Some changes in double-bond structure during the vulcanization of natural rubber

Linnig, Frederic J.; Parks, Edwin J.; Stewart, James E.

doi:10.6028/jres.068a.047

Cited by 7 publications

(2 citation statements)

References 19 publications

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“…V ulcanized samples were prepared between sheets of aluminum foil in the manner described previously [1,2]. The compositions of the vulcanized samples are tabulated in Spectra in the 650 to 33 cm -1 region were recorded with a Beckman IR-l1.2 Spectral slit widths (reciprocal dispersion multiplied by slit width) between 1 and 5 cm -1 were used throughout the far infrared region.…”

Section: Methodsmentioning

confidence: 99%

“…A goal of infrared spectroscopy is to observe and measure absorption bands and to determine the nature of the molecular vibrations which are responsible for 2 Certain commercial materials and equipment are identified in thi s paper in order to adquat ely specify the experim ental procedure. In no case does such identification impl y recommendation or endorsement by the National Bureau of Standards.…”

Section: Far Infrared Spectrum Of Natural Rubbermentioning

confidence: 99%

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The far infrared spectrum of vulcanized natural rubber

Stewart¹,

Linnig²

1967

J. RES. NATL. BUR. STAN. SECT. A.

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Earlier studi es of the infrared s pectra of natural rubbe r and some vulcan izates of rubber have been extend ed into th e 650 to 33 cm -J far infrared region. Some of the absorption bands originating in the crystalline portion of unvulcanized rubber have bee n studi ed by usin g polarized radiation and samples oriented by stretching. Vulcanization of rubbe r with sulfur alon e produces a general weaken· in g of all absorption bands and no new absorptions. Vulcan ization with sulfur and an accelerator also results in a red ucti on in intensity of th e rubber absorptions, but is accompanied by th e appearance of new bands. When the accelerator is tetram et hylthiuram di sulfi"d e (TMTD) the new bands are probably ind icative of a thioca rbamate structure. When zinc dibutyldithiocarbamate is used as an accelerator a band probably due to zinc sulfide occurs. Vulcanization with TMTD alone produces only slight changes in th e far infrared spec trum. Howeve r, when TMTD is used in the presence of zinc oxide a reaction occ urs in which zinc dim ethyldithioca rbamate (ZnDMDC) is formed. After vulcanization for a short period of tim e stro ng TMTD bands remain , but after long vulcanization the TMTD bands are replaced by ZnDMDC bands.

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Section: Methodsmentioning

confidence: 99%

Section: Far Infrared Spectrum Of Natural Rubbermentioning

confidence: 99%

The far infrared spectrum of vulcanized natural rubber

Stewart¹,

Linnig²

1967

J. RES. NATL. BUR. STAN. SECT. A.

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Formation of elastomeric network polymers from ambient heterogeneous hydrosilations of carboranylenesiloxane and branched siloxane monomers

Kolel-Veetil

Keller

2005

J. Polym. Sci. A Polym. Chem.

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The Karstedt catalyst‐catalyzed ambient‐condition hydrosilation reactions in hexane of a monomeric vinyl‐containing carboranylenesiloxane, 1, and three‐branched siloxane crosslinker monomers were discovered to produce elastomeric network polymers at very rapid rates of formation. The flexible and transparent films of the saturated elastomeric network polymers were observed to possess low glass‐transition temperatures (below −35 °C). Similar hydrosilation reactions at two different reactant ratios involving a diethynyl‐containing carboranylenesiloxane, 2, and the siloxane crosslinkers produced partially hydrosilated and completely hydrosilated polymeric networked systems, which were transparent and elastomeric at room temperature. The glass‐transition temperatures of all the polymeric systems formulated from 2 were below 0 °C. The elastomeric polymeric networks from 1 and 2 were found to have degradation temperatures in the range of 500–550 °C. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 147–155, 2006

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A chemical interpretation for the post-reversion upturn in the natural rubber/accelerated sulfur system based on the viscoelastic properties and cross-link density measurements

Pöschl,

Sathi,

Stoček

2024

Polym. Bull.

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The curing cycle of natural rubber (NR) with a conventional accelerated sulfur system (CV) generally exhibits three phases. The induction phase, the crosslinking phase, and the reversion phase. Prolonged curing of NR/CV system even at a temperature of 150 °C can show reversion. Many research reports are available in the literature with reference to the reversion behavior and the subsequent network modifications of natural rubber with accelerated sulfur. However, the literature regarding post-reversion curing behavior is scanty. This article describes the post-reversion upturn of natural rubber with a conventional accelerator sulfur system at a higher curing temperature. A network rebuilding after collapsing the initially formed network due to reversion was identified as the primary reason for the post-reversion upturn. The dynamic rheological testing capability of the Rubber Process Analyzer (RPA) was employed to characterize the network formed during curing, reversion and post-reversion phases. The cure-strain sweep data from the RPA indicated that the shear storage modulus (G′) of the broken network increased due to the post-reversion upturn. The chemical crosslink densities of the samples were also found to increase due to the upturn curing behavior. From these experimental results and the information conceived from the previous literature, two plausible mechanisms have been proposed to interpret the post-reversion upturn cure behavior.

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Some changes in double-bond structure during the vulcanization of natural rubber

Cited by 7 publications

References 19 publications

The far infrared spectrum of vulcanized natural rubber

The far infrared spectrum of vulcanized natural rubber

Formation of elastomeric network polymers from ambient heterogeneous hydrosilations of carboranylenesiloxane and branched siloxane monomers

A chemical interpretation for the post-reversion upturn in the natural rubber/accelerated sulfur system based on the viscoelastic properties and cross-link density measurements

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