 (8) ◽  
pp. 858-862
Author(s):  
Ece Unur Yilmaz ◽  
Ahu Kor Dayioglu ◽  
Seda Balaban
Keyword(s):  
Natural Rubber ◽  
Crosslink Density ◽  
Elevated Temperatures ◽  
Mechanical Performance ◽  
Operating Conditions ◽  
Rubber Composites ◽  
Rubber Mixture ◽  
Natural Rubber Composites ◽  
Different Temperatures ◽  
Auto Parts

Abstract Natural rubber composites are widely used in the automotive industry because of their improved viscoelastic characteristics that are mostly governed by crosslink density. However, rubber parts suffer deterioration of performance over long service lives. Therefore, optimization of crosslink density and prediction of changes in physico-mechanical properties over time at elevated temperatures is extremely important for the production of safe auto parts. In this work, the effect of vulcanization time on crosslink density and thus the performance and lifetime of natural rubberbased auto parts was investigated. The natural rubber mixture prepared in this context was vulcanized for 3, 5, 10 and 15 minutes at a constant temperature of 160 °C. The crosslink density of each vulcanizite was determined by equilibrium swelling tests and the Flory-Rehner equation. The maximum crosslink density (10.75 × 10-5 mol × cm-3) and the minimum permanent compression set values (10 % at 70 °C and 25 % at 100 °C) were recorded for the sample vulcanized for 10 minutes (v10). Aging behavior of the samples were investigated by stress relaxation tests performed at 85 °C, 100 °C and 120 °C. The service lives of the vulcanizites at different temperatures were predicted by linear Arrhenius fits of degradation times. The sample vulcanized for 10 minutes (v10) was shown to exhibit a service life of 2282 hours at 70 °C in air and the optimum physico-mechanical performance under real operating conditions. The performance and lifetime prediction procedure used in this work could be employed in an early design of rubber components for specific applications.

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.

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