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.

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.

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.

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.

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.

Natural Rubber Reinforced with Silica Nanoparticles Extracted from Jasmine and Riceberry Rice Husk Ashes

2018 ◽  
Vol 936 ◽  
pp. 31-36 ◽  
Author(s):  
Wichudaporn Seangyen ◽  
Paweena Prapainainar ◽  
Pongdhorn Sae-Oui ◽  
Surapich Loykulnant ◽  
Peerapan Dittanet
Keyword(s):  
Tensile Strength ◽  
Natural Rubber ◽  
Silica Nanoparticles ◽  
Rice Husk ◽  
Sol Gel ◽  
Rubber Matrix ◽  
Reinforcing Fillers ◽  
Rubber Nanocomposites ◽  
Jasmine Rice ◽  
20 Nm

Silica nanoparticles were synthesized by rice husk ash (RHA) produced from jasmine rice husk and riceberry rice husk via sol-gel method for the use as reinforcing fillers in natural rubber (NR). The obtained silica nanoparticles are spherical in shape and the particle sizes were observed to be in the 10-20 nm range with uniformly size distribution. The surface of silica nanoparticles was treated with a silane coupling agent confirmed by FTIR. The treated silica nanoparticles were then incorporated into NR and vulcanized with electron beam irradiation. The rubber nanocomposites with silica nanoparticles, produced from jasmine rice husk and riceberry rice husk, resulted in higher mechanical properties (tensile strength and modulus) than neat rubber vulcanizate. The modified rubber vulcanizates revealed rougher surface with tear lines as compared to the neat rubber vulcanizates, indicating the improved strength. Interestingly, the rubber nanocomposites with silica nanoparticles from jasmine rice husk showed higher tensile strength and modulus than silica nanoparticles produced from riceberry rice husk. The micrographs indicated better dispersion of NR composites with jasmine rice husk which leads to a strong interaction between silica nanoparticles and rubber matrix, thereby improving the strength.

scholarly journals Preparation and stress-strain behavior of in-situ epoxidized natural rubber/SiO2 hybrid through a sol-gel method

2018 ◽  
Vol 12 (2) ◽  
pp. 180-185 ◽  
Author(s):  
S. M. Li ◽  
T. W. Xu ◽  
Z. X. Jia ◽  
B. C. Zhong ◽  
Y. F. Luo ◽  
...  
Keyword(s):  
Natural Rubber ◽  
Sol Gel ◽  
Epoxidized Natural Rubber ◽  
Stress Strain ◽  
Gel Method ◽  
Sol Gel Method ◽  
Strain Behavior

Silica-reinforced natural rubber prepared by the sol–gel process of ethoxysilanes in rubber latex

2008 ◽  
Vol 109 (1) ◽  
pp. 424-433 ◽  
Author(s):  
V. Tangpasuthadol ◽  
A. Intasiri ◽  
D. Nuntivanich ◽  
N. Niyompanich ◽  
S. Kiatkamjornwong
Keyword(s):  
Natural Rubber ◽  
Sol Gel ◽  
Rubber Latex ◽  
Sol Gel Process

Inorganic-Organic Composite Materials from Liquid Natural Rubber and Epoxidised Natural Rubber Derivatives

2017 ◽  
pp. 128-140
Author(s):  
Wan Ahmad Kamil Mahmood ◽  
Mohammad Hossein Azarian
Keyword(s):  
Composite Materials ◽  
Natural Rubber ◽  
Sol Gel ◽  
Polymeric Materials ◽  
Metal Alkoxides ◽  
Inorganic Glass ◽  
Transparent Films ◽  
Polymer Component ◽  
Liquid Natural Rubber ◽  
Preparation Techniques

Organic-Inorganic composite materials (OICs) are used to describe the group of materials synthesized from polymers and inorganic metal alkkoxides. The interests in these materials arised from the need to ‘combine' the physical properties of inorganic glass materials and polymers such that the resultant OICs have the strength of the inorganic glass and flexibiliy of polymeric materials. Sol-gel technique have been the technique of choice due to much of its advantages, in particular the low temperature reaction. This is very important when natural rubber and its derivatives are used as the polymer component of the OICs. Work in our laboratory has demonstrated that OICs form liquid natural rubber (LNR) and 50% epoxidised natural rubber (ENR-50) can be prepared from various metal alkoxides, such silicon, zirconium and titanium. The OICs can be prepared as flexible transparent films, nanofibers and nanobeads. This Chapter will describe the preparation techniques and the properties of these OICs from various compositions of one and more metal alkoxides in both LNR and ENR-50. The applications of these materials in PANI will be briefly described.

In situ silica reinforcement of natural rubber by sol–gel process via rubber solution

2009 ◽  
Vol 52 (2) ◽  
pp. 219-227 ◽  
Author(s):  
Benjawan Chaichua ◽  
Pattarapan Prasassarakich ◽  
Sirilux Poompradub
Keyword(s):  
Natural Rubber ◽  
Sol Gel ◽  
In Situ Silica ◽  
Sol Gel Process
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