Chemical degradation of epoxidized natural rubber using periodic acid: Preparation of epoxidized liquid natural rubber

Abstract

ABSTRACT:Oxidative degradation of epoxidized natural rubber (ENR) was effectively performed in latex phase by using periodic acid at 30°C. The ENR was prepared from the epoxidation of natural rubber in latex phase using performic acid generated in situ by the reaction of hydrogen peroxide and formic acid. The prepared ENR latex was subsequently treated with periodic acid. It was found that the higher the amount of the periodic acid employed the faster the molecular weight of the ENR decreased. Different epoxidation levels of the ENR had no significant effect on the degradation reaction. Based on 1 H NMR analysis, the epoxide content in the epoxidized liquid natural rubber (ELNR) obtained was about the same as that observed in the ENR before degradation. FT-IR analysis showed an increase in carbonyl signal after prolonged reaction time or when higher amounts of periodic acid were employed. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 6 -15, 2005

Degradation of non-vulcanized natural rubber renewable resource for fine chemicals used in polymer synthesis

“…Numerous publications, as for example [21,[25][26][27][28][29][30][31][32][33][34][35][41][42][43][44][45][46][47][48][49][50][51][52][53][54] , are devoted to oxidative methods of degradation natural rubber. The widely used approach is degradation through the epoxidation reaction of isoprene units of the rubber polymer chain.…”

“…It is considered that the oxidative cleavage reaction takes place via the epoxidized isoprene units of the rubber at its consequent treatment, in most cases, by periodic acid. [25] , or in latex form [26] . The main reaction product isolated is oligomeric isoprene terminated by carbonyl groups.…”

“…Its structure is confirmed by 1 H-NMR, Certainly, all the researchers noted that they did not reach a complete epoxidation of the polyisoprene and the resulting products contained isoprene units, epoxidized isoprene units and carbonyl terminal groups [25][26][27][28]42] . However, Phinyocheep et al [26] suggest that the degradation of the epoxidized natural rubber (ENR) by periodic acid does not take place by the cleavage of the epoxy-containing isoprene fragments, but via C=C of the isoprene unit through the formation of the intermediate vis-diols. They compared the molar mass of the degradation products obtained from the ENR with different content of epoxy groups and did not find significant changes.…”

Caracterização físico-mecânica de filmes de borracha natural epoxidada curáveis em temperatura ambiente

“…A borracha natural epoxidada (ENR), com 25% de grupamento epóxido, foi sintetizada em laboratório, a partir do látex de NR estabilizado com surfatante, utilizando perácido orgânico gerado in situ (com ácido fórmico e peróxido de hidrogênio) [17,18] . A reação foi realizada em uma dada temperatura e com o tempo de reação necessário para obtenção do grau de epoxidação desejado.…”

Epoxidized natural rubber toughened aqueous resole type liquefied EFB resin: Physical and chemical characterization

“…Epoxide can make ENR susceptible to various chemical reactions that require hydrogen-donor molecules such as alcohols, amines, and carboxylic acids [9]. Miscibility is attributed to molecular interaction, such as donor-acceptor type of weakly acidic hydrogen , or dipole-dipole interaction [10].…”