Solubility of Organic Compounds in Rubber

Morris, Tommy C

doi:10.5254/1.3539370

Cited by 3 publications

(6 citation statements)

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“…Although the enzyme treatment and creaming reduced the nitrogen content significantly, it affected the PRI of the rubber adversely. It has been reported that normal skim latex contains more than 15 ppm copper ions on total solids, and an appreciable proportion of these copper ions are retained in the relatively small amount of coagulum obtained from the skim latex 10. It was found that the PRI could be improved by immersion of the coagulum in a 1% oxalic acid solution for 24 h, and the improvement observed for the enzyme‐treated sample may have been due to the extraction of copper ions from the rubber 15.…”

Section: Resultsmentioning

confidence: 99%

“…A possible solution appears to be the removal of the undesirable nonrubber constituents from the skim latex while the rubber is recovered. Morris10 developed a method to recover skim rubber by the addition of a pancreatic enzyme to skim latex before coagulation with sulfuric acid. Recently, another method was developed for recovering the small rubber particles in skim latex; it involves the concentration of skim latex by a membrane‐separation procedure 11.…”

Section: Introductionmentioning

confidence: 99%

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Characterization of enzyme‐deproteinized skim rubber

George

Alex

Joseph

et al. 2009

J of Applied Polymer Sci

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Skim natural rubber latex is a protein-rich byproduct obtained during the centrifugal concentration of natural rubber latex. Skim latex has a very low dry rubber content (4-8%), and the rubber particles are smaller in size. It has a higher proportion of nonrubber solids, which are mostly proteinaceous in nature. It is difficult to coagulate, and it takes more processing time. The proteins in skim latex can be decomposed by proteolytic enzymes. This article discusses the use of stabilized liquid papain from the papaya plant (Carica papaya) for deproteinization followed by creaming for quick and easy coagulation of skim latex. The technological properties and aging characteristics of the deproteinized skim rubber are compared with those of conventionally prepared skim rubber and block rubber. The deproteinized skim rubber showed enhanced quality parameters. Particle size analysis revealed that deproteinization and creaming of the skim latex did not markedly change the particle size. Gel permeation chromatography showed a reduction in the quantity of fatty acids after deproteinization and creaming, which was reflected in the improvement of the aging characteristics in comparison with the control sample. Vulcanizates prepared with the deproteinized skim rubber had higher resilience, lower heat buildup, lower compression set, and good tensile strength and elongation at break in comparison with conventionally prepared skim rubber, and the properties were almost comparable to those of block rubber. The improvement in the mechanical properties and aging characteristics could be attributed to the reduction of the protein content, the partial removal of unsaturated fatty acids, and the removal of metal ions that were pro-oxidants during the deproteinization and creaming process.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Characterization of enzyme‐deproteinized skim rubber

George

Alex

Joseph

et al. 2009

J of Applied Polymer Sci

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“…18 Because 2,5-anhydro-D-mannose, formed at the new reducing end, was unstable, as reported by Tømmeraas et al, 19 a reduction to 2,5-anhydro-Dmannitol was carried out by the use of NaBH 4 . Its molecular weight determined by gel permeation chromatography is shown in Table I (chitosan-L).…”

Section: Depolymerization Of the Chitosanmentioning

confidence: 90%

“…The coagulation of SNR latex can also be performed with proteolytic enzymes, such as trypsin, where the enzymatic deproteinization of SNR latex is achieved. 4 However, this process is not economical because it requires a large quantity of enzyme and necessitates further steps, such as deammoniation and the addition of sodium thiosulfate and formic acid or sodium chloride. To avoid problems due to the use of acid, the biocoagulation of SNR latex has also been studied.…”

Section: Introductionmentioning

confidence: 99%

Creaming of skim natural rubber latex with chitosan derivatives

Kongkaew

Loykulnant

Chaikumpollert

et al. 2009

J of Applied Polymer Sci

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To recover residual rubber from skim natural rubber (SNR) latex, a novel method was developed on the basis of the use of water-soluble chitosan derivatives. An anionic chitosan derivative, N,O-carboxymethyl chitosan (CMCh), and a cationic chitosan derivative, N-(2-hydroxy)propyl-3-trimethylammonium chitosan chloride (HTACh), were prepared. It was found that the creaming process could be achieved with both chitosan derivatives. By the addition of 7.34-10.3-g/L CMCh, SNR latex was almost completely creamed, and no coagulation of SNR particles in the cream phase occurred. In the case of HTACh, the creaming process was achieved with a lower concentration (<3.70 g/L) than in the case of CMCh, but the size of SNR particles in the cream phase was larger. Solid-state 13 C-NMR, thermogravimetric analysis, and f potential measurement results provided evidence that the creaming of SNR latex with CMCh and HTACh was controlled by the depletion flocculation and adsorption mechanisms, respectively.

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“…Thus, after enzymolysis, the proteins attached to rubber particles are removed and the possible remaining stabilizer on the particle surface is fatty acid soaps (Nithi-Uthai, 1998;Morris, 1954). d. Skim NR latex was recovered as concentrated skim latex by using deproteinization and salting-out techniques (DP/S) .…”

Section: Recovery Of Skim Rubber From Skim Latexmentioning

confidence: 99%