Sol-Gel Analysis to Estimate Chain Scission during Cure. I. Peroxide Vulcanization of Natural Rubber

1964 ◽  
Vol 37 (4) ◽  
pp. 904-909
Author(s):  
G. M. Bristow
Keyword(s):  
Natural Rubber ◽  
Sol Gel ◽  
Chain Scission ◽  
Dicumyl Peroxide ◽  
Degree Of Cure

Abstract Sol-gel analysis, that is, the measurement of the fraction of rubber remaining unconnected to the network as a function of the degree of cure, has been used to estimate the extent of chain scission in the vulcanization of natural rubber with dicumyl peroxide at 130° C. For peroxide concentrations in the range 1–5 per cent and masticated rubbers of Mn=0.84−2.67×105 there are only 1–3 sites of scission per 100 crosslinked isoprene units.

Use of Sol-Gel Analysis to Estimate Chain Scission during Vulcanization. II. Peroxide Vulcanization of Synthetic cis-Polyisoprene

1965 ◽  
Vol 38 (2) ◽  
pp. 367-369
Author(s):  
G. M. Bristow
Keyword(s):  
Natural Rubber ◽  
Sol Gel ◽  
Chain Scission ◽  
A Value

Abstract Sol-gel analysis indicates that in the vulcanization of synthetic cis-polyisoprene by cumyl peroxide there are only 2–3 sites of scission per 100 crosslinked isoprene units, a value closely comparable with that observed for natural rubber.

Epoxidized Natural Rubber / Silica Nanoscale Organic-Inorganic Hybrid Composites Prepared by Sol-Gel Technique

2004 ◽  
Vol 77 (5) ◽  
pp. 830-846 ◽  
Author(s):  
Abhijit Bandyopadhyay ◽  
Mousumi De Sarkar ◽  
Anil K. Bhowmick
Keyword(s):  
Tensile Strength ◽  
Natural Rubber ◽  
Hybrid Composites ◽  
Sol Gel ◽  
Hybrid Nanocomposites ◽  
Dicumyl Peroxide ◽  
Inorganic Hybrid ◽  
Gel Technique ◽  
Rubber Phase

Abstract Epoxidized natural rubber (ENR) / silica organic-inorganic hybrid nanocomposites were prepared by using a sol-gel technique. Tetraethoxysilane was used as the precursor for the in-situ generation of silica. The choice of ENR as a matrix was made because of its polar nature which can interact with the in-situ generated silica. The sol-gel reaction was carried out at room temperature by dissolving the rubber in tetrahydrofuran solvent using hydrochloric acid as the catalyst. The resultant composite films appeared transparent up to 50 wt% of tetraethoxysilane loading. Dispersion of the discrete silica particles having dimensions of 15 – 100 nm was observed through transmission electron microscope. Scanning electron microscopic studies did not produce any evidence for formation of silica network within the bulk of the composite. Infrared spectroscopic studies indicated the occurrence of chemical interaction within the rubber /silica organic-inorganic interfaces which was further supported by the insolubility of the respective samples in tetrahydrofuran under the ambient conditions. Mechanical reinforcement within the hybrid nanocomposites, both at high and low temperature regions, was demonstrated through dynamic mechanical analysis. The composites exhibited superior tensile strength and tensile moduli compared to the gum rubber samples. Further reinforcement was noticed when the rubber phase in the nanocomposites was cured with either benzoyl peroxide or dicumyl peroxide. The dicumyl peroxide cured hybrid composites displayed 112% improvement in tensile strength over the control crosslinked rubber sample, probably due to synergisms of nanosilica reinforcement and crosslinking of the rubber phase in the hybrids.

scholarly journals Evaluation of Electron Induced Crosslinking of Masticated Natural Rubber at Different Temperatures

Polymers ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1279
Author(s):  
Huang ◽  
Gohs ◽  
Müller ◽  
Zschech ◽  
Wießner
Keyword(s):  
Natural Rubber ◽  
Elevated Temperatures ◽  
Sol Gel ◽  
Complex Viscosity ◽  
Chain Scission ◽  
Nitrogen Atmosphere ◽  
Size Exclusion ◽  
Reactive Blending ◽  
Exclusion Chromatography ◽  
Branched Chains

In this work, natural rubber (NR) was masticated using an internal mixer to fit the requirements of reactive blending with polylactide and characterized by size exclusion chromatography (SEC), Fourier-transform infrared (FT-IR) spectroscopy and dynamic rheology measurements. Subsequently, the effect of elevated temperatures (25 °C, 80 °C, and 170 °C) on the electron beam (EB) induced crosslinking and degradation of masticated natural rubber (mNR) in a nitrogen atmosphere without adding crosslinking agents has been investigated. The sol gel investigation showed that the gel dose of mNR slightly increased with increasing irradiation temperature, which is also confirmed by the swelling test. The chain scission to crosslinking ratio (Gs/Gx) was found to be less than 1 for irradiated mNR at 25 °C and 80 °C, suggesting a dominating crosslinking behavior of mNR. However, a significant increase of Gs/Gx ratio (~1.12) was observed for mNR irradiated at 170 °C due to the enhanced thermal degradation behavior at high temperature. A remarkably improved elasticity (higher complex viscosity, higher storage modulus, and longer relaxation time) for EB modified mNR was demonstrated by dynamic rheological analysis. Particularly, the samples modified at higher temperatures represented more pronounced elasticity behavior which resulted from the higher number of branches and/or the longer branched chains.

