Products of the oxidation of rubber. I. Compounds boiling lower than water

Bevilacqa, E. M.; English, E. S.; Gall, John S.; Norling, Parry

doi:10.1002/app.1964.070080301

Cited by 23 publications

(3 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The other phenomenon that might lead to notable changes in the bulk viscosity of NR is thermo‐oxidation. NR has a chemical structure (poly( cis ‐1,4‐isoprene)), based around a double bond building unit, which makes it susceptible to thermal oxidation in the presence of molecular oxygen 14. Thermo‐oxidation of this polymer, in its solid state, is a complex process in which two competing phenomena occur: scission and cross‐linking.…”

Section: Introductionmentioning

confidence: 99%

Role of short polyisoprene chains in storage hardening of natural rubber

Ngolemasango

Ehabe²,

Aymard

et al. 2003

Polymer International

View full text Add to dashboard Cite

Drying of natural rubber (NR) crumb (grade TSR10) requires high temperatures (100-120 • C). In order to determine the changes in bulk viscosity during the drying process, ageing kinetics at 120 • C were studied on model NR samples. During the process, changes in Mooney viscosity and weight-average molar mass (M W ) were monitored. Rubber from clones GT 1 and PR 107, with a bimodal inherent molar mass distribution (MMD 0 ), was degraded in a two-phase process. During the first phase, Mooney viscosity and M W increased, undoubtedly owing to a predominance of storage hardening over chain scissions [0 < t (min) < 120]. During the second phase, chain scissions predominated (t > 120 min) and Mooney viscosity and M W decreased. For rubber samples from clone PB 217, with a unimodal MMD 0 , no or reduced storage hardening was observed throughout the ageing process. These results showed that the key parameter involved in storage hardening seems to be the quantity of short polyisoprene chains and probably the nature of the chain ends.

show abstract

Section: Introductionmentioning

confidence: 99%

Role of short polyisoprene chains in storage hardening of natural rubber

Ngolemasango

Ehabe²,

Aymard

et al. 2003

Polymer International

View full text Add to dashboard Cite

show abstract

“…The general mechanism for oxidative degradation of NR (or polyisoprene) involves the initial presence of alkylperoxyl radicals to induce a chain scission process [28,29] . In this process, side reactions, such as cyclization, epoxidation, rearrangement, and crosslinking, take place [30,31] . Each scission step is accompanied with the loss of carbon atoms from the hydrocarbon chain, to form volatile products and result in weight loss.…”

Section: Data Processingmentioning

confidence: 99%

Thermooxidative degradation and its kinetics of natural rubber coagulated by microwave radiation

Liao¹,

Liao²,

Li³

et al. 2012

Journal of Polymer Engineering

View full text Add to dashboard Cite

The thermooxidative degradation of natural rubber (NR) coagulated by microwave radiation (NR-m) was investigated by thermogravimetry (TG) analysis, and compared with NR coagulated by acid (NR-a). It was found that the degradation process is not a one-step reaction, the main degradation process occurs at 300 -400 ° C, and the equilibrium degradation temperatures of NR-m are higher than those of NR-a. Different methods were used to find the most probable kinetic model and the Arrhenius para meters (activation energy E and preexponential factor A ) for the main stage of thermooxidative degradation of NR-m. The results show that the values of E and A , obtained from the Coats-Redfern method, are highly variable with the kinetic model chosen and the heating rate ( β ), and the apparent activation energy ( E 0 ) when β approaches zero for the D n type kinetic model is in the range of 96.7 -106.4 kJ · mol -1 . The mean values of E , calculated by the Friedman and Flynn-Wall-Ozawa (FWO) methods, are 113.8 and 83.3 kJ · mol -1 , respectively, suggesting E in the range of 83.3 -113.8 kJ · mol -1 . Comparison of these two ranges indicates the most probable kinetic model to be D n type kinetic models, corresponding to a diffusion-controlled mechanism.

show abstract

“…The second mastication mechanism, the so called thermo‐oxidative mastication, is based on an oxidation of the double bonds of the polymer backbone. There are various reactions taking place, leading to a variety of different oxidation products . Most of the previous works describe the thermo‐oxidative mastication of NR as a statistical process, resulting in scission randomly distributed all over the polymer chains .…”

Section: Introductionmentioning

confidence: 99%

Mastication behavior of cis‐1,4‐polyisoprene as a model for natural rubber

Wortmann

Lindner

Dettmer

et al. 2013

J of Applied Polymer Sci

View full text Add to dashboard Cite

The mastication behavior of synthetic cis-1,4-polyisoprene (IR), deproteinized natural rubber (DPNR), and natural rubber (NR) in an internal mixer has been investigated at mixing temperatures from 88 to 186 C and different levels of mechanical energy, using Mooney viscosity and size exclusion chromatography (SEC). An envelope-shaped mastication efficiency curve and high similarity in the mastication behavior can be observed for IR and NR but not for DPNR. The minimum of the envelope-shaped curve shifts to lower temperatures when the mechanical energy is increased. Based on these findings, a mathematical description for the contribution of mechanical and thermo-oxidative mastication mechanisms has been established. Distinct statistical distribution of thermooxidative scission can only be observed in SEC measurements of materials masticated at high temperatures over 170 C.

show abstract

Products of the oxidation of rubber. I. Compounds boiling lower than water

Cited by 23 publications

References 0 publications

Role of short polyisoprene chains in storage hardening of natural rubber

Role of short polyisoprene chains in storage hardening of natural rubber

Thermooxidative degradation and its kinetics of natural rubber coagulated by microwave radiation

Mastication behavior of cis‐1,4‐polyisoprene as a model for natural rubber

Contact Info

Product

Resources

About