Effect of acid concentration and other reaction parameters on epoxidation of natural rubber latex

Abstract

Brosilow, C. B. Nonlinear Inferential Control. AZChE J. 1988,34,633-644. Patwardhan, A. A.; et al. Nonlinear Model Predictive Control. Chem. Eng. Commun. 1990,87, 123-141. Peterson, T.; et al. Nonlinear Predictive Control of a Semi Batch GENERAL RESEARCH Polymerization Reaction by an Extended DMC.Latex stage epoxidation of natural rubber was studied under different reaction temperatures with in situ formed performic acid. Overall kinetics of the reaction and effect of acid concentration were studied. Product distribution and optimum acid concentration were determined from experimental data. It was found that with increasing acid concentrations initially the overall rate constant increased, reached a maximum, and then sharply decreased. The maximum epoxidation level decreased with increased acid concentration.A new group contribution method, GCVOL, for the prediction of liquid densities as a function of the temperature is proposed. A table for 36 different group volume parameters is given. Using the proposed method liquid densities for even strongly polar solvents can be predicted with an error of approximately 1% in the temperature range between the melting temperature and the normal boiling point. Densities of amorphous polymers are predicted with an average error of 2.7%. T h e proposed method is able to describe densities for the complete molecular range, covering solvents, oligomers, and polymers.

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

“…Several types of ENR latex, i.e., 5 and 18–20% ENR were prepared for further investigation of the reaction with periodic acid. In all ENR samples obtained, no observation of signals corresponding to side reactions such as formation of diol and furan, as previously mentioned in the literature was detected in 1 H NMR 15–17…”

Epoxidação "in situ" aplicada ao látex de borracha natural

“…Ainda, podem ocorrer reações de reticulação, associadas à presença de radicais no meio reacional, formados pela decomposição da água oxigenada ou por grupos hidroxila e carboxila presentes, que reagem com outro grupo epóxido resultando em ligações cruzadas. A formação de ligação cruzada conduz a uma estrutura ramificada e pode levar a formação de gel [28][29][30] . Em nossos estudos, poucas amostras apresentaram tal evidência, cuja intensidade das bandas e/ou picos era muito pequena.…”

“…Segundo dados da literatura a reação de epoxidação procede em duas etapas [9,10,28,[30][31][32] onde a primeira etapa caracteriza-se por ser lenta e endotérmica e a segunda etapa, na qual o ácido perfórmico reage com as ligações duplas presentes no meio reacional formando o anel epóxi, caracteriza-se por ser rápida e exotérmica, sendo o …”

Branched EHNBR and its properties with enhanced low-temperature performance and oil resistance

“…[15][16][17] Epoxidation is the common and effective methods to improve the properties of non-polar rubber, [18][19][20][21] but few studies report epoxidation of polar rubber. 22,23 Epoxide natural rubber (NR) has been widely studied 24,25 and realized industrialization. Introducing an epoxy group endows ENR with air permeability and oil resistance.…”