Chlorination of low-molecular-weight Euphorbia lactiflua natural rubber

Gnecco, Sara; Pooley, Amalia; Lefimil, Claudia; Pino, Carolina; Valenzuela, Lissette

doi:10.1007/s002890050192

Cited by 9 publications

(8 citation statements)

References 9 publications

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“…The rubber from E. characias latex has a low molecular weight with a unimodal molecular weight distribution. As other low‐molecular‐weight natural rubbers, unsuitable for high‐performance application, E. characias rubber could be utilized as a feedstock for production of high value specialty polymer derivatives analogous to those produced from natural rubber 18…”

Section: Discussionmentioning

confidence: 99%

“…Low molecular weight rubbers, studied as the good models of natural rubber, are originated from the sunflower ( Helianthus annus ),14 the fig tree ( Ficus elastica and Ficus carica ),15, 16 the painted spurge Euphorbia etherophylla 17 and the shrub Euphorbia lactiflua 18. It is been reported that the low molecular weight fraction of guayule rubber can be modified to yield a low‐viscosity analog of epoxidized natural rubber 19.…”

Section: Introductionmentioning

confidence: 99%

“…The epoxidized polymer enhances the physical properties of cured rubber composition, particularly abrasion and oil resistance properties. Thus, even if low molecular weight rubbers are unsuitable for high performance application, they can be used as a plasticizer or processing aid, or could serve as a feedstock for production of high value specialty polymer derivatives analogous to those produced from natural rubber 18…”

Section: Introductionmentioning

confidence: 99%

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Extraction and characterization of a natural rubber from Euphorbia characias latex

et al. 2012

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A natural rubber was identified and characterized for the first time in the latex of the perennial Mediterranean shrub Euphorbia characias. Four different methods, i.e., acetone, acetic acid, trichloroacetic acid, and Triton® X-100, followed by successive treatments with cyclohexane/ethanol, were employed to extract the natural rubber. The rubber content was shown to be 14% (w/v) of the E. characias latex, a low content compared with that of Hevea brasiliensis (30-35%) but a similar content to other rubber producing plants. E. characias rubber showed a molecular weight of 93,000 with a M(w) /M(n) of 2.9. (1) H NMR, (13) C NMR, and FTIR analysis revealed the characteristic of the cis-1,4-polyisoprene typical of natural rubber. These results provided novel insight into latex components and will ultimately benefit the broader understanding of E. characias latex composition.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Extraction and characterization of a natural rubber from Euphorbia characias latex

et al. 2012

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“…Because the molecular chains of NR are in unfolding states in the solution, the chlorination reaction of NR can proceed more easily, and the structures and properties of the product are more homogenized and unanimous accordingly. [1][2][3] However, the traditional CCl 4 solution process has been prohibited in many countries because it has defects such as high equipment investment, the serious problem of environmental pollution, and harmfulness to the health of workers. This ensures that the production of CNR from latex has vast vistas.…”

Section: Introductionmentioning

confidence: 99%

Effects of stearates on the thermal stability of chlorinated natural rubber from latex

Heping

Zhong

et al. 2005

J of Applied Polymer Sci

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The effects of stearates on the dehydrochlorination (DHC) reaction of chlorinated natural rubber (CNR) from latex were studied by the measurement of the HCl evolving rate during the early stage of the thermal degradation of CNR and by the determination of the amounts of cyclic conjugated dienes formed on the CNR molecular chains. During the early stage of the thermal degradation of CNR at 150°C, HCl was eliminated from the CNR molecular chains, and the cyclic conjugated dienes were formed on the CNR molecular chains. Under the effects of barium stearate, lead stearate, cadmium stearate, and calcium stearate, the HCl evolving rates of CNR were reduced, whereas the amounts of cyclic conjugated dienes that formed on the CNR molecular chains were increased. When zinc stearate was added, because of the formation of ZnCl 2 , which was an active catalyst of the DHC reaction of CNR, both the HCl evolving rate from CNR and the formation of cyclic conjugated dienes were increased. The results indicate that the addition of stearates can reduce the thermal stability of CNR.

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“…This makes the production of CNR from latex an attractive alternative process. Zhong and others2–6 studied the preparation of CNR in aqueous media. There have also been studies of the molecular structure of CNR by IR spectroscopy and NMR 7–12.…”

Section: Introductionmentioning

confidence: 99%

Effect of atmosphere on the thermal decomposition of chlorinated natural rubber from latex

Cheung

Zhong

et al. 2001

J of Applied Polymer Sci

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ABSTRACT:The kinetics of the thermal decompositions of chlorinated natural rubber (CNR) from latex under both air and nitrogen atmospheres were studied with thermogravimetric analysis (TGA). The thermooxidative decomposition of CNR had two weight-loss step changes in the TGA curves, which occurred at the two distinct temperature ranges of about 160-390 and 390-850°C, respectively. The gaseous products of the first step change were mainly HCl with a little CO 2 , and the apparent reaction order (n) was 1.1. The reaction activation energy (E) increased linearly with the increment of heating rate (B), and the apparent activation energy (E 0 ), calculated by extrapolation back to zero B, was 101.7 kJ/mol. Bs ranging from 5 to 30°C/min were used. The initial temperature of weight loss (T 0 ) was 1.31B ϩ 252°C, where B is in degrees Celsius per minute. The final temperature of weight loss (T f ) was 0.93B ϩ 310°C, and the temperature of maximum weight-loss rate (T p ) was 1.03B ϩ 287°C. The decomposition weight-loss percentage at T p (C p ) and that at T f (C f ) were not affected by B, and the average values were 38 and 60%, respectively. The second weight-loss step change was an oxidative decomposition of the molecular main chain. The value of n was 1.1. E increased linearly with the increment of B, and E 0 was 125.0 kJ/mol. C f after the second step approached 100%, which indicated complete decomposition. The thermal decomposition of CNR in a N 2 atmosphere had only one weight-loss step change with an n of 1.1. E increased linearly with the increment of B, and E 0 was 98.6 kJ/mol. T 0 was 1.25B ϩ 251°C, T f was 0.91B ϩ 315°C, and T p was 1.09B ϩ 286°C. C p and C f were not affected by B, and the average values were 37 and 68%, respectively. The weight percentage of more stable, nonthermal decomposed residue was about 30%. The thermal decompositions of CNR in both atmospheres were similar, mainly by dehydrochlorination, at the low temperature range (160-390°C) but were different at the high temperature range (390-850°C).

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Chlorination of low-molecular-weight Euphorbia lactiflua natural rubber

Cited by 9 publications

References 9 publications

Extraction and characterization of a natural rubber from Euphorbia characias latex

Extraction and characterization of a natural rubber from Euphorbia characias latex

Effects of stearates on the thermal stability of chlorinated natural rubber from latex

Effect of atmosphere on the thermal decomposition of chlorinated natural rubber from latex

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