Vulcanization of natural rubber by dicumyl peroxide in the presence of sulphur

1973 ◽  
Vol 38 (2) ◽  
pp. 408-416 ◽  
Author(s):  
B. Bakule ◽  
J. Honskus ◽  
J. Nedbal ◽  
P. Zinburg
Keyword(s):  
Natural Rubber ◽  
Dicumyl Peroxide

Reinforcing efficiency and compatibilizing effect of sol–gel derived in situ silica for natural rubber/chloroprene rubber blends

RSC Advances ◽  
2014 ◽  
Vol 4 (102) ◽  
pp. 58816-58825 ◽  
Author(s):  
Bharat P. Kapgate ◽  
Chayan Das
Keyword(s):  
Natural Rubber ◽  
Sol Gel ◽  
Rubber Blends ◽  
In Situ Silica ◽  
Chloroprene Rubber ◽  
Compatibilizing Effect

The strong CR/in situ silica interaction causes filler accumulation at the interphase and enhances the compatibility and reinforcement in the NR/CR blend.

Aging of Natural Rubber Vulcanizates in the Presence of Dithiocarbamates

1959 ◽  
Vol 32 (3) ◽  
pp. 739-747 ◽  
Author(s):  
J. R. Dunn ◽  
J. Scanlan
Keyword(s):  
Stress Relaxation ◽  
Natural Rubber ◽  
Protective Action ◽  
Dicumyl Peroxide ◽  
Vulcanized Rubber ◽  
Aging Properties ◽  
Photochemical Aging ◽  
Natural Rubber Vulcanizates

Abstract The thermal and photochemical aging of extracted dicumyl peroxide-, TMTD (sulfurless)- and santocure-vulcanized rubber, in presence of a number of metal and alkylammonium dithiocarbamates, has been investigated by measurements of stress relaxation. The dithiocarbamates have a considerable protective action upon the degradation of peroxide- and TMTD-vulcanizates, but they accelerate stress decay in santocure-accelerated vulcanizates. The reasons for this behavior are discussed. It is suggested that the excellent aging properties of unextracted TMTD vulcanizates are due to the presence of zinc dimethyldithiocarbamate formed during vulcanization.

EXPERIMENTAL VALIDATION OF THE CHARLESBY AND HORIKX MODELS APPLIED TO DE-VULCANIZATION OF SULFUR AND PEROXIDE VULCANIZATES OF NR AND EPDM

2016 ◽  
Vol 89 (4) ◽  
pp. 671-688 ◽  
Author(s):  
M. A. L. Verbruggen ◽  
L. van der Does ◽  
W. K. Dierkes ◽  
J. W. M. Noordermeer
Keyword(s):  
Experimental Validation ◽  
Main Chain ◽  
Sol Gel ◽  
Chain Scission ◽  
Cross Linking ◽  
Cross Link ◽  
Practical Reality ◽  
Cross Links ◽  
The Cross ◽  
Theoretical Considerations

ABSTRACT The theoretical model developed by Charlesby to quantify the balance between cross-links creation of polymers and chain scission during radiation cross-linking and further modifications by Horikx to describe network breakdown from aging were merged to characterize the balance of both types of scission on the development of the sol content during de-vulcanization of rubber networks. There are, however, disturbing factors in these theoretical considerations vis-à-vis practical reality. Sulfur- and peroxide-cured NR and EPDM vulcanizates were de-vulcanized under conditions of selective cross-link and random main-chain scissions. Cross-link scission was obtained using thiol-amine reagents for selective cleavage of sulfur cross-links. Random main-chain scission was achieved by heating peroxide vulcanizates of NR with diphenyldisulfide, a method commonly employed for NR reclaiming. An important factor in the analyses of these experiments is the cross-linking index. Its value must be calculated using the sol fraction of the cross-linked network before de-vulcanization to obtain reliable results. The values for the cross-linking index calculated with sol-gel data before de-vulcanization appear to fit the experimentally determined modes of network scission during de-vulcanization very well. This study confirms that the treatment of de-vulcanization data with the merged Charlesby and Horikx models can be used satisfactorily to characterize the de-vulcanization of NR and EPDM vulcanizates.

scholarly journals Grafting copolymer cylic natural rubber with oleic acid using dicumyl peroxide as initiator

2020 ◽  
Author(s):  
Barita Aritonang ◽  
Tamrin ◽  
Basuki Wirjosentono ◽  
Eddiyanto
Keyword(s):  
Oleic Acid ◽  
Natural Rubber ◽  
Dicumyl Peroxide ◽  
Grafting Copolymer
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